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Papers and Proceedings of
The Royal Society 0f Tasmania
Edited by Dr Sally Bryant and published by the Society
Volume 154 December 2020
The Royal Society of Tasmania acknowledges, with deep respect, the traditional owners of this land, and the ongoing custodianship of the Aboriginal people of Tasmania. The Society pays respect to Elders past, present and emerging.
We acknowledge that Tasmanian Aboriginal peoples have survived severe and unjust impacts resulting from invasion and dispossession of their Country.
Asan institution dedicated to the advancement of knowledge, the Royal Society of Tasmania recognises Aboriginal cultural knowledge and practices and seeks to respect and honour these traditions and the deep understanding they represent.
Published by
The Royal Society of Tasmania GPO Box 1166
Hobart, Tasmania, Australia 7000
www.rst.org.au
9 December 2020
ISSN 0080-4703
Cover photograph: View from Tasman Island to “The Blade’, Tasman Peninsula: S Bryant.
Proofing by Ms Caroline Mordaunt Typesetting by Ms June Pongratz
Print Tasmania
PAPERS AND PROCEEDINGS OF THE ROYAL SOCIETY OF TASMANIA VOLUME 154
Contents
Kantvilas, G., Coppins, B.J., McCarthy, P.M. & Elix, J.A. New records of lichens from Tasmania, principally
from the 2018 TMAG Expedition of Discovery to Musselroe Bay ........eeeeeeeeeeeseeeeeceeececeeeeeeseeeasenes
Griffin, A.R., Hingston, A.B., Harwood, C.E., Harbard, J.L., Brown, M.J., Ellingsen, K.M. & Young, C.M. Potential pollen vectors of the mass flowering tree Acacia dealbata, within its natural range in southern Tasmania
Ridley, C. The tourist and tourism gazes upon Cradle Mountain and Freycinet National Park ............cceceeee000+
Robinson, S. & Dick, W. Black Rats eradicated from Big Green Island in Bass Strait, Tasmania ................0000-
Robinson, S. & Gadd, L. Unviable feral cat population results in eradication success on Wedge Island, Tasmania
Wapstra, M., Baker, M.L. & Daniels, G.D. Collecting history and distribution of the potentially invasive Disa bracteata (South African orchid) in Tasmania
Turner, P.A.M., Wapstra, M., Woolley, A., Hopkins, K., Koch, A.J. & Duncan, F. Long-term monitoring of the
threatened lesser guineaflower Hibbertia calycina (DC.) N.A.Wakef. (Dilleniaceae) in Tasmania ...............
Bryant, S.L. & Harris, S. Overview of Tasmania’s offshore islands and their role in nature conservation ............
SA /
AW UNIVERSITY of Tasmania TASMANIA
Explove the possibilities
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page
Publication of this volume was generously supported by the Government of Tasmania and the University of Tasmania.
iv
THE ROYAL SOCIETY OF TASMANIA
Council and Office Bearers from March 2020 to March 2021
Patron Her Excellency Professor the Honourable Kate Warner AC, Governor of Tasmania
President Mrs Mary Koolhof
Vice President Prof. Jocelyn McPhie
Immediate Past President Prof. Ross Large AO
Honorary Secretary Mrs Marley Large
Honorary Treasurer Mr David Wilson
Councillors Prof. Ross Large AO Dr Robert Johnson Dr Greg Lehman Dr Angela Ryan Dr John Thorne AM Dr Adele Wilson Ms Niamh Chapman Ms Shasta Henry Mr Peter Manchester Mrs Roxanne Steenbergen
Honorary Editor Dr Sally Bryant
Honorary Librarian Ms Juliet Beale
Honorary Solicitor Mr James Crotty
Honorary Membership Officer Mrs Roxanne Steenbergen
Representative of the Tasmanian Museum and Art Gallery Ms Janet Carding
Representatives of the Northern Branch Dr Frank Madill Mr David Morris Mr Robin Walpole
Papers and Proceedings of the Royal Society of Tasmania, Volume 154, 2020 1
NEW RECORDS OF LICHENS FROM TASMANIA, PRINCIPALLY FROM THE 2018 TMAG EXPEDITION OF DISCOVERY TO MUSSELROE BAY
by Gintaras Kantvilas, Brian J. Coppins, .Patrick M. McCarthy and John A. Elix
(with two plates)
Kantvilas, G., Coppins, B.J., McCarthy, P.M. & Elix, J.A. 2020 (9:xii). New records of lichens from Tasmania, principally from the 2018 TMAG Expedition of Discovery to Musselroe Bay. Papers and Proceedings of the Royal Society of Tasmania 154: 1-8. Tasmanian Herbarium, Tasmanian Museum and Art Gallery, Box 5058, UTAS LPO, Sandy Bay, Tasmania 7005, Australia (GK). Royal Botanic Garden Edinburgh, 20A Inverleith Row, Edinburgh, EH3 5LR, United Kingdom (BJC). 64 Broadsmith St, Scullin, A.C.T. 2614,
Australia (PMMcC). Research School of Chemistry, Building 137, Australian National University, Canberra, A.C.T. 2601, Australia (JAE). Author for correspondence: Email: Gintaras.Kantvilas @tmag.tas.gov.au
Nineteen lichen species are recorded for the first time from Tasmania: Amandinea conranensis Elix & P.M.McCarthy, Bacidia laurocerasi (Delise ex Duby) Zahlbr., Buellia extenuatella Elix & Kantvilas, Catinaria atropurpurea (Schaer.) Vézda & Poelt, Collema crispum (Huds.) - Weber ex KH. Wigg., Diploschistes euganeus (A.Massal.) J.Steiner, D. gyrophoricus Lumbsch & Elix, Endocarpon crassisporum P.M.McCarthy & Filson, Gyalecta pellucida (Coppins & Malcolm) Baloch & Liicking, Lecanora pseudogangaleoides Lumbsch subsp. pseudogangaleoides, L. strobilina (Spreng.) Kieff., Opegrapha niveoatra (Borrer) J.R.Laundon, O. spodopolia Nyl., O. varia Pers., Physcia austrostellaris Elix, Ramonia absconsa (Tuck.) Vézda, Trapelia concentrica Elix & PM.McCarthy and Xanthoparmelia xerica (Elix) Elix. The new combination Austroparmelina corrugativa (Kurok. & Filson) Elix 8 Kantvilas is proposed and Austroparmelina euplectina (Kurok. ex Elix). A.Crespo
et al. is reduced to synonymy. The salient morphological and anatomical features, ecology and distribution are discussed for each species. Key Words: lichenised fungi, taxonomy, floristics, Austroparmelina.
INTRODUCTION
Since the first checklists of Tasmanian lichens, for example those of Wetmore (1963), which listed 421 taxa, Kantvilas (1989: 633 taxa) and Kantvilas (1994: 762 taxa), the number of lichens recorded for Tasmania has risen steadily and now stands at 1309 (McCarthy 2020). The increases have been derived from taxonomic revision of existing herbarium collections, fortuitous and ad occollecting, as well as target- ed studies of particular locations (e.g. Jarman & Kantvilas 1994, Kantvilas et al, 2012), vegetation types (Jarman & Kantvilas 1995, Kantvilas & Jarman 2012) and taxonomic groups (e.g. Kantvilas 2012, Kantvilas & Coppins 2019). More recently, a formal survey program, the Tasmanian Museum and Art Gallery Expeditions of Discovery, has been initiated with the express aim of, inter alia, discovering new or hitherto overlooked species in Tasmania. The first of these expeditions, undertaken in ‘2017 in the Little Swanport area on Tasmania’s east coast (Baker et al. 2019),
proved exceptionally productive for lichens. Of the 170 °
species recorded, two were described as new to science (Elix et al. 2019a, McCarthy & Kantvilas 2018) and a further 19 were new records for Tasmania (Elix et al, 2019b, Baker et al. 2019); additional putative new taxa await further study. The second expedition was undertaken in late 2018 to the Cape Portland—Musselroe Bay area in the far northeast of Tasmania. Lichens again proved to bea rich source of novelties and, whereas an inventory of species will be presented elsewhere, new records for Tasmania are documented here. As with previous accounts of this nature, some of the discoveries arose entirely from fieldwork conducted during the expedition. In other cases, the expedition identification
work prompted a broader investigation of herbarium collections, and the novelties in question were found to be represented by additional specimens from other Tasmanian localities. It is particularly noteworthy that two of the new records are of species previously known only from their respective type collections: Ramonia absconsa (from South Carolina, U.S.A.) and Xanthoparmelia xerica (from South Australia).
MATERIAL AND METHODS
The study is based chiefly on material collected by the first author during the TMAG Expedition of Discovery at Musselroe Bay, northeastern Tasmania, during November 2018, anda second, follow-up field trip in September 2019. Specimens are housed in the Tasmanian Herbarium (HO), with selected duplicates sent to other herbaria as indicated in the text. Additional reference herbarium material, chiefly from HO, was: also consulted. Anatomical and morphological observations were undertaken using light microscopy, with thin hand-cut sections mounted in water, 10% KOH (Kk), lactophenol cotton blue, Lugol’s iodine after pre-treatment with dilute KOH, 50% HNO, (N) and ammoniacal erythrosin. Routine chemical analyses using thin-layer chromatography follow standard methods (Elix 2014). Nomenclature oflichen asci mainly follows Hafellner (1984). Ascospore measurements are presented either in the format: 5th percentile-average-95th percentile, with outlying values given in brackets and 7 being the number of measurements, or as a simple range.
2 Gintaras Kantvilas, Brian J. Coppins, Patrick M. McCarthy and John A. Elix
THE SPECIES Amandinea conranensis Elix & P.M.McCarthy
Characterised by a crustose thallus not containing any substances detectable by thin-layer chromatography, black apothecia 0.1-0.3 mm wide, 1-septate, Buellia-type ascospores, 9-14 x 5—8 um, constricted at the septum when older, and filiform conidia, 12-21 x 0.7-1 jum (see Elix et al. 2017). It is most similar to the common A. punctata (Hoffm.) Coppins & Scheid., which has larger ascospores (10-20 x 5-9 um) that do not become constricted. The Tasmanian specimen was collected from a fencepost in a paddock. The species also occurs in Victoriaand New South Wales where it is an epiphyte in coastal situations.
TASMANIA: Cape Portland, Musselroe Wind Farm, Tregaron Lagoons, vicinity of Turbine D8, 40°47'38"S 148°05'24"E, 30 m alt., 10 Sep. 2019, G. Kantvilas 256/19 (HO).
Austroparmelina corrugativa (Kurok. & Filson) Elix & Kantvilas comb. nov. MycoBank No. MB834192
Parmelia corrugativa Kurok. & Filson, Bull. Natl Sci. Mus. ser. B, 1: 38 (1975); Pseudoparmelia corrugativa (Kurok. & Filson) Hale, Smithsonian Contr. Bot. 31: 25 (1976); Canoparmelia corrugativa (Kurok. & Filson) Elix & Hale, Mycotaxon 27: 278 (1986). Type: South Australia: near Balhannah, 3 June 1966, R.W. Rogers 553 (holo— MEL!).
Parmelina euplectina Kurok. ex Elix, Mycotaxon 47: 116 (1993); Austroparmelina euplectina (Kurok. ex Elix). A.Crespo, Divakar & Elix, in Crespo et al., Syst. e Biodiv. 8: 216 (2010). Type: New South Wales: Raymond Terrace to Bulahdelah Road, N of Karuah, 9 May 1965, R.B. Filson 7176 (holo— MEL!)
With its grey foliose thallus of rather rounded, imbricate lobes containing lecanoric acid (medulla C+ red), black underside with an extensive, pale brown marginal zone, and lack of isidia or soredia, this species closely resembles the common and widespread A. pseudorelicina (Jatta) A.Crespo et al. It differs by containing the orange pigment euplectin (K+ violet), visible as a thin, orange layer in the lower part of the medulla. In Tasmania, this species occurs as an epiphyte in dry sclerophyll woodland and scrub in the northeast of the State where it is usually sympatric with A. pseudorelicina. It has a similar ecological distribution in southeastern Australia.
TASMANIA: Glen Esk Road near Middle Run Hill, 41°48'S 147°27'E, 220 m alt., 24 Aug. 2001, G. Kanwvilas 754/01 (HO); Sawpit Hill Road, c. 1 km SE of Diabobble Hill, 41°31'S 147°23'E, 420 m alt., 5 Sep. 2001, G. Kantvilas 815/01 (HO); Tomahawk River, 40°52'S 147°45'E, sea-level, 1 June 2003, G. Kantvilas 108/03
(HO); Cape Portland, Musselroe Wind Farm, Tregaron Lagoons, “Copperhead Road”, 40°46'49"S 147°58'00"E, 2 m alt., 9 Nov. 2018, G. Kantvilas 326/18, 328/18 (HO).
Bacidia laurocerasi (Delise ex Duby) Zahlbr.
This name has been variously applied in herbaria to specimens from Australia and elsewhere, often incorrectly. Based on the comprehensive account by Ekman (1996) and comparison with reliably identified reference specimens, it
_ is characterised as follows:
Thallus crustose, pale brownish grey to greenish grey. Apothecia biatorine, 0.3—0.8 mm diam.; disc reddish brown to dark brown ox blackish, sometimes a little piebald, matt, epruinose, plane at first, later becoming convex; proper exciple concolorous with the disc ora little paler at the upper edge, usually pale reddish brown at the sides, persistent or becoming reduced and inapparent in the oldest, most convex apothecia, in section 60-90 pm thick, colourless within, at the edges reddish brown to purplish brown, K+ purplish brown, N+ orange-brown, lacking crystalline inclusions. Hypothecium 50-100 pm thick, colourless to pale yellowish, intensifying yellowish in K. Hymenium 65-85 pm thick, not inspersed, colourless, with a brown to purplish brown epihymenial layer, K+ purple-brown intensifying, N+ orange-brown. Ascospores acicular, tapered towards the distal end, side-by-side or loosely coiled in the ascus, (40—)42—56.6-70(-72) x 3-3.5-4(-4.5) um (7 = 40), with 12-17 septa distinct in water. Chemistry: no substances detected (plate 1A).
Critically, this species lacks any greenish, N+ crimson-red pigments, a feature that separates it from the otherwise similar B. wellingtonii (Stirt.) D.J.Galloway. In Tasmania, B. laurocerasi appears to be associated with lowland, often swampy Melaleuca ericifolia-dominated vegetation. In Australia, it has been recorded with certainty from Kangaroo Island (Kantvilas 2019), but ‘other records
remain unconfirmed.
TASMANIA: Moores Hill near Beaconsfield, 41°14'S 146°52'E, 80 m alt., 27 Apr. 1981, G. Kantvilas 256/81A (HO); Tatlows Beach Coastal Reserve, 40°47'S 145°17'E, 1 malt., 15 May 2019, G. Kantvilas 154/19 (HO); Cape Portland, Musselroe Wind Farm, between Petal Point Road and Tregaron Lagoons, 40°47'S 147°58'E, 10 m alt., 9 Nov. 2018, G. Kantvilas 343/18 (HO).
Buellia extenuatella Elix & Kantvilas
This species is superficially similar to Amandinaea conranensis and A. punctata in having a highly reduced thallus and black apothecia, but is distinguished by the combination of a scurfy, membranaceous or sorediate upper surface, Buellia-type ascospores, 11-19 x 5-8 um, and bacilliform conidia, (3—-)4—6 x 0.5-1 um. The Tasmanian specimen was epiphytic in Allocasuarina-dominated woodland, a habitat consistent with its occurrence on the southern Australian mainland (Elix & Kantvilas 2013).
New records of lichens from Tasmania 3
dark squamulose thallus with small, dark coloured apothecia. (C) Diploschistes gyrophoricus, with perithecioid ascomata. (D) Lecanora pseudogangaleoides subsp. pseudogangaleoides. Scales = 1 mm.
TASMANIA: Cape Portland, Musselroe Wind Farm: “Cadaver Ridge”, 40°48'28"S 148°04'05"E, 65 malt. 11 Sep. 2019, G. Kantvilas 225/19 (HO).
Catinaria atropurpurea (Schaer.) Vézda & Poelt
Characterised by a thin, undelimited crustose thallus, the typically reddish brown to blackish brown, biatorine apothecia, 0.2-0.8 mm wide, the 8-spored, Cuatillaria-type asci where the well-developed tholus is uniformly amyloid and lacks internal differentiation, the slender, paraphyses with reddish brown, swollen apices, and the hyaline, ellipsoid, 1-septate ascospores, 10-17 x 5—7.5 pm, with a gelatinous perispore c. 1 pm thick. Ascus structure distinguishes this species readily from several superficially similar genera, especially Megalaria, which also has 1-septate ascospores. Catinaria atropurpurea is widespread in temperate regions throughout the world. In Tasmania, it occurs on the bark of various trees and shrubs, mainly in coastal vegetation, but has rarely also been recorded inland in wet forest.
TASMANIA: Flinders Island, Yellow Beaches, 40°13'S 148°15'E, 2 m alt., 8 Aug. 1978, J.S. Whinray 1231 Pp: (HO); Cape Deslacs, 42°59'S 147°33'E, 1 Jun. 1980, G. Kantvilas 231/80 (BM, HO); Swan Basin, 42°12'S 145°1G'E, sea-level, 21 Jan. 2000, G. Kantvilas 33/00 (HO); southern slope of South Sister, 41°32'S 148°10'E, 640 m alt., 10 Nov. 2004, G. Kantvilas 377/04A (HO); Florentine Bridge, 42°30'S 146°27'E, 360 m alt., 2 Nov. 2005, G. Kantvilas 315/05 (HO); Little Musselroe River estuary, 40°46'S 148°03'E, 5 m alt., 6 Nov. 2018, G. Kantvilas 181/18 (HO); St Helens Point, 10 m alt., 2020, G. Kantvilas 99/20 (HO).
Collema crispum (Huds.) Weber ex F.H.Wigg.
Characterised by a thallus of minute, squamiform lobes and lobules mostly up to c. 0.2 mm wide, and conspicuous apothecia to 1 mm wide, with a red-brown to black- brown, plane disc, a proper exciple of elongate (rather than paraplectenchymatous) hyphae, and 3-septate ascospores, 22-34 x 10-16 um, occasionally with an additional longitudinal or oblique septum (plate 1B). In Tasmania, this species has been recorded on man-made substrata
4 Gintaras Kantvilas, Brian J. Coppins, Patrick M. McCarthy and John A. Elix
(for example, the mortar of a ruined building) as well as on calcarenite in coastal heathland, and it has a similar distribution and ecology in other parts of the world (Gilbert et al. 2009). In his monumental work, Degelius (1974) did not formally record C. crispum from Tasmania, although he noted the existence of sterile specimens which might be this species. One such annotated specimen (G.C. Bratt 70/568, HO) was located but is considered here to be Collema
subflaccidum Degel.
TASMANIA: Flinders Island, Trousers Point, 40°13'S.
148°02’E, 10 m alt., 23 Mar. 2014, G. Kantvilas 368/14 (BG, HO); Cape Portland, Musselroe Wind Farm, The Ruins, N end of Home Beach, 40°45'12"S 147°57'28"E, 10 m alt., 8 Nov. 2018, G. Kantvilas 299/18, 302/18 (HBG, HO).
Diploschistes euganeus (A.Massal.) J.Steiner
Diploschistes euganeus is one ina complex of morphologically similar species which grows on non-calcareous rocks and has perithecioid ascomata (Mangold er al. 2009). ‘It is characterised best by lacking lichen substances, a feature that distinguishes it from D. gyrophoricus and D. sticticus (K6rb) Mill-Arg. (with gyrophoricacid) and from D. aeneus (Miill.Arg.) Lumbsch and D. actinostomus (Pers.) Zahlbr. (both with lecanoric acid). This widespread species has a scattered Tasmanian distribution on exposed rocks in low rainfall areas and displays a similar ecology in other parts of temperate Australia.
TASMANIA: Glen Morey Saltpan, near Tunbridge, 42°09'S 147°29'E, 180 m alt., 8 Noy. 1984, A. Moscal 8802 (HO); Cape Portland, 40°45'S 147°57'E, 5 m alt., 8 Nov. 2018, G. Kantvilas 282/18 (HO).
Diploschistes gyrophoricus Lumbsch & Elix
Like the preceding species, D. gyrophoricus is one of a group of morphologically similar species with perithecioid ascomata (plate 1C). It is characterised by the presence of gyrophoric acid and is distinguished from the chemically identical D. sticticus by subtle differences in the size and shape of its muriform ascospores. In D. gyrophoricus, these are (18—)20-—23.3-27(-30) x (11-)13.5-15.5-18(-20) um, broadly ovate-ellipsoid with broadly rounded apices, and with a length/width ratio of 1.3-/.5-1.8 (Tasmanian specimens, 7 = 55). In contrast, the ascospores of D. sticticus are ellipsoid and relatively longer and narrower: (22-)24- 34. 9-40 (—42) x (11-) 12-17. 1-20(-21) pm, witha length / width ratio of 1.7—2.0-2.4 (Tasmanian specimens, n = 28). Diploschistes gyrophoricus is widespread in Tasmania on exposed rocks in rough pasture and dry sclerophyll woodland. Itis also known from southeastern mainland Australia, New Zealand and South America.
TASMANIA: Hunting Grounds, Dysart, 42°34'S 147°10'E, 400 m alt., 7 Aug. 1981, G. Kantvilas 473/81 & P.W. James (HO); Spiky Bridge, 42°11'S 148°04'E, 0
m alt., 2 Feb. 1984, G. Kantvilas 166/84 & P.W. James (HO); c. 1 km NW of Tinderbox, 43°03'S 147°19'E, 160 m alt., 23 Jul. 2015, G. Kantvilas 253/15 (HO); “Wind Song’ Property, Ronnies Spur, 42°21'14"S 147°55'01"E, 30 m alt., 25 Oct. 2017, G. Kantvilas 238/17 (HO); Cape Portland, Musselroe Wind Farm, woodland W of Xanthorrhoea Ridge, 40°47'53"S 148°01'08"E, 70 m alt., 6 Nov. 2018, G. Kantvilas 365/18 (HO).
Endocarpon crassisporum P.M.McCarthy & Filson
With its grey-brown to reddish brown squamae, c. 2-10 mm wide, this species is superficially similar to E. simplicatum (Nyl.) Nyl., the most common species of Endocarpon in Tasmania. It is characterised by its consistently 1-spored asci and large, brown, muriform ascospores, 80-130 x (30-) 40-60 pm (see McCarthy 2001). It was found on consolidated, dolerite-derived soil in a very degraded coastal tussock grassland with extensive patches of bare soil and pebbles, a habitat consistent with its ecology on the
Australian mainland.
TASMANIA: Cape Portland, N of Semaphore Hill, 40°45'S 147°57'E; 10 m alt., 8 Nov. 2018, G. Kantvilas
252/18 (HO).
Gyalecta pellucida (Coppins & Malcolm) Baloch & Licking
This taxon was initially described in the genus Belonia by Coppins and Malcolm (1998) on account of its crustose thallus with a Trentepohlia photobiont, its pale pink, perithecioid apothecia, 0.2-0.3 mm wide, that have a proper exciple of rounded cells, thin-walled asci with a non-amyloid tholus but a thin, faintly amyloid wall, and acicular ascospores, 60-80 x 2.2-3(—4) um, with ¢. 35-45 transverse septa. The genus Gyalecta in the traditional sense differs chiefly by having apothecioid ascomata witha plane to strongly concave or urceolate disc, and ellipsoid to fusiform, transeptate or muriform ascospores. The close relationship between these two genera was established by DNA-sequence data (Baloch et al. 2010). Gyalecta pellucida is an extremely inconspicuous species, very rare in Tasmania where it has been recorded from blackwood (Acacia melanoxylon)- or paper-bark (Melaleuca ericifolia)-dominated coastal swamps; it is also known from New Zealand.
TASMANIA: Stanley Peninsula, c. 30 m E of Wells Road, 40°45'S 145°17'E, c. 50 m alt., 28 Feb. 1998, A. Gray s.n. (HO); Cape Portland, Musselroe Wind Farm, northern end of Musselroe Bay, 40°48'36"S 148°06'41"E, sea-level, 11 Sep. 2019, G. Kantvilas 239/19 (HO).
Lecanora pseudogangaleoides Lumbsch subsp. pseudogangaleoides
Characterised by a prominent, continuous, yellowish grey to greenish grey thallus containing atranorin, usnic acid and
psoromic acid, and apothecia 0.5—1.3 mm wide, with a red- brown to black-brown disc and with large crystals, insoluble in KOH, in the margin; see Lumbsch and Elix (2004) fora complete description (plate 1D). The presence of psoromic acid, which distinguishes it from the very similar L. wilsonii Miill-Arg., can usually be detected by the P+ yellow reaction of the thallus. In Tasmania, this lichen is known only from outcrops of granite or quartzite in coastal heathland and dry sclerophyll woodland. It is also recorded from southeastern mainland Australia.
TASMANIA: The Gnomon, 41°11'S 146°02'E, 475 m alt., 25 May 1991, G. Kantvilas 236/91 (HO); unnamed hill c. 1 km NE of Coles Bay township, 42°07'S 148°17'E, 100 m alt., 23 Apr. 2007, G. Kantvilas 170/07 (HO); Cape Portland, Musselroe Wind Farm, “The Prairie”, in the vicinity of Turbine D14, 40°48'35"S 148°06'23"E, 20 m alt., 11 Sep. 2019, G. Kantvilas 248/19, 251/19 ‘(CANB, HO).
New records of lichens from Tasmania 5
Lecanora strobilina (Spreng.) Kieff.
Lecanora strobilina is a member of the L. symmicta group, and the latter name has been broadly applied in Australia to specimens that contain atranorin and zeorin and have yellowish to brownish biatorine apothecia. As noted in
several studies of Australian specimens (e.g. Lumbsch &
Elix 2004, Kantvilas & LaGreca 2008, Pérez-Ortega &
Kantvilas 2018), the group is complex and individual taxa
can be difficult to distinguish. Even so, several species of the L. symmicta group are recognised in Tasmania, namely L. helmutii Pérez-Ortega & Kantvilas, L. subtecta (Stirt.) Kantvilas & LaGreca and L. coppinsiarum Kanwvilas, as well as L. symmicta (Ach.) Ach. itself: Similar problems of species delimitation occur in the Northern Hemisphere (LaGreca & Lumbsch 2013), where L. strobilina is distinguished essentially by having apothecia with a persistent, crenulate thalline margin (plate 2A).
The Lecanora symmicta group was well-represented in the Musselroe Bay survey and included: L. subtecta, distinguished by having bright yellow, often pruinose, biatorine apothecia; L. symmicta, with pale yellow,
PLATE 2 — (A) Lecanora strobilina; note the apothecia with a persistent, crenulate, thalline margin. (B) Opegrapha spodopolia, with irregular, lirelliform apothecia with a central slit. (C) Physcia austrostellaris. (D) Ramonia absconsa, with tiny, semi-immersed apothecia with a central apical pore. Scales = 1 mm.
6 — Gintaras Kantvilas, Brian J. Coppins, Patrick M. McCarthy and John A. Elix
epruinose, biatorine apothecia; and a third entity with persistently lecanorine apothecia with a prominent crenulate margin. The name L. strobilina is applied to this last taxon, pending a more detailed review of the entire group. This lichen was observed frequently on bleached, split-eucalypt fenceposts and droppers in paddocks, as well as in patches of native vegetation where it grew on dead, standing wood.
TASMANIA: Cape Portland, Musselroe Wind Farm: vicinity of Turbine D8, 40°47'38"S 148°05'24"E, 30 m alt., 10 Sep. 2019, G. Kantvilas 252/19 (HO, MA); northern end of Musselroe Bay, 40°48'36"S 148°06'41"E, sea-level, 11 Sep. 2019, G. Kantvilas 232/19 (HO, MA); “Cadaver Ridge”, 40°48'28"S 148°04'05"E, 65 m alt., 11 Sep. 2019, G. Kantvilas 224/19 (HO).
Opegrapha niveoatra (Borrer) J.R.Laundon
Characterised by simple, straight or curved lirellae, 0.4-1 mm long, with a black, K+ olive exciple (in section), and (3—-)7-septate, acicular ascospores, 22—40 x 3.5—4 pm, with all cells + equal in size (Pentecost & James 2009, Kantvilas 2019). In Tasmania, this + cosmopolitan species has been collected mainly on Melaleuca ericifolia and appears to have a widely scattered distribution in the State.
TASMANIA: Passage Island, Bass Strait, 40°31'S 148°19'E, 11 m alt., 11 Oct. 1979, J.S. Whinray 1331 (MEL); Moores Hill, near Beaconsfield, 41°14'S 146°52'E, 80 m alt., 27 Apr. 1981, G. Kantvilas 253/81 (HO); Westwood Road, 41°29'S 146°59'E, 150 m alt., 21 Sep 2005, A.M. Buchanan 16307b (HO); Cape Portland, Musselroe Wind Farm, Tregaron Lagoons, “Copperhead Road”, 40°46'46"S 147°57'58"E, 2 m alt., 9 Nov. 2018, G. Kantvilas 324/18 (HO).
Opegrapha spodopolia Nyl.
This species is characterised by the following salient characters: thallus pale grey, cream-grey or fawn brown, occasionally somewhat scurfy; ascomata lirelliform, black, mostly 0.3—0.6 mm long and up to 0.4(-0.6) wide, mostly elongate but sometimes approximately as long as wide; exciple usually highly convoluted, contorted and sulcate, closed or gaping at the apex, invariably open at the base, in section K+ olive-greenish; hymenium inspersed with oil droplets, with a brown, K+ pale olive epihymenial layer; ascospores (4—)5—6(-7)-septate, 20-26(-30) x 4-6 um, with a gelatinous perispore that swells in KOH and becomes roughened with age; conidia rod-shaped, 4-6 x 0.5-1 pm (plate 2B). Originally described from New Zealand, this species was recently recorded from Kangaroo Island, South Australia (Kantvilas 2019). It is widespread along the coastlines.of Tasmania, occurring on a wide variety of rock types including dolerite, quartzite, granite, serpentiniteand mudstone. It grows in the rocky littoral zone in shaded sheltered overhangs. The genus Opegrapha is still poorly known in Tasmania. Many herbarium collections of saxicolous and corticolous species are yet to be identified,
not least from coastal rocks. Features that best distinguish O. spodopolia are the basally open exciple and the dimensions and septation of the ascospores.
TASMANIA: Sleepy Bay, 42°08'S 148°19'E, sea-level, 2 Feb. 1984, G. Kantvilas 143/84 & P. James (BM, HO); Hibbs Pyramid, 42°36'S 145°16'E, 4 Feb. 1984, A. Moscal 6128c (HO); Doctors Rocks, 41°01'S 145°47'E, sea-level, 19 Feb. 1984, G. Kantvilas 391/84 & P. James (BM, H, HO); Lousy Gully, Curio Bay, 43°11'S 147°43'E, sea- level, 4 Feb. 2001, G. Kantvilas 154/01 (HO); Maingon Blowhole, 43°12'S 147°51'E, 40 m alt., 14 Oct. 2006, G. Kantvilas 359/06 (HO); Lion Rock, 43°36'S 146°49'E, sea-level, 27 Dec. 2007, G. Kantvilas 435/07 (HO); Mars Bluff, Bruny Island, 43°15'S 147°24'E, 5 m alt., 15 Mar. 2008, G. Kantvilas 40/08; Lion Rock, 43°36'S 146°49'E, 1 malt., 21 Apr. 2013, G. Kantvilas 34/13 (HO); mouth of Interview River, 41°35'S 144°53'E, 3 m alt., 31 Jan 2015, G. Kantvilas 142/15 (HO); Goat Island, 41°08'S 146°08'E, 5 m alt., 24 Oct. 2016, G. Kantvilas 388/16 (HO); Cape Portland, Musselroe Wind Farm, shoreline near the Stone House, 40°45'S 148°01'E, 2 m alt., 9 Noy. 2018, G. Kantvilas 151/18 (HO); Cape Portland, 40°44'40"S 147°56'29"E, 2 m alt., 8 Nov. 2018, G. Kantvilas 261/18 (HO); northern end of Godfreys Beach, Stanley, 40°45'S 145°18'E, 1 m alt., 13 May 2019, G. Kantvilas 170/19 (HO).
Opegrapha varia Pers.
Characterised by relatively short lirellae with a K+ brown exciple, and the fusiform, 4—G-septate ascospores, 1 8-38 x 6-8 pm, in which the central cell is noticeably enlarged. In Tasmania, this species has a scattered, coastal distribution and grows on wood or bark. It has been widely recorded throughout the world, including from mainland Australia. A detailed description is offered by Pentecost and James
(2009).
TASMANIA: Flinders Island, Cave Beach, 40°01'S 147°53'E, 5 m alt., 23 Jan. 2006, G. Kantvilas 84/06 (HO); Bonnet Island, Macquarie Harbour, 42°13'S 145°13'E, 1 m alt., 14 May 2013, G. Kantvilas 144/13 (HO); Flinders Island, The Dock, 39°48'S 147°52'E, 10 m alt., 21 Mar. 2014, G. Kantvilas 298/14 (HO); Cape Portland, Musselroe Bay Conservation Area, Abalone Rocks, 40°47'26"S 148°06'08"E, 3 m alt., 7 Nov. 2018, G. Kantvilas 388/18 (HO)
Physcia austrostellaris Elix
Characterised by an essentially orbicular thallus, with radiating, + rounded, esorediate lobes to c. 2 mm wide at the margins, a pale brown to ivory under-surface, apothecia to 2.5 mm wide, with a brown-black disc that is often thickly greyish pruinose, and by the presence of the triterpene, 20a-acetoxyhopane-6a,22-diol, in addition to atranorin (plate 2C). Although found occasionally in dry sclerophyll vegetation, where it occurs on the bark of understorey trees
such as Allocasuarina, or on wood or rocks, this species is most commonly seen on exotic trees in parks and along roadsides. The Musselroe Bay specimen was collected from dolerite boulders in an Allocasuarina verticillata-dominated woodland. In earlier literature pertaining to Australian lichens, this species was referred to as P stellaris (L.) Nyl., a name now applied strictly to a superficially similar Northern Hemisphere species that differs by having narrower lobes, often with secondary lobules in the centre of the thallus, numerous, simple or branched, whitish to dark brown or grey rhizines that often protrude beyond the lobe margins and lacks any triterpenes additional to atranorin (Elix er al. 2009).
TASMANIA: Poatina, 41°48'S 146°58'E, 900 m alt., Jan. 1964, G.C. Bratt 1315 (HO); Lake Tooms Road, 42°03'S 147°30'E, 19 Dec. 1974, G.C. Bratt 74/1245 & M. Gilbert (HO); Reeves Creek, Picnic Rocks, 40°59'S 148°19'E, 20 ‘m alt., 13 Sep. 1983, A. Moscal 2668 (HO); Red Rocks, 41°00'S 148°19'E, 20 malt., 19 Oct. 1983, A. Moscal 3646 (HO); Campbell Town, 41°56'S 147°29'E, 14 Feb. 1984, G. Kantvilas 454/84 & P. James (BM, HO); Don Heads, 41°10'S 146°20'E, 3 m alt., 27 May 1990, G. Kantvilas 282/90 (HO); 2 km W of New Norfolk, Glenora Road, 42°47'S 147°02'E, 90 m alt., 19 Feb. 1997, G. Kantvilas 72/97 (HO); St Helens, 41°19'S 148°14'E, 10 m alt., 20 Feb. 2001, G. Kantvilas 270/01 (HO); Evandale, edge of Rodgers Lane, 41°34'S 147°15'E, 160 m alt., 21 Mar. 2001, J. Jarman s.2. (HO); Glen Esk Road near Middle Run Hill, 41°48'S 147°27'E, 220 m alt., 24 Aug. 2001, G. Kantvilas 755/01 (HO); Windmill Hill, Launceston, 41°26'S 147°09'E, 18 Jul. 2001, J. Jarman s.7. (HO); Auburn Road, 42°00'S 147°19'E, 230 m alt., 12 Dec. 2001, G. Kantvilas 1297/01 (HO); Mole Creek, 41°34'S 146°24'E, 240 m alt., 2 Mar 2002, G. Kantvilas 141/02 (HO); Cape Portland, Musselroe Wind Farm, woodland W of Xanthorrhoea Ridge, 40°47'53"S 148°01'08"E, 70 m alt., 6 Nov. 2018, G. Kantvilas 357/18 (HO).
Ramonia absconsa (Tuck.) Vézda
This species is characterised by the following salient features: thallus crustose, effuse, very thin and patchy, pale grey- green, with a Trentepohlia photobiont; apothecia 0.3-0.5 mm wide, at first immersed or semi-immersed and visible
as a ‘bump’ in the thallus, pierced by a minute central ~
pore with a grey rim, emergent when mature, becoming globose to hemispherical, with a dark brown, strongly incurved, radially split proper exciple, and a central pore to c. 0.15 mm wide, revealing a pale grey, urceolate disc; exciple in section cupulate, hyaline to brown, composed of thomboidal or subglobose, parenchymatous cells 3-7 um wide and lined along the inner edge with periphyses 5-10 x 2-3 um; asci 32-spored, of the Gyalecta-type, with a thin, KI+ blue wall and non-amyloid, poorly developed tholus; ascospores (12) 13—19(—20) x 5—6.5(—7) um, 3(—5)-septate, ellipsoid, blunt or acute at the apices, with a gelatinous perispore (plate 2D).
New records of lichens from Tasmania 7
This is a remarkable discovery for Tasmania, based on a single collection from the papery bark of an old Melaleuca ericifolia in a lowland, coastal swamp. Prior to this collection, it was known only from the type specimen, collected in the nineteenth century from the bark of maple in South Carolina, U.S.A. (Vézda 1966, 1967).
TASMANIA: Cape Portland, Musselroe Wind Farm, ‘Tregaron Lagoons, 40°46'55"S_ 147°58'09"E, 2 m alt., 2019, G. Kantvilas 230/19 (E, HO).
Trapelia concentrica Elix & P.M.McCarthy
Recently described from New South Wales and the A.C.T. by Elix and McCarthy (2019), this species is characterised by a thallus of minute, highly dispersed, scabrid areoles to 0.3 mm wide, scattered apothecia to c. 0.5 mm wide, and ascospores. 11-17 x 6-10 pm. Elix and McCarthy (2019) compare it to 7° crystallifera Kantvilas and Elix, which in Tasmania occurs exclusively on soil. However, the single Tasmanian specimen of 7) concentrica is from rock, and is therefore more likely to be confused with the common, widespread and highly variable 7. coarctata (Sm.) M.Choisy.
It grew on dolerite pebbles in a highly degraded tussock grassland.
TASMANIA: Cape Portland, N of Semaphore Hill, 40°45'S 147°57'E, 10 m alt., 8 Nov. 2018, G. Kantvilas 253/18B (HO).
The genus Trapelia in Tasmania is complex and requires considerable further study. An additional, as yet unidentified species was also collected at the study site (Kantvilas 226/19; HO). It grew on consolidated soil and had scattered, sorediate squamules containing gyrophoric acid, and ascospores 24-31 x 12-17 ym.
Xanthoparmelia xerica (Elix) Elix
Characterised by an almost subcrustose, grey or blackened thallus of minute, tightly adnate lobes, mostly only to 0.1 mm wide, which become rather spidery at the thallus margins, with a pale brown underside, sparse, globose isidia and containing atranorin and stictic acid. Previously known only from the type locality on the Eyre Peninsula, South Australia, this rare lichen was collected in Tasmania on a granite boulder in coastal scrubby heathland. It could potentially be confused with the very common and widespread X. mougeotinaand_X. xanthomelaenawith which it grows, both of which contain stictic acid but differ by also containing usnic acid instead of atranorin, and have a black under-side; the latter differs further in lacking isidia.
TASMANIA: Cape Portland, Musselroe Wind Farm, “The Prairie”, in the vicinity of Turbine D14, 40°48'35"S 148°06'23"E, 20 m alt., 5 Nov. 2018, G. Kantvilas 210/18 (HO).
8 — Gintaras Kantvilas, Brian J. Coppins, Patrick M. McCarthy and John A. Elix
ACKNOWLEDGEMENTS
The 2018 TMAG Expedition of Discovery was generously supported by Woolnorth Wind Farm Holding Pty Ltd and the Friends of the Tasmanian Museum and Art Gallery. Jean Jarman prepared the images that accompany this paper.
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(accepted 15 July 2020)
Papers and Proceedings of the Royal Society of Tasmania, Volume 154, 2020
POTENTIAL POLLEN VECTORS OF THE MASS FLOWERING TREE ACACIA DEALBATA, WITHIN ITS NATURAL RANGE IN SOUTHERN TASMANIA
by A. Rod Griffin, Andrew B. Hingston, Christopher E. Harwood, Jane L. Harbard, Michael J. Brown, Kristi M. Ellingsen and Catherine M. Young
(with three figures, three plates, six tables and two appendices)
Griffin, A.R., Hingston, A.B., Harwood, C.E., Harbard, J.L., Brown, M.J., Ellingsen, K.M. & Young, C.M. 2020 (9:xii): Potential pollen vectors of the mass flowering tree Acacia dealbata, within its natural range in southern Tasmania. Papers and Proceedings of the Royal Society of Tasmania 154: 9-26. ISSN 0080-4703. Discipline of Biological Sciences, University of Tasmania, Private Bag 55, Hobart, Tasmania 7001, Australia (RG*, CEH, JLH, CMY); Discipline of Geography and Spatial Sciences, University of Tasmania, Private Bag 78, Hobart, Tasmania 7001, Australia (ABH); 211 Channel Highway, Taroona, Tasmania 7006, Australia (MJB); 16 Auvergne Avenue, Mount Stuart, Tasmania 7000, Australia (KME). *Author for correspondence: Email: rodgriffin@iinet.net.au
In Tasmania, Acacia dealbata flowers from July to September when weather conditions are non-conducive to activity by the insects which are generally considered to be major pollinators of the genus. This paper examines the presence and behaviour of insect and bird visitors as potential pollen vectors. Very few insects were observed to visit the flowers. However, several bird species fed on the flower-heads and foraged for small invertebrates inhabiting the blossoms. These feeding behaviours resulted in adhesion of pollen to feathers likely to be transferred from one genet to another as birds moved. During feeding, rosellas were observed to not only ingest flower-heads but the presence of branchlet clip under 57% of A. dealbata trees surveyed is evidence of the widespread occurrence of these species foraging on flowers. However, given the profusion of flowers and the small numbers of birds observed, it is difficult to conclude that birds are wholly responsible for outcross pollination and we discuss the possibility that wind may also be an important pollen vector. Although the floral attributes of A. dealbata are more aligned with insect pollination, we failed to definitively identify any one major pollinator of the species
in this environment and suggest that the pollination syndrome may most accurately be described as generalist. Key Words: Acacia dealbata, pollination syndrome, bird pollination, insect pollination, wind pollination, mass flowering.
INTRODUCTION
Silver Wattle (Acacia dealbata) is native to southeastern Australia with a range extending from Tasmania and western Victoria to northern New South Wales. It is common in forest and woodland communities in Tasmania from sea level to.900 m, and dominates many transitional forests on disturbed sites (Kitchener & Harris 2013), varying in size from a low shrub on dry sites to a tall tree over 25 m in height on deep soils in wetter sites (Boland eg al. 2006). The species has also been widely planted outside Australia for ornamental purposes, perfumery and fuelwood (Griffin etal. 2011) and has a reputation for weediness via both seed and root suckering (Gibson et a/. 2011, Fuentes-Ramirez er al. 2011, Montesinos et al. 2016). Because of the tendency to sucker (Nghiem e¢ al. 2018), pollen transfer between trees is not always an outcrossing event and we use the term ‘genet’ to indicate trees of different genotype.
The species produces a spectacular display of bright yellow flowers from July to September, a time of year characterised by low temperatures with frequent strong winds and rain, not conducive to insect flight activity. However, substantial pollen transfer between genets is presumed to occur as Broadhurst e¢ al. (2008) found that seed from elsewhere within the natural range was highly outcrossed. The vector(s) mediating such cross-pollination in Tasmanian populations are by no means obvious.
According to the pollination syndrome hypothesis, convergent evolution may lead to unrelated plants sharing
the same suite of floral traits when they are pollinated by the same abiotic or functional group of biotic vectors (Faegri & van der Pijl 1979, Rosas-Guerrero et al. 2014). For biotic pollinators, floral traits include rewarding (e.g. nectar and pollen) and non-rewarding attractants (e.g. floral colour, shape and scent), while the wind-pollination syndrome is typically associated with an absence of attractants, the flowers being nectarless and lacking bright colours and scent (Faegri & van der Pijl 1979, Sedgley & Griffin 1989).
Acacia species are generally considered to be pollinated by insects, particularly bees (Bernhardt ‘1989, Stone et al. 2003), but the floral traits do not map tightly onto any of the major pollinator syndromes as defined by Faegri and van der Pijl (1979). In terms of gross morphology,
_ the flowers are remarkably uniform, a characteristic feature
being the prominence of anther filaments which generally determine the shape, size and (generally yellow) colour of the flower-heads, which may be globose to spicate (Kendrick 2003). The number of individual flowers per head and heads per inflorescence are variable and all may not be perfect. Pollen is aggregated into polyads containing 4<32 grains. The flowers do not produce nectar and while extra- floral nectaries are generally present (Boughton 1981), in many species, including A.dealbata, they are only vestigial (Marazzi et al. 2019) and offer no reward to visitors. Low reproductive success is also a characteristic of the genus with typically less than one pod produced per flower-head (Wandrag et al. 2015). Nevertheless, because of the large number of flowers per tree, individuals may produce several
10 AR. Griffin, A.B. Hingston, CE. Harwood, J.L. Harbard, M.J. Brown, K.M. Ellingsen and C.M. Young
thousand seeds/m?/yr! (Gibson et al. 2011) which can remain viable in the soil for many decades.
Although birds are not considered to be major pollinators of Acacia (Ford et al. 1979), there are examples of birds feeding on or within flowering crowns of several species (Sargent 1928, Ford & Forde 1976, Knox et al. 1985, Vanstone & Paton 1988), raising the possibility of a role as pollen vectors. The possibility of wind pollination was not considered in earlier reviews of the pollination ecology of the genus (Bernhardt 1989, Stone er al. 2003) but there is sufficient evidence to suggest at least a contribution to gene flow. Polyads have been collected downwind of A.mearnsii trees (Moncur et al. 1991, Kendrick 2003); Smart and Knox (1979) found Acacia polyads in the atmosphere over Melbourne during spring; and allergy to airborne Acacia pollen has been reported from a number of countries (Ariano et al. 1991). A recent experimental study of A. longifolia in Portugal found that seed set was enhanced when flowers were exposed to wind (Giovanetti et al. 2018).
The effectiveness of any particular flower visitor as an outcrossing agent is a function of its morphology and behaviour (affecting the probability of collecting pollen during the course of feeding and of deposition on flowers of a different genet) and of population size relative to the number of flowers produced by the host plant population. Together these variables determine the potential flux of pollen between trees (Griffin et al. 2009). For effective pollination the pollen must obviously be viable when
deposited, so it is important to understand the temporal decay in viability post-anthesis. As a contribution to understanding the pollination ecology of A.dealbata, this paper reports an observational study of the presence and behaviour of the diurnal visitors to the crowns of trees in natural populations near Hobart, Tasmania. It also considers the possibility of wind pollination and tentative conclusions are drawn regarding all the relative importance of the potential vectors in effecting outcrossing.
MATERIALS AND METHODS Reproductive characteristics of A. dealbata
Flowers are arranged in globose heads which, when the filaments are fully expanded, measure about 9 mm wide by 8 mm long with a fresh weight of 20 mg (Griffin unpubl. data). The number of individual flowers per head varies between 22 and 42 (Roger & Johnson 2013, Correia et al. 2014) with varying numbers being male only. Each flower has an average of 33 stamens (Correia et al, 2014). Heads are arranged in axillary racemes or false panicles on branch apices which collectively form a highly visible mass blossom (pl. 1) and Figure 1 in Nghiem et a/. (2018). Pollen is aggregated into 16 grain polyads which average 46 pm in diameter (Nghiem et al. 2018). The flowers do not produce nectar and the extra-floral nectaries are vestigial (Marazzi et al. 2019) and offer no reward. The low fruit:flower ratio
PLATE 1 — Flowering (26/8/18) and corresponding mature pod crop (1/1/19) on adjacent trees at Site 4. The bright yellow colour of Tree 4 (left) indicates it was in full flower, while Tree 5 (right) was past the peak. Both the flowers and resulting pod crops were distributed uniformly from the topmost branches to the lowest in the crown on each tree (photos J. Harbard).
Potential pollen vectors of the mass flowering tree Acacia dealbata, within its natural range in southern Tasmania 11
=> i, oO
Oo oo ro)
Brown Thornbills
a Green Rosellas 0.60
0.40
0.20
No. of birds/no. of obs. periods
0 20 40 60 80 100 80 60 40 20 0 Flowering phenology (%) 22 16 6 4 5 2 3 3 0 9 Uf Total no. of observation periods for each phenology stage
FIG. 1 — Ratios of total number of birds sighted on A. dealbata crowns to total number of observation periods at each flowering phenology stage, summed across the five observation points at Knocklofty, for Brown Thornbills and Green Rosellas. Numbers above
each bar show the total number of birds sighted for each phenology stage. Flowering phenology scored as the proportion of flowers judged to be fully open on a scale of 0 (pre- and post-flowering) to 5 at peak flowering.
of the species aligns with the rest of the genus. In Portugal, Correia et al. (2014) reported fruit developed from only 0.7% of the total number of flowers observed. In South Africa, Rodger and Johnson (2013) reported that after open pollination 14% of A. dealbata flower-heads matured one or more fruit while, fora range of natural populations in NSW, infructescences per flower-head varied between 0.03<0.31, (Broadhurst & Young 2006, Wandrag e¢ al. 2014).
the foothills of kunanyi/Mount Wellington to the west of Hobart, where A. dealbatais presentasa result of regeneration following fire or other disturbance, although the density and age class structures differ, with likely effects on the pool of potential pollinations. All are within 15 km of Site 1 and between 50-300 m elevation (Site 1 is at 220 m).
Floral phenology Observation sites It is highly probable that the state of flower development within a tree crown affects desirability as a food source for visiting animals, so we characterised this for each observation date. In A. dealbata there isa gradual colour change associated with flower opening, from pale to brighter yellow and then paler again past the peak. Each time observations were made,
The core study was conducted at the Knocklofty Reserve near Hobart (Site 1) but we also report data collected from a number of other sites within the region (table 1). All sites can broadly be regarded as part of a single ecosystem in
TABLE 1 — Observation sites
Site Location Latitude S Longitude E Elevation Distance Data collected No. : (m asl) from Site 1 (km) 1 Knocklofty Reserve ~ 42°53'07" 147°18'07" 220 - Bird and invertebrate observation, mist netting 2 Mt Nelson 42°54'48" 147°19'23" 140 3.7 Bird observation Lower Longley 42°58'20" 147°11'41" 200 14.5 Bird observation Turnip Fields Rd 42°54'51" 147°16'20" 300 3.6 Wind dispersal, seed : ; production 5 Waterworks Reserve 42°54'32" 147°16'12" 160 2.4 Mist netting birds 6 BOM Station 094029 42°53'20" 147°19'34" 50 1.5 Meteorological data
Ellerslie Rd, Hobart
12 AR. Griffin, A.B. Hingston, CE. Harwood, J.L. Harbard, MJ. Brown, K.M. Ellingsen and C.M. Young
the flowering state of each tree at each Observation Point (OP) was placed in one of 11 categories according to the percentage of heads which were fully open, from 0 < 100% (peak flowering) at 20 percentile intervals reducing from this peak date to 0%, again in 20 percentile steps, as the proportion of open heads declined over time. Individual trees thus moved through a progression from 0% to peak (100%) flowering and back to 0%. An average score was then calculated for all trees at each bird OP at each study site on each date. For the invertebrate study there was only one target tree at each OP and for results presentation we averaged values over the four trees observed on each visit date.
Meteorological data
A basic tenet of the study was that the pollination ecology of winter/spring flowering A. dealbata may differ from many other Acacia species which flower at warmer times of the year, so we documented the ambient weather conditions through the flowering period using data from the Australian Bureau of Meteorology Station 094029 at Ellerslie Rd, Hobart (table 1) for the study period June-Sept 2018 (Bureau of Meteorology 2018).
Invertebrates visiting or resident within the blossom
Four trees at Site 1 were chosen for study. The locality, described by Nghiem etal. (2018), is dry sclerophyll eucalypt woodland dominated by Eucalyptus globulusand E. viminalis, with an understorey of A. dealbata and other species, but is known to have been more open in the past, with a complex history of degradation and revegetation (Harwood et al, 2018). Each tree was flowering heavily at a height that was easily accessible from the ground. Observations were made on nine days between 30 June 2018 prior to flowering and 18 September, when flowering was completed. Observation days were chosen as being dry and without strong winds, since we expected insect activity to be low under less favourable conditions. For one 10-minute period per tree per observation day we recorded larger flying insects which could be potential pollen vectors. An observer stood close to a heavily flowering part of the crown and noted the number of each taxon which came into view. Where there was some doubt about identification, samples were collected for later examination or in some cases photographed in situ. Where . possible, identification was made to the Family level but, with the exception of bees and Syrphid flies, which Bernhardt (1987) considered to be particularly important vectors of Acacia pollen, summary at the level of Order was considered sufficient to meet the study objectives.
We also sampled the small invertebrates living among the inflorescences which represent a potential food source for foraging birds. On each sample day four different flowering branches on each tree were sharply beaten with a 40-cm stick, at an approximate foliage height of 150°cm. A container held immediately below the branches collected the organisms which were dislodged. In order to minimise loss of flying insects the container was fitted with a flexible
plastic cover which could be removed and replaced with minimum delay for each of the collections. The pooled contents were then inspected and numbers of each taxon counted. Since a few of the more vigorous flyers (mainly Diptera and Hymenoptera) did escape during the counting process there is some bias associated with the method. However, the more stationary invertebrates are presumed the more likely food for birds, so we do not consider this a critical issue. Where identification was difficult, a digital photographic image was taken for immediate inspection or in some cases later consultation of databases. The camera used was a Canon EOS6D, with Canon MPE65 mm macro lens and Macro twin lite MT-26EX-RT, permitting identifiable images of invertebrates greater than around 2 mm in length. In order to judge whether the invertebrate fauna was different on flowering and non-flowering trees, on four of the observation days we also beat the foliage of an entirely vegetative tree growing next to Tree 1. Our capacity to identify the various taxa increased from Species, Genus, Family to Order. For the purposes of this paper we were primarily interested in determining the diversity of organisms over the flowering season and presentation at the level of Order was considered sufficient. More detailed data to Family level are provided in appendix 1, where we also indicate the developmental stage observed, since some taxa were present in a range of immature states (as determined from morphology and/or size) as well as adult form.
Bird visitors
At Site 1, five fixed OPs were chosen within an area approximately 250 m by 150 m. Each OP gave an uninterrupted view of 1-5 mature A. dealbata trees from a viewing position next toa nearby tree or shrub that provided
- cover for the observers. Observations were made on 18
days during the period from 26 June (about 2 weeks prior to first anthesis) to 29 September 2018 by which time all flowering had finished. Data were collected by either one or two experienced bird observers with binoculars and cameras. Intervals between the observation days averaged 5.8 days but ranged from 3 to 10 days, depending on the availability of observers and weather conditions.
A second series of observations over the flowering season (26 July to 19 September 2018) was made by another observer at Site 2 (table 1). Ten OPs were selected, seven located within low dry sclerophyll forest with many flowering A. dealbata stems 2-8 m high originating from a past fire event and three in suburban settings near the forest but within 20 m of buildings that included 1-4 larger A. dealbata trees. The number of observations at each OP ranged from 17 to 31.
A third data set was collected at Site 3 (table 1). Observations were made on a total of ten days between 2 August to 12 October 2018 at a single OP adjacent to a row of five large roadside A. dealbata trees on a lightly wooded rural property surrounded by wet sclerophyll forest.
At all sites, observations commenced between 7.30 am to 3 pm, with the majority of observations made in the mornings. Periods of the day with very high winds
Potential pollen vectors of the mass flowering tree Acacia dealbata, within its natural range in southern Tasmania 13
(terrestrial Beaufort scale >7, large trees-in motion) and/ or heavy all-day rain were excluded. Ambient temperatures at the time of observation were mostly within the range 10-15°C. A point count of ten minutes was made at each OP. During each count, all bird species visible from the OP, or identified from their nearby calls, were recorded. The numbers of birds of each species that alighted on the A. dealbata trees under observation, and the numbers that moved between A. dealbata trees, were recorded. At Sites 1 and 2 the behaviour of birds in A. dealbata tree crowns was noted and each visit recorded as either feeding on inflorescences; contacting flowers; or perching. The frequency of visits by birds that foraged on or among inflorescences of A. dealbata in relationship to flowering phenology stages was examined by calculating the proportions of visits to observation periods for each phenological stage.
Indirect evidence of rosella feeding
It was noted that where Green Rosellas (Platycercus caledonicus) had been feeding on A. dealbata flower-heads, the ground under the tree was often littered with freshly clipped flower-bearing branchlets, each severed with a characteristic clean diagonal cut (pl. 2). This provided an indirect measure of activity. To estimate the proportion of trees where this type of feeding had occurred, we inspected the ground under A. dealbata trees at nine regional locations where many trees were in heavy flower and there was relatively little undergrowth. Surveyed trees were classified as either
plus or minus evidence of rosella feeding (three or more clipped branchlets found under the crown were classified as plus). Results were expressed as percentage of trees with evidence of rosella feeding. It was not possible to judge the time the material had been on the ground and when the feeding had occurred, so we cannot say whether one or more
feeding events were involved.
Pollen carried by birds
For a bird to be an effective outcross pollen vector there must be transfer of polyads from anthers to the bird during the course of a feeding event and from thence to stigmas on another genet. To obtain relevant data we mist-netted bush birds from 7:00 to 11:00 am at Sites 1 and 5 (table 1) while the A. dealbata were flowering. Site 5 was first sampled on 22 July, early in the flowering season, with many more trees flowering during the subsequent visit one month later. At Site 1 nets were set near two of the four bird OPs on three occasions at approximately weekly intervals around the peak flowering season in August.
To obtain a pollen swab, doubled-sided tape was applied to a glass microscope slide and, while the bird was still in the mist net (that is before pollen could be rubbed or shaken off), the slide was applied sequentially to the head, beak, feet and chest feathers. Slides were observed through a compound microscope at 400x magnification, viewing transects across the slide until the whole slide had been observed. Total number of polyads was recorded and classified to at least the Family level.
PLATE 2 — Green Rosella feeding on flower-heads from a clipped branchlet of A. dealbata (photo M. Brown).
14 AR. Griffin, A.B. Hingston, C.E. Harwood, J.L. Harbard, M.J. Brown, K.M. Ellingsen and CM. Young
Pollen viability on feathers
It was not possible to directly determine viability of pollen carried by birds so we conducted a simulated trial. An equal number of flower-heads was harvested from each of four trees at Site 4 and mixed prior to pollen extraction. Since anthers were closed, the flower-heads were left under lights for 30 minutes causing dehiscence and exposure of the polyads. Flowers were then placed in an Endecotts test sieve with a 63 um stainless steel mesh over a petri dish containing clean feathers from a mist-netted Crescent Honeyeater (Phylidonyris pyrrhopterus). Gentle rubbing separated the polyads from the anthers which settled on the feathers. These were left in a petri dish in an unheated room (temperature range 6—11°C) which was within the range of outside air temperatures over the observation period (Bureau of Meteorology 2018). At intervals between 0 and 17 days, a sample of polyads was collected by gently scraping a dissecting needle over the feathers onto a petri dish containing 1% agar, 20% sucrose and 0.01% boric acid kept at the same ambient temperature. Preliminary experiments determined that maximum germination of fresh polyads was achieved after 48 h so this was set as the test period. Viability was assessed by viewing pollen tube growth on the nutrient agar at 160x magnification with an inverted Nikon microscope; 100 polyads were observed on each occasion. A polyad was counted as viable if one or more pollen tubes had germinated and the length was greater than the diameter of the polyad. On Day 3, as germination rate had obviously slowed, the dish was inspected again at 72 h. From Day 7, in order to achieve maximum germination, petri dishes were transferred to a growth room at a higher temperature (15—23°C).
Wind dispersion of flower-heads
From casual observation it was evident that whole flower- heads detached rather easily in windy conditions and were frequently seen on the ground among the trees. It is possible to extract viable pollen from such heads (J. Harbard unpubl. data 2018) so this may be regarded as a possible pollen dispersal mechanism. Following a particularly windy week we documented the dispersal of heads away from a forest margin at Site 4. Three parallel transects were laid out across grassland and all heads within a 0.75 m2 wooden frame were counted at 1.5 m intervals out from below _ the edge of the canopy to a distance of 50 m. Counts were then converted to a per 1 m2 basis and plotted against distance.
Pod and seed production
In parallel with this study we have also made a detailed investigation of the floral biology and seed production of this Acacia species. Full details will to be reported elsewhere, but we present some information which, in conjunction with the observed activity of potential pollen vectors, assists inference regarding the overall level of outcross pollination.
If the species is strongly outcrossing and only sets pods
after pollination by biotic vectors, we postulate that the pattern of pod set should be patchy because at the visit frequencies we report in this paper it is unlikely, for both stochastic and micro-environmental reasons, that pod set would be even across the whole crown of a tree. We could not quantify such pattern in pod set but we are able to present photographic evidence of trees in full flower and again at pod maturation (pl. 1).
The literature suggests that outcrossed flowers of A. dealbata produce a higher number of full seed per pod than selfs (Rodger & Johnson 2013, Correia et al. 2014), so full seeds per pod may be taken as a rough indication of the level of outcrossing. We determined this trait for pods harvested from the top, middle and bottom of crowns of five trees at Site 4. These trees ranged in total height from 12-24 m. Two separate samples of pods at each level, ranging in number from 48 to over 500, were dried to open and all seeds extracted and classified as one of four categories: (1) full, black 5 mm; (2) full, brown 5 mm; (3) small, black 3 mm; (4) vestigial, < 2 mm. The total number was counted but only category 1 considered to be good seed. The numbers of total and good seed per pod were then calculated together with the proportion of good seed as a percentage of total seed. The data sets for these three variates were analysed using ANOVA, with tree and height level as the treatment factors in factorial combination.
RESULTS
The trees at Site 1 flowered over 76 days between 16 July and 29 September with a’ median date for peak flowering of 24 August The mean number of days that a tree carried
_ some open flowers was 51 and, although there was variation
among trees, no genets were fully temporally isolated.
During the flowering period the mean minimum and maximum daily temperatures at the Bureau of Meteorology (Ellerslie Rd site) were 6.4°C and 15.1°C. Mean temperature at 9 am was 9.5°C rising to 13.1°C at 3 pm; at that time mean wind speed was 31 km h7! with a maximum of 71 kmh and a mean relative humidity of 53.5% (minimum 25%). During the flowering season a total of 91.6 mm of rain fell with 0.2 mm or more on 41 of the 71 days (58%). Weather conditions on bird observation days are noted in appendix 2 together with the respective flowering phenology records.
Invertebrate visitors
_ For invertebrates, we documented visits by larger mobile
and potentially pollinating insects and also the array of small invertebrates which fell from the blossoms when the branches were beaten and are assumed to be the target of foraging birds. Potentially pollinating insects from 29 Families within seven Orders were observed on flowering branches of A. dealbata (appendix 1). Of these, 41% of individuals were Dipterans (55% of which were Syrphidae) (table 2a) and 41% were Hymenoptera (of which 38% were Honey
Potential pollen vectors of the mass flowering tree Acacia dealbata, within its natural range in southern Tasmania
Bees Apis mellifera and 15% native bees). Coleoptera was a distant third in terms of frequency.
A diverse array of small invertebrates of varying developmental stages (appendix 1) was captured when flowering branches were beaten. In all, 47 Families from 10 Orders were represented but 94% of the total catch came from five Orders which each contributed between 11 and 25% (table 2b). Within the more common Orders the most numerous Families were: Coleoptera— Chrysomelidae (leaf beetles), Diptera— Chironomidae (Midges), Hemiptera— Psyllidae (psyllids), Hymenoptera— Platygastridae (parasitoid wasps) and Araneae—‘Thomisidae (crab spiders). On the non-flowering tree, adjacent to flowering Tree 1, there was a reduced diversity of taxa. Over the four days when both trees were sampled, Tree 1 yielded 106 invertebrates from 19 families while the non- flowering tree collection was only 30 individuals from 11 Families (appendix 1).
Bird visitors
Across Sites 1 and 2 a total of ten bird species was seen to make contact with the inflorescences of A. dealbata trees during one or more of the 10-minute observation periods. A further 11 species perched on branches of A. dealbata trees but flew off without making contact with inflorescences or exhibiting feeding behaviour (table 3).
Of the ten species that contacted inflorescences, six did so only occasionally, briefly and incidentally, during the course of feeding on flowers of an adjacent Banksia marginata tree (Eastern Spinebill); hawking airborne insects around the
15
tree crowns (Grey Fantail and Black-headed Honeyeater); or as a result of chasing or mating-related social behaviour (Yellow-throated Honeyeater, New Holland Honeyeater and Yellow Wattlebird).
Four bird species did actively work the flowering crowns of A. dealbata, moving between adjacent trees while doing so. On some’ days they remained in the crowns for the entire 10-minute observation period and beyond. Brown Thornbills and Silvereyes appeared to be searching for and feeding on small invertebrates (pl. 3) while the Green Rosellas and Eastern Rosellas were observed to feed within the blossom-bearing crowns, selectively picking and consuming individual pollen bearing and/or galled flower-' heads (pl. 2). The presence of clipped branchlets on the ground below 97% of the trees at Site 1 (table 4) suggested that the Green Rosellas visited there more frequently than we were able to observe. Green Rosellas commenced visiting OPs at Site 1 once anthesis had commenced on some of the trees and were not observed on trees which were past peak flowering (fig. 1). Brown Thornbill visits were concentrated from early to peak flowering, but they also made a few visits before flowering commenced and after it had completed (fig. 1).
At Site 2, Silvereyes showed similar foraging behaviour to Brown Thornbills as did the Eastern Rosella to that of the Green Rosellas. At Site 3, Brown Thornbills were observed feeding among the A. dealbata flowers, moving from crown to crown during the 10-minute observation periods on seven of the ten observation days. Grey Fantails made accidental contact with the inflorescences on one day while hawking insects around the crowns. Although
TABLE 2a — Total flower visitors during 10-minute observation periods per tree on seven days throughout the 2018 flowering season.
Observation Date
Order
Family 20Jul 7Aug 14Aug 24Aug 4Sep 11Sep 18Sep ‘Total Diptera 2 0 1 8 22 14 9 56 (Syrphidae 0 0 0 2 12 11 6 31) Hymenoptera 0 0 2 DY, 11 14 6 55 (Apidae 0 0 2 15 2 2 Oe 1) (Halictidae 0 0 0 2 1 1 2 6) (Colletidae 0 0 0 0 1 1 0 2) Coleoptera 0 0 3 1 3 7 2 16 Hemiptera 3 0 0 0 0 0 1 4 Lepidoptera 0 0 1 0 0 1 0 2 Neuroptera 1 0 0 0 0 0 0 1 Thysanoptera 0 0 = 0 0 1 0 1 Total : 6 0 7 31 36 37 18 135 Flowering status! 5 35 60 100 85 65 25 -
1 Mean % of flowers across sample trees which were judged to be fully opened (100 = peak flowering). Data from four trees were pooled. Within the total observations for Diptera and Hymenoptera the numbers for Families with highest putative pollination potential according to the literature are also detailed. For more
complete data see Appendix 2.
16 A.R. Griffin, A.B. Hingston, CE. Harwood, J.L. Harbard, M.]. Brown, K.M. Ellingsen and C.M. Young
TABLE 2b — Numbers of small invertebrates captured by beating flower-bearing branches throughout the 2018 flowering season.
Capture date
Order 3July Jul 20Jul 7Aug 14Aug 24Aug 4Sep 11Sep 18Sep Total Hymenoptera D 13 9 13 28 32 26 33 41 200 Hemiptera 12 24 13 18 13 24 16 23 26 169 Diptera 17 26 15 33 11 18 15 18 9 162 Coleoptera 3 11 7 9 12 26 22 15 17 122 Araneae 7 9 6 12 13 11 17 6 9 90 Neuroptera 0 2 1 3 3 3 6 1 3 22 Acari 1 0 1 2 2 5 3 0 0 14 Thysanoptera 0 0 0 0 2 0 4 2 0 8 Lepidoptera 0 0 0 1 1 0 2 1 2
Blattodea 0 0 0 0 0 0 0 0 2 2 Total 45 85 52 91 85 119 111 99 109 796 Floweringstatus!. 0. 0 5 35 60 100 85 65 25 -
"Mean % of flowers across sample trees which were judged to be fully opened (100 = peak flowering).
Data from four trees pooled. For details see Appendix 1.
PLATE 3 — Brown Thornbill feeding within the blossom of A.dealbata (photo M. Brown).
Green Rosellas were not observed to visit the flowering crowns, the presence of clipped branchlets under 34% of nearby trees (table 4) indicated that they had made recent
feeding visits. Indirect evidence of rosella feeding
‘The surveys of clipped flowering branchlets on the ground below flowering A. dealbata trees at nine locations (table 4) suggested that Green Rosellas, and possibly Eastern Rosellas, fed on many of the trees. The proportion of trees below which clip could be detected ranged from 6% at Waverley Flora Reserve to 97% at Site 1, with a mean value across all nine sites of 57 % (table 4).
Pollen carried by birds
Seventeen birds were caught and swabbed (10 at Site 1 over 3 days and 7 at Site 5 over 2 days) and nine of these carried pollen from various plants (tables 5a and 5b). Acacia polyads were recovered from five birds and on three of these (a Green Rosella and two Brown Thornbills) this was the only pollen present.
Pollen viability on feathers
‘The germination percentage of polyads experimentally placed on bird feathers was highest when freshly removed from the anthers. After 48 h incubation atambient temperature, 60% had germinated (fig. 2). Thereafter viability declined more or less linearly to 16% at Day 12, with no germination of the final sample taken at Day 17. :
Potential pollen vectors of the mass flowering tree Acacia dealbata, within its natural range in southern Tasmania 17
TABLE 3 — Number per species for birds observed at two sites through the period of the study, indicating behavioural characteristics.
Site 1 — Knocklofty Site 2 — Mt Nelson
Common Name Scientific name
Perching on Contacting Feeding Perching Contacting. Feeding branches flowers on/ on flowers on/ among. «branches among inflor- inflor- escences escences Psittaciformes Green Rosella Platycercus caledonicus 19 19 19 19 ; 19 19 Eastern Rosella Platycercus eximius = = = 4 4 4 Musk Lorikeet Glossopsitta concinna = ae i 4 zi - Passeriformes Silvereye Zosterops lateralis = Bs es 33 4 94 Brown Thornbill Acanthiza pusilla 14 14 14 5 5 5 Yellow-throated Nesoptilotus flavicollis 5 * 2 10 i Honeyeater z Yellow Wattlebird Anthochaera paradoxa 6 * a 7 New Holland Phylidonyris oe = is 9 a Honeyeater novaehollandiae o Crescent Phylidonyris = x a 1 vf Honeyeater pyrrhopterus 7 Eastern Spinebill Acanthorhynchus 3 * = 4 tenuirostris es Tr Black-headed Melithreptus affinis 1 oe ey 2 & Honeyeater 5 Strong-billed Melithreptus ~ 2 ies = ag if Honeyeater validirostris a Scarlet Robin Petroica boodang i ee ee = is Grey Fantail Rhipidura albiscapa 3 * a cc o Superb Fairy-wren Malurus cyaneus 5 = oe = a Grey Currawong Strepera versicolor 2 pet ee 1 e Grey Butcherbird Cracticus torquatus fi 2 1 e Forest Raven Corvus tasmanicus 1 is ie ie, a Golden Whistler Pachycephala pectoralis 1 os si Es io Grey Shrike-thrush Colluricincla harmonica 1 es te = e z Common Blackbird Turdus merula 1 is iy i # Not identified ri be
Fa at ana eg DO i a a
sie wanee incidental contact only
18 AR. Griffin, A.B. Hingston, CE. Harwood, J.L. Harbard, M.J. Brown, K.M. Ellingsen and C.M. Young
TABLE 4 — Surveys of clip under A. dealbata trees at nine locations around Hobart, indicating feeding of Rosellas.
Transect No. Date Location No. of trees with No. of trees Percentage of trees clip under tree without clip with clip (%)
1 Aug 12. Knocklofty* (Site 1) 31 1 97
2 Aug 13 Peter Murrell Reserve! 36 6 86
3 Aug 17 ~~ Waverley Flora Reserve 29 6
4 Aug 18 — Geilston to Shag Bay walk 2 21
5 Aug 28 31 Turnip Fields Rd (Site 4) 32 34 48
6 Aug 29 — Lenah Valley Creek track 51 20 72
7 Aug 29 30 Turnip Fields Rd (Site 4) 16 15 52
8 Aug 30 — Cleggs Rd, Ferntree (Pipeline Track) 20 8 71
9 Sep 02 Lower Longley (Site 3) 10 19 34 Total 200 153 57
' Green Rosellas seen feeding on A. dealbata crowns at these locations at the time of survey.
TABLE 5a — Numbers of pollen grains observed on
Date (2018)
Species
birds captured at Waterworks Reserve.
Pollen
22 Jul
22 Jul 22 Jul 20 Aug 20 Aug 20 Aug 20 Aug
Crescent Honeyeater
Crescent Honeyeater Scarlet Robin
Dusky Robin Eastern Spinebill Green Rosella
Crescent Honeyeater
65 Banksia, 3 Pinus, 1 Eucalyptus?
334 Banksia 0
0
414 Ulex 15 Acacia 28 Banksia
TABLE 5b — Numbers of pollen grains observed on
birds captured at Knocklofty Reserve.
Date Species Pollen
(2018)
14 Aug Superb Fairy-wren 0
14 Aug Brown Thornbill 0
14 Aug Brown Thornbill 0
14 Aug Brown Thornbill 0
22 Aug Crescent Honeyeater 90 Ulex, 439 Melaleuca,
6 Banksia, 2 Acacia
22 Aug Yellow-throated 6 Acacia, 9 Myrtaceae Honeyeater
22 Aug Brown Thornbill 2 Acacia
29 Aug Brown Thornbill 6 Acacia
29 Aug Superb Fairy-wren 0
29 Aug Superb Fairy-wren 0
TABLE 6 — Mean number of full seeds from pods harvested at three levels within the crowns of five trees at Site 4.
Full seed/pod by crown position
Tree Tree Total Low Mid Top Weighted ht no.pods (%) (%) (%) mean (m) extracted 1 24 623 3.0 333 ahy/ 3.3 (84) (75) (67) 2 13 521 3.1 3.8 3.9 3.6 = 2(70) em (1) 9172) 3 15 808 1.3 1.4 1.4 1.4 (43) (42) (43) 4 19 817 sH5 ah) 3.9 ah 7/ (62) (78) (82) 5 20 1680 AS A) 5} 3.7
(81) (77) _ 64)
Pooled data from two separate samples of pods at each level per tree, also expressed as a % of the total seed per pod. Differences between trees in number and % full seed significant, p < 0.001. No significant variation between levels within trees or tree x level
interaction, p > 0.05.
Max. germination after 48-72 hrs at 15-23°C
60
Polyad germination (%)
Fresh 1 3 7 12 17 Days old
FIG. 2 — Viability over time of pollen placed on feathers at Day 0 and re-sampled at intervals up to 17 days. Material was kept dry and at ambient temperature.
Potential pollen vectors of the mass flowering tree Acacia dealbata, within its natural range in southern Tasmania 19
150
50
No. of flowerheads/m?
) 3} GC Y 10 % 3 A Distance from canopy edge (m)
——— Transect 1
——memene Transect 2
——eee §=Transect 3
24 27 30 33 36 39 42 45 48
FIG. 3 — Dispersion of detached flower-heads on three transects run perpendicular to forest margin across open paddock at Site 4.
Wind dispersal of flower-heads
Head dispersal was surveyed on 17 August after a period of particularly windy weather. On the six previous days, maximum daily gusts at Ellerslie Rd ranged between 44 and 102 km h7!. For transects 1 and 2 which were perpendicular to the forest margin across open grassland, over 80% of heads fell within 15 m of the canopy margin, though occasional heads were still detected at the limit of observation (49.5 m) (fig. 3). The greater variability of Transect 3 could be attributable to the effect of several trees about 30 m away to the side of this transect.
Pod and seed production
Both flowering and mature pod production were essentially uniform within a tree crown as can be seen from the photographs of two trees which flowered heavily at Site 4 (pl. 1). Pod production from the very topmost branches is interesting in thatit seems unlikely that, under the commonly prevailing weather conditions, these very exposed locations would be favoured as feeding sites by any of the insect visitors or even the birds; however, this is speculation. The mean number of full seed per pod was quite uniform among trees except for Tree 3 which was highly parasitised and only averaged 1.4 full seeds per pod, less than half the number of the nearby Trees 4 and 5 (table 6). Among the height levels in the crown there was no significant pattern of variation (p > 0.05, table 6). Although the pods from the top of Tree 5 had fewer seeds than lower in the canopy, it should be noted that this was the earliest maturing individual and it is possible that some seeds were already shedding from the dehiscing pods by the time we made the harvest.
The ovaries of A. dealbata flowers contain an average of 13 ovules (Correia et a/. 2014). In the current study about one-third (4.26) were fertilised and developed to the point they could be classified as a seed, of which an average of 74% or 3.14 per pod were full.
DISCUSSION
The floral biology of A. dealbata is most closely aligned with an insect pollination syndrome; however, the weather conditions during the late winter/early spring flowering season are not conducive to insect flight activity and very few such visitors were observed until late in the flowering season (table 2a). Itappears very unlikely that these numbers were sufficient to have a major impact as pollinators. A more objective determination of this point would require estimation of both flower numbers and the period over which individual stigmas remain receptive and is outside the scope of the present study. The introduced honey bee was the most common insect visitor, as was also the case where the species is growing as an exotic in South Africa (Rodger & Johnson 2013), Portugal (Correia et al. 2014) and Italy (Giuliani et a/. 2016 ), but the maximum number of individuals seen in a single observation period was only 15 across the four trees at the time of peak flowering (table 2a). As in an earlier study of three other species of Acacia in Tasmania (Hingston & McQuillan 2000), small numbers of native bees, flies and beetles were also observed visiting the flowers. Of the native bees, which Bernhardt and Walker (1984) regarded as extremely significant pollinators of Acacia species, we observed only six individual Halictidae and two Colletidae over the whole study period. Stone et al. (2003) reported that over a range of Acacia species native bees
. represented only 1—5% of flower visits, so the generalisation
regarding importance of native bees as pollinators is worth revisiting at least for cool temperate Australia. In a study of two spring/summer flowering Acacia species in Western NSW (Gilpin et al. 2014) only honey bees were found in high abundance and only they and two beetle species carried pollen on their bodies. Syrphid flies, also noted by Bernhardt (1989) as potentially important vectors, were the mostcommon Dipteran visitors to the study trees (table 2a). A. dealbata is the earliest flowering of all Tasmanian acacias and if outcrossing by insects was of critical evolutionary importance then we might expect that selection pressure on the phenology would have caused a shift to later flowering.
20 A.R. Griffin, A.B. Hingston, CE. Harwood, J.L. Harbard, M.J. Brown, K.M. Ellingsen and CM. Young
The species does not produce nectar from either flowers or extra-floral nectaries and this, together with the yellow flowers and distinctive scent, is inconsistent with traditional bird pollination syndromes which are characterised by the production of abundant nectar to support energetic needs, red colour, and little scent (Faegri & van der Pijl 1979, Nadra et al. 2018). However, since some bird species were observed to consistently feed on and among the flowers (table 3) they must clearly be deriving some benefit. Brown Thornbills and Silvereyes have previously been documented working among flowers of other Acacia species (Ford & Forde 1976, Knox et al. 1985, Vanstone & Paton 1988), but in those cases they were feeding primarily from extrafloral nectaries which are vestigial in A. dealbata (Marazzi et al. 2019). However, Silvereyes and a Striated Thornbill Acanthiza lineata also occasionally pecked at flowers of A. pycnantha, and invertebrates and pollen were both suggested as the possible food items targeted (Ford & Forde 1976, Vanstone & Paton 1988). Our data clearly show that small invertebrates are a likely food source because of their abundance within inflorescences of A. dealbata. In a study in Victoria, Haylock and Lill (1988) found that thornbill diet was dominated by Coleoptera and Hymenoptera which we have shown are common on A. dealbata flowering branches at Site 1 (table 2a). The great majority of taxa we collected were within the size range of <4 mm which Tullis e¢ ad, (1982) reported as making up 72% of the diet of two species of thornbill in Western Australia.
‘The importance of the micro-habitat of Acacia flowers to small invertebrates is evidenced by the greater diversity on flowering than non-flowering crowns (appendix 1). On a flowering tree 45% of the total catch was Chrysomelid beetles in larval form, Chironomid midges, and comb- footed spiders (Theridiidae), but of these taxa, only two beetle larvae were present in samples from an adjacent non-flowering tree, where 50% of individuals were Psyllids. These differences are explainable in terms of feeding preferences. Larvae of some species of Chironomid may feed on pollen (Armitage et al. 1995); spiders presumably prey on other small invertebrates which are present in greater numbers on the flowering tree; many beetle larvae including Chrysomelids are adapted to consuming pollen (Bernhardt 1989) and can sometimes cause very significant damage
to flowers of A. dealbata by eating the filaments, anthers and styles (Griffin unpubl. data). In contrast, the Psyllids are sap suckers and presumably vegetative shoots without flowers are also attractive to them. The seasonal pattern of occurrence of the small invertebrates was quite different to that of the larger insect flower visitors. Populations of the former were present within the inflorescences from well before flowering began (table 2b). These increased once trees began to flower, after which the total catch per day across the four sample trees was quite uniform through the rest of the season, though the maximum number was recorded at the time of peak flowering. In contrast very few potential pollinating insects were recorded until the trees reached peak flowering and numbers declined again towards the end of the season (table 2a). The extended availability
of small-invertebrate food explains why Brown Thornbills were also observed among the blossom throughout the complete season (fig. 1).
The foraging behaviour of Green Rosellas at flowers of A. dealbata was very different to that of Silvereyes and Brown Thornbills as they were observed to harvest and ingest whole flower-heads at a stage prior to complete anthesis (fig. 2). Several previously documented cases of bird pollination of nectarless flowers also reported that floral tissues were consumed (Sérsic & Cocucci 1996, Dellinger et a/. 2014, Nadra et al. 2018). We are unable to comment on the relative nutritional value of the floral components and/ or parasitising gall insects, but it is known that two other species of parrot occurring in our study region (Swift Parrot Lathamus discolor and Musk Lorikeet Glossopsitta concinna) intentionally consume and digest the pollen of Eucalyptus (Gartrell & Jones 2001, Hingston et al. 2004a). Green and Eastern Rosellas both have been observed foraging on open flowers of Eucalyptus (Hingston & Potts 2005), so the pollen is likely to be important as a food resource, a conclusion consistent with the decline in the bird visits at Site 1 after peak flowering (fig. 1). Magrath and Lill (1983) observed similar feeding behaviour in Crimson Rosellas (P? elegans) on eucalypts in Victoria, concluding that flower buds and associated gall larvae formed nearly 50% of their seasonal diet. These authors noted that, consistent with our observations, feeding rosellas always drop debris, so relative frequency of occurrence on the ground was used in estimating the diet in that study. Pollination by flower- consuming Meyer's Parrots Poicephalus meyeri has also been documented in African ‘acacias’ (Boyes & Perrin 2009).
Although these two rosella species are destructive foragers, they most likely pollinate numerous flowers as they clamber among the blossom and the prevalence of clippings beneath many flowering A. dealbata trees (table 4) shows that such activities are common and widespread. Given the mass flowering and characteristically low flower: fruit ratio in this and other Acacia species, the loss of some flowers may be an affordable price to pay for the pollination services provided by these species.
The feeding habits of these two functional groups of birds explains their presence in and among the flowers but to act as pollen vectors they must pick up pollen in the process. We were able to recover small amounts of Acacia pollen from the feathers of Green Rosellas and Brown Thornbills (table 5a, 5b) and have demonstrated that once pollen is removed from the anthers it can retain over half its viability for at least seven days (fig. 2), substantially longer than the three days reported by Sedgley and Harbard (1993) for tropical acacia taxa. Presumably this is time enough for birds to make many inter-tree visits before pollen viability is lost. Although both the number of birds sampled and the pollen recovered from those individuals was small, the data support the contention that these birds play a role in outcross pollination. The clip surveys (table 4) found that 57% of the A. dealbata trees across the region had been visited by rosellas which are strong-flying birds capable of many inter-tree movements. However, the numbers of individuals observed foraging on or among the flowers was
Potential pollen vectors of the mass flowering tree Acacia dealbata, within its natural range in southern Tasmania 21
small (table 3). Thornbills and Silvereyes were relatively more numerous at all three observation sites but it seems unlikely that either functional group could have been solely responsible for the total number of pollen transfer events needed to set the observed heavy fruit crop.
Possibility of wind pollination
Though the detached flowerheads have a substantial mass and over open ground were mostly deposited within 20 m of the crowns (fig. 3), this distance is more than enough for pollen transfer within stands of A. dealbata given the windy conditions which are prevalent during the flowering season in this region (Bureau of Meteorology 2018). It remains to be demonstrated that polyads are also blown off the open anthers under some conditions but the literature suggests that this is possible. Flowers of Acacia do not exhibit morphological traits normally characteristic of wind pollinated plants (Sedgley & Griffin 1989, Gibson eg al. 2011) and the polyads which average 46 pm in diameter (Nghiem etal. 2018) are larger than the 25 um that is typical of the wind pollination syndrome (Knox 1979). However, as noted by Kendrick (2003), the disc shape of the polyad may have aerodynamic properties which serve to counteract their relatively large size. Reviews of the pollination ecology of the genus by Bernhardt (1989) and Stone et al. (2003) do not discuss the possibility but there are some records of wind dispersal of Acacia pollen (Moncur et a/. 1991, Smart & Knox 1979, Kendrick 2003, Giovanetti et al. 2018) and allergy to airborne pollen has been reported from.a number of countries (Ariano etal. 1991). Millar eral. (2014) offered
long-distance wind-mediated dispersal of small insects as an -
explanation for their finding of substantial gene flow between dispersed populations of A. woodmaniorum in Western Australia. While Keighery (1980) listed Acacia as being primarily insect pollinated in that region, he acknowledged that bird and wind transference could play a minor role in pollination and noted that “more observations are needed on (pollen vectors) of this important genus”.
Factors determining efficiency of wind pollination are very different from those with biotic vectors. ‘There is no issue of population number in pollen transfer since wind is a more or less general phenomenon in the region during the flowering season of A. dealbata. While biotic vectors would target flowers during feeding, wind dispersion is effectively random in space but with density in the air as the major determinant of the probability that a polyad would land on a receptive style. It is likely that geitonogamous pollination (transfer of pollen between flowers within a single genet) within a tree crown or between ramets of a clone would be a much more frequent outcome than transfer between different genets, so impact of vector type on the breeding system needs to be considered.
Studies of the species as an exotic in South Africa (Rodger & Johnson 2013) and Portugal (Correia et al. 2014) found that A. dealbata is partially self-fertile and demonstrated that autonomous pollination is possible (see also review by Gibson 2011), although Broadhurst ez a/. (2008) found that only outcrossed seed were produced under natural
pollination conditions in populations of the species in New South Wales. Mechanisms favouring preferential development of outcrosses may operate in Acacia as in Eucalyptus (Griffin et al. 1987) but this remains to be demonstrated. If the plants are strongly reliant on biotic outcross pollination in order to set seed and pollinators are scarce relative to the large number of flowers produced, then we would expect to see a patchy distribution of pods within each tree crown. The pod -and seed production data are therefore useful in gaining an appreciation of the likelihood of such pollen limitation. We were not able to quantify total flower or pod crops per tree but ~ it was evident from inspection that pod set in 2018 was generally both heavy and uniformly distributed within the crowns to the very topmost branches (pl. 1 and table 6). The consistent uniformity of production of full seed pods throughout the crown (table 6) strengthens the possibility that wind pollination may be important and is in contrast to Eucalyptus globulus, a common dominant tree species in southeast Tasmania which is known to be pollinated by both birds and insects (Hingston et al. 2004b). In that species Hingston and Potts (2005) found significantly less flower-visiting bird activity in the lower than higher halves of the crowns and Patterson et al. (2004) showed this pattern was associated with higher outcrossing rates for the seeds from the upper part of the canopy. In our study, observed population mean number of full seeds per pod of 3.14 (table 6) is substantially higher than the maximum mean of 1.2 found in the ten NSW populations studied by Broadhurst and Young (2006), or the 1.04 in an exotic population in South Africa (Rodger & Johnson 2013) and _ can be taken as another indication of probable high levels of outcrossing. Genetic analysis of seed samples from Site 4, to be published elsewhere, has confirmed this assumption. The mating system is definitely strongly outcrossing (t = 0.89 + 0.92) (R. Vaillancourt unpubl. data).
In summary, the study failed to definitively identify any one major pollinator of A. dealbata in this environment yet we infer from the heavy and uniformly distributed pod crops and from the genetic analysis, that outcrossing must be occurring. The species is best viewed as having a generalist pollination system, a conclusion reached by the study of Montesinos et al. (2016) in exotic populations in Portugal and consistent with many other plant species
“in southern Tasmania (Hingston & McQuillan 2000).
Evolution of reproductive attributes amenable to pollination by a range of different vectors may be of adaptive advantage (Hingston & McQuillan 2000, Ollerton et a/. 2009), with the consequence that current major pollen vectors cannot be predicted from consideration of floral traits alone.
ACKNOWLEDGEMENTS
The authors wish to acknowledge Elise Jefferies of Hobart City Council for permission to conduct the studies at Knocklofty Reserve, Astrid Wright of the Friends of Knocklofty for access to historical records of vegetation management, Dr David Paton for advice on bird observa-
22 ALR. Griffin, A.B. Hingston, CE. Harwood, J.L. Harbard, M.J]. Brown, K.M. Ellingsen and C.M. Young
tions, and Geoffand Janet Fenton for bird data from Longley. Mist-netting was conducted under the following permits held by CMY: Animal Ethics approval from University of Tasmania (A0015838), Australian Bird and Bat Banding Scheme project licence (2833-1), scientific permit from the Tasmanian Department of Primary Industry, Parks, Water and Environment (FA 18153) and Hobart City Council research permit (03-2018). We also thank the anonymous reviewer for their helpful comments.
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(accepted 22 July 2020)
24 ALR. Griffin, A.B. Hingston, CE. Harwood, J.L. Harbard, MJ]. Brown, K.M. Ellingsen and C.M. Young
APPENDIX 1
Invertebrate survey data from branch beating and observation on four flowering trees and one non-flowering tree. Total numbers across all trees and seven observation dates.
Class Order Family Common name State Invertebrates Invertebrates Invertebrates Total BEATING BEATING OBSERVED (flowering (non- (flowering) (flowering) trees only) flowering tree) Insecta Blattodea Ectobiidae Cockroach Adult 0 2 0 2 Insecta Coleoptera Attelabidae Leaf rolling Adult 0 2 0 2 weevils Insecta Coleoptera Cerambycidae Longicorns Adult 0 0 1 1 Insecta Coleoptera Chrysomelidae Leaf beetles Adult/ 2 61 6 67 Larvae Insecta Coleoptera Cleridae Clerid beetles Adult 0 2 0 2 Insecta Coleoptera Coccinellidae Ladybirds Adult 0 23 1 24 Insecta Coleoptera Curculionidae Weevils Adult 0 0 1 l Insecta. Coleoptera Latridiidae Minute Adult 0 30 0 30 scavenger beetle Insecta Coleoptera Nitidulidae Sap beetles Adult 0 3 0 3 Insecta Coleoptera Scarabaeidae Scarab beetles Adult 0 0 u 7 Insecta Coleoptera Tenebrionidae Darkling beetles Adult 0 1 0 1 Insecta Diptera cf. Root maggot Adult 0 0 1 1 Anthomyiidae flies Insecta Diptera Cecidomyiidae Gall midges Adult 0 9 0 9 Insecta Diptera Chironomidae —_ Midges Adult 0 106 19 125 Insecta Diptera Chloropidae Frit flies Adult 0 9 0 9 Insecta Diptera Empididae Dance flies Adult 0 5 0 5 Insecta Diptera Lauxaniidae Lauxaniid flies Adult 0 0 1 l Insecta Diptera Phoridae Scuttle flies Adult ] 3 0 3 Insecta Diptera Sciaridae Fungus gnats Adult 0 15 1 16 Insecta Diptera Syrphidae Hoverflies Adult 0 f 31 38 Insecta Diptera Tachinidae Tachinid flies Adult 0 0 3 3 Insecta Diptera Diptera Adult 0 8 0 8 Unknown Insecta Hemiptera cf. Callipappidae Bird of paradise Adult 0 0 1 l flies Insecta Hemiptera Cicadellidae Leafhoppers Adult/ 3 7 0 7 nymph Insecta Hemiptera Miridae Plant bugs Adult/ ‘J 75 1 76 nymph Insecta Hemiptera Monophlebidae — Giant scales Adult 0 0 1 1 Insecta Hemiptera Pentatomidae Shield bugs Adult 0 0 1 1 Insecta Hemiptera Pseudococcidae Mealy bugs Adult 0 3 0 3 Insecta Hemiptera Psyllidae Psyllids Adult/ 16 74 0 74 nymph Insecta. Hemiptera Reduviidae Assasin bugs Adult 0 I 0 1 I . ‘. : nsecta Hemiptera Tingidae Lace bugs Adult 0 9 0 9
Potential pollen vectors of the mass flowering tree Acacia dealbata, within its natural range in southern Tasmania
25 Class Order Family Common name State Invertebrates Invertebrates Invertebrates Total BEATING BEATING OBSERVED (flowering (non- (flowering) (flowering) trees only) flowering tree) Insecta Hymenoptera Apidae Bees Adult 0 0 21 21 Insecta Hymenoptera Bethylidae Aculeate wasps Adult 0 2 0 2 Insecta Hymenoptera Braconidae Braconid wasps Adult 0 5 2 7 Insecta Hymenoptera Colletidae Short-tongued Adult 0 1 2 3 bees Insecta Hymenoptera Diapriidae Parasitoid wasps Adult 1 1 0 1 Insecta. Hymenoptera Encyrtidae Parasitoid wasps Adult 1 7 0 7 Insecta Hymenoptera Eulophidae Parasitoid wasps Adult 0 12 1 13 Insecta Hymenoptera Formicidae Ants Adult 1 11 2 13 Insecta Hymenoptera Halictidae Burrowing bees Adult 0 0 6 6 Insecta. Hymenoptera Ichneumonidae — Ichneumon Adult 0 0 11 11 wasps Insecta Hymenoptera Platygastridae Parasitoid wasps Adult 1 146 1 147 Insecta. Hymenoptera Pteromalidae Parasitoid wasps Adult 1 9 0 9 Insecta. Hymenoptera Tiphiidae Flower wasps Adult 0 0 2 2 Insecta Hymenoptera Hymenoptera Adult 0 6 7 13 Unknown Insecta. Lepidoptera Geometridae Loopers Larvae 0 1 0 1 Insecta Lepidoptera Lymantriidae Tussock moths Larvae 0 1 2 3 Insecta Lepidoptera Ocecophoridae Concealer moths Adult 0 1 0 1 Insecta. Lepidoptera Lepidoptera Larvae 0 4 0 4 Unknown Insecta Neuroptera Chrysopidae Green lacewing Larvae 0 1 0 1 Insecta Neuroptera Coniopterygidae Dusty wings Adults 0 18 1 19 Insecta Neuroptera Hemerobiidae Brown lacewings —_ Larvae 0 3 0 3 Insecta Thysanoptera Thysanoptera Thrips Adult 0 8 1 9 Unknown Araneae Araneidae Orb weavers Adult/ 0 1 0 1 spiderlings Araneae Clubionidae Sac spiders Adult/ 0 2 0 2 spiderlings Araneae Salticidae Jumping spiders Adult/ 0 1 0 1 spiderlings Araneae Theridiidae Comb-footed Adult/ 0 33 0 33 spiders spiderlings Araneae Thomisidae Crab spiders Adult/ 0 46 1 47 spiderlings Araneae Araneae Adult/ 2 7 0 7, Unknown » spiderlings Acari Unknown Mites 2 14 0 14
! For photographic records of most taxa by K. Ellison see: https://www.flickr.com/photos/zosterops/albums/72157698885625455/pagel
26 ALR. Griffin, A.B. Hingston, CE. Harwood, JL. Harbard, M.J. Brown, K.M. Ellingsen and C.M. Young
APPENDIX 2 Daily records of bird species observed visiting A. dealbata crowns over a 10-minute observation period at each of five observation points at Knocklofty (Site 1). Ambient conditions and flowering status of observed trees are shown for each observation point.
lite Hite gy sales aa Days from start (26 June) point flowering
I Oo A Al a aE 20) 28) 2 OW GG WD
1 Brownlhornbil ieee sees ee
me TT ieee Poe
Yellow = pe Wattlebird
Yellow-throated 1 ee Honeyeater
Other IED a Le — ee — 1 1 Ee Flowering 0 0 0 0 0 0 2° 5 WD Ww DW Go a io
(% receptive)
2 Brownslhornbill Beet em a Green Rosella = = ne ae
Yellow = eae Wattlebird
Other 1 1 1 So re es a ES l
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Papers and Proceedings of the Royal Society of Tasmania, Volume 154, 2020 27
THE TOURIST AND TOURISM GAZES UPON CRADLE MOUNTAIN AND FREYCINET NATIONAL PARK
by Chantelle Ridley (with four text-figures and four tables)
Ridley, C. 2020 (9:xii): The tourist and tourism gazes upon Cradle Mountain and Freycinet National Park. Papers and Proceedings of the
Royal Society of Tasmania 154: 27-35. ISSN: 0080-4703. 6 Braelands Court, South Hobart, Tasmania, Australia 7004. Email: chantelle.ridley17@gmail.com
The natural aesthetic resource is an important element of natural and cultural heritage and an attractor of tourists. It is important for heritage management to understand the scenic attractors of tourists. Photographs of Cradle Mountain (150) and Freycinet National Park (149) were collected from a range of sources to determine whether there is a constancy of gaze between those who promote tourism and those who tour, and between the two visually distinct destinations. Publicly available images from four different sources were used to compare content attributes and mise en scéne attributes between localities using Chi-square and ANOSIM. The photographs were then ordinated using the same attributes, and the results were displayed using photographic average composites. The Discover Tasmania and Google Images photographs were similar, both better conforming to advanced compositional principles compared to the Instagram and promotional images, which were similar, especially in the featuring of people in landscape foregrounds. There may bea reciprocal interaction between promotional and tourist images, rather than a one-way process. The contrasting features in the images from the two places were largely a product of the very different physical environments. However, the photographs at Freycinet were taken from several geographic locations, whereas the vista of Dove Lake and Cradle Mountain dominated all image sources at Cradle Mountain. The content analysis of the images was consistent between places, except where a feature of an artefact or natural feature created opportunity for artistic expression. Key Words: aesthetic resource, content analysis, Discover Tasmania, Google Images, Instagram, mise en scéne, images, promotional
images.
INTRODUCTION
“Nature was tamed, put into perspective with, and by, the human eye, as a landscape picture, a single vision of order.” (Urry & Larson 2011, p. 131)
Wilderness landscapes, once terrifying and depressing, are now places for pleasure, solitude and contemplation (Schirpke et al. 2013). Natural aesthetic resources that tend towards the sublime (Beza 2010, Kirillova et a/. 2014) are an intangible asset in protected areas (Mendel & Kirkpatrick 1999) as they attract tourists, and therefore economic development.
In 2019, most tourists have the technological means to immediately and globally communicate their arrival at a tourist icon through social media via image and hashtagged caption. The presence of tourists at scenic icons may be motivated by the images of previous visitors, or by the images presented by professional agents. These sources indicate destinations in which tourists can view the extraordinary (Stylianou-Lambert 2012). Phelps (1986) classifies promotional images as secondary images and images generated by tourists as primary. Tourists are regarded as passive consumers of scenes by replicating the images they see in promotional material; or as active participants, recreating scenes through the lens of their own experiences (Stylianou-Lambert 2012). The latter perspective may be particularly apposite to social networking sites, such as Instagram.
There are few published comparisons between primary and secondary images (Stephchenkova & Zhan 2013, Paiil . i Agusti 2018). Sources are usually treated independently and are examined through the lens of a single discipline (Stylianou-Lambert 2012). It is important to examine primary and secondary sources though a multidisciplinary lens, to extend our understanding of tourist behaviour and perception. One widely used method to quantify visual preferences for landscapes is content analysis (Linton 1968, Wang et al. 2016, Tieskens et al. 2018, Pickering et al. 2020). Content analysis examines landscape elements within an image, such as quality and quantity of vegetation, distance to vegetation, water bodies (Shafer & Brush 1977, Patsfall et al. 1984) and mountains (Mendel &
Kirkpatrick 1999).
Integrating content analysis with mise en scéne techniques may reveal hidden relationships previously not studied in destination imagery. Mise en scéne, or ‘to appear on stage’ is a traditional theatrical technique used to convey narrative and mood, via composition, lighting, setting and clothing (Giannetti 2014). This same technique is applied cinematically and photographically, within a frame. Preferences for, and perceptions of, desirable landscapes are influenced by position on the continuum from realistic to abstract representation in destination images (Daniel & Meitner 2001).
The social media component of the study was conducted using the smartphone image-sharing platform ‘Instagram’, which allows users to share images publicly or privately.
28 Chantelle Ridley
Instagram was chosen because of its popularity in the current social climate (Choi & Sung 2018) and its use in recent studies on its application by tourists (University of Tasmania 2019). However, using Instagram has limitations as the samples include only images from accounts that have been made publicly accessible. Images are in Instagram using keywords that relate to either a title (user), geotag (location) or a hashtag (category). Location can easily and automatically be applied to an image if the GPS services are activated on the device. Hashtags are used to categorise the image to reach niche demographics.
Data visualisation is the transformation of quantitative or qualitative data into graphic representation. When large
and complicated data sets are transformed into aesthetic graphics, information becomes accessible, comparable and better understood among general audiences (Felton et al. 2016).
Photographic averaging composites are a post processing method that aligns and blends photographs together (Felton et al. 2016). This method has been widely used to illustrate specific collectives, such as in portraiture to find the average face and the similarity of photographs taken of tourism icons (Felton er al. 2016, Bergh er al, 2018).
In this study the contents and mise en scene of images were compared to determine whether there is a constancy of gaze between those who Promote tourism and those who tour, and between two visually distinct destinations, I determined whether contents and artistic designs differ between images collected from four distinct sources: printed Promotional material (i.e., tourism brochures), Discover Tasmania Instagram site (henceforth Discover Tasmania), Google Images and Instagram. I used the two most iconic national park destinations in Tasmania: Freycinet
and Cradle Mountain. Photographic average composites |
illustrate the differences between sources, ©
METHODS The study area
Tasmania (41.640079°S, 146.315918°E) is an island state of Australia, located 240 km south of the mainland (fig. 1). Tasmania has a population of 529,903 (Australian Bureau of Statistics 2018) ina total area of 68,401 km2 (Geoscience Australia 2020). The rich and distinctive geodiversity and biodiversity of the island result in natural landscapes of great beauty. Tasmania has 42% (2.9 million ha) of its land dedicated to national parks and reserves (Tasmania Parks & Wildlife Service 2020) with 1.58 million ha of this in the Tasmanian Wilderness World Heritage Area, declared for both cultural and natural values (DPIPWE 2016). Tourism campaigns promote natural features, gourmet produce, wildlife and the arts (Tourism Tasmania 2016). Before the impact of the Covid-19 pandemic, tourism directly and indirectly contributed $3.03 billion (10.4%) to Tasmania’s Gross State Product (Tourism Tasmania 201 9a). In 2017-2018, 1.32 million people visited the state with 307,000 international visitors and 1.09 million arriving
FIG. 1 — The island state of Tasmania showing the study areas of Freycinet National Park and Cradle Mountain-Lake St Clair National Park.
from interstate (Tourism Tasmania 201 9a, b). International and interstate tourists on holiday are more likely to visit a national park than those visiting Tasmania for business activities or to visit friends and relatives (Tasmania Parks
& Wildlife Service 2019). Site selection
‘Two popular, and environmentally different, tourism icons were chosen for the study (fig. 1). The coastal Freycinet National Park has the highest number of visitors of any national park in the State (Tasmania Parks & Wildlife Service 2019). The subalpine/montane Cradle Mountain, located to the west, is the second most visited location in the national park estate (Tasmania Parks & Wildlife Service 2019).
Selection of images
Images were selected if they satisfied the following criteria: * images were taken within the park boundary and
viewpoints were accessible without overnight camping; * images were of landscapes.
Images were collected from tourist information brochures, social media and the web using the Google Images search engine. All images were collected in the 2018-2019 summer peak tourism season. All data were manually retrieved.
Printed promotional material was used to obtain the images that private companies used to attract customs ers. This material consisted of brochures advertising accommodation and private tours. Printed promotional material was collected from three tourist information centres in Tasmania in February 2019. All images from the study areas were used.
A Google Images search on the web was conducted using variants of the locality names. The keywords ‘Freycinet
The tourist and tourism gazes upon Cradle Mountain and Freycinet National Park 29
and ‘Cradle Mountain’ received the highest number of images. It was assumed that images that first appeared in the search would be more likely to represent professional material, as advanced development of their website/image allowed the image to be there in the first place. Images were sampled sequentially from the first image.
For Instagram (i.e., a photo and video sharing social networking service owned by Facebook), it was decided that location was to be used to select images as more images per day were uploaded using location than those hashtagged. Images were selected from ‘Freycinet National Park’ and ‘Cradle Mountain’, between 1 October 2018 and 31 March 2019, using a random number generator.
Tourism Tasmania’ Official Instagram account “Discover Tasmania (https://www.instagram.com/tasmania/) was used to represent destination images promoted by the State Government. ‘Discover Tasmania is created through user- generated content where hashtagging #discovertasmania or #tassiestyle, gives permission for the organisation to use the image in online promotions.
Two hundred and ninety-nine images were sampled (table 1). All were freely available to the public. One hundred images were from promotional/professional sources, 100 from recreational and 99 from a professional source using recreational user-generated images. A running mean for the presence of water in randomly selected images from the selection was calculated. The presence of water in an image equalled one and its absence zero. This mean stabilised at around 25 images. The process was repeated with mountains, with the same outcome.
Content analysis — location and subjects
The most popular viewpoints for each media type at Cradle
and Freycinet were determined using the author's know- ledge of the areas. Local knowledge was required to assess the location of the image. Location was coded as marine, ifit was taken on the water, and by the nearest geographical feature if terrestrial. When available, captions and hashtags were used to cross-validate these data. The percentage of images taken at each geographical location in each national park was calculated to determine which were the most popular sites to photograph across all media sources and within and between national parks (fig. 2a and 2b).
The presence/absence of landscape elements were recorded. These were: water bodies, mountains and vege- tation as a feature (e.g., tree trunks, shrubbery, cushion
plant). The measurement method of Oktas was used to determine cloud cover and as an estimate of the weather conditions: clear: 0-10%, scattered: 10-50%, broken: 50— 90%: overcast: 90-100%. Artefacts included menuments (lighthouse, shed, accommodation, hut), infrastructure (boardwalk, trail, railing, sign), transportation (boat, car, plane, kayak, paddleboard), natural features (rock, geology, driftwood, milky way), weather phenomena (snow, mirrored reflections on still water), animals and toys.
Mise en scéne criteria
The mise en scéne component of lighting, conveying mood, tone and focus within the frame was captured in six time-of- day categories (sunrise, early morning, day, late afternoon, sunset, night). Shot and camera proxemics describe how much of the subject is in the frame and how much of the human subject is within the frame. Each image was classified as either terrestrial, marine or aerial. The nature of the composition of the image was recorded for each of: the rule of thirds in which the subject matter is organised in nine equal rectangles, with important details placed off centre where the lines intersect; the use of the golden rule; the use of geometric features in the image; the use of features as leading lines; central location; and, split design in which
there is symmetry in the image. Three characteristic depths of field were recorded.
Data analysis
Chi-squared was used for individual class variables to determine whether there was deviation from random in data related to source (promotional, Instagram, Discover ‘Tasmania and Google Images) or location (Freycinet, Cradle Mountain). Pearson’s Method was used to determine the p value. These analyses were done in Minitab18. Non-metric multidimensional scaling was used to ordinate the images using the qualitative (1/0) content and mise en scéne variables listed above. The default options in DECODA were used for this process. An ANOSIM analysis of differences between the combination of places and sources was undertaken in DECODA using the scores on the four dimensions of the ordination with the use of 10,000 permutations to calculate the probabilities associated with the R statistic. In all analyses the null hypothesis was
“rejected if p < 0.05.
TABLE 1 — The most photographed locales at Cradle Mountain and Freycinet National Park by source, showing the number of images for the source by locality.
Image source
Freycinet National Park
Cradle Mountain
No. Most Frequent No. Most Frequent Promotional 7/22 Wineglass Lookout 6/23 Dove Lake Google Images 9/28 Freycinet Peninsula 5/27 Dove Lake Instagram 11/50 Wineglass Lookout 8/50 Dove Lake Discover Tasmania 10/49 Mount Amos 11/50 Dove Lake
30 Chantelle Ridley
y fo = Legend /* Pencil f Pine S Cradle — * Valley F Boardwalk Cradle e Valley Lake Lilla Crater @ Dove Lake lake. Marions Lookout Cradle ® Plateau ¢ Hansons Peak e Screenshot Cradle . Mountain Cradle Mountain - Lake St Clair National Park f * Barn NS Bluff — A 2 km
Legend
@ 11-15%
Friendly
° Beaches \ @ 6-10%
© 1-5% ° <0.99%
t Tasman
\ Sea
Bluestone Bay
} Cape
fee * Tourville Richardsons Beach 4 Sleepy Ba Honeymoon Bay @ : Pyenoy, ae Seis Mount 4 @ Amos Wineglass Bay @
Lookout
Screenshot
Wineglass Bay Beach 4 ® Wineglass Bay
Hazards Beach*
Freycinet National
Park \ Mount N Freycinet +
2 km
* Mount B Graham
FIG. 2 — Percentage of images taken at geographical locations across all media sources at (A) Cradle Mountain and
(B) Freycinet, Tasmania.
Creation of photographic average composites
The photographic average composites (PAC) were based on the significant results derived from the mise en scéne and content analysis. The process was applied to one or a few locales with the highest frequency of images. The iconic landscape value informed the centre point. Having this visual anchor creates greater harmony in the PAC and a pivot for the remaining scene to play out.
To construct the PAC, landscape long shot images of the most photographed locale were selected from each source type. Printed promotional material was not used to construct a PAC as it required digitisation and there was excess visual noise with the graphic design.
Images were not resized so as to retain the quality of the information. PAC were constructed on a large blank project and were not cropped in the final presentation. This was both an aesthetic and data integrity decision, as the final presentation revealed information about the original orientation of the images. The one exception to this rule were the Google Images shots of Freycinet. These images were aerial and therefore did not have an optimal viewpoint or consistency in landscape shot types. Due to a low number of images, all shot types had to be utilised. ‘The decision to resize the images was based on aesthetics, as the alterations created a more visually harmonious PAC.
Images that are closest to the front of the stack provide the details (Felton er al. 2016).
RESULTS
Freycinet had a higher number of locales photographed compared to Cradle Mountain (table 1, fig. 2). Thirty percent of the 299 images that were photographed were at Dove Lake below Cradle Mountain, followed by Mount Amos (14%), Wineglass Bay Lookout (8%) and Honeymoon Bay (6.4%) all at Freycinet. The most photographed locale was constant between sources for Cradle Mountain (table 1).
The stress for the four-dimensional ordination was 0.163. The overall ANOSIM R value for the differentiation by source and place was 0.0276 (p = 0.012). There was significant differentiation between all combinations of place and medium with Discover Tasmania and Instagram images (table 2). There was also significant differentiation between all combinations of place and medium with promotional images and Google Images (table 2). Thus, Discover Tasmania images were similar to Google and promotional images. Instagram images were also similar to Google and promotional images. Promotional images and Google Images shots were similar to Discover Tasmania and Instagram images (table 2).
The tourist and tourism gazes upon Cradle Mountain and Freycinet National Park 31
TABLE 2 — Combinations of place and source that were significantly different on the four-dimensional ordination scores for all qualitative variables (ANOSIM R-statistic).
DF DC IF IC PF PC GF GC DF i * * 4K oa 2 i = DC * xX * KK ia a a 2 IF * * xe * = ‘ es a IC 2K 210K * xX S 2 s ee PF a a = me X * OK 210K PC us on ~ jak * Xe 7K * GF a es ve a 20K OK XG OK GC a a 4s = OK * 20K X
*™* = p < 0.001, ** = p < 0.01, * = p =/< 0.05, - = p > 0.05. X marks no results as self-comparison. DF = Discovery Tasmania/Freycinet, DC = Discovery Tasmania/Cradle, IF = Instagram/Freycinet, IC = Instagram/
Cradle, PF = Promotional/Freycinet, PC = Promotional/Cradle, GF = Google/Freycinet, GC = Google/ Cradle.
TABLE 3 — The percentage frequency of content and mise en scéne variables by source for those that vary significantly (Chi-squared). Variable Discover Google Instagram Promotional P-Value _____ Tasmania _ Images Extended long shot 14 29! 6 20 <0.001
Geometry 34 20 22 4 <0.001 Thirds 17 51 32 76 <0.001 Terrestrial 88 82 95 98 0.012 Water 82 98 89 82 0.020 Mountains 87 68 89 0.001 Day 44 0h 86 93 <0.001 Very wide shot figure 33 ll 16 38 <0.001
' The higher percentage is shown in bold.
TABLE 4 — The percentage frequency of content and mise en scéne variables by place for those that varied significantly (Chi-squared).
Variable Cradle Freycinet P-Value Geometry vw 2. oon Spite 12 5 0.023 Terrestrial 100 81 <0.001 Aerial 0 13 <0.001 Water . 78 97 <0.001 Mountains 86 Vidi 0.035 Scattered clouds 26 42 0.003 Broken clouds 25 15 0.046 Landscape vegetation 92 97 0.041 Feature vegetation 16 7 0.011 Medium close-up 11 3 0.006 figures
Boardwalk” 12 5 0.023 Rock 13 23 0.015 Reflection 7 : 0 _ 0,001
' The higher percentage is shown in bold.
32 Chantelle Ridley
FIG. 3 — Photographic average composites (PAC) of Dove Lake, Cradle Mountain, Tasmania. PAC were created from the overlay of multiple images sourced from (A) Discover Tasmania; (B) Instagram; and (C) Google Images search.
‘The Discover Tasmania images had the highest percentages of geometric design (table 3). The Google Images shots had the highest percentages of extended long. landscape shots and the greatest proportion of presence of water (table 3). The promotional images had the highest proportions of composition by thirds, terrestrial scenes, mountains, daytime shots and very wide shot figures (table 3).
Most of the differences between the images taken at Cradle Mountain and those at Freycinet reflected differences in their physical environment, some possible exceptions being more medium close-up figures and split images at Cradle Mountain and more aerial shots and use of geometric composition at Freycinet (table 4).
The PACs of Cradle Mountain differed in the contrast between dawn and dusk skies in the Discover Tasmania images (fig. 3A), compared to clear daytime skies in the Google (fig. 3C) and Instagram images (fig. 3B), and the wider frame and greater complexity of the Google
PAC compared to the others. At Freycinet, the most popular Discover Tasmania image was from Mt Amos, with Wineglass Bay sitting like a lake below, framed by mountains (fig. 4A). The most popular Instagram image
was from the Wineglass Bay lookout (fig. 4B). The most
popular Google Image was of Wineglass Bay from the south (fig. 4C).
DISCUSSION
This study highlights the complex feedbacks between promotional/ professional images and tourist images. The current rise in user-generated content for advertising (or ‘influencing’ as it has been repackaged) through social media, has added complexity into image sources and their feedbacks beyond the simple influence model (Stephchenkova & Zhan 2013).
It was expected that Google Image shots and promotional material would represent the professional aspect of the study, and Instagram and Discover Tasmania would represent the perceptions of the tourist. However, the images from Discover Tasmania were very similar to professional material and promotional images. Despite Discover Tasmania images being sourced from Instagram, the former had a closer relationship to the artistic Google Images than
| | | q
The tourist and tourism gazes upon Cradle Mountain and Freycinet National Park 33
FIG. 4 — Photographic average composites (PAC) of (A) Mount Amos; (B) Wineglass Bay lookout; and (C) Freycinet Peninsula at Freycinet National Park, Tasmania. PAC were created from the overlay of multiple images sourced from (A) Discover Tasmania; (B)
Instagram; and (C) Google Images searches.
to those in the Instagram pool. As Instagram were more related to Google Images and promotional material, it
_ is likely that the images from the Instagram pool were
those that conformed to mise en scéne principles and a particular aesthetic related to time of day. Google Images and promotional material were related to Instagram and Discover Tasmania, emphasising that there is a complicated feedback process between image sources.
While tourists may be influenced to seek the reality of an image, they may not necessarily be able to seek the optimal photographic timing (Stylianou-Lambert 2012). because of a short visit ora lack of compositional skills. The Discover Tasmania PAC of Cradle Mountain is reminiscent of paintings from the Romantic period containing uncultivated and undeveloped landscape, mood lighting, warm hues and figures dwarfed by the landscape (fig. 3a). The romantic gaze symbolises solitude and undisturbed natural beauty (Urry 2005, Pan et al. 2014). Tourism images have been also been Sound to prefer warmer hues (Yu et al. 2020).
The high degree of similarity of promotional material to Instagram shots may indicate that the creators of the material have a strong understanding of tourist preferences or that images used in promotions were created by tourists. User-generated content is believed to have high authenticity, and therefore more likely to induce feelings and behaviours generated by emotions such as envy and desire than more professional work (Hajli et a/, 2018). Tourists, therefore, may be both the consumer and the producer (Stylianou- Lambert 2012).
Previous studies have highlighted that the perception of beauty is influenced by social and cultural climate (Urry & Larsen 2011). Natural features, artefacts and photographic technique were largely constant between the two tourist icons, suggesting a constancy of society and culture. Natural features such as vegetation and mountains in this study were depicted using geometric shape and symmetry. Natural features such as the curvature of a beach and the mirrored reflection of a lake senile a strong base for composition.
34 Chantelle Ridley
Tourists desire the unspoilt and remote (Stylianou- Lambert 2012), preferably containing relative relief and water (Mendel & Kirkpatrick 1999). Indicators of development are often omitted (Stylianou-Lambert 2012). However, I sampled images that were taken by tourists that featured artefacts. Artefacts, such as wooden boardwalks, when snaking off into the distance or between trees, can have aesthetic appeal. The information from tourist images
can help architects design artefacts that are less obtrusive, ©
or even attractive, in a landscape.
Discover Tasmania had a high incidence in traditional landscape techniques of advanced composition and conscious timing of day for optimal lighting. As they are mise en scéne elements, it could be inferred that Discover Tasmania was biased towards ‘mood’ images, which is reinforced by the PAC. The aquamarine water and white sand beaches highlighted in the PAC reveal that colour, hue, brightness and saturation is a mise en scéne element that is worth consideration in future studies (Yu et al. 2020).
Google Image’s advanced landscape camera shots, perspective and inclusion of artefacts and landscape elements, reflects advanced photographic equipment and technique. The traditional photographic landscape technique is further reflected in the homogeneity of landscape orientation in the PAC. The mise en scéne in the Google Images shots contrasts with Discover Tasmania in offering a new perspective and enhanced landscape detail. Although time of day did not differ between Freycinet and Cradle Mountain, visual analysis of the PAC reveals that the average time of day was early in the morning when light was still of photographic quality. Landscapes that contained mountains and water, were more desirable than the exclusive framing of a mountain or water Gridien et al. 2016), while beaches that are deserted and pristine are highly desirable (Stylianou-Lambert 2012). The rustic shed at Dove Lake adds further appeal, like water, by softening the sharpness of the mountain.
Promotional material was similar to Google Images shots in relation to perspective and landscape elements. Mountains were found to be of high incidence; however, the limitation of this finding is that, at Cradle Mountain, the mountain is of iconic landscape value, whereas the mountain range at Freycinet serves more as a backdrop to the iconic landscape value of Wineglass Bay.
Instagram contrasted with Google Images, promotional material and Discover Tasmania in that the content was centralised around a human figure in the landscape. A mid shot places emphasis on the figure while keeping the background visible. The tourist gaze produces images that allow one to be seen in the desirable location (Hajli et al. 2018). It is striking that the PAC are very similar in visual appearance between Freycinet and Cradle Mountain. The images are clustered together, suggesting that the majority are taken from a similar viewpoint; the overall colour of the images is similar as majority of images are taken during the day and adhere to the traditional landscape format. ‘The PAC reaffirm the aforementioned notion that tourists travel to see the iconic landscape value irrespective of the time of day. Image conventions are passed on through
advertising and promotional material, influencing the tourist gaze (Stylianou-Lambert 2012). As an example, the Instagram and Google PAC bear strong a similarity in framing, orientation and content. It could also be argued that these visual conventions were established in painting, decades before the invention of photography (Urry &
Larsen 2011).
An unexpected finding of this present study, revealed by the PAC, was the influence of photographic equipment on the tourist gaze. This effect is most clearly illustrated in the Cradle Mountain PACs which successively shorten in scene down the cascade of technical ability from Google Images, to Discover Tasmania to Instagram. When comparing the Cradle Mountain and Freycinet Instagram PACs, it is
striking that they bear such a strong resemblance. Visualisation of data through the PAC technique is a
new method to validate content and mise en scéne analysis. It is an exciting way to reveal patterns and relationships previously not considered and to visualise data sets for
science communication.
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(accepted 30 September 2020)
Papers and Proceedings of the Royal Society of Tasmania, Volume 154, 2020
BLACK RATS ERADICATED FROM BIG GREEN ISLAND IN BASS STRAIT, TASMANIA
by Susan Robinson and Wayne Dick (with four text-figures and four tables)
Robinson, S. & Dick, W. 2020 (9:xii): Black Rats eradicated from Big Green Island in Bass Strait, Tasmania. Papers and Proceedings of the Royal Society of Tasmania 154: 37-45. ISSN: 0080-4703. Biosecurity Tasmania, 13 St Johns Avenue, New Town, Tasmania
7008, Australia (SR*); Tasmania Parks and Wildlife Service, Furneaux Field Centre, 2 Lagoon Road, Whitemark, Tasmania 7255, Australia (WD). *Author for correspondence. Email: sue.robinson@dpipwe.tas.gov.au
Big Green Island is a 129-ha Nature Reserve and part of the Furneaux Group of islands in Bass Strait, southeastern Australia. Beginning in April 2016, Black Rats Rattus rattus were targeted for eradication using poisoning with 50 ppm brodifacoum wax blocks via a 25 x 25 m grid of bait stations (16 stations per ha) checked daily for a four-week period followed by three one-week visits over an eight-week period. After six weeks, rodent chew-cards were deployed exposing pockets of rat activity on the island. Island-wide monitoring led to the capture of six rats, the last known rat being killed in November 2016. Monitoring for signs of rats proceeded for a further two years and
the island was declared rat-free in November 2018. The project encompassed partnerships between government agencies, industry and non-government organisations, and involved a significant volunteer contribution.
Key Words: island eradication, invasive species, rodent, Black Rat, Rattus rattus, brodifacoum, bait station.
INTRODUCTION
In 2006 the Australian Government listed exotic rodents (Black or Ship Rats Rattus rattus, Norway or Brown Rats R. norvegicus; Pacific Rats R. exulans; and House Mouse Mus musculus) on islands as a key threatening process under the Environment Protection and Biodiversity Conservation Act 1999 (EPBC Act). A threat abatement plan for invasive rats and mice on islands less than 100,000 ha (Commonwealth of Australia 2009) was subsequently developed. The state of Tasmania has over 600 vegetated islands around its coast- line, with at least 39 known to have invasive rodents and probably more with unrecorded populations.
Tasmania’s first island eradication for rodents (Black Rats) was on Fisher Island (1 ha) in 1974 (Serventy 1977). The next was Macquarie Island (12,800 ha) for Black Rat and House Mouse (plus European Rabbit Oryctolagus cuniculus) in 2011 (Springer 2016). Fisher Island again had rodents eradicated in 2013 (House Mouse and Black Rat, S. Robinson unpublished data).
The Tasmanian Parks and Wildlife Service (PWS) identified there would be significant environmental and economic gains in eradicating Black Rats from Big Green Island Nature Reserve (129 ha) in the Furneaux Group, Bass Strait. The two islets immediately north of the main island were considered potential habitats for small species of
seabirds (e.g., Fairy Tern Sterna nereis, White-faced Storm °
Petrel Pelagodroma marina and Common Diving Petrel Pelecanoides urinatrix) which were likely to be prevented from successfully breeding by the presence of rats. The economic gains from eradicating rats were that the cost of ongoing control through baiting by the PWS would no longer be required, and the reduction in pasture seed loss to rats would be a gain for the island’s lessee.
The Black Rat has a global distribution and is listed among the worst invasive species in the world (Global Invasive
Species Database 2019). They likely arrived in Australia with Dutch ships in the 1600s and fully established with European settlement in the 1780s (Banks & Hughes 2012). Black Rats are generalist omnivores, a trait shared with many successful vertebrate pests. They will eat almost any food up to their own body weight including vegetation, seeds, invertebrates, small vertebrates and the eggs and young of larger vertebrates (Banks & Hughes 2012). The direct impacts of Black Rat on wildlife are not well documented, with much of the evidence recorded through the recovery of native species after rats are eradicated from islands, particularly in New Zealand (Towns etal. 2006).
An adult Black Rat weighs up to 225 g and lives about a year. The species has a gestation period of 21 days and weans its young at around 20 days. A female can have 5-10 young per litter and produce up to six litters per year in ideal conditions (Van Dyck & Strahan 2008).
SITE DETAILS Description
Situated in Bass Strait, 3 km west of Flinders Island, the main island of the Big Green Island group is 125 ha, mostly granite and gently rising to 30 m (fig. 1). The island was intensively managed to provide food for the Aboriginal settlement at Wybalena from the 1830s, including sheep, rabbits, Cape Barren Goose (Cereopsis novaehollandiae), Short-tailed Shearwaters (Ardenna tenuirostris) and their eggs (Backhouse 1843). The vegetation is now mostly non- native pasture species fringed by a coastal strip of native ‘Tussock Grass (Austrostipa stipoides) (Harris et al. 2001). ‘There is a patch of succulent herbfield in the north and invasive African Boxthorn (Lycium ferocissimum) along the northeastern bay, east coast and scattered across the group
38 Susan Robinson and Wayne Dick
Flinders
146°E|
FIG. 1 — Location of Big Green Island relative to Tasmania and Flinders Island.
(Harris et a/, 2001). The islets to the north, which are joined by a rocky isthmus at low tides, maintain an assemblage of native plant species including Tussock Grass, Saltbush (Atriplex sp.) and succulents (Sclerostegia sp. shrubs). The main island is fully accessible by foot and the nearby islets require low tides for access.
The freehold island was sold to the PWS in 1980 and declared a Nature Reserve to establish a secure breeding site for Cape Barren Geese which had a declining population at the time. Sheep grazing continued under a lease agreement to maintain the short grass that is favoured by geese. The island has two cottages and a shearing shed that are used by the island’s lessee on a regular basis. Access is by boat from Whitemark, Flinders Island, 6 km to the northeast.
An estimated 22,000 pairs of Short-tailed Shearwater and 400 pairs of Little Penguin (Eudyptula minor) breed on Big Green Island (Brothers et a/. 2001). Other breeding seabirds include low numbers of Pacific (Larus pacificus) and Silver Gulls (LZ. novaehollandiae), Pied (Haemotopus longirostris) and Sooty Oyster-catchers (H. fuliginosus), Black-faced Cormorant (Phalacrocorax _fuscescens), Caspian Tern (Sterna caspia) (Brothers et al, 2001) and around 26 breeding pairs of Cape Barren Goose (G. Hocking pers. comm.).
It is unknown when rats arrived, but they likely came with the first settlers to the island in the 1830s. European Rabbit were introduced in 1832 (Backhouse 1843) and
died out due to drought around 1914 (D. Cooper pers. comm.). House Mouse were reported around buildings on the island between 1965 and 1968 (Norman 1970) but none have been recorded since then. Flinders Island (3 km away) has Black Rat, Brown Rat and House Mouse.
Rodent baiting history
Rodent control has been undertaken on Big Green Island sporadically since 1984 by the current lessee. Rats were a significant problem for pasture regeneration due to the consumption of seed-heads. Purchased seed was spoiled
- through gnawing of packaging and consumed when newly
sown. Rodent baiting with sodium monofluroacetate (i.e. 1080) occurred from 1984. From the initial trials with 1080, a regime of frequent poisoning was developed (two to three times a year) using a gridded network of over 700 bait stations (halved plastic 20-litre sheep drench containers). By 1996 the rat population had increased markedly despite continued poisoning. Brodifacoum baits were used until 2003, followed by flocoumafen in 2004. In 2008, Aegis-RP lockable bait stations were installed to replace the ageing drench containers. An eradication attempt occurred at about this time using one of the second- generation rodenticides but was likely unsuccessful due to stations not being regularly refilled beyond the initial bait-take because of difficulties accessing the island and stations not being deployed on the nearby western islet which connected to the main island at low tide. Development of a rodent eradication plan for Big Green Island by PWS and Biosecurity Tasmania, both divisions within the Department of Primary Industries, Parks, Water and Environment (DPIPWE) commenced in 2013. In 2014 it was decided that all poison bait in the bait stations on the island needed to be removed as soon as practicable to reduce the possibility of rodents becoming physiologically tolerant to toxins due to consumption of sub-lethal doses of degrading bait. Flocoumafen and bromadiolone poison blocks were used until stations were removed in January
2015.
METHODS
The eradication project was managed by the PWS Flinders Island Field Centre with technical advice provided by Biosecurity Tasmania. A feasibility study was completed in January 2015 (Robinson & Dick 2015) and recommended ground baiting with stations. An operational plan (Robinson & Dick 2016) was finalised in February 2016 after being independently reviewed. In January 2015, 864 lockable plastic bait stations were collected, cleared of bait and cleaned. A low number of stations (c. 10) in thick vegetation were not located during this collection. In March 2016, an additional 1,193 new plastic rodent bait stations (Aeg#s) were taken by barge to the island.
The GPS-linked field data management program Fulcrum (www.fulcrumapp.com) was selected to manage the installation of stations on a 25 x 25 m grid (i.e.,16 stations/
Black Rats eradicated from Big Green Island in Bass Strait, Tasmania. 39
ha) and bait delivery to this array. Data were recorded in real time and available to the baiting team once uploaded through the mobile phone network. Over 2,200 bait stations were installed by staff and volunteers between 8 and 13 March 2016 using mobile phone network-linked hand-held devices (iPads, Apple) preloaded with Fulcrum and a purpose-built eradication application (‘app’) with grid points on a Google Earth base-map. The accuracy of iPad GPS is described as 3-6 m, but it was usually within 1-2 m. Additional stations were installed around the buildings, increasing the density to a 12.5 m grid over 6.25 ha as a contingency for mice. It was decided the buildings would be the most likely place for mice, if still present on the island. A second Fulcrum ‘app’ was developed in June 2016 for tracking the location and use of monitoring devices across the island.
Islets and outcrops joined to the main island at low tide also had bait stations installed. Additional stations were placed around the coast giving a total of 2,208 bait stations by the end of May 2016. Stations were anchored using a 12°cm metal spike or a suitable rock. About 100 g of commercial rodent food pellets (Peckish™) were added to each station and left for five weeks to assist the habituation of rats to entering stations. Twenty rats were trapped for DNA as recommended by Broome et al. (2011) in March 2016. Bird and invertebrate surveys were conducted during April-May 2016 but are not reported on here. Sheep remained on the island for the duration of the program.
Baiting strategy
The baiting strategy was to use a grid of bait stations across the island with brodifacoum as the active ingredient in wax bait blocks as developed through discussions with the Tasmanian PWS staff, eradication experts in New Zealand, and from the ‘Agreed Best Practice for using Bait Stations (Broome et al. 2011). Stations were to have bait available for four weeks and checked daily, followed by another eight weeks of less frequent checking. It was recommended that baiting could cease one month after the last known bait-take and, if all went well, this would occur within the 12-week baiting period. Because the situation with House Mouse was unresolved, bait station spacing was reduced from the recommended 50 m (Broome et al. 2011) to a grid of 25 x 25 m. Though this was not a proven spacing for eradicating mice, it would likely provide a greater chance of success with mice if they were present, than 50 m. The alternatives were not considered feasible (i-e., 10 m grid spacing or aerial baiting). In addition, a 6.25 ha area around the buildings, the most likely place for mice if they were not island-wide, had the bait station grid reduced further to 12.5 m. Stations were to be installed several weeks in advance of baiting to minimise neophobia in rats around the new bait
stations and for baiting to begin in autumn. ‘The breeding .
season of rats on Big Green Island was unknown but it was considered less likely they would be breeding in autumn and winter. Even if breeding was occurring, the strategy of maintaining baits in stations for 12 weeks should ensure any emerging juvenile rats would be exposed to bait.
Baiting
Talon X-Pro (Selleys) 20 g wax blocks containing 50 ppm brodifacoum were secured in stations from 26 April, with the addition of X- Verminator (Daviesway) c. 18g blocks (50 ppm brodifacoum) from 18 May onwards. Stations had bait checked and replenished daily from 26 April-22 May 2016 (28 days) followed by checks from 6-11 June, 20-26 June, and 4—10 July. Up to six teams of two people checked and replenished all bait stations every 1.5—2 days. A minimum, of two baits were provided per station, but some had up to six baits at a time being consumed and these were replaced as needed. Baiting required volunteer teams of at least ten people for three consecutive ten-day shifts (equating to 28 days) followed by three further one-week shifts with at least six volunteers as described above. A total of 56 volunteers and six staff were engaged over the baiting phase of the project. A commercial supplier provided 200 kg of Talon X-Pro and agreed to hold an additional 200 kg in stock but this was not available when required. X-Verminator was used in its place. A Minor Use permit from the Australian Pesticides and Veterinary Medicines Authority was required for brodifacoum baits to be used for an ‘off-label’ application (i.e., away from buildings) and covered the use of both Talon X-Pro and X-Verminator.
During station checks, data on bait added to stations were entered into the Fulcrum ‘app’ so that bait consumption could be calculated. Minimal or zero consumption of the second bait X-Verminator occurred due to the rat population being near zero when this bait was deployed. There was also difficulty in distinguishing between possible consumption by rats and crumbling of this bait in some
instances, thus no bait uptake estimates for X-Verminator are provided. in the results.
Monitoring for rat activity
A range of rodent activity monitoring devices were deployed at various times from week six of baiting, and included chew cards (35 x 80 mm plastic corflute cards containing 5 grams of peanut butter), WaxTags (a waxy peanut butter lure which retains tooth marks; Pest Control Research Ltd. New Zealand) and Reconyx Hyperfire2 motion sensing cameras distributed in areas of boxthorn and tussock grass, the preferred habitat of rats. Snap traps (Aegis) were set 10-20 m apart in the areas where monitoring devices indicated ratactivity. Other devices used for both monitoring and killing were A24 CO, powered traps (GoodNature) and ‘rat motels’ (700 x 700 x 150 mm, lidded marine ply box internally partitioned containing food, bedding, poison bait, wax tag, snap trap and two 70 mm entry holes) and baited stations. From late July to early December 2016, eight visits to the island of one week with two staff were undertaken. In 2017, three-day monitoring visits were undertaken every two months then reduced to every three months in 2018. A rodent detector dog trained for rats and mice visited the island on five occasions, beginning four months after baiting finished (i.e., November 2016). Two years of regular island- wide monitoring concluded the program in November 2018.
40 Susan Robinson and Wayne Dick
RESULTS Stations and bait consumption
A total of 2,208 stations (tables 1 and 2) had 29,182 visits recorded between 26 April (Day 1) and 10 July 2016, with over 99% of the bait consumption occurring before 10 May 2016 (Day 15), the period when only Talon X-Pro was used (table 3 & fig. 2). Bait take was highest at Day 5 and decreased to zero (or wasn’t discernible) at Day 20 (fig. 2). It was possible a small pulse of bait-take occurred around Day 43 but was difficult to measure due to being very small amounts. Fresh bait remained in stations until at least mid-July (Day 84). A low level of bait uptake record- ing errors occurred during data entry (typing errors, double entries). Obvious errors were corrected in the database and the remaining error (related to recording bait consumption) was estimated to be 4.4%. An estimated 200.6 kg + 8.7 kg (4.4 %) of Talon X-Pro was consumed by rats (table 3). The highest bait consumption occurred in coastal areas of African Boxthorn and Tussock Grass, with the mid-east coast of the main island showing pockets of very high consumption (> 640 g, or 32 blocks, per 25 x 25 m grid square) (fig. 3). The first dead rat was seen on 28 April and a strong odour of dead rats was discernible by 10 May particularly on the west and north islets.
Locating remaining rats
Bait-take declined over time and appeared to be at zero by 21 May. Field staff noted, however, that in early June, small amounts of bait may have been consumed and in order to check for possible remaining rats, 381 chew-cards were deployed. These were placed 20-50 m apart and located where bait may have been consumed and in areas of preferred rat habitat including the vegetated perimeter of the island and features such as rocky outcrops between 3 and 8 June. On 10 June, damage to 21 chew-cards indicated rats were still present. In response, the project adopted intensive monitoring with chew-cards, wax tags, snap traps, cage traps, Elliott traps, motion-sensing cameras, tracking tunnels and CO, powered A24 traps (table 4). Chew-cards, and to a lesser extent wax tags, were the most effective tools for locating rat activity. Multiple snap traps with a variety of food lures were set in the areas where activity was identified. A total of six rats (3 male, 3 female) were killed in snap traps: three in June, two in July and one in November (fig. 4). The last known positive rat sign was an adult female rat killed on 3 November 2016. None of the three female rats were pregnant or lactating. No sign of mice was found.
The grid of baited stations remained in place until mid- July 2016 then was progressively removed over a three-week period beginning with the areas of pasture where bait consumption (a proxy for rat density) had been lowest. Over 30 baited stations were maintained at beaches, landing points and around buildings, in addition to those deployed where rat sign was located. Monitoring equipment remained in place from June 2016 to November 2018 (table 4),
Number of bait blocks
1500 1000 500 | 0 [ope ae ee 3 6 9 12
15 18 22 Day of baiting
FIG. 2 — Number of 20 g bait blocks recorded consumed on each day from 28 April 2016 (Day 3) onwards. Initial baiting of stations occurred on Days 1 and 2. Two days were required to check all stations.
= Parry’s Rock
w Reef Islet
North Islet 2 North Islet 1 = “|
FIG. 3 — Bait block (Talon X-Pro) consumption per 25 x 25m grid square for all the areas of Big Green Island. The highlighted 6.25 ha square contained stations at higher density around the
buildings.
Black Rats eradicated from Big Green Island in Bass Strait, Tasmania. 41
TABLE 1 — Names and areas (above high tide) of individual islands, numbers of bait stations installed and Talon X-Pro bait
consumed. a
Site Area ha Number of stations Bait consumed kg
Main island 124.80 2128 187.8
West Islet! 0.18 6 1.1
North Islet 1 2.26 40 6.9
North Islet 2 1.50 28 4.6:
reef islet (no name) 0.06 2; 0.1
Parry's Rock 0.11 2 0.1
TOTAL 128.91 2208 200.6
' Refer to Fig. 3 for locations of islets.
TABLE 2 — Station deployment and visit details.
Total Comment Total 25 x 25 m grid squares 2064 Main island and islets combined Additional stations over 6.25 ha 93 Contingency for House Mouse Total stations 2208 — Includes extra coastal stations
Visits to stations (26 Apr-17 May 16) 18,722 Talon X-Pro bait only Visits to stations (18 May—10 July 16) 10,460 X-Verminator and Talon X-Pro
TABLE 3 — Bait deployment and consumption.
Measure Total Comment
Total 20 g blocks consumed 10,028 Talon X-Pro only
Total bait consumed (+ error) 200.6 (+ 8.7) kg Talon X-Pro only
Average consumption /station —_0.1 kg (5 blocks) Averaged over 129 ha
Average consumption/ha 1.6 kg Averaged over 129 ha
Total bait deployed 400 kg Spoiled baits were removed
TABLE 4 — Monitoring tools deployed from 3 June 2016 to the end of the project on 3 November 2018.
Monitoring tool 3 Jun-27 Nov 16! 02Dec16 28May17 12Q0ct17 19 Apr18 22Aug18 1 Nov 18 Chew-cards 667 383 396 169 187 - 187 187 Snap traps ~ 473 : 3 4 4 3) 3 3 Cage traps 6
Elliott traps 5
CO2 trap locations Dsus 5 )
Tracking tunnels 15
Bait stations c. 40 1 38 37 39 ay) 38) Wax tags 89 18
Camera locations : 16
Rat motels 6 6 6 6 Rodent detector dog days 3 2.5
' Total installed over this period
42 Susan Robinson and Wayne Dick
Buildings
11 June 12 June | RR
R
R - rat killed
FIG. 4 — Dates and locations of rats killed by snap traps on the main island of the Big Green Island group subsequent to the main baiting knockdown.
which included a two-year monitoring period (Broome et al. 2011) with no further rat sign detected.
Non-target impacts
Baiting teams were highly vigilant for sick and dead rats with a total of 20 animals collected to reduce the possibility of secondary poisoning of non-target species. Five Pacific Gulls died from consuming poisoned rats as indicated by haemorrhaging seen externally on their carcasses. Trapping resulted in the deaths of three Brown Quail (Coturnix ypsilophora) in uncovered snap traps and a Cape Barren Goose hatchling that squeezed into a station containing a snap trap.
Effort and cost
Approximately 605 days of volunteer time supported the rat eradication work, with station deployment and baiting consuming the most time. Government agency staff contributed at least 408 days to the project.
Purchases of project equipment and services totalled $114,000. Total salary costs were estimated at $120,000. In Australia, volunteer time is costed at $41.72 per hour (Australian Bureau of Statistics 2018) making the volunteer contribution $201,925.
Biosecurity
A Biosecurity Plan (Tasmania Parks & Wildlife Service 2016) has been drafted for the island. To minimise biosecurity issues during the eradication program and the monitoring phase, public visitation to the island was suspended until at least November 2016. To reduce the risk of reinvasion of the island by rodents, supplies and equipment travelling to the island are now checked as part of ongoing biosecurity requirements overseen by PWS staff. For on-island biosecurity, six ‘rat motels’ and 32 baited stations are maintained on the island (including adjacent islets) with checks aimed at 3—6-month
intervals.
DISCUSSION
Tasmania is notable for having achieved the world’s largest Black Rat eradication: 12,800 ha Macquarie Island in 2011 (Springer 2016). Interestingly, apart from this and the Big Green Island attempt, the only other island rodent eradications in Tasmania were for the tiny 1 ha Fisher Island in 1974 for Black Rat (Serventy 1977) and again in 2013 for House Mouse and Black Rat (S. Robinson, unpublished data). Big Green Island was one of the 22 ‘uninhabited’ Tasmanian islands recorded with invasive rats and had a long history of rodent control and a previous attempt at eradication. For the eradication attempt described here, potential non-target issues from primary poisoning (i.c., native species and livestock) were minimised by choosing bait stations as the eradication method. The 50 m grid recommended by Broome ef a/. (2011) was increased in density to a 25 m grid as a contingency for the possible presence of mice, accepting that the recommended grid for baiting mice is 10 x 10 m (Harper et al. in press). The 25 m bait station grid required a substantial labour force (mostly volunteers) to check stations over the 12-week baiting period and a data management system capable of tracking the distribution of bait over such an array.
The field data management program Fulcrum was integral to the project. Most volunteers quickly mastered the use of iPads and Fulcrum for recording data, though more training would have improved data quality and reduced errors. There were a number of small issues with the data input design related to inexperience of structuring an ‘app’ for this type of work. The baiting ‘app’ was not suitable for recording the dynamic situation with monitoring tools being deployed across the island, and a second ‘app’ specifically for monitoring needed to be produced. In hindsight the monitoring ‘app’ should have been available at the beginning of fieldwork alongside the baiting ‘app’.
Rodent eradication projects on islands generally do not undertake intensive verification monitoring until two rat breeding seasons (equating to two years) after the knockdown (Broome et al. 2011), as for example, Macquarie Island (Springer 2016). This allows time for any rodents to increase in number to a detectable level. The potential issue with this method is that if rodents have survived the eradication attempt, allowing two
Black Rats eradicated from Big Green Island in Bass Strait, Tasmania. 43
years of reproduction will likely mean the full eradication will need repeating and this additional cost may not be economically viable. The island-wide deployment of monitoring devices after the main knockdown period was not part of the original plan but was suggested by a rodent eradication expert (Department of Conservation, New Zealand) as a good way to check on how the operation was progressing. Other practitioners have used a similar idea and developed detailed rapid eradication assessment models (Samaniego-Herrera et al. 2013, Russell er al. 2017) where monitoring begins soon after baiting and these are particularly suited to smaller islands. A batch of 500 chew-cards was made on the island and these were available for deployment when field staff thought there could be some late bait consumption.
Chew-cards were checked in early June and indicated rat activity. It was possible these remaining rats could have been tolerant to brodifacoum due to the population’s long history of exposure to rodenticides or were choosing not to consume bait or to enter bait stations and had thus avoided being poisoned at least at that stage. Bait was still available across the grid and in addition to this, in the case that rats were not entering stations or taking bait, managers decided to allocate staff to actively locate and capture rats, not knowing at the time if there was a high or a low rat population remaining. The appearance of a pulse of activity a few weeks after bait-take has declined to (near) zero is not unusual during a baiting operation (K. Springer pers. comm.). It may have been that remaining rats would have eventually consumed bait if they hadn't been trapped, but the team chose to act to ensure that other lethal methods were available in case the remaining rats were not susceptible to poisoning. Snap traps were firstly set inside stations, which was not successful, then outside of stations under debris and vegetation (to minimise potential bycatch). The main bait station grid was removed between late July and early August 2016 because it was thought remaining rats were avoiding stations, as seen in the lack of success with snap traps set inside stations. Six rats were caught in snap traps between June and November 2016, and no further sign was found during the next two years. The island was declared rat-free in November 2018.
Notwithstanding it is possible all rats could have eventually been killed with poison and that the monitoring could have been delayed, possible explanations for rats being present after the main period of bait consumption include:
Black Rat live for about one year in the wild (Strahan 1983). Ideally an island would be bait-free for at least one year prior to an eradication so that rats exposed to bait during their lifetime (and survived) have died from other causes. The bait-free period prior to eradication for Big Green Island was planned to start in January 2015 when all field-based stations were collected. It transpired in July 2015, however, that sheds and buildings were still being baited which reduced the island’s bait-free period to eight months. It was therefore possible that rats that had been exposed to bait, and developed a tolerance to it during this period, could still have been alive at the time of eradication and avoided being poisoned.
The rat population’s long history of exposure to multiple poisons may have resulted in the survivorship of neophobic or bait-tolerant individuals over time.
‘Bitrex’, a bittering agent, was present in the bait Zalon X-Pro and rats may have been detecting it or repelled by it. Note, however, that X-Verminator was also present in stations and does not contain ‘Bitrex’ so rats may eventually have taken baits if they hadn’t been trapped first.
Interestingly, four of the six remaining rats were trapped within 100 m of the buildings. The risks and implications related to long-term rodenticide use at islands selected for eradication need to be carefully considered during the planning phase. At sites where rodenticides have been used for many years, allowing two years for the site to be free of rodenticide would reduce the chance of bait-tolerant or neophobic individuals being present. This additional time may need to be included in future project planning.
Rat density and bait consumption
Using bait consumption as an index of rat density showed that native Tussock Grass and African Boxthorn were the most favoured habitats for rats. The highest rat density occurred on the mid-east coast in a narrow strip of African Boxthorn. The nearby islets (West, North Islets 1 and 2) also had high bait consumption (8-15 blocks/grid square) inferring high rat density. The small (30 x 20 m and 45 x 15 m), sparsely vegetated, rocky islets to the north also had rats present. These two outcrops join up at low tides. At the lowest tides, a shallow channel 100 m wide, exists between North Islet 2 and the unnamed ‘reef islet’, but is well within arats’ swimming ability, with studies concluding Black Rats can swim up to 1 km distance in favourable conditions (Spennemann & Rapp 1989), though 500-m is
considered more realistic. Project partnerships
‘The Big Green Island rat eradication project was supported by groups of up to 12 volunteers at a time. Volunteers assisted with a variety of tasks throughout the eradication process: deploying stations across the island; data collection; checking and rebaiting stations; removing stations; constructing, deploying and checking hundreds of chew- cards. Significantly, the grid of 2,208 bait stations would not have been an economical option for the project's budget if salaried staff were used. Pre-eradication surveys for birds and invertebrates were conducted by volunteers experienced in these fields.
More and more conservation work is being supported through alternative funding sources and thus projects like these must include strong partnerships between
- government, industry and non-government organisations.
Both the volunteer and philanthropic contributions to this rat eradication project were critical to its success.
44 Susan Robinson and Wayne Dick
Maintaining a rodent-free island
Whilst having an island inhabited and with a livestock grazing lease presents challenges for maintaining biosecurity, the presence of the island’s leaseholder likely reduces the numbers of opportunistic visitors and campers. Biosecurity guidelines for island visitors are provided on the PWS website. The local PWS staff have biosecurity processes in place to check stock-feed going to Big Green Island and have the responsibility of maintaining the island’s rodent bait stations. The time and cost required for biosecurity-related tasks are significantly less than that expended for annual, island-wide and ongoing rodent baiting for control purposes. It is important to note that now the island is free of Black Rats, it is vulnerable to invasion by other species of rodents such as Brown Rats and House Mouse (but also reinvasion by Black Rats) all of which occur on Flinders Island, 3 km distance at the narrowest crossing. Brown Rats can swim 1 km (Russell et al, 2008) but have also been recorded swimming at least 2.5 km (K. Broome pers. comm.).
Post-eradication wildlife monitoring
Post-eradication monitoring includes the long-term Short-tailed Shearwater monitoring by the Tasmanian Governments Marine Conservation Program. Baseline information on invertebrates, shore birds and other birdlife were collected during the eradication project, and similar surveys will be repeated in the future to examine changes
and recovery in native species.
CONCLUSIONS
Big Green Island has a long history of poison baiting which brought additional considerations into planning for a rat eradication. The project required detailed planning to operate over 2,200 bait stations, a task that was made possible by a mobile phone-linked data collection program and a large group of volunteers. The decision to monitor for rodent activity soon after the main bait consumption period was an important factor in the success of the project because it allowed surviving rats to be located and dispatched before breeding occurred. Effective and ongoing biosecurity for the island is critical for protecting the investment of this rat eradication program, with the island potentially vulnerable to colonisation from any of the three introduced rodent species that occur on nearby Flinders Island. Surveys of shorebirds and small burrowing petrels, as well as invertebrate and reptile fauna, will hopefully soon show the benefits of the work and commitment undertaken to remove Black Rats from Big Green Island.
ACKNOWLEDGEMENTS
The authors thank all the dedicated volunteers; Tasmania Parks and Wildlife staff Peter Mooney, Cindy Pitchford, Mark Donald, Luke Gadd, Noel Carmichael, Mark Monks, Nick Whiteley and Stan Matuszek; the Tasmania Parks and Wildlife support staff; Biosecurity Tasmania staff and Phil Wyatt for his GIS support. The authors also thank Pete McClelland for expert advice; the Pennicott Foundation; the Estate of G.J. Kole; the island’s lessee Dennis Cooper; Peter Vertigan, Greg Hocking and Birdlife Tasmania. Keith Springer and Keith Broome are thanked for their valuable additions to the manuscript.
REFERENCES
Australian Bureau of Statistics 2018: Assigning value to your volunteer labour, https://www.fundingcentre.com.au/ help/valuing-volunteer-labour
Backhouse, J. 1843: A narrative of a visit to the Australian colonies. Hamilton, Adams and Co., London: 560 pp.
Banks, P.B. & Hughes, N.K. 2012: A review of the evidence for potential impacts of black rats (Rattus rattus) on wildlife and humans in Australia. Wildlife Research 39: 78-88.
Broome, K.G., Brown, D., Cox, A., Cromarty, P., McClelland, P., Golding, C., Griffiths, R. & Bell, P. 2011: Current Agreed Best Practice for Rat Eradication — poison bait in bait stations (Version 1.3). New Zealand Department of Conservation internal document DOCDM-839096. Department of Conservation, Wellington, New Zealand: 25 pp.
Brothers, N.B., Pemberton, D., Pryor, H. & Haley, V. 2001: Tasmanias Offshore Islands: Seabirds and Other Natural Features. Tasmanian Museum and Art Gallery, Hobart, Tasmania: 643 pp.
Commonwealth of Australia 2009: Threat Abatement Plan to reduce the impacts of exotic rodents on biodiversity on Australian offshore islands of less than 100 000 ha. Unpublished Report of the Department of the Environment, Water, Heritage and the Arts, Canberra: 24 pp.
Global Invasive Species Database 2019: 100 of the World’ Worst Invasive Alien Species, www.iucngisd.org/gisd/100_ worst.php (accessed 18 August 2019).
Harper, G.A., Pahor, S. & Birch, D. (én press) The Lord Howe Island rodent eradication: lessons from the ground- baiting operation. 29th Vertebrate Pest Management Conference. University of California (Davis), USA.
Harris, $., Buchannan, A. & Connolly, A. 2001: One Hundred Islands: The Flora of the Outer Furneaux. Tasmanian Department of Primary Industries, Water and Environment, Hobart: 361 pp.
Norman, EI. 1970: Food preferences of an insular population of Rattus rattus. Journal of Zoology, London 162: 493-503.
Robinson, S. & Dick, W. 2015: Big Green Island Black Rat Eradication Feasibility Report. Unpublished Report for Tasmanian Parks and Wildlife Service. Hobart: 22 pp.
Robinson, S. & Dick, W. 2016: Big Green Island Black Rat Eradication Operational Pian. Unpublished Report for Tasmanian Parks and Wildlife Service. Hobart: 23 pp.
Russell, J.C., Binnie, H.R., Oh, J., Anderson, D.P. & Samaniego- Herrera, A. 2017: Optimizing confirmation of invasive species eradication with rapid eradication assessment. Journal of Applied Ecology 54: 160-169.
Black Rats eradicated from Big Green Island in Bass Strait, Tasmania. 45
Russell, J.C., Towns, D.R. & Clout, M.N. 2008: Review of Rat Invasion Biology. Implications for island biosecurity. Science for Conservation No. 286. Unpublished Report of the Department of Conservation, Wellington, New Zealand: 54 pp.
Samaniego-Herrera, A., Anderson, D.P., Parkes, J.P. & Aguirre- Munoz, A. 2013: Rapid assessment of rat eradication after aerial baiting. Journal of Applied Ecology 50: 1415- 1421.
Serventy, D.L. 1977: Seabird Islands: Fisher Island, Tasmania. Corella 1(3): 60-62.
Spennemann, D.H.R., Rapp, G. & Early, D.S. 1989: Can rats colonise oceanic islands unaided? An assessment and review of the swimming capabilities of the genus Rattus (Rodentia: Muridae) with particular reference to tropical waters. Zoologische Abhandlungen des Museums fiir Tierkunde Dresden, 45(1): 481-491.
Springer, K. 2016: Methodology and challenges of a complex multi-species eradication in the sub-Antarctic and immediate effects of invasive species removal. New Zealand Journal of Ecology 40(2): 273-278.
Strahan, R. (ed) 1983: Complete Book of Australian Mammals. The Australian Museum, Sydney: 530 pp.
Tasmania Parks & Wildlife Service 2016: Big Green Island Biosecurity Management Plan 2016. Draft Report for Parks and Wildlife Service, Hobart: 21 pp.
Towns, D.R., Atkinson, ILA.E. & Daugherty, C.H. 2006: Have
* the harmful effects of introduced rats on islands been exaggerated? Biological Invasions 8: 863-891.
Van Dyck, S.M. & Strahan, R. (eds.) 2008: The Mammals of
Australia. New Holland Publishers, Sydney: 887 pp.
(accepted 30 September 2020)
| | |
Papers and Proceedings of the Royal Society of Tasmania, Volume 154, 2020 : 47
UNVIABLE FERAL CAT POPULATION RESULTS IN ERADICATION SUCCESS ON WEDGE ISLAND, TASMANIA
by Susan Robinson and Luke Gadd (with one text-figure and one table)
Robinson, S. & Gadd, L. 2020 (9:xii): Unviable feral cat population results in eradication success on Wedge Island, Tasmania. Papers and Proceedings of the Royal Society of Tasmania 154: 47-50. ISSN: 0080-4703. Biosecurity Tasmania, 13 St Johns Avenue, New Town, Tasmania 7008, Australia (SR*); Tasmania Parks and Wildlife Service, Mt Field National Park, 66 Lake Dobson Road, National Park, Tasmania 7140, Australia (LG). *Author for correspondence. Email: sue.robinson@dpipwe.tas.gov.au
Wedge Island in southeast Tasmania is 43 ha in size and is habitat for Little Penguin (Eudyptula minor) and Short-tailed Shearwater (Ardenna tenuirostris) populations. The island was subject to a feral Cat (Felis catus) eradication attempt in 2003 when 13 cats were captured with the assistance of trained detection dogs. It was known at least one cat remained. No further cats were captured during two subsequent visits in 2003 and 2004 and a single dead cat was found in 2012. It appeared the cat population never recovered from the initial knockdown and this ultimately resulted in eradication success. Methods used and details of cats caught are provided and the program is discussed in terms
of criteria required for a successful eradication.
Key Words: island eradication, feral Cat, Felis catus, eradication criteria, Tasmania.
INTRODUCTION
Like other islands of the world, Tasmania’s offshore islands have been subjected to deliberate and inadvertent introductions of non-native vertebrates, typically rats (Rattus rattus or R. norvegicus), House Mouse (Mus musculus), European Rabbit (Oryctolagus cuniculus) and Cat (Felis catus). Cats have been taken to islands by residents as companion animals and to control pest rodents that have established after arriving in cargo; rabbits have historically been introduced to islands as a food source for fishers, residents and mariners. Around 10% of Tasmania’s 600 vegetated islands and islets are recorded as having vertebrate pests and at least 20 islands have had cats introduced. Feral cats were eradicated from two islands in the Furneaux Group (Little Green and Great Dog) in the 1980s (Campbell er al. 2011), from subantarctic Macquarie Island in 2000 (Robinson & Copson 2014) and from Tasman Island in 2010 (Robinson et al, 2015). After the Macquarie Island cat eradication monitoring period concluded in 2002, staff, traps and cat detection dogs became available for use on further projects. The removal of feral cats from Wedge Island, southeast Tasmania, was attempted in 2003 with support from the Marine Conservation Program, Department of Primary Industries, Parks, Water and Environment (Tasmania). European Rabbit and Sheep (Ovis aries) were introduced to Wedge Island in 1930 by fishers (N. Brothers quoted in Beh 1995). Rabbits outcompeted the sheep for food, so the sheep were removed in 1939. Cats were first recorded on the island in 1939 and were probably introduced for rabbit control. It appears these cats died out some years later (Beh 1995). Sheep were then returned to the island at a subsequent unknown date prior to 1970. Myxoma virus was released on Wedge Island through the 1970s, and in 1976 cats were re-introduced (apparently one pregnant female) to help control the rabbits that were again impacting vegetation and sheep grazing (Beh 1995). The rabbits died
out around 1978 and the sheep were removed in 1986 but cats remained (Beh 1995). No rodents or other introduced mammals are present on the island, leaving seabirds as the main food source for cats.
STUDY SITE
Wedge Island (43°08'S, 147°40'E), located on the western side of the Tasman Peninsula, was reserved as a Conservation Area in 2004 and is 800 m in distance from the closest point to mainland Tasmania. Orientated north-south, Wedge Island is approximately 1.3 by 0.6 km with an area of 43 ha. The island has steep dolerite cliffs on the western side tapering to a rocky shoreline in the east. The island rises to 96 m. Tussock Grass (Poa poiformis) and Saggs (Lomandra longifolia) are the dominant vegetation with patches of succulents (Carpobrotus rossii), Kangaroo Apple (Solanum laciniatum) and a small remnant eucalypt (Eucalyptus viminalis) and she-oak (Casurina sp.) woodland (Brothers et al. 2001).
The island has a significant seabird fauna, including 12,000 pairs of Short-tailed Shearwaters (Ardenna tenuirostris) and 1000 pairs of Little Penguin (Eudyprula minor) (Brothers et al. 2001, Vertigan 2010). Other vertebrates include the Tasmanian Native Hen (Gallinula mortierri) and two species of skink (Niveoscincus metallicus and WN. ocellatus). Fairy Prions (Pachyptila turtur) are believed to have been breeding on the island up to the 1970s (N. Brothers quoted in Beh 1995). Fur seals (Arctocephalus pusillus and A. forsteri) are present on the coastal rock platform.
. METHODS
Field teams of two people camped on the island three times during 2003 and 2004. Methods available to capture cats
48 Susan Robinson and Luke Gadd
were wire mesh drop-door cage traps (600 x 300 x 300 mm) (Mascot Wireworks, Preston, Victoria), rubber-jawed leg-hold traps (Victor, no. 3: Woodstream Corp. Lititz, PA, USA) and shooting with a .22 calibre rifle under spotlight or when located by trained cat detection dogs.
Brief visits to the island to check for cat signs (footprints in sand or scats, etc.) were made opportunistically from 2007 to 2010. Four remote sensing cameras (Scoutguard SG-550) were installed on the island for four weeks during September and October 2008 and nine Reconyx Hyperfire remote sensing cameras from January to April 2012 and again from May to July 2012. Whilst land managers were generally confident no cats remained from 2012 onwards, the availability of a cat detection dog facilitated an additional final check for cat sign in 2019.
RESULTS
The effort to eradicate and monitor the cat population on Wedge Island is summarised in table 1. A primary knockdown of 14 days in 2003 was followed by 12 days of further effort but this was insufficient to capture the last cat/s. The project was unable to gain additional investment support for several years. In 2003, 13 cats were captured and at least one cat was known to remain giving a population of at least 14 individuals. At least one cat was known to be present until December 2010. This cat likely died in late 2011 and its body was found in May 2012.
Thirteen cats were captured in 2003: seven adult males (mean 4.1 + SD 0.3 kg, n=7), five adult females (mean 2.9 + SD 0.6 kg, n=4) and one juvenile female in poor
condition (1.1 kg). Of these cats, 12 were white with patches of tabby, tortoise-shell or black, and a single animal had a solid tabby pelage. Three of the males had very worn teeth and one had a tattooed ear from the Beh (1995) study. The cat found dead in 2012 was a tabby.
For the first island visit (21 July to 4 Aug 2003) cage traps and leg-hold traps were set for cats. No cats were caught in either trap type. All cats captured over this 14- day period were located in seabird burrows as indicated by two detection dogs (fig. 1). Burrows were dug open by hand and cats humanely euthanised with a .22 calibre rifle. A second visit (27 Aug to 4 Sep 2003) was unsuccessful in capturing cats. Cat prints in sand and a freshly killed Little Penguin were recorded. During a four-day field trip in winter 2004, cat sign was again found (prints, scent and scats) but no capture resulted.
Stomach contents from cats euthanised in 2003 mostly contained remains of Little Penguins, including body parts of small chicks and adults. In July 2003, Little Penguins were incubating eggs or recently hatched young. Fish was present in cat diet and could have been from penguin stomachs or scavenged from the shoreline. Invertebrates were also present (beetles and caterpillars, species not identified).
With the total number of cats being at least 14 individuals in 2003, the density for Wedge Island was around 0.33 cats per ha. From the detailed field notes of Nigel Brothers in 1984 (State Library of Tasmania Archives), 15 to 17 individual cats could be identified for Wedge Island, 12 of which were trapped and tagged over 12 days in July and August 1984 as part of an unpublished energetics study. The ecological study by Beh in 1995 estimated “not more than a total of 15 individuals (cats) on the island”.
TABLE 1 — Visits to Wedge Island: eradication effort and cat sign recorded from 2003 to 2019.
Trip date Trip StafF_ Dog Trap nights Spotlight Camera — Cats Comments days days days Cage Leg-hold hours nights
21 Jul 03 14 14 28 Uyfs) 210 30 - 13 dead At least 1 cat (tabby) remaining
27 Aug 03 9 9 18 45 le, 24 - - Cat scent detected by dogs; cat prints and scats
29 Jun 04 4 4 8 12 60 ~ 12 = = Cat scent detected by dogs; cat prints and scats
7 Sep 07 0.25 0.25 - = = ~ - - Cat prints
5 Sep 08 1 0.5 - = = ~ 160 - Cat prints and scats; no cats recorded on cameras
23 Aug 10 O25) Ws) - = = - - - Cat prints
17 Dec 10 =20 - = - - - - llive Tabby. Observation by University of ‘Tasmania
23 Jan 12 1 3 1 - - = = - 2 old scats. No fresh scent located by dog
11 Apr 12 1 1 - - - _ 711 - No cats recorded on cameras
31 May 12 1 7 1 ~ - = - 1 dead Tabby, desiccated; no fresh scent located
. by dog 13 Jul 12 1 1 - - - = 344 - No cats recorded on cameras
27 Sep 19 1 1 1 = = =
- - No sign of cats found
Unviable feral cat population results in eradication success on Wedge Island, Tasmania 49
[>\ Short-tailed shearwater colony
Little penguin colony
0 50100 200 300 0 Metres
FIG. 1 — Map of Wedge Island, southeast Tasmania, showing locations of cats caught in 2003 (dots) and found dead in 2012 (triangle); seabird distribution is from Beh (1995) and Vertigan (2010).
DISCUSSION
In 2003, it was likely the Wedge Island cat population was reduced to either one cat or to a low number of cats of the same sex. This outcome left the cat population unviable and it died out in 2011. In 2012, with the establishment of the ‘Invasive Species Branch’ as part of Biosecurity Tasmania, it was decided to finalise the project through monitoring and locating any remaining cats. Camera monitoring and a thorough search of the island with a team of seven people and a cat detection dog found one dead cat that had likely died several months earlier. No other evidence or fresh cat sign has been found since.
The most effective method of locating cats on Wedge Island was with cat detection dogs indicating which seabird burrows were occupied by a cat. Interestingly, no cats entered cage or leg-hold traps. Dissected cats showed full stomachs of mostly Little Penguin remains, suggesting food was plentiful in July and why food lures in traps were not effective. Leg-hold traps were set outside the seabird colonies to avoid catching Little Penguins. It appeared that cats were mostly denning and feeding within the seabird colonies thus may have not encountered the leg- hold traps. It is possible the remaining cat/s retreated to the inaccessible southwest cliffs to avoid the high level of
human and dog activity during field trips and thus evaded capture. In hindsight, poison baiting could have helped target remaining cats in the autumn when seabirds are absent and food availability low.
For island-based vertebrate pest eradication attempts to be successful, it is accepted that several criteria need to be met (Bomford & O’Brien 1995, Clout & Veitch 2002). These criteria are:
Animals must be killed faster than they reproduce; All animals can be put at risk by the methods used; Immigration is zero;
Methods are socially acceptable;
The project has sufficient institutional support and funding.
The Wedge Island cat eradication attempt in 2003-04 was undertaken on a very small budget. After an effective primary knockdown, the follow-up effort and methods were insufficient, or not appropriate, to catch the last individuals (i.e., Criterion 2 was not met). No further funding was available to support the project (i-e., Criterion 5 was not met) after 2004. Cat activity on the island was sporadically monitored over the ensuing eight years, often in addition to boat trips already occurring in the area. Despite the criteria for eradication apparently not being met, the eradication was eventually successful because the remnant cat population was not reproductively viable, i.e, Criterion 1 had actually been met but this was not known at the time.
Another Tasmanian island where an eradication of cats was attempted on a limited budget was Tasman Island, 29 km to the southeast of Wedge Island. Seven visits between 1977 and 1982 utilised shooting and 1080 baits to remove cats. Population reduction was being achieved and further visits planned (Brothers 1982). The final effort to remove the cats, believed to be very low in number (e.g., three or less) did not occur (N. Brothers pers. comm.), and highlights the importance of securing sufficient resources for eradication work. The remnant cat population unfortunately recovered rather than dying out but was finally eradicated in 2010 (Robinson et al. 2015).
The cats on Wedge Island fed primarily on seabirds because most other common prey species were not present (e.g. rats, House Mice or European Rabbits). In 1984, Brothers (1984) noted 13 adult Little Penguins killed and/or consumed by cats over 12 field days during July and August. Examination of cat scats between May and September 1995 (Beh 1995) had Short-tailed Shearwater as the most prevalent dietary item in May (prior to their northward migration) and Little Penguin increasing with a peak in July. Native Hen remnants were also present in smaller proportions throughout Beh’s 1995 study period. Eggshell fragments in scats increased in July and were likely from the eggs of Native Hens or Little Penguins. Beh (1995) reports caterpillars (species not recorded) increasing in prevalence in cat diet from July to September. Little Penguins and Native Hens, with the addition of caterpillars, supported cats through the low-food months when Short-tailed Shearwaters were absent. Some of the adult cats captured in 2003 showed extreme wearing
50 Susan Robinson and Luke Gadd
of teeth, suggesting items like intertidal limpets (Class Gastropoda) or mussels (Class Bivalvia) may have been prised from rocks and consumed.
The tabby coat colour of cats was not common on Wedge Island in 2003, with only two of 14 recorded with this pelage. It is feasible the tabby coloured cat observed in 2003, 2004 and 2010, and found dead in 2012, was in fact the same animal. This would give a minimum age of nine years at its death. From an ear-tattooed cat found in 2003, marked in the Beh (1995) study, it was known that cats on Wedge Island could live at least eight years. Interestingly, the cat coat colours recorded by Brothers in 1984 were mostly tabby (9 of 12 trapped) with others being tabby with a white front (2), white with black patches (1) or all black (1). Beh (1995) did not describe coat colours but provided a black and white image of a tabby or tortoiseshell cat with white legs and underparts.
CONCLUSION
Leaving individuals remaining on an island is not a recommended or desired outcome, but when island-based pest eradication work is undertaken on a very low budget, there can be higher risks to achieving success. Detecting survivors can be labour-intensive and costly, and projects may be left without sufficient funds. Fortunately for Wedge Island and its seabirds, the eradication of cats was eventually successful despite the presence of survivors. The primary knockdown left the remnant cat population, which could have been a single animal, so low that reproduction was impacted. This resulted in an unviable population that ultimately died out.
ACKNOWLEDGEMENTS
The authors thank the Marine Conservation Program staff (DPIPWE); Tasmanian Parks and Wildlife Service staff; S. Brookes, J. Cleeland, R. Gaffney, M. Holdsworth, M.
Johnston, B. Lazenby, M. Pauza, P. Vertigan and P. Marmion for their assistance. The authors are also grateful to T: Priestley for assistance with the figure and N. Brothers for providing additional information.
REFERENCES
Beh, J.C.L. 1995: The winter ecology of the feral cat, Felis catus (Linnaeus 1758), at Wedge Island, Tasmania. Unpublished BSc Honours thesis, University of Tasmania, Hobart.
Bomford, M. & O’Brien, P. 1995: Eradication or control for vertebrate pests? Wildlife Society Bulletin 23: 249-255.
Brothers, N. 1982: Feral cat control on Tasman Island. Australian Ranger Bulletin 2: 9.
Brothers, N. 1984: Original field notebook 24/8/84 Wedge Island. NS2366/1/67 State Library of Tasmania Archives, Hobart.
Brothers, N., Pemberton, D., Pryor, H. & Halley, V. 2001: Tasmania’s Offshore Islands: Seabirds and other Natural Features. Tasmanian Museum and Art Gallery, Hobart, Tasmania: 643 pp.
Campbell, K. J., Harper, G., Algar, D., Hanson, C.C., Keitt, B. S. & Robinson, S. 2011: Review of feral cat eradications on islands. Jz Veitch, C.R., Clout, M.N. & Towns, D.R. (eds.): Island Invasives: Eradication and Management. Gland, Switzerland. Proceedings of the International Conference on Island Invasives, IUCN: 37-46.
Clout, M.N. & Veitch, C.R. 2002: Turning the tide on biological invasion: the potential for eradicating invasive species. In Clout, M.N. & Veitch, C.R. (eds.): Turning the Tide: The Eradication of Invasive Species. Gland, Switzerland and Cambridge, UK. Proceedings of the International Conference on Island Invasives, IUCN: 1-3.
Robinson, S.A. & Copson, G.F. 2014: Eradication of cats (Felis catus) from subantarctic Macquarie Island. Ecological Management & Restoration 15(1): 34-40.
Robinson, S., Gadd, L., Johnston, M. & Pauza, M. 2015: Long- term protection of important seabird breeding colonies on Tasman Island through eradication of cats. Journal of Ecology New Zealand 39(2): 316-322.
Vertigan, C. 2010: The life-history of short-tailed shearwaters (Puffinus tenuirostris) in response to spatio-temporal environmental variation. Unpublished PhD thesis, University of Tasmania, Hobart.
(accepted 5 October 2020)
pape? and Proceedings of the Royal Society of Tasmania, Volume 154, 2020 51
COLLECTING HISTORY AND DISTRIBUTION OF THE POTENTIALLY INVASIVE DISA BRACTEATA (SOUTH AFRICAN ORCHID) IN TASMANIA
by Mark Wapstra, Matthew L. Baker and Grant D. Daniels (with two text-figures, five plates and one table)
wapstra, M., Baker, M.L. & Daniels, G.D. 2020 (9:xii): Collecting history and distribution of the potentially invasive Disa bracteata (South African orchid) in Tasmania. Papers and Proceedings of the Royal Society of Tasmania 154: 51-60. ISSN: 0080-4703. Environmental Consulting Options Tasmania, Lenah Valley, Tasmania 7008, Australia (MW*); Tasmanian Herbarium, Tasmanian Museum and Art Gallery, Sandy Bay, Tasmania 7005, Australia (MLB); North Barker Ecosystem Services, Hobart, Tasmania 7000, Australia (GDD). *Author for correspondence. Email: mark@ecotas.com.au
pe collecting history of Disa bracteata Sw. (South African orchid) in Tasmania (Australia), the state’s only naturalised member of the oschidaceae family, is presented. Details of its distribution in Tasmania, since it was first discovered in 2005, are included and discussed with information on habitat, abundance and management. The species is primarily distributed across the north coast (Smithton to Mus- s¢Jroe) with an outlier in Huonville in the state's south. Most sites are from verges along public roads and highways, but the species has also cen detected on several private properties and other less disturbed habitats. Many sites with the species have been actively managed with the objective of eradication, although some sites are now well-established so eradication will require concerted effort. It is recommended {pat the species be added to the Tasmanian Weed Management Act 1999 as a declared species with the primary objective of eradication.
Key Words: Disa bracteata, Orchidaceae, distribution, naturalised, weed, invasive.
INTRODUCTION
‘fhe Orchidaceae family is extremely widespread and diverse, with an almost cosmopolitan distribution, and its species can pe found growing in a wide range of habitats except for the mostarid. Itis one of the largest plant families, with estimates suggesting it contains up to 30,000 species (Mabberley 2008, Chen et al. 2009). Being such a large group of plants, it js surprising that its members are relatively uncommon as paturalised species (e.g. Ackerman 2007). For example, of the nearly 1,400 species that are recorded in China, only one is considered to be naturalised (Chen et al. 2009); and of New Zealand’s ca. 117 species, only three are considered 0 be naturalised (Gardner & de Lange 1996, Howell & Sawyer 2006, Breitwieser eta/. 2018). A similar pattern occurs in Australia, where a small number of species (Arundina graminifolia (D.Don) Hochr., Disa bracteata, Epidendrum sp., Eulophia graminea Lindl., Serapias neglecta De Not., Vanilla planifolia Jacks. ex Andrews) are reported to have become naturalised, compared to some 1,300 native species (Jones 2006, Clements & Jones 2008, Conran et al. 2011). Jn most cases, these are localised occurrences of species that have escaped cultivation (Jones 2006). The subject of this paper, D. bracteata, is widely naturalised in parts of southern Australia and is far more capable of self-establishment and long-distance dispersal than any other introduced orchid.
The genus Disa Bergius contains over 160 species and is naturally distributed in sub-Saharan Africa, the Arabian Peninsula, Madagascar and the Mascarene Islands (Leistner 2000, Goldblatt & Manning 2000, Mabberley 2008). The highest diversity for the genus occurs in southern Africa, with 131 species (Leistner 2000).
Disa bracteata (plate 1, plate 2) is endemic to South Africa where it is widespread and common throughout the highly diverse fynbos that extends across the Western Cape
and Eastern Cape provinces (Linder 1981). In its natural range it grows in undisturbed and disturbed habitats but is most frequent and abundant in areas of disturbance such as neglected pasture, roadsides and wasteland where it is considered a pioneer species (Linder 1981). It has been recorded in a wide range of habitats, including those with light and heavy soils, from sea level to 1,500 ma.s.l., grows in full sun or shade and tolerates a wide range of rainfall regimes (Linder 1981). The species is a deciduous perennial geophyte that grows up to 40 cm tall. Each plant produces numerous leaves and a single, stout, cylindrical flowering spike. It dies back in summer and overwinters as a pair of fleshy tubers. The species flowers from late spring through summer. The self-pollinating flowers produce prodigious quantities of minute seed (Jones 2006) that are readily spread over long distances primarily via wind, but also through other vectors such as contaminated soil on vehicles. The tubers produce numerous fleshy roots that make uprooting entire plants by hand almost impossible in all but the sandiest of soils (M. Wapstra pers. obs.). With its broad tolerance to a wide range of habitats, prolific seed production and its success as a pioneer species, it was perhaps not surprising that D. bracteata became widely naturalised in Australia (fig. 1), one of many plant species from South Africa to have successfully done so (e.g. Scott & Delfosse 1992, Scott & Panetta 1993). Jones (2006) noted that its introduction to Australia remains a mystery, with anecdotal statements suggesting that it arrived in Australia on ships from South Africa in the eighteenth
"century. Several species, and horticulturally derived hybrids
of Disa, are cultivated for their ornamental appeal (Synge 1977). However, D. -bracteata is purported to not be widely used in horticulture. It was first detected in Australia in 1944 from the rural district of Youngs Siding, near the port city of Albany, in Western Australia. At the time it was thought
52 Mark Wapstra, Matthew L. Baker and Grant D. Daniels
PLATE 1 — Disa bracteata (A) in situ at Latrobe site and (B) excavated. (Image: P. Tonelli)
e ; + Newcastles & thy es 8 SYDNEY" Hee Adelaid ; : ; £.. Canberra F Seed ry 4 os e ® 5 ° 5 : e 8 ve ® 5 Geo ® 2 a Hobag*
FIG. 1 — Distribution of Disa bracteata in Australia (source: Atlas of Living Australia, 8 August 2020).
Collecting history and distribution of the potentially invasive Disa bracteata (South African orchid) in Tasmania 53
PLATE 2 — (A) Clump of Disa bracteata in situ on Badgers Head Road, (B) close-up i ; -up image of whole plant , and (C) hand- plant showing lack of tubers and roots, which have remained embedded in the ground. (Images: M. Wass) se ga hes
sf a 2 =| ah PN as 5 é 12 oie sd zi 10 ' 7 Go a 5 Se 7 1c A Pale oi 4 nS
- approx. 100 km _ er NOS NEN PEST SISTENT EESTI
FIG. 2 — Distribution of Disa bracteata in Tasmania (numbers cross-reference to table 1).
54 Mark Wapstra, Matthew L. Baker and Grant D. Daniels
to be a newly recorded native species and was described as Monadenia australiense Rupp (Rupp 1947). Since its discovery, it has become widely naturalised in southwestern Western Australia between Cervantes and Esperance. In South Australia, where it was first discovered in 1988, it is most common in and around the Adelaide Hills area, through to the Fleurieu Peninsula and Kangaroo Island, and around Mt Gambier. In Victoria, the species was first formally recorded in 1994 and is now widespread across southwestern Victoria and eastern parts of Gippsland. The only other region of Australia where it occurs is in Tasmania, where it was first detected in 2005 from a roadside near Bridport in the state’s northeast. In Australia, D. bracteata is commonly referred to as the ‘South African orchid’ or ‘African weed-orchid’.
In Western Australia, South Australia and Victoria D. bracteata is regarded as a significant environmental weed with a propensity to spread and invade bushland (Richardson et a/. 2016), although there is little empirical evidence that shows it has a serious negative ecological impact. In Tasmania, the species is still in the early stages of establishment but with the recent discovery of new populations, the purpose of this paper is to document its current extent of occurrence, identify areas potentially at risk of invasion and describe how weed management legislation may aid in eradication efforts.
METHOD Database and collection review Several sources of records of native plants were interrogated
and reviewed to produceacomplete list ofall known locations of D. bracteata in Tasmania. These wereas follows: collections
PLATE 3 — Examples of excavated plants showing tubers. (A) Badger Head Road, October 2015; (B) Bass Highway, March
2016). (Images: M. Wapstra)
at the Tasmanian Herbarium, Tasmanian Museum & Art Gallery (HO); Department of Primary Industries, Parks, Water & Environment’s Natural Values Atlas database (NVA, DPIPWE 2020); Atlas of Living Australia (ALA 2020); the Australasian Virtual Herbarium (AVH 2020); public Facebook groups Zasmanian Native Orchids, Tasmanian Weeds, Tasmanian Flora and Field Naturalists of Tasmania (with several ‘posters’ contacted direct for additional information); and iNaturalist (with the search terms ‘Disa’ and ‘South African orchid’) (www.inaturalist.org, accessed 19 August 2002).
The data were ‘cleaned’ to produce a definitive worksheet of known locations of the species. ‘Cleaning’ included removal of obvious database duplicates; removal of records lacking sufficient information to precisely place the site, and shifting of point locations to more precise sites where sufficient information was provided (e.g. records currently shown in the sea were shifted to a nearby terrestrial location if collection notes indicated an obvious location). Data were managed in Excel and transferred to ArcGIS for review.
Field survey
Field surveys were opportunistic by the authors as part of other ecological assessments or undertaken by the observers noted in Table 1 (and information gathered through personal communications). The intent of field surveys was to document abundance and extent, as well as persistence potential and threat to adjacent native vegetation (ifpresent).
Where practical, observed plants were removed by trowel (to gather the tuber and root system), bagged and removed from the site. Some specimens were curated to create voucher collections for the Tasmanian Herbarium and several sites were visited on numerous occasions (noted
in table 1).
Collecting history and distribution of the potentially invasive Disa bracteata (South African orchid) in Tasmania 55
TABLE 1 — Collection details of all Tasmanian populations of Disa bracteata.
Site No. ! Location ? Details 3 Comments la “Bridport Road, 4km SE _ T: State Growth 14 Nov. 2005, HO536631, A. Jungalwalla & D. Farmery. of Bridport” I: Flinders “Roadside verge” (from HO536631). M: Dorset This is the first formal collection of D. bracteata from Tasmania. N: North Unfortunately, at the time of collection there was confusion as to whether the specimen had been collected from Bridport Road or Greens Beach Road, but the collectors have indicated that Bridport Road is the most likely. Further discussions indicated that they had “recalled several plants” although only one was submitted. “On 6 Dec. 2005; the site was surveyed by Alan Gray, Alex Buchanan and Matthew Baker from the Tasmanian Herbarium along with Jamie Cooper, the North East Regional Weed Officer. The species in question was not found” (from HO536631). lb Bridport Road T: State Growth 2 Mar. 2016, no specimen, A. North. I: Flinders Single, seasonally dead, roadside plant on Bridport Main Road M: Dorset between Bridport and Scottsdale near junction with Duncraggen N: North Road; in a scattered infestation of spanish heath sprayed in January; “unfortunately looks like it has shed seed” (A. North pers. comm.). This is effectively the same site as the original population (1a). Ic Bridport Road T: State Growth 17 Dec. 2017, no specimen, K. Ziegler. I: Flinders Nine point-locations representing 68 individuals, most fertilised M: Dorset and gone to seed, with some plants pulled up (K. Ziegler pers. obs.). N: North This indicates a significant proliferation of the original population (Ja). 20 Dec. 2018, no specimen, A. Williams. 500 + 110 individuals on west side of Bridport Road, plants predominantly located on flat area of road reserve above batter. 50 + individuals on east side of Bridport Road. Population is approximately 1.1 km north of Boddington Road. Plants hand pulled. ld Bridport Road T: State Growth 17 Dec 2017, no specimen, K. Ziegler. I: Flinders Single plant, seed shedding, hand pulled. M: Dorset 20 Dec. 2018, no specimen, A. Williams N: North Six individuals, hand pulled. Site located west side of Bridport Rd, 730 m north of Beddineen Road. Ic & ld Bridport Road T: State Growth 8 Dec. 2019, no specimen, J. Cooper. I: Flinders 58 individuals at sites 1c & 1d. Plants hand pulled. Sites 1c & 1d M: Dorset surveyed together, including area of road reserve between sites. (J. N: North Cooper pers. comm.). 2 “Latrobe, council- T: Local government 12 Nov. 2009, HO559795, P- Tonelli.
Sa
maintained waste site”
“Spreyton/Tarleton area”
Settlers Road, Latrobe
Parkers Ford Road, Port
Sorell
I: Flinders M: Latrobe N: Cradle Coast
T: Private
I: Flinders
M: Latrobe
N: Cradle Coast
T: Private
I: Flinders
M: Latrobe
N: Cradle Coast
T: Local government I: Flinders
M: Latrobe
N: Cradle Coast
“In-fill wasteland; introduced grasses and pasture weeds, some low quality prostrate native plants (e.g. Hibbertia procumbens) in W end close to collection site. Only a single specimen located [excavated]; an extensive search of the local area failed to locate any others”
(from HO559795). Refer to Plate 1.
8 Nov. 2016, HO586101, G. Pocknee.
“Semi-rural 3-acre block, front weedy lawn — sparsely grassed area with mosses and weeds; 5 plants” (from HO586101).
“Still finding the occasional one &