Review of the Distribution, Causes for the Decline and Recommendations
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Conservation Science W. Aust. 6 (1) : 13-73 (2007) Review of the distribution, causes for the decline and recommendations for management of the quokka, Setonix brachyurus (Macropodidae: Marsupialia), an endemic macropodid marsupial from south-west Western Australia PAUL J. DE TORES1', MATTW. HAYWARD2,3.4, MICHAEL J. DILLON3 AND ROBERT I. BRAZELL5 I Department of Environment and Conservation, Wildlife Research Centre, P.O. Box 51 Wanneroo, Western Australia 6946 2 School of Biological, Earth and Environmental Science, University of New South Wales, Sydney, New South Wales 2052 3 Department of Environment and Conservation, Dwellingup Research Centre, Banksiadale Road, Dwellingup, Westem Australia 6213 4 Current address: Mammal Research Institute, Polish Academy of Science, 17-230 Biglowieja, Poland 5 Department of Environment and Conservation, Wellington District, P.O. Box 809 Collie, Western Australia 6225 . Contact person for correspondence: Paul de Tares, email: [email protected] ABSTRACT Specific conservation management actions are recommended, namely: (i) Implementing an active The former and current distribution of the quokka, adaptive management program in the northern jarrah Setortix brachyurus, was mapped from published and all forest to determine quokka population response to available unpublished records. At the time of European habitat manipulation through the use of fIre, fox baiting settlement the quokka was widespread and abundant and and pig control; (ii) Surveying the Stirling fumge and its distribution encompassed an area of approximately Green Range populations with emphasis placed on 2 41 200 km of south-west Western Australia inclusive of determining population size and population genetic two offshore islands, Bald Island and Rottnest Island. structure; (iii) Surveying the reported occurrences from Historical reports indicated an extensive population the Swan Coastal Plain, with emphasis on unambiguously decline occurred in the 1930s. The decline continued, determining presence. If confirmed, priority should he with a previously undocumented decline apparent in the directed to assessing population size and determining period from 1980 to 1992. However, this decline may the management requirements to ensure persistence of be an artefact of the time scales used for mapping and the population; (iv) Surveying southem forest and south may well equate with a previously reported decline lor a coast populations to assess quokka population size, the suite of south -west mammals in the 1970s. By 1992 the extent of movement between sllbpopulations and quokka's distribution had been reduced to an area of assessment of the range of habitat types used by quokkas. 2 approximately 17800 km • An increased awareness of The latter should be combined with spatial analyses of the presence of the quokka on the mainland has resulted known extant populations and suitable and potentially in numerous reportings of quokka presence since 1992, suitable habitat; (v) Determining the role of tire in has confimled the existence of several populations at the establishing and maintaining preferred habitat ofsollthern northern extent of the quokka's known geographic range forest and south coast populations; and (vi) Establishing and indicated the cmrent, 2005, distribution to be similar a program to assess the potential effects from to that in 1992. However, survey and population management operations. estimates at six of these mainland locations from the northem jarrah forest indicated low abundance. There Keywords: quokka, Setotlix brach.'1urus, distribution, fox have been no population estimates elsewhere on the predation, flre, adaptive management mainland. Two populations have been reported ti'om the Swan Coastal Plain, but neither has been confirmed extant. INTRODUCTION Predation by the introduced fox, Vulpes l'ulpes, is implicated as a major cause of the quokka's initial decline, The quokka, Setonix brachyurus (Macropodidae: while ongoing predation, habitat destruction and Marsupialia) (Quoy & Gaimard 1830) is a small to medium modification through altered tire regimes have sized macropodid marsupial, endemic to the mainland of contributed to the continued decline. south-west Western Australia and two offShore islands - P.J. de Torres et a/. 14 Bald Island, cast of Albany and Rottnest Island, 20km At the time of European settlement of south-west west of Perth (Fig. I). Adult males range in weight from Western Australia, the mainland distribution of the 2.7 to 4.2 kg and adult females from 1.6 to 3.5kg quokka was thought to extend from the Moore River (Hayward ct al. 2003; Kitchener 1995). The quokka is district 80-100 km north of Perth (Baynes 1979), to known to the Aboriginal, or Noongar, people of somh areas south and south-east of Perth at locations within west Western Australia by a range of names including the Swan Coastal Plain, the jarrah, Eucal)'Ptusmarginata, 'Ban-gup', 'Brmgeup', 'Quak -a) (Gould 1863; and karri, E. di)'crsic%r, forests south-east of Perth, the Shortridge 1909), 'kwoka' and 'ba1Wop' (Abbott 200b). Cape Leeuwin-Cape Naturaliste region, the south coast The ql10kka was the second Australian marsupial and east to the Hunter River east of Bremer Bay (Baynes recorded by Europeans, the first appears to have been 1979; Baynes et aL 1975; Glauert 1933; IGtchener 1995; Francis Pelsart's description of the Tammar Wallaby from Ride 1970) (Fig. 1). In addition to the Rottnest Island the HOlltman Abrolhos on 1629. The first European and Bald Island populations, quokkas were reported fi'om record of a quokka is attributed to Samuel Volckertzoon Breaksea Island, near Albany (Western Australian (or Volckerscn) who, in 1658, when visiting the then Museum records), 'Twin Peak' Island and other offshore un-named Rottnest Island otf the coast near Perth, islands near Esperance (Shortridge 1909). Subsequent described the qllokka as 'a wild cat ,"esembling a civet references to the quokka's historic distribution on the cat but with browner hair' (Alexander 1914). In 1696 mainland, at or prior to the time of European settlement, when Willem de Vlamingh \~sited the island he described have included the south coast of Western Australia as far the qllokka as 'a kiud of rat as big as a common cat) east as Esperance (Shortridge 1909; Troughton 1965). (Alexander 1914). He named the island Rottenest (now This inferred former distribution was based on the Rottnest), meaning rat's nest. The quokka is often above reports and location records. All location records erroneollsly reported by local media as occurring only were within four biogeographical regions, or bioregions, on Rottnest Island. Its presence on the mainland was as identified in the Interim Biogeographical Regionalisation described in 1957 as largely unreported (Barker et al. for Australia (IBRA) (Thackway & Cresswell 1995), 1957) and it is still widely thought of as only occurring namely the Swan Coastal Plain, the Jarrah Forest, the on Rottnest Island. Warren and the Esperance Plains bioregions (Fig. 1). Figure 1: The four biogeographical regions, a. defined by the Interim Biogeographical Regionatisation for Australia (IBRA) (Th.cl<w.y and Cre.swell. 1995), wilhin south-west Western Australia which encompass all records of occurrence of the quokka. Selonix brachyu",s. Previously unpublished ; ----,j trapping iocatlons are shown as + for sites trapped in the period 1992 10 2002 10 confirm presence and/or 10 derive L---': . an estimate of abundance Area~ of enfargement t:1 Biogeographical Regions m esperance Plains Jarrah Forest PERlH Swan Coastal Plain Albany IiighWily, Tnwll.rs' AimS Sir. ~Warren Ow.'lIngup SunbUl')' Manjimup Norlh Twin Peak 1'51a(ld 50 100 200 300 400 ± !---IIi---+1--+--Kd-om-l-I.-".-,-+---II- .......-I F!~zlre 1. The jilur bitLlJcILlfraphical regions, as defined by the Interim Biogeographical Regionalisatilm for Aum'alia (IBRA) ( J f}{ukn>ay and Cmm'cit 1995) withi1l tJ. - TTl A . S .' ~ . '. ' SOli J west rvcstern ustralta wbzch encompass all records of occurrence oft/Jc quokka etlfillUX achyurus. Prn1101Isly unpublished traPP.ing locatillns are sbOll>U as + fill' sites trapped in the period 1997 to 2002 :0 COtl Inn presC1lct Mid/or to deN)'c an estimate ofabundance - Distribution of the quokka 15 Various authors have expressed concern at the extent assesses the probable causes of the species decline and of the quokka's decline from this inferred historic proposes specific conservation management distribution and attributed different levels of threat to its recommendations. The conservation status is reviewed conservation status. Clarke (1948) suggested the quokka in a forthcoming publication. was almost confined to Rottnest Island. White (1952), although noting there was a misleading impression of rarity on the mainland, conceded the quokka was METHODS becoming less abundant there. Loaring (in Serventy et al. 1954) believed quokkas had vanished frOm their ~ttnY Distribution maps and terminology haunts' in the Darling Plateau by the 19205. Sharman (1954) noted the quokka appeared common only on Location records for the qllokka were obtained from Rottnest and Bald Islands with isolated colonies at some published and unpublished accounts of fossil, sllbtossi! mainland sites. and surface cave deposits, published and unpublished Barker et al. (1957) cited a 1957 newspaper article records of distribution/presence, database records of which suggested the quokka was extinct on the mainland. the Western Australian Museum (WAM), database That report