The application of Zoos Victoria's 'fighting extinction' commitment to the conservation of leadbeater's possum 'Gymnobelideus leadbeateri'

2012·1.8 MB·English

by  Dan Harley

/
Contributions
The application ofZoos Victoria’s 'Fighting Extinction’ commitment
to the conservation ofLeadbeater’s Possum Gymnobelideus leadbeateri
Dan Harley
WildlifeConservationandScienceDepartment,ZoosVictoria
Email:[email protected]
Abstract
Aspartofits‘Fighting Extinction’program,Zoos Victoria has developed criteria toguidewhen it will initi-
atecaptive-breedingprogramsfornativethreatenedspecies.Applicationofthesecriteria,whicharebasedon
extinctionrisk,hasresultedintheidentificationoftwentyprioritythreatenedspeciesforexsituconservation.
This list includesthegenetically-distinctlowland population ofLeadbeater’s Possum. Asa result, a captive-
breeding program has been initiated to prevent theextinction ofthis population. The ‘Fighting Extinction’
strategyrepresentsamorestructured,systematicandintegratedapproachtohowZoosVictoriaisattempting
todelivertangibleconservationoutcomes.Notably,measuresofsuccessaretiedtotheconditionofwildpopu-
lations. Aspectsofthe ‘FightingExtinction’strategyand the Leadbeater’s Possum captive-breedingprogram
aredescribed.(TheVictorianNaturalist 129(5)2012, 175-180)
Keywords: Leadbeater’s Possum;captive-breeding;zoo;threatenedspecies;extinction
In its 20-yearstrategic plan, Zoos Victoria has focused on population size and trend, extent
committed to transforming itself into a ‘zoo- ofdistribution and key threatening processes.
based conservation organisation’ that delivers Inaddition to theeleven captive-breedingpro-
tangible conservation outcomes for wildlife grams that Zoos Victoria already had in place
populations. Considerable effort has gone into forspeciesoccurringinsouth-easternAustralia
defining precisely what this means, and the (seven ofwhich targetedVictorian species; see
strategy highlights that the organisation is not Table 1), this review identified nine additional
just concerned with the captive collection, but Victorian species warranting ex situ recovery
isvery much focused on the condition ofwild measures (Table 2), including Leadbeater’s
populations.Intermsofdeliveringtangibleout- Possum Gymnobelideus leadbeateri. Hence,
comes, the conservation of native threatened Zoos Victoria has arrived at a priority list of
species has been identified as a clear priority, 20 native threatened species. This list will be
andformsoneofthecentralelementstoamore reviewed periodically, and species added or
holistic conservation approach that has been removed as new data become available and
developed under the banner ‘Fighting Extinc- or circumstances in thewild change. Note that
tion’. Partofthisapproach isoutlinedbelow. under these criteria, exsitu intervention is not
triggered for species that are in decline within
‘FightingExtinction’
To create greater transparency around when VictoriabuthavestrongholdsinotherStatesor
Territories.
wnaetiwviellthinrietaitateenecdapstpievcei-esb,retehdeinfgolplroowgirnagmcsofmo-r Having a clear understanding ofwhy we are
focused on certain species and not others has
mitmenthasbeenmade:
created greater clarity in where Zoos Victoria
‘Zoos Victoria will ensure that no Victorian invests resources. New captive programs have
species of terrestrial vertebrate become ex-
alreadybeeninitiatedforfouroftheninespecies
tinct.’
The focus on terrestrial vertebrates reflects listed in Table 2. For these additional species,
theexpertiseatZoosVictoria’sthreeproperties, our approach first involves the establishment
Melbourne Zoo, Werribee Open Range Zoo ofcaptive populations, followedbysubsequent
releasestothewildto recoverpopulations.
and HealesvilleSanctuary.
Three ofVictoria’s highest profile threatened
In applying this criterion, Victorian species
have been assessed and prioritized based on species highlight the important role that zoos
canplayinconservation.ThemainlandEastern
theirlikelihoodofextinctioninthewildoverthe
Barred Bandicoot Perameles gunnii unnamed
next 10years. Thesequalitative determinations
Vol 129 (5) 2012 175
Contributions
Table1.The 11 nativethreatenedspeciesincludedinZoosVictoriascaptive-breedingprogramspriorto2011.
Common
Scientific Conservation Year Captive Reintro-
Name Name Status commenced breeding duction
(EPBCAct)
TasmanianDevil Sarcophilus Endangered 2006 S
harrisii
MountainPygmy Burramysparvus Endangered 2007 S
Possum
EasternBarred Peramelesgunnii Endangered 1990 S S
Bandicoot(mainland) unnamedsubspp.
Orange-belliedParrot Neophema Critically 1991 y V
chrysogaster Endangered
Helmeted Lichenostomus Endangered 1989 s V
Honeyeater melanopscassidix
Regent Anthochaera Endangered 2002 s
Honeyeater phrygia
SpottedTreeFrog Litoriaspenceri Endangered 2006 y V
SouthernBarredFrog Mixophyesbalbus Vulnerable 2001 s
Southern Pseudophryne Endangered 2008 s V
CorroboreeFrog corroboree
Northern Pseudophryne Vulnerable 2010 V s
CorroboreeFrog pengilleyi
LordHoweIsland Dryococelus Critically 2003 V
StickInsect australis Endangered
Table2. ThenineadditionalVictorianthreatenedspeciesidentifiedaswarrantingexsituinterventionunder
ZoosVictorias‘FightingExtinction’commitment.
CommonName ScientificName Conservation
Status(EPBCAct)
LeadbeatersPossum (YellingboESU) Gymnobelideusleadbeateri Endangered
Brush-tailedRock-wallaby(SouthernESU) Petrogalepenicillata Vulnerable
SmokyMouse Pseudomysfumeus Endangered
NewHollandMouse Pseudomysnovaehollandiae Vulnerable
SouthernBent-wingBat Miniopterusschreibersiibassanii CriticallyEndangered
GrasslandEarlessDragon Tympanocryptispinguicolla Endangered
AlpineShe-oakSkink Cyclodomorphuspraealtus Endangered
GuthegaSkink Liopholisguthega Endangered
BawBawFrog Philoriafrosti Endangered
subspp. would be extinct ifit were not for the captive-breeding and release programs. Con-
breeding and release program undertaken by versely, each of these breeding programs has
Melbourne Zoo. Similarly the Helmeted Hon- been in place for about 20 years and yet wild
eyeater Lichenostomus melanops cassidix may populations for each species remain at risk.
be extinct ifit were not for the breeding and Thus,some adjustmentsare requiredto there-
release program undertaken by Healesville coverymodelsbeingapplied.
Sanctuary. And the Orange-bellied Parrot Ne- In recognition ofthe need to increase the ef-
ophema chrysogasteris predicted to go extinct fectivenessofcaptive-breedingandreleasepro-
in the wild during the next fiveyears; however grams,ZoosVictoriahasmadeseveralchanges
a large insurance population has been estab- in howit is approachingthreatened speciesre-
lished in captivity. All the recovery potential covery. Weareworkingwith recoveryteamsto
for these Victorian species rests on successful achievegreaterclarityandintegrationofthere-
176 TheVictorianNaturalist
Contributions
coverytargets for the wildand captivecompo- mature,hollow-bearingtreesthatprovidedens,
nents to these programs. Too often in the past, the species is currently listed as ‘endangered’
the parties driving in situ and exsitu recovery under the Commonwealth Environment Pro-
measures have operated independently ofone tection and Biodiversity Conservation Act 1999
another. Ifthecaptive-breedingprogramsexist and ‘threatened’ under the Victorian Flora and
fundamentallytoservethewild,thenultimately Fauna Guarantee Act 1988. Notably, the Black
theyshouldberesponsivetotherecoveryneeds Saturdaywildfires in 2009burntapproximately
ofthewildpopulations. 45% ofthe high quality habitat for the species
Inordertominimisethelossofgeneticdiver- (S. Smith, unpubl. data), greatly elevating the
sity in captive populations, we are looking to extinction riskforthisspecies.
manage our threatened species as part ofcap- ZoosVictoriahasassessedtheextinctionlike-
tive-wild metapopulations. This involves peri- lihood for Leadbeater’s Possum populations in
odic transfer ofindividuals between all popu- montane habitats and at Yellingbo against its
lations, regardless ofwhether they are captive ‘Fighting Extinction’ criteria (i.e. our trigger
or wild, to maintain gene flow. This is already forcaptiveintervention).Themontanepopula-
being done effectively for the Helmeted Hon- tionsare inseriousdecline,particularlyfollow-
eyeater. We also recognise that the quality’ of ingthe BlackSaturdayfires, andtheextinction
the individuals being bred in captivityhas im- riskisveryrealovercomingdecades. However,
portantimplicationsforsuccesswhen wecome thespeciesisnotlikelytobecomeextinctacross
to releaseto thewild. Thishasbecome a major the entire Central Highlands during the next
research focus for Zoos Victoria, and includes 10 years, and hence they do not yet trigger ex
the application oftechniques to promote mate situ intervention. Moreover, the keychallenges
choiceandtheretentionofappropriatewildbe- in the Central Highlands are related to habitat
haviours incaptivepopulations. conditions, and captive-breeding is not an ap-
Finally, the ultimate measure of success for propriate toolto addressthisproblem.
our ‘Fighting Extinction’ programs is the con- In contrast, the small, genetically-distinct
dition of wild populations. Specific five-year lowland population at Yellingbo does meet
and 20-year recovery objectives have been de- Zoos Victoria’s criteria for exsitu intervention,
velopedforeachspeciesin thewildandcaptiv- as a singlefirecouldeliminate theentirepopu-
ity,resultingingreaterintegrationofinsituand lation given its localized occurrence. Hence,
exsituapproaches. this population is the focus ofZoos Victoria’s
captive-breedingand releaseprogram.
Leadbeater’sPossum
Population monitoringfor the lowland Lead-
Leadbeater’s Possum is a small (110-160 g), beater’s Possums at Yellingbo has been un-
arboreal marsupial that was thought to be ex-
derway for 17 years (Harley 2005; Harley and
tinct prior to its rediscovery near Marysville Antrobus unpubl. data). Data describing the
oinnly196s1pec(iWeislkoifnsnoant,iv1e961m)a.mTmhaelporsessturmictiesdthien bsepesctiaesv’aiplaobpluelafotrioannydyVincatmoircisanatmathmismasilte(igsivtehne
droiansntgmreoibniusttcaioonnnefeihnnatebidriettlaoytstaoi7nV0itcxhtoe8r0iVaik,ctmaonradiraeintascCceeunnrttrrreeandlt titheistaotcallopsoepduploaptuiloantiisosnaamnpdlemdoerveertyhayenar9)0.%Thoef
Highlands (see Harley 2004). A single, rem- annual monitoring program results in several
measures of population condition, including
nant, outlying population occurs in lowland
total population size, distribution, territory
habitats at Yellingbo Nature Conservation Re- stability, mean colony size, reproductive rate,
serve (Harley et at. 2005). Molecular data have annual recruitment and dispersal. The current
revealed that the lowland population at Yell-
oicngcbuopyiisnggenmetoinctalalnyedihsatbiintcattsfro(mHapnospeunlat2i0o0n8s; siinzdeiviodfuatlsh,eapnodpuitlahtaisodnecilsinaepdprboyx4im6a%tedluyri6n0g
the past nine years (Harley and Antrobus,
Hansen and Taylor 2008; Hansen et at. 2009). unpubl. data). Changes in the genetic charac-
Owingto its restricteddistribution, small pop-
ulation size(<2000 individuals) andthelossof teristicsofthepopulationoverthepast 10years
are currentlybeing assessed. The key threat to
Vol 129 (5) 2012 177
Contributions
thispopulation istheserious decline inhabitat ingto maintainkeywildbehavioursin thecap-
conditionsinthereserve,andasaconsequence tive possums, and this is being reflected in the
the availability ofsuitable foraging habitat has typesofanimalmonitoringweareundertaking
become the key limiting factor (Harley et al. (e.g. filmingvisitation to food stations and ac-
2005; Harley, unpubl. data). tivity periods). We are usingthe behaviour ex-
ZoosVictoriahasdevelopedfive-yearand20- hibitedbythewild-caughtfoundersasabench-
year objectives for the recoveryofLeadbeater’s mark againstwhich we can assess captive-bred
Possuminlowlandhabitats(coveringbothwild y1.ounginfutureyears.
and captive populations). The five-year objec- Ourultimategoal is recoveryofwild popula-
tives developed for the wild emphasise the tions ofLeadbeater’s Possum in lowland habi-
needtoaddresshabitatdecline atYellingbo,the tats. The 20-year objectives for the wild define
key threatening process at this site. To achieve ourvision ofsuccess, and areas follows:
this,ZoosVictorianeedstoworkwithpartners Wild population size at Yellingbo exceeds
such as ParksVictoria, highlightingtheimpor- 150individuals.
tance ofintegrating insitu and exsitu recovery 2. Greaterthan 25%ofthe Cockatoo and Mac-
measures. clesfield Creek floodplains provide high
In captivity, the five-year objectives are as qualityhabitatforLeadbeater’sPossums.
follows: 3. Populationandhabitatmonitoringprograms
1. Healesville Sanctuary and Melbourne Zoo maintained for Leadbeater’s Possum at Yell-
house aviable captive insurance population ingbo.
comprising at least 20 individuals for the 4. Establishmentofatleastone additional low-
genetically-distinct lowland population of landpopulationcontainingaminimumof50
Leadbeater’sPossumatYellingbo. individuals.
2. Captive possums are managed to promote Note that these objectives list a minimum
successful breeding and maintain wild be- populationsizeforYellingbo(>150individuals)
haviours. thatshould be self-sustainingin termsofpopu-
3. Release techniques aredeveloped to success- lation processes. They also specify the area of
fullyestablishcaptive-bred individualsinthe habitat required to achieve this population tar-
wild. get,andidentifytheneedtoestablishadditional
4. ZoosVictoria providesunique opportunities lowland populations away from Yellingbo. The
for the public to engage with Leadbeater’s latterpointhighlightsthatsuccesswiththisspe-
Possum and its conservation. cies ultimately means that we would no longer
The first four founders for the captive requirean insurancepopulation incaptivity.
population were collected during May 2012 There are two key reasons whyZoos Victoria
and are now housed at Healesville Sanctuary. has directed its conservation efforts at the
The collection schedule for founders is four Yellingbo population of Leadbeaters Possum:
possums per year for three years. Collection (i) this population is at the greatest risk of
has been staggered over time to minimise extinction in the short-term (i.e. within 10
any negative impact on the wild population. years), and (ii) the population is genetically
Individuals are being selected based on their distinct. In 2011, the Leadbeaters Possum Re-
genetic attributes and to avoid disrupting covery Team debated whether conservation of
colony structure (e.g. collection of dispersal- theuniquelowlandgenesatYellingboisofhigh
age subadults). The target size oftheinsurance importance. The consensus was it is important
population is 20-30 individuals, and this will to protect them. Moreover, conservation ofge-
be spread across two properties, Healesville netic diversity across a species’ range is an im-
Sanctuary and Melbourne Zoo. We intend portant principle, and this has been reflected
to manage the insurance population as part in the approach ofthe Victorian Government
of a captive-wild metapopulation, albeit this where several high-profile threatened species
requires us to be able to successfully establish recovery programs target subspecies or ge-
captive-bredyounginthewild. netically-distinct populations (‘Evolutionary
We areplacingconsiderableemphasison try- Significant Units’), e.g. Red-tailed Black-Cock-
178 The Victorian Naturalist
Contributions
atoo, Helmeted Honeyeater, Eastern Barred raisetheprofileofthesespecies. Partofthis in-
Bandicoot, Brush-tailed Rock-wallaby, Moun- volvesa majorcampaignat Healesville Sanctu-
tain PygmyPossum. ary that aims to get children to connect with
Action for the Yellingbo population ofLead- Leadbeater’s Possum through the creation ofa
beaters Possum alone is clearly insufficient to cartoon character(Lunar) andan animatedin-
adequately conserve this species. The species’ teractivedisplay(Lunar’sSecretForest).
stronghold is in the montane forests of the Conclusion
VictorianCentralHighlands,andconsequently Several distinct changes are evident in how
the main conservation focus fromgovernment
Zoos Victoria is currently tackling threatened
should be directed there. Greater recovery fo-
cus on the montane populations following the species recovery through its ‘Fighting Extinc-
tion’program. Theseincludethefollowing:
BlackSaturdayfires isclearlywarranted. In ap- • criteriatoguidewhenwewillinitiatecaptive-
plying a holistic conservation strategy for this breedingprogramsfornativespecies;
species (that incorporates risk-spreading), re- • closer integration between management of
covery models (and actions) should be articu- thewildandcaptivepopulations;
lated forall three foresttypesthat Leadbeater’s • measures of success that are tied to the
Possum inhabits (i.e. montane ash forest, sub- condition ofwildpopulations;
alpine woodland and lowland swamp forest) • establishment of captive-wild metapopu-
that take account ofthe different threats and lationstominimisethelossofgeneticdiversity
managementissues. andmaintainappropriatebehaviours;
CommunityEngagement • research programs directed at improving the
qualityofindividualsbredincaptivity;
MelbourneZoo,WerribeeOpenRangeZooand • major focus on increasing community
Healesville Sanctuary attracted approximately understanding and engagement with our
1.9 millionvisitors in 2011. A high proportion threatened species programs. This includes
of this audience lives in urban environments, use of the Connect-Understand-Act model
yet the majority of threatened species issues topromotebehaviourchange inourvisitors.
occur in regional areas. Zoos have a unique This strategy represents a more structured,
opportunity to bridge this gap, connect people systematic and integrated approach to how
with the issues and provide them with simple ZoosVictoriaisattemptingto deliver‘tangible’
things they can do to assist. In recognition of conservationoutcomes.
this, Zoos Victoriahasdeveloped specificVisi-
Acknowledgements
troerleoabsjeecttairvgeest’s.toTshiteal‘oWnigpseidefoorurWiblrdleiefdei’ngcaamn-d MZoaonsyVpiecotporlieahsa‘vFeigchotnitnrgiEbxuttiendcttioont’hepdroegvrealmo.pmIennptaro-f
paignatHealesvilleSanctuaryurgingvisitorsto ticular,Iwouldliketoacknowledgethecontributions
use recycled toilet paperto reduce thenumber made by the following Zoos Victoria staff: Rachel
of trees harvested is an example of this ap- Lowry, MichaelMagrath, Chris Banks, Marissa Par-
proach. Importantly,subsequentuptakeamong rott,EmilyDunstan, RusselTraher, Melanie Lancas-
ter and Paul Watson. Valuable ideas have also been
visitors is being measured. In association with contributed by Graeme Gillespie, Andrew Weeks,
the Leadbeater’s Possum program we are pro- RichardHill,GraemeCoulson,JoanneAntrobusand
moting the use of Forest Stewardship Council severalrecoveryteams.Thesuccessoftheseprojects
(FSC) certified timber and paper products. wbyoutlhdenVoitctboeripaonssiDbelpeawrittmheonutt tohfeSsuustpapionratbiplritoyviadnedd
These programs apply the Connect-Under- Environment and Parks Victoria. The manuscript
stand-Act model developed by Rachel Lowry, was improved by comments from Michael Magrath
Zoos Victoria’s Director ofWildlife Conserva- andMarianneWorley.
tion & Science, to promote behaviour change References
amongst our visitors in ways that will benefit Hansen BD (2008). Population genetic structure of Lead-
wildlifepopulations. beaters possum Gymnobelideus leadbeateri, and its im-
plications for speciesconservation. PhD Thesis, Monash
Zoos Victoria’s 20 priority species are being University,Clayton,Australia.
promoted to the Victorian community under Hansen BDand TaylorAC (2008). Isolated remnantor re-
thebanner‘Loveyou Locals’. Andwearein the cLeenatdbienattreordsuctpioosns?uEmsstibmyatgienngettihcepanraolvyesnisanacnedofboYtetlllienngebcok
process oftesting some different techniques to simulation.MolecularEcology,17,4039-4052.
Vol 129 (5) 2012 179
1
Contributions
Hansen,BD,Harley,DKP,Lindenmayer,DBandTaylor,AC Harley, DKP, Worley, MA and Harley, TK (2005). The dis-
(2009).Populationgeneticanalysisrevealsalong-termde- tributionandabundanceofLeadbeatersPossumGymno-
cline ofa threatened endemicAustralian marsupial. Mo- belideusleadbeateriinlowlandswampforestatYellingbo
Harlleceuyl,arDKEcPol(o2g00y4)18.,A33r4e6v-i3e3w6o2f.recentrecordsofLeadbeat- N7-a1t5u.reConservationReserve.AustralianMammalogy27,
er’sPossum(Gymnobelideusleadbeateri). InThe Biology Wilkinson,HE(1961).TherediscoveryofLeadbeatersPos-
ofAustralianPossumsandGlidingPossums,pp.330-338. sum,GymnobelideusleadbeateriMcCoy. VictorianNatu-
EdsRGoldingayandSJackson. (SurreyBeattyandSons: ralist78,97-102.
Sydney)
Harley, DKP (2005). The life history and conservation of
LeadbeatersPossum(Gymnobelideusleadbeateri)inlow- Received13September2012;accepted13September2012
landswampforest.Ph.D.Thesis,MonashUniversity,Clay-
ton,Australia.
Forest Ecology - A Victorian Perspective
Abstract from apaperpresentedto the FNCV BiodiversitySymposium 201
Stephen Mueck
SeniorConsultantBotanist,BiosisPtyLtd,38BertieStreet,PortMelbourne,Victoria3207
Forest communities typically are defined by Forestsareoftendescribedintermsoftheirage,
their floristic composition and structure. This with conservation efforts often focused on the
dataiscollectedusingquadratbasedsurveysand concept of old growth’. This tends to concen-
analysed statistically using a nearest neighbour trate on theageandstructureoftheoverstorey
algorithm. Tens ofthousands ofsuch quadrats and time since disturbance. However, studies
havebeencollectedacrossVictoriaandthisdata ontheageofdifferentunderstoreyspeciesindi-
has been used to identifynumerous vegetation catesthatsomehaveindividuals,ifnotpopula-
communities known as ecological vegetation tions, which are older, sometimes significantly
classes (EVCs). While EVCs are locally based so, than the overstorey. Carbon dating results
on floristics they are more broadly defined by from common, often dominant, understorey
a consistentsetofphysicalandclimaticparam- species collected from Victorias Central High-
eterssuchasrainfall,aspectandsoilconditions. landsWetForestincludeSoftTree-fernDickso-
Wet Forest in East Gippsland therefore may nia antartica (5.3 m tall350 ±50years), Rough
have quite different floristics from those in the Tree-fernCyatheaaustralis (12.5mtall370±70
OtwayRanges, but as theyoccur undersimilar years), Musk Daisy-bush Olearia argophylla
environmental conditions, support similar life- (-100yearsfromwithin 1939 regrowth Moun-
formsandhavesimilarstructuralcharacteristics tainAshEucalyptusregnans)andTreeGeebung
theyareidentifiedasthesameEVC. Persooniaarborea (12mtall320-510years).
The composition and structure of a forest These ‘old growth’ understorey components
communityisalsogovernedbythetype,inten- areoftenresproutersandcanbeveryinfluential
sityandfrequencyofdisturbance(i.e.fire,frost, inboththeongoingstructureandcomposition
disease,windthrow,landslide,timberharvest). of the forest and the post-disturbance recov-
Plants recover from disturbance using one or eryprocess. However, where thedisturbanceis
a combination oftwo strategies including res- morephysical,suchasthatassociatedwithtim-
proutingfroman organ (i.e. lignotuber,epicor- berharvesting,theseresproutersoftenfarevery
mic shoots, rhizomes etc.), which survives the poorly in the post disturbance recovery proc-
disturbance, or establishing a new individual ess in comparison to their survivorship after
from seed or spore. The individual life history fire. Such changes undoubtedlyhaveecological
strategiesofspeciesthereforegoverntheirabil- consequencesforforestregeneration.
itytopersist indifferent ecosystems underdif-
ferentdisturbanceregimes.
180 TheVictorian Naturalist