Surveys for the Eltham copper butterfly 'Paralucia pyrodiscus lucida' Crosby (Lycaenidae) in Victoria in late 2011

2012·1.4 MB·English

Contributions
Surveys for the Eltham copper butterfly Paraluciapyrodiscus lucida
Crosby (Lycaenidae) in Victoria in late 2011
E Bayes1, F Douglas2, JWhitfield3, BD Van Praagh4, RP Field5, ALYen6andTRNew7
1,3DepartmentofSustainabilityandEnvironment,POBox3100,BendigoDeliveryCentre,Victoria3554
2POBox37,Rainbow,Victoria3424
1Invert-Eco,25JacarandaPlace,Craigieburn,Victoria3064.
5,6BiosciencesResearchDivision,DepartmentofPrimaryIndustries,621 BurwoodHighway,Knoxfield,Victoria3156
andBiosciencesResearch,LaTrobeUniversity,Victoria3086.
7DepartmentofZoology,LaTrobeUniversity,Victoria3086(contact:[email protected]).
Abstract
RecentsurveysfortheElthamcopperbutterflyParaluciapyrodiscuslucidaCrosbyhaverevealedseveralpievi-
ouslyunknownpopulations in theWimmera (1), near Castlemaine (4) and near Bendigo (1). Theirsignifi-
canceisdiscussedinrelationtothebutterfly’sconservationandmanagement, includingdesignoffuelreduc-
tionburningforoccupiedsites(TheVictorianNaturalist129(3),2012,114-118)
Keywords: Elthamcopperbutterfly,Paraluciapyrodiscuslucida,conservation,invertebrate,management
Introduction
The Eltham copper butterfly Paralucia pyro- edge, itwasa primecandidatefor investigation
discus lucida Crosby (ECB), is of significant in order to furthercharacterise its distribution
conservation interest, and is amongst the best and seek additional populations that might be
documentedthreatenedinsecttaxain Victoria, vulnerable to fuel reduction burns anticipated
where it has become a notable flagship for in- for assetprotectioninareaswhere it might oc-
vertebrate conservation (Canzano et al. 2007, cur (Newetal. 2012). Some occupied sites are
New 2010). The few known populations, each close to residential developments, where regu-
small and isolated, are concentrated in three lating fires may be both a high priority and a
main regions, namelyouter north-eastern sub- verycomplexexercise to undertakesensitively.
urbs of Melbourne (Eltham, Greensborough), Negotiationson optimalfireregimesto protect
the central wooded countryside spanning Cas- ECB, ifthose regimes can be defined, are also
tlemaine and Bendigo (with recent discover- likely to be complex. Any strictures on burn-
ies in the latter area reported by Canzano and ingoperationsclosetohumansettlementsmay
Whitfield 2008), and a smaller representation needverycarefulconsiderationtoachieveasset
near Kiatain the Wimmera area. Thebutterfly protectionwithoutfurtherthreateninganyspe-
isinvariablyassociatedwithits solelarval food cieslistedundertheFloraandFaunaGuarantee
plantBursariaspinosaCav. andcaterpillarsalso Act 1988.
have a mutualistic association with ants, Noto- Inthisnote,wereporttheoutcomesoftarget-
ncus spp. Bursaria spinosa and identified host ed surveys for the butterfly undertaken in late
species ofNotoncus are widespread, and occur 2011,basedonsearches foradultbutterflies.
in many places in Victoria where Paralucia is Methods
absent, some ofthese appearing entirely suit- During the main adult flight season ofP.p. lu-
ableforhabitation. cida in late 2011 (November, December), sys-
The ECB is one ofvery few Victorian inver- tematicsurveysoftheregionalnon-Melbourne
tebrates for which site managementbycontrol populations were undertaken by trained ob-
burning has been attempted in the past (New servers familiar with the butterflyand unlikely
et al. 2000) and for which tentative fire pre- to confuse it with any other taxon. Surveys
scriptionscanbebased on practicalexperience included known occupied and historically oc-
and knowledge of the species’ biology, albeit cupiedsites,andadditionalareasofpotentially
at sites near Melbourne rather than the areas suitablehabitat within the wider regions. Dur-
explored here. With such background knowl- ing the time available, we have attempted to
TheVictorianNaturalist
114
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Contributions
undertake sufficient additional field investiga- Salisbury Bushland Reserve, from where his-
tiontoexplorethepresenceandsizeofpopula- toricalrecordsexist;asnospecimenshavebeen
tionsofthe Eltham copper in all known extra- seen at Salisbury during a number oftargeted
Melbourne localities, and to search for further searchesoverthelastdecade,itmaynowbeex-
populations within the potential range, guided tinct there.ThemainpatchofBursariaat Salis-
by presence of Bursaria, and recording such bury is fenced to exclude grazers, but current
potential habitat. Although Notoncus is also a weedinvasion isanadditionalthreat.
critical resource forECB, itwas not soughtdi- A previously unknown and seemingly strong
rectlyon the sitesvisited. Each sitevisited was population of ECB was discovered along the
characterised, its position mapped for future sides of Nursery Road abutting a Sugar Gum
referenceand possiblere-survey,andpresence/ plantation on the north-east boundary ofWail
absenceofadultP.p. lucidanoted. State Forest, at 54H0595925 UTM 5960515
Altogether, 15 sites in the Wimmera were (36° 29’ 47.00”S, 142° 04’17.12”E, south-east)
explored (by FD). Extensive searches (coordi- to 54H0595640 UTM5960861 36° 29’ 37.87”
(
natedbyJW)wereundertakenoverpublicland S, 142° 04’07.14”E, north-west). Theroadsides
within the large potentially habitable region supportastrongBursariapopulationandarein
around Castlemaine and Bendigo. Over a six- good natural condition. Eight newly surveyed
week period, the potential habitat areas were sites,eachwithstrongBursariapatchesthatdid
traversedatabout60mintervals insearchofB. not yield ECB, included those at and around
spinosa as abasis for categorising habitat suit- Winiam, Dimboola, Nhill, Antwerp and West
,
abilityand a focusfor future searches. Around Wail.
Castlemaine, 1565 ha of potential habitat in-
cluded 63 core habitat sites and a further 54 CastlemaineIBendigo (Fig. 1
smallerpatches ofBursaria. NearBendigo, 980 All previouslyrecordedsites still support ECB.
The great majority ofadditional sites inspect-
haincluded23corehabitatsitesand26smaller
ed did not yield ECB, and a number of core’
patches. These categories were separated by
amountofBursaria — core habitat’ units were sites have been noted for additional survey in
the future. Some are on areas that have been
areaswith>200plantspresent,withthesmaller
disturbed in the past, such as along roadsides
patches consideredvaluable inpromotingcon-
and channels. Previously unknown popula-
nectivitybutlesslikelytosustainbutterflypop-
tions, most recorded from individual sightings
ulations. Limited time forthe surveys preclud-
ed revisiting many potentially habitable sites (with low numbers possibly reflecting surveys
outside the peak flight period, as for absences
indicatedbypresenceofBursaria andtheseare
, from other sites), were found in each region.
priority for inspection to determine status of
ECBinthe2012-2013flightseason.Despitethe Four were around Castlemaine, one near
work reported here, much further exploration Bendigo. They are: (1) a north-facing slope
south of the Castlemaine-Muckleford Road,
isneededwithinthis region. and within a recently-conducted fuel reduc-
Results tion burn area (55HO250766, UTM 5896499;
Detailed information on all sites surveyed is 37°2' 34.9"S, 144° 1’ 55.9"E); (2) eastofYoung-
available in a report submitted to the Depart- man’s Track, and in a recently burned area,
ment of Sustainability and Environment (Yen as above (55H0251826, UTM 5897640; 37°
and New 2012). The following is a briefsum- L 59"S, 144° 12' 40.1"E); (3) a roadside site to
maryoffindingsinthetwo regionssurveyed. the south ofCastlemaine,on Dingo Park Road
Wimmera (55HO255015, UTM 5892398; 37° 4' 51.9" S,
Paralucia pyrodiscus lucida was confirmed C1r44e°ek14’(5452H.09"2E5)3;05(94), BUroTaMd R5o8a9d1,53C8a;mp3b7e°ll5s'
present at five sites within the Kiata Flora Re-
serve, which is thus endorsed as harbouring 23.8" S, 144° 13' 17.9" E); and (5) a site to the
south ofBendigo between Kangaroo Flat and
majorconcentration ofpopulations within the
Strathdale,withsuitablehabitatextendingover
region and ofsubstantial conservation impor- 30 ha (55H0257100, UTM 5924217; 36°47’
tance. However, it was not found at the nearby
Vol 129 (3) 2012 115
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42. 4"S, 144° 16' 44"E). The last is regarded as themostsignificantpopulationsofECB.
aprioritysite, on which largeareas ofBursaria The discovery ofseveral new populations of
shouldbeexcludedfromburns. P.p. lucida isaverypositiveoutcome fromthis
Discussion work. These populations all appear to be very
In both regions surveyed, Bursaria is very restricted in extent, and isolated, but confirm
patchy in the landscape, and numbers of the the importance ofconcentrated surveys in de-
plant very variable. Many small patches are tecting such elusive and patchily-distributed
perhaps unlikelyto support viable ECB popu- taxa. Despite the importance oflarge sites, the
lations, andapparentlysuitable habitat patches small site areas in Eltham that have supported
are sparse within the wider landscape. How- populationsforatleastseveraldecadesdemon-
etvhearn, 2behcaa,uasseaErCouBndcaEnltthharmi,veisoonlatsiitoensmoafylebses sftorratceonaslesrovatthieoni.mpWoertasnucggeesotfvtehartyrsamtahlelratrheaans
more relevant than size in explaining absence. leadingtoaperceptionthatthebutterflyismore
Around Castlemaine/Bendigo, the large and widely distributed than previously known, the
continuous populations ofBursaria as at Ka- newdiscoveriesurgeaneedforevengreatersite
limna Park (Castlemaine), appear t,o support protection; thiswould enable connectivity and
Fig. 1. Indicative relative posi-
tions of populations of Paralucia
pyrodiscus lucida within the Cas-
tlemaine/greater Bendigo region:
populations discoveredduringthis
survey (open circles) are shown
together with previously known
populations (solidcircles).
116 TheVictorianNaturalist
Contributions
3.
protect all known populations and sites ofall furtherpopulationsnearCastlemaine,adding
sizesuntiltheirrealstatusisclarified.Whilstthe tothoseintheCastlemaine Botanic Gardens
newly discovered presence ofECB on recently and Kalimna Park. Two are within a Zone 1
burnedsitesisanencouragingsignofitsresist- Asset ProtectionZone,asistheBendigosite,
ancetothattreatment, numbersseenwerevery and so have potential to be burnt every 5-8
low and the regimes and impacts ofthe burns yearsand tohave90% oftheareas treatedto
unclear. Anyfutureburnson thesesitesshould reduce fuelhazard tomoderatelevels.
heedthedistributionofthebutterflythere,and The increased documentation ofP. p. lucida
be undertaken sympathetically in assuring its supports the commonly held view that popu-
conservation. Theoptimal burning regimesfor lations are largely discrete (closed and demo-
ECB conservation have not been investigated graphically independent) and very limited in
beyond Eltham, so that such a precautionary area. However, proximityofsomeofthese (for
approach seems imperative. From experiences example, at Castlemaine) leaves open the pos-
in burning two sites at Eltham, wherethe but- sibility ofa metapopulation structure, so that
terfly’s phenology is somewhat different from landscape level conservation management in
that at the sites discussed here, burns were the regions ofoccurrence is clearly needed to
considered to be safest’ ifundertaken in early oppose further fragmentation, as well as pro-
autumn (when caterpillars were the onlystage mote individual management forsustainability
present, were part-developed prior to winter, ofallinhabitedsites.
and ableto take refugein Notoncusnests), and The other major outcome is endorsement
when ‘hotspots’ ofknown abundancecould be that the butterfly is indeed absent from much
protected bydamping down. However, for any apparently suitable habitat, including patches
site to be burned, there is likely to be conflict closetoconfirmedpopulations.Theseabsences
between community concerns and optimal based on systematic targeted searches suggest
timing adjudged from biological information. (notwithstanding the ‘single visit’ limitation
Thesmalloccupiedareasalso endorsetheneed noted earlier, and lack of searches for Noton-
for (and wisdom of) small scale mosaic man- cusants) therealityofthebutterfly’spatchiness
agement,beitbyfireorothermeans, tosustain and highly localised distribution and that it is
suitability. Ideally, these should follow surveys truly ofconservation concern, rather than the
to detect any ‘hotspots’ ofECB to be shielded documented distribution simplyreflecting un-
from loss and, so, augment conservation ben- der-recording. Within any site, butterflies are
efit from burns undertaken primarily for fuel also restricted: the newly discovered Wail site,
reductionandassetprotection. for example, supports a population occupying
The former population at Salisbury was not onlyabout400x30monaroadsideverge.Such
rediscovered and itislikelythatthis isnowex- sites merit special notice as vulnerable to road
tinct. maintenance works and similar disturbance,
The majornewdiscoveriesare: and should be signalled to the responsible au-
1. a population in the Wail State Forest, as an thority for protection. However, the apparent
important intermediate locality between suitability to P. p. lucida ofmany vacant sites
Kiata and Castlemaine and, perhaps consti- suggeststhatthemajorcriticalresourcesforthe
tutingafurther‘fragment’indicatingthatthe butterflyarenotinthemselvessufficientindica-
historicalrangeofthebutterflywasmoreex- tors oflikelihood ofits occurrence: predictive
tensivethan atpresent; modeling for the butterfly’s incidence cannot
2. a further population in the southern area of yet be formulated soundly, with preliminary
Bendigo. We note thatthis site is within the trials based on both incomplete information
area ofan Asset Protection burn scheduled and inadequate understanding. Prudence dic-
for autumn 2012, and that much ofthe area tates that nopopulation isexpendableandthat
explored in the region, as around Castle- all occupied sites should be conserved. Cur-
maine, is within the Asset Protection Zone rent population sizes on the newly discovered
susceptible to fuel reduction burning over sitesareunknown,asistheextentoffunctional
thenextfewyears; isolation of butterfly populations on each. At
Vol 129 (3) 2012 117
1
Contributions
Kiata and at Kalimna Park, Castlemaine, it is nisation or as sites for deliberate translocation
known that ECB is quite mobile andcan track shouldcurrentlyoccupiedsitesbecomeunsuit-
patches of Bursaria across distances of up to ablethroughdegradationorhumanimpacts.
several hundred metres (Canzano et al. 2007, Acknowledgements
New2010). Largesitesadjacentto known pop- Funding for these surveys from the Department of
ulations may thusbe particularly important to Sustainability and Environment, Victoria, is grate-
conserve. fully acknowledged. In addition to authors, the
A more general lesson is that anycontempo- ftohellBoewnindgigoco/nCtarsitbluetmeadinteortehgeione:xtPenCsliuvneies,uGrveNeyvsilli,n
rary allocation of formal conservation status S Small, A Smith, TWilliams, with site mappingby
to a poorly-known invertebrate taxon must be FWilson.
open to review as new information accrues,
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118 TheVictorianNaturalist