Observations of Spencer's 'Skink Pseudemoia spenceri' from within the high canopy of an overmature Mountain Ash 'Eucalyptus regnans'

2014·1 MB·English

Contributions
Observations ofSpencer’s SkinkPseudemoia spenceri from within the
high canopy ofan overmature Mountain Ash Eucalyptus regnans
M
Grant Harris1 Brett Mifsud2 and Graeme RGillespie3
J ,
'SchoolofLifeandEnvironmentalSciences,DeakinUniversity,221BurwoodHighway,BurwoodVictoria3125
27ColstonAvenue,Sherbrooke,Victoria3789
3FloraandFaunaDivision,DepartmentofLandResourceManagement,VanderlinDrive,
Berrimah,NT0828
Abstract
DuringMarch2012,whilstundertakinganaerialsurveyofanovermatureMountainAshEucalyptusregnans
inToolangiStateForest,aSpencersSkinkPseudemoiaspenceriwasobservedinthecanopyataheightof-50m
abovegroundlevel.Inthefollowingyear,whilstsurveyinganotherovermatureE. regnans,apairofP.spenceri
wasdetectedatsimilarheightwithinthecanopy.ThesesightingsdemonstratethatthermoregulationinP.spen-
ceriisnotrestrictedtodeadtreesandthathighcanopiesofovermaturetreesmaybeanimportantcomponent
ofitshabitat.Duetothedifficultyofaccessingtheforestcanopyitislikelythatourunderstandingofarboreal
habitatusehasbeenunderestimatedforsmallvertebratessuchasskinks.Ourserendipitoussightingsempha-
sisetheneedforfurtherresearchinthisarea. (TheVictorianNaturalist131(I)2014,24-27)
Keywords: Spencers Skink Pseudemoia spenceri, Mountain Ash Eucalyptus regnans arboreal,
,
canopy
Introduction ObservationsofSpencer’sSkink
Spencers Skink Pseudemoia spenceri is an in- In March 2012, as part ofan ongoing project
sectivorous species found in wet sclerophyll to document Victorias largest trees (Mifsud
forest (Rawlinson 1974) and montane dry 2003), a Mountain Ash Eucalyptus regnans 73
woodland (Clemann 2002). With well devel- minheightand245.5m3trunkvolume(Mifsud
oped five-toed (pentadactyl) limbs, dorso- 2012unpubl. data)wasclimbedwiththeuseof
ventralflatteningand high agility, R spenceri is arboriculturalmethods(DialandCarl 1994) in
the most arboreally adapted of south-eastern Toolangistateforest (37° 33'59S 11"S, 145°27'
Australian scincids (Brown 1986). The use of 47.43" E). The treewas overmaturewith abro-
aerial tree microhabitats provides opportuni- ken top, which is characteristic ofthis growth
tiesforbasking(Webb 1985;BrownandNelson stage (Ashton 1975). Using records of stand
1993), foraging(Brown 1986),shelter (Rawlin- replacing fires in the area as a dating method
son 1974;GibbonsandLindenmayer2002) and (Ashton 2000), the tree was estimated to be
predator avoidance. Previous records of the -400years ofage. The tree waslocated within
vertical extentoflivetree usebyP.spenceriare an area ofwet sclerophyll forest characterised
10 m (Pengilley 1972 cited in Webb 1985), 22 byanoverstoreyofE. regnans,amidstoreytree
m (BrownandNelson 1993)and 15m (Homan layer ofBlackwood Acacia melanoxylon, Silver
2011) above ground level. Rawlinson (1974) WattleAcaciadealbata, Myrtle Beech Nothofa-
documentedtheuseofaerialmicrohabitats50- gus cunninghamii and a tall shrub layer ofSoft
75mabovegroundlevelbutbelievedPspenceri Tree-fernDicksoniaantarctica RoughTree-fern
,
to be restricted to dead trees andprimarily as- CyatheaaustralisandMuskDaisy-bushOlearia
sociatedwithpost-firestandsinwetsclerophyll argophylla(Costermans 1983). Duringthissur-
forest. The validity of Rawlinsons report was vey, askinkwas observedwithin thecanopyat
m
questioned (Webb 1985) andasadditional ob- aheightof-50 abovegroundlevel.Thisindi-
servationsofP. spenceriat this heighthave not vidual did not exhibit an evasive response and
been documented it remained unclearto what activelyclimbed onto the legs andbodyofthe
extentthisandotherspeciesmay usetheforest surveyor (Fig. 1). On 23 March 2013, during
canopyintemperatesouth-easternAustralia. the survey of another overmature E. regnans,
24 TheVictorianNaturalist
Contributions
Fig. 1.SpencersSkinkontheleg-strapofasurveyorsharness.PhotobyMikeHanuschik.
m m
65 in heightand 170 3 trunkvolume (Mif- Discussion
sud 2013 unpubl. data) and also in Toolangi Rseudemoia spenceriforages on theforestfloor
State Forest, a pairofP. spenceri was observed and in aerial tree habitats with detritivorous
ataheightof50mabovegroundlevel. One in- insects such as saprophagous flies (Diptera),
dividualwasbaskingin asunspotonthetrunk cockroaches(Blattodea)andtermites(Isoptera)
(height 55 m) and the other was stationaryon formingasignificantcomponent(40.7%within
a dead limb below thefirst. Neither individual sample, n=82) ofits diet (Brown 1986). Obser-
m
exhibitedanevasiveresponse orchanged posi- vations of ground based habitat use (<1.2
tionsasweascendedadjacenttotheirlocations. above ground level) recorded logs as the most
Theindividualthathadbeenbaskingproceeded commonly occupied substrate (78% ofobser-
to climb onto the bodyofa surveyor, remain- vations) withthemajority(96%) ofthese being
ing mainly stationary with periodic shuttling partlydecayed(Webb 1985). Assubstrateuseis
betweenthesurveyorsarm,shoulderandback oftenassociated with preycaptureitcan bein-
foraperiod of15 minutesbefore beingcoaxed ferred that decaying coarse wood mayprovide
to return to the tree trunk (Fig. 2and 3). With important foraging opportunities at ground
the exception of the aforementioned encour- level; however, gut content analysis by Brown
agementtoleave thesurveyors body there was (1986) indicates thatarboreal invertebrateprey
nohandlingorintentional interaction with the obtained from aerial tree foraging also form a
animals. A dark brown-olive colouration with majorproportion (52.3%within sample, n=82)
golden-cream dorsolateral stripes, which are ofthedietofP.spenceri. Goldingayetal(1996)
diagnosticcharacteristicsofP.spenceri(Cogger noted a greater abundance ofP spenceri with
2000; Wilson and Swan 2010) were present in an increase in log density following timber
theobservedanimals. harvestingand an absence ofP. spenceri in un-
Vol 131 (1) 2014 25
Contributions
Fig.2.SpencersSkinkonthearmofasurveyor.PhotobyDamienNavaud.
loggeddryforestplots.Thissuggeststhatdead- allow it to function as a photosynthetic organ
wood with environmental moisture conditions (Sillettetal. 2010). Thesightings reported here
conducive to the establishment of wood de- ofP. spenceribaskingonthesmooth E. regnans
cay and associated saprophagous invertebrate barksupportsthe proposition that foran agile
communities could be a critical resource for heliothermsuchasP.spenceri,thelevelofinso-
P spenceri. In addition to the quantityofdead lation received on a live overmatureE. regnans
organicmaterial (logs and litter) thelevel ofin- stem is likely to be sufficient for basking and
solation is an important influence on patterns suggeststhatthermoregulation isnotrestricted
of habitat usage in skinks within sclerophyll todead trees.
forests(Kutt 1999). Both elevationabovetheunderstoreyandthe
Climbing emergent trees to rise above un- presence ofaerialdeadwoodare defining char-
derstoreyvegetationandtherebygain accessto acteristics of overmature E. regnans (Ashton
direct sunlight forthermoregulation, may be a 1975; Mifsud 2003), and ourobservations sug-
driver ofarboreal behaviour (Rawlinson 1975; gest that these trees may provide an important
Webb 1985;Kutt 1999). Thishypothesisissup- combination of resources for P spenceri. The
ported by the findings of Brown and Nelson availabilityoftheseresources(aerial deadwood
(1993), who noted the absence of P. spenceri andelevationforinsolation) provided byliving
at ground level in the successional stages of E. regnansarelikelytoremainlongerthanpost-
wet sclerophyll forest with the densest canopy firestagswhich aremoredisposedtostructural
cover (11-63 years old). At the scale ofan in- collapse (Gibbons and Lindenmayer 2002),
dividual overmatureE. regnans theisobilateral thus allowing P. spenceri populations to use
leafshapeallowshighlevelsoflightpenetration oldgrowth forest. This hypothesisissupported
throughthecanopy(Keithetal.2009),allowing by the findings ofKutt (1999) who recorded a
insolation ofthe trunk. It has been suggested significantly greater abundance of P. spenceri
thatsufficientlightreachesthe smooth bark to in mature growth compared to 25-35 year old
26 TheVictorianNaturalist
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Thankyou to Julia Chilcott, Mike Hanuschik, Ewan WesboubthGeAast(e1r9n85A)usHtarbailtiaatnusskeinaksn.dIanctTivhietybipoaltotgeyrnosfAinusstroamle-
cMounrtrraiyb,utDiangmioeutnstNaanvdaiungdtarneedcIlnigmrbiidngO,opshtoerthougirsapfhoyr iHanEfhrmogasnann(dRoryepatlilZeso,olpopg.i2c3a-l30S.ocEidetGyoGfrNieggw,SRouSthhinWealaensd:
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