Natural History Notes on the Eastern Blue-tongued Skink 'Tiliqua scincoides scincoides' from the Basalt Plains around Melbourne

2010·2.9 MB·English

by  Grant S Turner

Research Reports
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Speciale-D’analamazaotra, Madagascar: the effects ,
of human disturbance on endemic species diversity.
StMoBicBokdiin(v2eK0rA0si8,t)yLTuaosnusdreiaCuosnmDs,earfBfveiacntteisdoetnlhle2,Vb,6e0hW3ai-vs6ieo15um.raanlNbudagnedtOorfatmhse Received19June2009;accepted11February2010
Natural history notes on the Eastern Blue-tongued Skink
Tiliqua scincoides scincoides from the basalt plains around Melbourne
Grant S Turner
103SettlementRoad,Bundoora,Victoria3083
Abstract
Dataandobservations aregiven on theappearance, size, habits anddietof163 Eastern Blue-tongued Skinks
hliquascincoidesscincoidesinhabitingthebasaltplainsgrasslandsto thenorth andwestofMelbourne Blue-
ht79oa)nd.guSreenlsoautptio-vsetlsoye-svnseaenrdtroalwneenagrvtehhsreaargdaesnogcfeodsmepfvareronemdda7r6toktoabdo3udl4ty0s.bmaBmnlduse(-n(t5=on-1g0u9;8e)snaw=nedr90em)aaacstnsidvfesreiovnmean8lldtmoaor5kn4t5thaigsl(bonafn=tdhs6e8)(y.4eaJ-ruv1ee0ix-rcinelpe=ts
winter. Surface stones were the main retugia available and were used by Blue-tongues throughout the year.
ParturitionoccurredfromFebruarytoApril(n= 11).Blue-tonguesfedonavarietyofendemicandintroduced
fruits and aithropods. Basedon the monthlyvariation ofbodysizes and a low numberofrecaptures, sexual
matuiityisprobablynotattaineduntilatleasttwoyearsofage. (TheVictorianNaturalist127(3),2010,70-78)
Keywords: Blue-tongues, basaltplains, size, habits, activity
Introduction
The Eastern Blue-tongued skink Tiliqua scin- (Koenig et al. 2001), and its commonness and
coides scincoides is a readily identifiable, wide- occurrenceinnearlyallnaturalhabitatsineast-
spread species that only relatively recently has ern Australia (Shea 1998; Cogger 2000; Wil-
been thesubjectofecological research (Koenig son and Swan 2003). Historically the species
et al. 2001, 2002; Christian et al. 2003). This is occurred throughout much of the Melbourne
despite its being the first Australian reptile to area, from woodlands east ofthe city, through
be formally named (Shea 1993a), its ability to theopenRedGumwoodlandstothenorth,and
live in highly modified human environments thetreelessgrasslands to the west (Schulzetal.
70 TheVictorian Naturalist
Research Reports
1991; Larwill 1995; Museum Victoria 2006). snout to the posterior edge ofthe interparietal
Blue-tongues were very common on the ba- scale along the midline) and head width (HW;
saltplains to the north and west ofMelbourne; atthewidestpoint) were measuredto the near-
mm
indeed Fleay (1931: 9) noted that ‘In the stone est 0.1 using a vernier calliper, and mass
walls of Laverton and Werribee, I have of- (M) was measured to the nearest gram using
ten collected more Blue-tongues than snakes’ an Ohaus spring balance. Reproductive status
Snakes remain very common in these areas, (gravid/non-gravid) and general condition
wheresufficientgroundcoverexists,andsotoo (presence ofectoparasites, pre/post sloughing,
are Blue-tongues (Larwill 1995;pers. obs.). The scarringetc.) werenoted. Sexcouldnotbe reli-
native grasslands and grassy woodlands that ablydetermined at all in immaturelizards, and
once covered the basalt plains have undergone even in adults is fraught with difficulty when
a drastic reduction in area due to expanding based on external morphology (see Hitz and
residential,industrial andagricultural develop- Ziegler 2004); only in about a third of adults
ments, making the lowland temperate grass- was sex confidently assigned. Blue-tongues of
lands one ofthe most criticallyendangered ec- either sex were deemed to be sexually mature
osystems in Australia (Ward 1966; DCE 1990; ifSVL > 240 mm, based on data for Victorian
Lunt 1991; McDougall and Kirkpatrick 1994). and South Australian specimens in Shea (1992;
Notes on the natural history of T. s. scincoides 1993b). Neonates were identified bytheir fresh
gathered as part of a broader survey ofbasalt umbilicalscars. Dorsal/ventralcolouration, the
plains reptiles aredetailed here. number and pattern of dorsal/tail bands were
recorded, and other individual identifying
Methods
markings were noted. Faecal pellets produced
gtSihrteaessMsleealxnbadomsuirannneded CgwreBarsDesylaonwcdoaotcedodlnas1in5sdttseodt2oo5ftkhrememnfnorarontmth lb(adytelriszeiadxredassmiadnunerddi.ntghTipchrkeoncelesossnsgoiefnsgtstw(oednrete)saroenctdcauispnhieoedrdtaenbsdyt
and west ofMelbourne’s suburban fringe, pri- Bl2u)e-tongues were measured to the nearest
marily in the suburbs ofBundoora, Mill Park, centimetre using a flexible tape measure. Am-
Epping, Craigieburn, Deer Park, Laverton and bient temperature and substrate temperature
Altona. All measurement data were gathered beneath refuges were recorded (± 0.1 °C). As
between 1990 and 1993, when there were 107 the introduced snake mite Ophionyssus natricis
separate visits to sites, covering all months of was present in populations, care was taken not
each year and ranging in duration from 1 to 7 to facilitate its spread, by avoiding the use of
hours; on 92visits atleastone Blue-tonguewas holding bags and by mist-spraying measuring
either sighted or measured. Some observations instruments and hands with Orange-Medic™
predate this period, the earliest being in 1983. after processing. Lizards were released at the
During visits the ground surface was visually pointofcapture.
scanned and anynoise indicative ofmovement Data for body size variables were bimodal,
in amongst grass tussocks was investigated. due to a ‘gap’ in the body size measurements
From suitable vantage points binoculars were (seebelow) andthuswerenotnormallydistrib-
used to scan potential basking sites. Surface uted even when transformed. However, when
debris (primarilybasalt stone) wasturned (and partitioned into sexuallymature and immature
replaced), stone piles and crevices, and dry- sizeclasses,thedatawerenormallydistributed;
stone walls were carefully inspected for the this was confirmed by the Shapiro-Wilk and
presence of reptiles. Blue-tongues were cap- D’Agostino-Pearson K1 tests (Zar 1996). Data
tured by hand, measured and carefully exam- analysis of (non-partitioned) body size vari-
inedforapproximately 15 minutesbeforebeing ables was therefore limited to non-parametric
released. Snout-to-vent length (SVL), inter- methods performed using SPSS (V.ll), though
limb distance (ID; as measuredbythe straight- noneoftheresultswasalteredwhenperformed
line distance from the axilla to groin), andmtamil using parametric methods. Data on refuge di-
length (TL) were measured using a 500 mensions and numbers of dorsal/tail bands
rigidwood-laminateruler,andmid-bodywidth were normally distributed. Ordinary least
(BW, when at rest) using a vernier calliper; all squares regression was used to examine the
were measured to the nearest millimetre. In
quantitativerelationship between pairsofbody
addition, head length (HL; from the tip ofthe
Research Reports
sizevariables,andtheassumptionsofthistech- colouration ranged from bluish-grey (in speci-
nique were checked. Both SVL and HL were mens with grey dorsal ground colouration) to
used as independent variables where appropri- white, cream or yellow and various shades of
ate. Scatter-plots were first madebetween pairs orange. Typicalventral patternwasdarkbrown
ofuntransformed variables and then again for variegations (74%); dark brown flecks (18%)
natural-log (In) transformed variables. The forming longitudinal lines towards the middle
Pearson correlation coefficient (r) and Spear- oftheventralsurface (8%) werelesscommonly
mansrankcorrelationcoefficient(r)wereused seen(n=92).Twelvepercentofindividualshad
(where appropriate) to assess the strength of anunpatternedventralsurface(cf. 7.3%inShea
the linear relationship between variables and (1992)). In most individuals (87%) the under-
the null hypothesis ofno (linear) relationship side ofthe tail differed in colouration from the
wastested. Acomparison ofbodysizevariables ventral surface, being bright orange or yellow,
between the sexes was not performed due to usually clean, although there was sometimes
the relatively low number of adults in which a continuation of the dark (dorsal) tail bands
sex was confidently assigned. The chi-squared onto this surface. All individuals possessed a
statistic was used to compare frequencies, with prominent dark brown temporal stripe. Dorsal
Yates correction for continuity applied (Sokal head colouration in nearly all individuals was
and Rohlf 1995). The growth rate was calcu- the same as the dorsal ground coloration. The
lated for a low number ofrecaptured lizards by gularregionwastypicallyoff-whiteandsparse-
dividing the change in SVL by the number of lyfleckedwithdarkbrown. Tonguecolouration
months between capture and recapture. Tests in adultsvaried from mediumto darkblue; ne-
were one-tailed unless otherwise stated and onates all possessed dark blue tongues. In one
deemed significantat the0.05 probabilitylevel. adulttheproximal thirdofthetonguewaspure
white and sharply demarcated from remaining
Results
darkblue.
One hundred and sixteen Blue-tongues were Morphometricdataformatureandimmature
measured in the field, a further 47 were ob- Blue-tongues are given in Table 1. The largest
served in the field but not measured, and the individual had a SVL of 340 mm and a TL of
remains ofeight dead lizards werelocated. 150 mm (mass not recorded); this SVL ex-
Appearanceandsize ceeded those ofall museum specimens in the
There was considerable variation in both col- south-eastern states (Vic., SA, NSW; from data
bouarnadtsiobnetawnedepnatttheernax.iTllhaeannudmgbreoirnovfadrairekdbforodmy inneoSnhaetae(w1i9t9h2)a).SVThLeosfm7a9llmesmt,inadiTvLidoufal33wamsma
5 to 9 (X = 7.0, sd = 0.8, n = 90). The band- andamassof8 g. Theheaviestindividualwasa
ing pattern varied greatly from smooth-edged gravid female weighing 545 g while the heavi-
solid straight bands to ragged-edged bands estnon-gravidlizardwasafemalelocated mid-
with intrusions ofdorsal ground colour, bifur- winterweighing405 g.
cations and thin longitudinal lines connecting Scatter plots of each size variable against
adjacentbands. Darktailbands showedgreater SVLwere strongly linear (r2> 0.82, P< 0.0001
variation in number, ranging from 4 to 10 in all instances) and consequently a linear
X = 7.0, sd = 1.3, n = 79) and in most indi-( (y=ax+ b) ratherthanapowerfunctionmodel
viduals the bands merged towards the tip. The was used. The slope (a) andBiWntercept (b) with
number ofdarkbands on thebody and tail fall standarderrors (±se)were: 0.204±0.0085,
within the range of variation documented by 0.9 ± 1.86 (n = 80); ID 0.699 ± 0.0105, -9.0 ±
Shea (1992) for southern and eastern popula- 2.24 (n = 77); TL 0.509 ± 0.0128, -7.4 ± 2.77
utieosnsaroefaTt. st.hsecilnocwoeirdeesn, dthoofugthhisbortahngme.eaNneavrally- a(nnd=S1V02L).wTahsealnsaotusrtarlolngolgyarliitnheamrowfibtohthregmraesss-
all individuals had an elongated blotch on the sion equation: InM = 2.86 ± 0.077 InSVL- 10.3
upper lateral edge ofthe neck identical in col- ± 0.42 (r2= 0.96, P < 0.0001, n = 57); the 95%
our to the dorsal bands. The dorsal ground confidence interval for the slope was 2.7H1W-
colouration exhibited relatively little variation 3.02. The relationship between HL and
and was either grey or yellow, with the latter was non-linear; however, transformation of
more common (n = 69 vs 23). Ventral ground HL produced a strong linear relationship with
72 The Victorian Naturalist
Research Reports
Tinabmliell1i.mMetorrepshwohmieltermiacsdsatisaifnorgrEaamsst.erTnhBelumee-atno,ngsuteasndTairldiqdueavsicaitnicoonid(essd)s,cimnacoxiidems.umLe(nmgatxh),memaisnuiremmuemnt(smianr)e
vlaenlgutehs,aHndWsa=mhpelaedsiwziedt(hn,)BarWeg=ivbeon.dyAbwbirdetvhiaatniodnsI:DS=ViLnt=erslniomubt-dtisot-avnecnet(lseenegtMhe,tThLod=stfaoilrldeetnagitlhs,).HL= head
SVL TL HL HW BW ID Mass
Mature
mean 270 130 38.2 37.8 55 175 282
sd 20.8 12.9 2.69 2.69 6.2 13.7 63.5
max 340 155 44.5 44.5 76 205 545
n 47 43 45 45 37 33 34
Immature
mean 160 74 26.7 24.4 34 103 101
sd 44 24 4.69 5.87 10 33.7 78.2
min 76 33 19.3 13.6 17 43 8
n 61 59 50 52 43 44 34
HW
regression equation: = 34.7 ± 0.72 InHL - tongues had increases in SVL ranging from 21
88.8 ± 2.47 (r2= 0.91, P < 0.0001, n = 95; Fig. to 162 mm, spanning periods from two to 14
1), indicating that larger Blue-tongues have months. The average growth rate varied from
relatively broader heads compared to smaller 7.3 mm/month to 13.5 mm/month, although
Blue-tongues. thelattervaluewasforatwo-monthperiodonly.
The monthly distribution of SVLs exhibits a A growth rate of11.6 mm/month was obtained
gap (between approximately 170 and 210 mm) forthelongestperiodbetween recaptures.
thatseparates cohorts, theyoungercohort con-
sisting exclusively of immature lizards, and a Timingofreproduction
Only four gravid females were located in the
presumed mixed-age cohort consisting ofboth
immature and mature lizards (Fig. 2). The gap fOineled poonst8-,p9aratunrdie2n8tJfaenmuaalreywaansdlo1c3atFeedbrounar2y.8
is evident from February to October inclusive.
Fewlizards with SVL < 200 mm were recorded February. Neonateswere recordedfrom February
in January and February. Six recaptured Blue- through to April (n = 11: six in February, three
MONTH
Fig. 1. Scatter plot ofthe head width (HW) versus Fig. 2. Monthlydistributionofsnout-to-ventlengths
natural logarithm of head length (HL) in Eastern (SVLs) of Eastern Blue-tongues Tiliqua scincoides
gBrleuses-itoonngeuqeusatiToinl:iquHaWsci=nc3o4i.d7e4s IsnciHnLcoi-de8s8.w8i3thr2re=- scincoides(n= 116).
(
0.91,n=95).
Vol 127 (3) 2010 73
inMarchandtwo in April), indicatingthatpar- depressions beneath stones. One adult was
turition extends into autumn. locatedalmostcompletelysubmergedwithonly
Habitatandrefuge use its snout protruding as a result ofwinter rains
Blue-tonguesoccurredinavarietyofhabitatson flooding its retreat-site. The lowest daytime
the basalt plains wherever there was sufficient temperature recordedbeneathan occupied ref-
ground cover. Natural habitats included stony- uge in winter was 9.3°C while in summer the
rises with Hedge WattleAcaciaparadoxa/Black highesttemperaturewas 21.3°C.
WattleAcacia mearnsii/DroopingSheoakAllo- Some Blue-tongues had dug through surface
casuarina verticillata River Red Gum Eucalyp- clay to gain access to over-wintering refuges
tus camaldulensis woo,dlands, Kangaroo Grass beneathstones.Thiswasindicatedbytheirhead
Themeda triandra-dominated treeless grass- and forelimbs being caked’ in dry clay when
lands,escarpmentliningcreekswithLightwood discovered inactive during winter (n = 13).
Acacia implexa/Tree Violet Melicytus dentatus, Furthermore, excavated soil was sometimes
aswellasintergradesofthese. Highlydisturbed present at the edge ofthe stone (n = 9). When
habitats included pasture with surface stones there was no visible surface entrance or gap, it
gathered into piles or bordered by dry-stone seems likely that lizards gained access beneath
walls, and former pasture/cropland invaded by stones through gaps that had since been closed
exotic grasses and herbs such as Serrated Tus- up by the swelling ofthe surrounding claysoil.
sockNassella trichotoma and Artichoke Thistle Blue-tongues also occupied loam soil cavities
Cynara cardunculus. Common to all habitats beWnheaetnh stones in stony-risehabitat.
was the presence of abundant surface stones. inactive, Blue-tongues almost invari-
The intactness ofthe native vegetation seemed ablyassumedacurledupposturewith thehead
to have little influence on the occurrence of and tail in direct contact (or nearlyso). Lizards
Blue-tongues, though few were recorded in were typically semi-torpid and initially unre-
dense stands ofthe introduced Gorse Ulex eu- sponsivetoexternalmovementwhenexamined
ropaeus and Cape Broom Genista monspessu- inwinter,thoughtheywereresponsivetotouch
lana in degraded northern grasslands, despite (bloatingand hissingwere typical responses).
undisturbed stony ground cover. They were Eight species of reptiles and frogs were re-
also uncommon in heavily grazed areas with corded beneath stones with Blue-tongues dur-
minimal surface stone. ingwintermonths:LittleWhipSnakesParasuta
Refuge sites used by Blue-tongues largely flagellum (n = 8), Eastern Brown Snakes Pseu-
seem to reflect availability. Surface stone was donaja textilis (n = 3), Striped Skinks Ctenotus
the most abundant surface refuge in the grass- robustus (n = 4), Striped Legless Lizard Delma
lraencdosr,deadndbe8n2e%ath(63groofun77d)coofvearllwBelruee-bteonnegautehs giumipcahreno(tni=(n1=),2)G,aTrudsesnocSkkSikniknsksLaPmsperuodpohmooliias
stones. The remainder were located beneath pagenstecheri (n = 3), Growling Grass Frogs
artificial ground coversuch as corrugated iron, Litoria raniformis (n = 2), Spotted Marsh Frogs
linoleum and carpet. Fallen hollow limbs of Limnodynastes tasmaniensis (n = 6) and the
River Red Gums Eucalyptus camaldulensis oc- Eastern Banjo FrogL. dumerilii (n = 1). In each
curred sparsely in some grasslands but were instance the species were well separated (> 0.1
not observed to be used by Blue-tongues. m) and it seems likely neither was aware ofthe
tSioesmebenBelauteh-tsotnogneusesthaotvewre-rweinatbearenddoniendcbauvri-- otWhheirlseprmesaennyce.different types of stones were
rows of the House Mouse Mus musculus (n used by Blue-tongues as refuges, particular
= 5) and the Fat-tailed Dunnart Sminthopsis stones were favoured and were nearly always
crassicaudata (n = 3). In three instances ju- occupied when searched. For example, a total
of five adult Blue-tongues was recorded using
viennsiildee tBhleues-phteornigcuaelsgrwaessrenesftosunodf Mc.urmluesd-cuup- one particular stone over a four-year period.
The underside ofthe stone was concave and
lus in depressions beneath stones. The major- it
was situated on a well drained, exposed, north-
ity of over-wintering retreat-sites (76%) oc-
cupied by Blue-tongues had moist substrates facing slope. It had been used frequently by
(as opposed to either dry or wet). Four Blue- Blue-tongues for at least ten years (pers. obs.).
tongues were found over-wintering in flooded The stone only ever had one lizard beneath it
74 The Victorian Naturalist
Research Reports
at atime and often the same individualwas re- Activityandbehaviour
corded beneath it for several weeks during the Nineteen percent (22 of 116) of Blue-tongues
active season and longer over winter. At least recorded were in the open (active or basking);
six other stones were repeatedly used by Blue- the rest were located beneath ground cover (n
tongues. = 77) or concealed amongst groundvegetation
The length of stones used by Blue-tongues (n = 17). Blue-tongues were observed active
ranged from 0.15 m to 1.50 m and the thick- or basking in all but the winter months (June
ness from 0.04 m to 0.35 m (n = 48 for both). to August). The lowest air temperature that a
Mean dimensions (± sd) ofrefuges were0.55± Blue-tongue was observed basking (or active)
0.24 m x 0.37iO.llmx 0.17±0.08 m (n = 48 was 14°C in late May. During winter and also
for each). SVL was significantly and positively during cooler periods at other times of the
correlatedwithlengthdimensionsofstonesbut year,theywererecordedbeneath stones during
not with thickness (du t2= 0.10, P = 0.021; dn daylight hours. Almost the same numbers of
r2= 0.21, P = 0.002; r2= 0.00, P = 0.450; n = 48 Blue-tongues were recorded from May to Au-
for each); however, two ofthese tests lack suf- gust inclusive as in the rest ofthe year (82 vs
ficient power. Thus, data are only suggestive of 81);thisdepartssignificantlyfromtheexpected
a tendency for smaller Blue-tongues to favour frequencies (41 vs 122) based on equal num-
smallerrefuges. bersineach month (y2= 21.2, ldf, 2-tailed, P<
0.0001). This result reflects the greater ease of
Diet locating individuals beneath stones (when in-
Information on the diet of Blue-tongues was active) comparedtowhentheyareactive. Only
obtainedfromthe examination offaecalpellets six Blue-tongues were recaptured and these
of 21 Blue-tongues (Table 2) and indirect ob- were all found within 150 m of their initial
servations offeeding. Black Field Crickets Tel- pointofcapture.
eogrylluscommodusareveryabundantingrass- Sloughing occurred during months when
lands in late summer and autumn and at these Blue-tongues were active. Individuals that had
times were consumed by Blue-tongues. One recently sloughed (or were about to slough)
adultBlue-tongueproducedthreefaecalpellets were located in January, February, April, May,
packed exclusively with T. commodus remains. November and December (n = 14). Restricting
Millipedes (order Julidae) and Slaters Porcel- the sample to mature Blue-tongues, sloughing
lio scaber were regularly encountered beneath occurred in January, February and November
tsurrofdaucceesdtConoesmmanodnweGraerdaelsnoScnoanilsuCmaendta.rTehuesains-- s(nlo=ug7h) aanndd aappseprairnsgto(pcoositn-cbirduemwaittihona)ssulmoumgehr.
persa is especiallycommonin grasslands north Some immature Blue-tongues likely slough a
ofMelbourne (pers. obs.),andclustersofsnails thirdandfourthtimeduringayear,asoccursin
were frequently encountered on the underside
Blue-tongues kept in outdoor enclosures north
of stones. Blue-tongues’ affinity for garden ofMelbourne (pers. obs.).
snails is well known and yellow-brown stains Blue-tongues exploited artificial stone piles
around the mouths and chins of lizards that and dry-stone walls both for refuge and for
had been recently feeding on snails were ob- foraging. This was indicatedbythe presence of
served during spring, summer and autumn (n lizards in stone cavities and within stone piles
= 17). The small orange fruit ofthe introduced and walls during winter (n = 18) and obser-
Boxthorn Lycium ferocissimus was consumed
vations of active Blue-tongues retreating into
by Blue-tongues in spring and autumn; eight them when approached (n = 7). Three Blue-
Blue-tongueswereobservedwith orange stains tongues were observed weaving in and out
aroundtheirmouths, indicativeoftheirhaving of stone walls whilst apparently foraging; one
recently fed on these fruits. Hips ofthe intro- was observed attempting to consume a cricket.
ducedSweetBriarRosa rubiginosaandfruitsof Where ground cover was sparse, individu-
the native Tree Violet Melicytus dentatus and
als were observed to seek the shade of small
Volcanic Plains Tree Violet M. sp. aff. dentatus shrubs,bushesandtrees (Boxthorn,TreeViolet
were consumed. These shrubs commonlygrow
and BlackWattle) duringthehottestpartofthe
amongst outcrops and dry-stone walls. Ex- dayinsummer(n = 5). Two Blue-tongueswere
pelledseeds ofthese fruitswere intact. also found inthecoolinteriorofstonewallson
hotsummerdays.
Vol 127 (3) 2010 75
Research Reports
Table2. DietaryitemsconsumedbyEasternBlue-tongues Tiliquascincoidesscincoidesbasedonthecontentof
taecalpelletsfrom21 individuals (n = thenumberofpelletscontainingeachitem).
Item Comments
CBloamckmFoineldGaCrridceknetSnTaeilleoCgarnytllaurseucsomasmpoedrsuas 94 TSmharlelespheelllletfsrcaognmteanitnsedonlycricketremains
Millipedes (OrderJulidae) 6 Onepelletcontainedtheremainsofmorethan
onemillipede
SlatersPorcellioscaber 2 Onepelletcontainedmorethan 10slaters
BoxthornLyciumferocissimus 5 Onepelletcontainedthesefruitsexclusively
TrVeieolVeitolMe.tMspe.laiffc.ytduesntdaetnutsatus/DwarfTree 6 Smtawlolpnelulmetbserinscl(<ud1e0d)booftfhrusiptps.ineachpellet;
SweetBriarRosa rubiginosa 2 Twohipswerepresentinonepellet
Other:
Grassleaves 3 Fragments
Sloughed-skin 1 Fragments
Almost all Blue-tongues were located singly this figure is an underestimation of the true
in the field when active and all occurred singly frequency of occurrence. High frequencies of
beneath ground cover. The one exception in- miteshavebeenrecordedinBlue-tonguepopu-
volvedtwoadultsobservedbasking 1.5 mapart lations from grasslands around Melbourne, al-
(but within clear view of each other) in mid- thoughsamplesizesweresmall (Watharowand
October. Reid2002).
Activeorbasking Blue-tongues reacted to be- Injuriesand/ordiseasewerenotedin 13lizards.
ing approached by either ‘freezing or retreat- Six ofthese were tail injuries in which the dis-
ing to the nearest cover (either grass tussocks, tal portion was missing (< 15 mm ofregenera-
where they remained perfectlystill, orbeneath tion; n = 5) orthetailhadnumerouskinks (n =
a stone). Ifindividuals that stood their ground 1). Single instances ofcataract and respiratory
were approached at closer quarters (< 2 m), disease were noted. Another three individuals
they would engage in the characteristic threat- were in poor condition, being emaciated and
display for which the species is well known: with extensive mite infestations. Eight dead
dorsoventral flattening of the body accom- Blue-tongues were found; the cause ofmortal-
panied by mouth gaping, hissing and extrud- ity was evident in only two, where burnt car-
ing the tongue. Agitated juveniles would often casses were found within days of fires having
grasp objects placed near their heads and then burnt the grasslands. A live, but badly burned
perform a series ofbody-rolls. Some juveniles adultlizardwas also recorded in recentlyburnt
lifted their dorso-ventrally flattened bodies grassland. The stomach ofa dead adult Eastern
clear of the substrate and oriented it towards Brown Snake was found to contain juvenile
the perceivedthreat. Blue-tongue remains.
Generalcondition andsourcesofmortality Discussion
Scale damage was observed in nine Blue- Thisstudyisratherlimitedinextentandinscope
tongues, all except one ofwhich were sexually butnonethelessitispossibletodrawsomegen-
mature adults (both sexes). In two individuals, eral conclusions from it. Eastern Blue-tongues
there were extensive patches ofnecrotic scales. inhabiting the basalt plains around Melbourne
Pitting ofthe dorsal (‘shoulder’) scales wasvis- areverycommonwheresufficientgroundcover
ible in all mature females that could be reliably exists. They consume both endemic and intro-
sexed (n = 13) and is presumed to be the result duced plants and animals, are solitary, capable
of the males ‘grip-bite’ during courtship and ofrapid growth, moderately fecund (up to 17
mating. young; Turner 1996) and potentiallylong-lived
Introduced snake mites were recorded on lizards (> 20years; Shea 1998). Sourcesofmor-
17 lizards, with some having large infestations talityrecorded in thepresent studyinclude fire
around the neck, eyes, ears and body-limb and large elapid snakes (see below). The ability
junctures. As the processing of Blue-tongues of Blue-tongues to cope with changes to their
wasbrief,itiscertainthatindividualswithonly habitat is indicated in this work by their use of
minor infestations were overlooked and that dry-stone walls and artificial stone piles, their
76 TheVictorian Naturalist
Research Reports
occurrenceinseverelydegradedgrassland,and adult Blue-tongue (SVL 265 mm) by an adult
the inclusion in their diet ofintroduced plant Eastern Brown Snake, and an adult Lowland
and animal species. How Blue-tongues have Copperhead Austrelaps superbus was found
copedwithhabitatmodificationandlossdueto to contain a recently ingested sub-adult Blue-
urbanisationisnotknown,andalthoughpopu- tongue (R. Valentic, pers. comm.). Watharow
lations persist in some suburbs (pers. obs.), (2002) also recorded a juvenile Blue-tongue
the degree to which these populations are re- in the diet of an Eastern Brown Snake from
liant upon creeks, parklands, railway reserves, Eltham. These observations indicate that both
adjoining agricultural lands and other rem- adult and immature Blue-tongues are poten-
nant habitat is unclear. A recent study ofBlue- tiallyvulnerableto predationbylargeelapids.
tongues inhabiting suburban regions around The gap in the monthly distribution ofSVLs
Sydney (Koenig et al. 2001; 2002) found that (Fig. 2) can be explained by the rate ofgrowth
the species’ survival may be due to, or is de- ofBlue-tongues. Thepotentialforrapidgrowth
pendent on, (i) the existence ofvegetated cor- in Blue-tongueshasbeen demonstratedincap-
ridors, (ii) therepeateduseofsheltersites,sub- tivity under conditions promoting continuous
urban gardens and large suburban blocks, (iii) growth,withmaturityreachedby 10 months of
the distribution oftraffic movements and (iv) age (Phillips 1986 Fig 2A; Walls 1996). Growth
the availabilityofintroducedfood species (esp. of Blue-tongues in the field appears, however,
GardenSnails).Itseemslikelythatatleastsome to occur more slowly. It is hypothesised that
ofthese criteria apply to Blue-tongue popula- the two SVLs defining the gap (i.e. 170 and
tionslivingonMelbourne’ssuburban fringe. 210 mm) approximate the maximum and the
Blue-tongues are known to be omnivorous minimum SVLs attained by successive cohorts
and opportunistic in their feeding habits (Shea atthebeginning oftheirfirst, second and third
1998) andthoseinhabitingthebasaltplains are winters respectively. Given that Blue-tongues
no exception. Snails, millipedes and slaters are aroundMelbournearebornintheperiodfrom
probably available year round since they are February to April (see above; this is also con-
routinelyfoundbeneath surface stonesaccessi- sistent with the timing of parturition in local
bletoBlue-tonguesallyear,butfruitsandcrick- captive Blue-tongues kept outdoors; Turner
etsarehighlyseasonal. Adult BlackFieldcrick- 1996) andthatinmostyearsactivityhaslargely
etsprobablyconstituteasignificantfoodsource ceased by the end of April, there is a growth
for Blue-tongues in late summer and autumn period of, at most, three months betweenbirth
whentheyaremostabundant.Severalotherliz- and their first winter. Given this short period
ard species inhabiting the basalt plains exploit of time and their small size at birth (SVL 64
crickets as a food source: faecal pellets packed -104 mm; Turner 1996 and references cited
with cricket remains have also been observed therein) itisveryunlikelythat ajuvenile could
in Cunningham’s Skinks Egernia cunninghami attain an SVL exceeding 170 mm before the
(pers. obs.) and a dietary shift predominantly onset oftheir first winter, but it is feasible by
to cricketsinlatesummeroccursintheStriped the onset of the second winter. Blue-tongues
LeglessLizardDelmaimpar(Kuttetal. 1998).It have usually resumed activity by the end of
islikelythatBlue-tonguesplayaroleinthedis- September, which means their first full growth
persalofseedsofbothendemicandintroduced period (October to April) spans approximately
plant species that form part oftheir diet. The seven months. Using a neonate SVL of90 mm
seedsarenotchewedorcrushedandsomehave andthesmallestandlargestgrowth ratefigures
been successfully germinated from faecal pel- obtained from recaptured individuals (7.3 and
lets (Melicytus spp.; pers. obs.). The consump- 13.5mm/month),maturity(i.e.SVL>240mm)
tionofBoxthornandTreeVioletMelicytusspp. canbeattainedbythreeandbytwoyearsofage
fruitsisknownalsoinbasaltplainspopulations respectively. Furthermore, the SVLs calculated
ofE. cunninghami (pers. obs.) and in the Cor- at the onset ofeach winter avoid the observed
angamite Water Skink Eulamprus tympanum gap: 112, 163, 214 mm (smallest growth rate);
mm
marnieae (Peterson 1997). 131, 225 (largest growth rate); from the
Large elapid snakes are predators of Blue- resumption ofactivity by late September there
tonguesonthebasaltplains.Valentic (1996) re- is approximately four months of growth until
ported the regurgitation ofa recently ingested lizards reach three andtwoyears ofage respec-
Vol 127 (3) 2010 77
Research Reports
tivelyandbythistimetheyhaveattained matu- LuntID(1991)Managementofremnant,lowlandgrasslands
rity). Clearlytherateofgrowth iscriticaltothis and grassy woodlands for nature conservation: a review.
argument, as is the assumption that it is con- McTDhoeugVaicltlorKiananNdatuKriarlkipsattr1i0c8k,J5B6-(6e6d.s) (1994) Conservation
stant; additionalestimatesofthis rate are need- ofLowland Native Grasslands in South-Eastern Australia.
edadttaontoenstetthheelheyspsotihnedisciasteprtohpaetrlsye.xTuhale mavaatiulraibtlye Mu(tshWeeofrualmudnVWaiicotdfoergirFaeua(nt2ed0r0fM6oe)rlMNbeaoltuburornueer:.nSe(y’dMsnuWesiyle)dulimfe:ViAcftioerlidag/uCiSdeIRtOo
is probably not attained until at least two years Publishing,CollingwoodVic.)
tohfeaggea.pOifn ctohuersSeV,Laldtiesrtnratiibvuetieoxnplaraenaatlisoonspofso-r Pe(tthUeernspEouunbllaGimsph(re1ud9s97Bc)oSmEccpoll(eoHxgoyni,ns)ecveonTlthuretasilios,nsouaLtnahdTwrecosobtneesrenUrnviVavitecirtosonirtiyao,.f
sible, e.g. high juvenile mortality, inadequate Melbourne)
sampling, etc., but require a more comprehen- PhitlolnigpsueJdA(s1k9i8n6k)sOTnitloiqgueanyscoifncmoeitdaesb.oliHcerppreotcoelsosveiscain4B2l(u4e)-,
sive studyto determine their importance. 405-412.
A mark-recapture study of Blue-tongues SchulzM,BeardsellCandSandifordK(1991)Sitesoffaunal
would be useful in determining the current sliifgeniBfriacnacnhce,iDnetphaerWtemsetnetrnowfetCloannsdesrvoaftMieolnboaunrdneE.nv(iWriolnd--
status and long-term viability of populations ment:EastMelbourne)
inhabiting Melbourne’s urban fringe and in SheaGM(1992)TheSystematicsandReproductionofBlue-
abutting suburban regions. Information on VtoonlguumeeliIzIar&dsIoVf(thUenpguebnluisshTeildiqPuhaD(STqhueasmias,taU:niSvceirncsiidtaye)o.f
Blue-tongue patterns of movement, growth Sydney; Electronic Version: http://setis.library.usyd.edu.
ratesandto whatextenttheseareinfluenced by au/sGheMsys/index.html)
the availabilityofground cover and diet would Shtehae East(e1r9n93Bal)ueT-hteonagnuaetoSmkiisntkJToihlniqHuuanstceirnc(oi1d7e2s8-(1S7q9u3a)-,
be useful in identifying factors critical to their mata:Scincidae)andthediscoveryofherbivoryinskinks.
survival in these regions. ArchGivMesofNaturalHistory20,303-306.
Shea (1993b)ThemalereproductivecycleoftheEastern
Acknowledgements Blue-tonguelizardTiliquascincoidesscincoides(Squamata:
Thanks are due to Rob Valentic for sharing his ob- pSpc.in3c9id7a-e4)0.3.InEdHserDpetLoulnongeyyinaAnudstDraAlyirae-sa.d(iSvuerrrseeydiBsecaitpltiyne&,
servations of this species with me, Glenn Shea for Sons:Sydney)
directing me to an on-line version ofhis thesis, and Shea GM (1998) Backyard Blue-tongues. Nature Australia
ttohethmeanruesfcerreieptf.ormakingsignificantimprovementsto Sh1e9a9G8-M9,9(KSouemnmiegrJ),an3d0-3S9h.ine R (2002) The Eastern Blue-
tongueSkinkTiliquascincoidesintheSydneymetropolitan
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uthrebacnityl:izpaartdtser(nTsiloifquaactsivciitnyc,oiidnejs)u.ryJaounrdnamlorotfalHietrypeitnosluobg-y ZaJrerJsHey(1U9S9A6))BiostatisticalAnalysis.(Prentice-HallInt.:New
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LeglessLizardDelma impar(Squamata:pygopidae) inthe
western (basalt) plainsgrassland,Victoria. AustralianZo-
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78 TheVictorian Naturalist