Temperature Regulation in the Sand Goanna Varanus Gouldii (Gray)
TII4PF,RJ.T.IJRE RXGUIATTOi{ T[ trTE
SAßTD GOAÀII\IA Varanuq_ egufdil ç eanY )
by Rj-chard Dennj-s Kjlrg B.Sc., 1l .Sc" (Univers.ity of British Colunbia)
Departnent of Zoology University of Aclel¿,ide
A thesis subnitted. to the University of Adelaide ín part ful-filment of the reqr:_lrements for the d.egreg of Doctor of Philosophy October 1,97t. ftr,,..'{t td /":!"'t' '", / ?'-1j C0IITEìI]S
SUIT:ARY
ACi:i, ¡,:, ¡¿ÐGEi l r-]' T S
I GElMzuJ I=I'IRODUCTIOi[ 1
]I FIEID STUD]ES
1" Introd.uction 5 2. Ficl-d tcchniqu_cs e" Capturc 9 b. l[arking 11 c. Tclcmetry ri.cr¡iccs - loc¿.tions 11 d. Burro¡,v d.imcnsions EJtd- conCitions 1 2 c. StonacÌi contcnts 1 3 f. BrccC-ing condition 1 4 s, = Ho¡rc rangc 1 + 1," lcrnpcratitrc nc¿:su:r:cilcnts 1 4 3. Gcncre,"l ccology a. Iurrow locations, dimcnslons ¿:.nd. microc l_iroi-t c 1B b. Scasonal a"cti";ity pattcrns 28 c. Food. 31 d. Brccd.ing concì.ition 33 e " Homc rarlgc 37 f . Density of popul¿:-bions 40 4 Thcrmal ccol-ogy ã. Ðaily activity pa-rttcrns 4 2 b. Thcrmal- rcgulation 5 B
IT] IABOzuTCTìY STUDIES 1. Bchavlour a:rd. prcfcrrcd. tcnpcraturc e. l,latcrials and ¡rcthod.s 6B b. Echavi-our j_n grad.icnts 74 c. Prcfcrrcd tcmpcraturcs 77 . d.. Discussion B6 2. i{ead.-bcùy tenperature d.ifferences e. Liaterial-s and methods 91 b. Unrestra.ined. a:limals 94 c. Restrained. animals 96 d.. Iieat e;pplied. to l-imited parts of the animal-s 100 e. Diseussion 1C1 3. Na"sal teiaperi"tures a. I.rasal morpholo.'ry 108 b. lfethods of L'leasuring temperatures 109 c " Nasal temperattires 111 d.. Discusslon 11+ 4, Skin refl-ectivity 117
IV GENERAI ÐISCUSSfON 121
APPEITDIX
BIBITOGRJ,PTIY SüMttl¿lRy
Tire therraoregul-a tory beliavi_cur and aci:ivíty
p:ttterns ol V.eoul_dii r.¡ere stu-díed in the l_e,r,-'ora,:oz.y and at tïrree f ield are:rs. Iiiini_auuri;ed 1:ele:iiet:r¡¡ devices ÞIere lu'líLlzed -to in.'tt:e f ielcl stud:,' l;ionii;¡r tl:e bc<1 ;r tem¡;eratures oi active, unrestrained. floan*åc and to de'ierm.ine tìteir- l_c:a.ij_cns and a.ctivit¡.,.
cor:.aidenabie d i-f f erence-e exie -t iii ti.le environ- rnentaj- conditior:s cn the t1¡.ree stuciSr areâs, but ti:e eccrj-tic te,'ûljeratures of gÐar¡nas :ìs deÊerinined t3,
telemetrJZ were similar on a11 areas durin¿1 Ll¡e cunînxer. hlean deep body'1;enrperatur:es at'bi:et tine of JreüÍ. ranf¡ed f rci'ir 3l ,i- 4c 36 .9goC. Ti:íe sin-iíl-ari-i;r -u¡¿" c1-¡le to tL::_e d ír'f ereu-¡ces in bel¡aviour of ì/. gould. l i ûn 1;h.ese c.reas. Botir dai]-y and seasonal act,Lvit¡ i-ra-ûterns ciffer.ed bet¡veen aninta]-e on äan¡laroo Ts]-anri and a"i i;he o.t her ct"Jdy sites. Goannas on tiie arid an,c se¡F.í-arid. areae spent iîeore iinre sirei'fering in tlleir'Durrc,,^rs Ëjien ciid those on äangaroo rs r and on bo,;ii e ôaíLy anr a seaocnal_
Las is .
On Ií,angaroc ïsland, goeriìrrs elnergeõ f roin tireir burrov¡s ihroughoui tire yeer. , all-itcugi.r l;ileì r clcac¿l 1 te¡Ípeï.€,.iures generaJ-J-¡¡ rei?ia ineci l-ow riuring winter , wi: i1e V. gould ií j-n sr id ai:d serni-arid regions are inacti.ve curing'ül^e wínter froni ap.Ðroxj_¡ia.;ej.y l,larcl. ic Septc-rnber . 9irnilarities exist in the breeding cycl-es and f ood habits of goanirac on the rnecic anC ariC areas. ovariar eggc reacir ti:.eir rnaximui'n sJ-ze Lrt roeraaf-e v.gouldii
f ro:ii Octoi:er to Decein'cer in bcth areao , e.n¿u eggc ar. e f ou-¡-:d in tae cviducËs d.urirr.g l{ovenber sncl Deceinber.. Sand goannaG åre ollúortunistic predatorc v¡jrich feect 1:rirne.rily on reptiles aad J_arge inver.';ebratee, btlt will- utLLLze other f ood l.rhicþ is ].oca1ly av:ri]-ab].e. In tire laboratory, tiie prer_"erreci tern¡leraturec of ani:nal-s frorn al-1 tTiree subspeciee were i¡etween TLj ,Ozc ae .l8oC ía tire::ma-1 ¿radients. Their behaviour in the gradieri-ss wes similar, and was aigi:1y vatiable beiween and witiriî individ-,¡a]-s.
i{ead-body tenrperature differenceo Tvere deterrnined in both active aird restrained Li_zarcis and the iriiportance of trpantingttor gular flu€tering in nair.,taín- ing ã stat¡le bea¡i'iernge"ature dr.rring ¡leríocis of eievaterj ambíent ternpcraturee .wes assessed. Intra-cranial_
'i;em¡-'erature r{as maintaineci at apprr.:li:..1:i.eJ-y g8. Go
õ9.O'C l'oi'¡.reriods of ¡nore ti¡.an one i-.o-.rr b:¡ üì:,ie r.leanc when ¿rnin.-als vrere placed in teìïilerature cabinets aì: 42oC, ;vhi1e cloacal ternilerature nra:.cL:ed vaLuee s1i¿;htl-y al.¡ove air ter.:peratul" e. Temperatures of inspireõ ârrc expired ai¡ were measured in three species of this gellus and it r^ras found tl;;'a'c expired air temperatureo 'r'rere rower than body ternp- eraËr.1res by ae much as11-{-ìoc. Thíe is of iin¡:,ort.ance bo-!h in regulatirrg heat ilux and, ¡rro-uably;iacre iinportantLy, in conserving trater in these speciee. Tlre *eilectivity of tire dorsaL skin of the three eubspecies was rneasured, and that f ror,.l -Ehe a¡id zoîe subspecíes i:ad the iríghest reflectivi.ty whil-e samples f rom gcannas f rorn Kangaroo rel-anc had the lowest ref lectance values. There was so;îre variation in ref lectance va].ues oro individua-te witili.n each sr:bs¡lecies. jiåQiyiS,lL+-aJ
This thesis contains no nateri-a} r¡¡hich has beeir. acce*,ted for' aíry otl¡er d.egree or d-iplcna at arÌy ',iniversit¡r, and., to tlie best of i.,ry knor¡lledge coiitains no nateri-a.l- l.revi-ousiji i;¡¡i¡¿en or published 'b"' anot6er person c.:cet)t vrirere d.uc reference is ;iad.e in tÌre text of tlie thesis. åci-*qË-iUll. 'lli,å
I tha¡k Professor FI.G. A:.Ldrcvr'aÍt,ia for acting as my supervieor d_uriil3 this study, ::itd for naking helpful criilci=,,rs of thc nai:.uscript. Dr. ii.rg"B" Sm¡,th al-so trcindly read- and. offercd. surgcstions on thc rlaniiscript. iiuch gratitud e is ,-i;;c to Erian Green v¡ho su,rgestcd- the possibility of such a stud_y, provid.ed consi,lerabl-c a-osista.:rce in both thc ficld a.nd. the laborato;:¡r d.u-ring tirc initi¿.1- -.art of thc ii'o_rli, al_l_or,-;ed_ me acceFis to nis nnpubl-isl:led, ficì-d notcs, anc. :rad.e mej.r.y uscful su,".g;cstlons during thc course cf this study. I[ai:; othr:r pecplc have aidcd me in a nu_nber of 'r',Iaj'/s, with advice a"äd assi.t¡¿ncc du-rlnq ficl-c trips and laboratory worlc, a"nd. I tnank thcrn a.1f . In particular r acknowledgc thc h-eli: of Tíichaci Brayshcr, lieil Brcwcr, Jlctcr cairncy, lcs Dohcrty, Robcrt lTcnzcl-l-, Ða1.: R.oberts, lony iì.o'r;inson and- R.obcrt .sharr¿:r1. i{y -pccia''l ilranks go to Broiiw;,n Tioilour?,ð,r Bcv Joncs, anrL cspecially to Earbara Fcd.l-cr, whcsc hclp d.u.rj-n,1J i;hc prcpa.ratlon of this thcsis cn¿.'l,.ledr its comi:1¡tion. I a"n gratcful for tl.',-: suppcrt ';viiich rl.;as provi,lcd -bhc for t-his urork by Alistral_ian li'oof Xoa::,J_, in th.: _iornr of a Scrrior Post-gra-d*:.tc Schol_a::ship, and b1' thc Zoolog;,- Dcpartnoüt of ti'ic 'JnivcrsitS' oí Âdol-¡ ídc. Ï. General Introductioir
DaiJ-y and seascnal fluctuations in tire eíviron- mentaJ- temperatures wliiil: occ.úr in the ternperâte areas,
and particularly in the ten'iperate deserts in wiiíc?t r,;"enyr apecieo of rept il-ee occ-úr, are wide . As both ex-irer,'ree of temperature are oftea in exúess of the J-iinits which a?e J-etha1 to ectotherr¡i j-c verteb¡ates, it is obvious that iernperate zoee reg)-üiies rnust regulate their bocl¡r temperatures withj-n a rnuch more natrow range than that of the environrnental- tei."peratures v¡hich they encounter. It has J-ong been lr-nown that the use oi burrows and other therrnaJ- ref r-rges is necessary f or the surviva i of reptiles in rnany areas, and that tlne activitSz palcterr,s oi these anirnale variec in response to seaso:nâL changes ín environmenta]- conditione. Lj-tt]-e .yrork was done on t jle thermoregulation of repti1.es, however, untíi tire stud;r of Cowles and Bogert (Í-944) initiated interest in the topic. They state¡J that rrthermal control through beliaviour i-s one of thå ouüstanding characterístics of des'u-r-ü reptil-esrr, a].tfiougìl they a]-so ccnsidered the plìJ-3io1ogica1 rneans used "oy reptiJ-es to 1-ower-their Ì-iod¡r temileraturee during tírnes of heat stress. Subsequent studies on reptilian therrnoregulation have genere. 11y concentrateC on either I_aborator¡r studies, oi an essential-ly physio1-oglcal naturer or on the observat;c¡: 2 of anirna]-s in t¡ie f,ie]-d and their responoes to ti¡e prevaili ng environnental co;róitions and tire determination of the diurnal and seasor-ra1 patterns cf activity of the anima]-s. Continuous oi¡eervation and determination of the locations anô body temperatures of the animal-s during a wíóe rsnge of condítions i-e desirable i¡ sucTr f ieJ-d studi-es. This, honever, is of ten dif f icult or imposoible, As a result , trtàttli f ieJ.d stud j-es have consísted of cotrJ-ecting large numbers of animals witich were captured or ki1J-ed, and the nean value of their body temperatures Þras then stated as the eccritíc iemperature of the species. Unf ortunateJ-y, in n'tany stuCies, little or nothir:g was known of the behaviour of ttrle animals at the tíme prior to theír capture, and there r,Jas often littl-e or no consideration gi-ven to their postures or orientation at the tirne of col-1.ection, or of ihe range of environrnental- oondit j-ons which was ava il-able to them. The developrnent of radio-tele¡"netry devices, -øhich. were first used in fie1,3 str¡dies of reÐtil-es by MacÍ{ay (l-954), has been of greai val-ue in studies of this kj-nd. The technique is now v¡ide1y used, and allows data to be col.lected either continuousJ-y or at selected intervals :<
f rom f ree-rangír,g an j-rnals in tÌreir naturaL hab j-i-at.. Âe -Detter a result , rnuch more an
Varanus ou]-d ii (Gra¡-) is a coffiilion and consÐicuotrs species of Lj-zard iiir.oughout most cf l:ustralia. Labora.bonii studj-es of this and otirer s?€císos of varanid Lt_zards br¡ Lr,srthol-ornew and rt¿cker (í964) suggestec that they poosessed a much gr.eater degnee of physiological controi of their body terrrperature th.an do other spec.ies of Lj.-zetr.js. rt T{åa further suggested that tl'eir -therrnoreguiatcry abili-ties r^rexe B resu].t or= the higir rnetabolic nates, specialized cardiovascul_ar functi_on, and degree of endogenoue heat product-i oi:. wh:i ch cou]-C be at.i,ained. It r,Jae stated that the varen-ics bridged tile gap wh-i cir had been assumed, to exíst Ì¡etween manirnal-s ¿.n1" rept:-1es in rr,êtz.bol-ic rates (Eartholomew and Tucker !964). Recent studies by Green (j_g69 ) on w¿rter and eiectrol-yte bal-ance, by Eennett (j-9171) orr oxygen trar-rspor-c and energy,-netabolisrn, anri by T{ebb (LgZ1_) on card,iac mor.lhol-ogy an<1 functi-on, aG reiated to therrnoregulation, have provided rnuch information on the physiol-ogical ^ capebi-1-ities of -firis speciee. 'vlíth the excepticn of ';he ;.rork of Green (1969 ) and "rianka (X97A) , however, 1i5tJ,e i:as bilen done or1 the ecoJ.ogy of the ar.:.iffial in the f ieJ-ct, and j-itt l-e inf crir'at iore c-rÌ tee the rnoreguJ-atory bei:avio'¿r' of tire anirnal- in ';he fietd i-s avail-ab]-e. ?he vri-de C¿is;rj-butiori of th,is specíes and the relativel¡r J-arge si-¡;e of the ar¡.inna1e ere bofi-, helpfu]- in a study oi their
..1;l:ern oregul-at ion. The range of environmental- condit iens encountered by tiie ani;naLe is considerable and veries r+ideJ-y -i"rt the dif f ereni areas in v¿þ.ich they occur.
1,1 inj-a-i'.1re radio-teJ-ei.letr-v devices can easiJ-y be carriec: bj¡ l-izarCs cf thelr size, nithout seri,¡usJ-y a]-teríng or i:índering the activities oÊ tne anímaIs. A etudy oi
-tl,r -lhue e r¡'nor è g'c.14 ion o f Varanus ¡;cuJ-d J-i was be 8ún r j-nvoi-ving'ooth J-ai¡orator¡r and fieJ-d work, tû deterr=¿íne tire behaviolrral- anci ¡irhysioJ-ogica!. means l¡y- whích thís e'ctoth.eri'nic speci-es regul-ates its bod;r ternperai;ure in a r¡íCe and variablc rârrg€ of i-.,abitats. t.: rr. ( 1) Intr oduct iorr
The ?ar,íLy \rarani
Af rica, e outherri Asia, .and ¿luetre3-ia . lhere is consiCera'ol-e var i¿t icrz ín tÀ ze be ûween si:ec ies, !tt:.T a]-]- ere si-niiI.ar i-n Aenera1- r-,orpì:oLoEy. T:le genus has radiated v'ride].y' in .Þ.tlstra1ia, wtrere tnero are ig speciee (Dtertens :19C6, Stc:'r n-954, l-96ô ) whicii cccuf in a v¡lde var iety of habi tats throughout the con?inent, wii:li tire excep-ú: ion of Tae,'nania. 'i^liri-l-e ii íe a general-]-;r ¡3¡¡a* uncêe cLc-Lizea iroup, sotae epecíee are restr j-cted 7;c part icuJ-ar habitet types (!f,ianka '7J?2 ) wh:-cir renge f rom arid to i'.quetic and f roiy'" ari:cre¿f io terresir LaL. Ail mem'¡ers ct '1, 1:e gentrs are d iurna 1 carnivorec., f eed j ilg c11 a var iet:,¡ cf prey and carrion, anC oiten foraEing cver large arees. L4osi opecies uoe irurrol¡s, or cÉrviTies rn treeo or roc':-e, âs refuge sitee. The oand ËoaÍna, Varanus gcliJ.dii ,asan ubiqui-tous species found throughoul; tþ.e Austral-ian main1.and (Pianl;a L972 ) and on a number of islands, inclucirig
2 meters ia J-ength â:-¡C 7 itilo¡¡rarns ín weigirt, aJ-tlicugh in rnost part€ oí: its range it does not approach tt¡is size. '5.
This species occur6 throughout Scu?h Australía, j-vided and is current 1y d into 3 subspecies (Èîertens 1958 ) which. are: (a) V.g.rosenbe¡gi: a melani-stic form which is
f ound in south,west '¡lestern Australia. and some coasta1- areas of South .Austral_ia, inclurÍing
iíangaroo Island. This su'ilspecies reaches a
meximum sLze of approximateLS' j- metef in 1_engtl: and 13tO grams ín weight.
(b) V.B.gouJ.dii: widely opread, ovep rnoe t of the contiaent, amd varying consirSerably irr size and coJ-our patterne . T-rt South AustraJ-ia Lt tends t,a be int ermeci ia te in sj-ze and colourat íon between the other 2 suirspecies. (c) 1'I .g.flavi-rufus: the in].and arid zone form, which io generaliy of smal-J-er size than the other subepecies.
These etrbspecíes tend to occlrpy habiiats of, different aridity (Green 1959) whi-ch are respectíveJ-y mesic, semi-arid, an,i ariC. Ttre speciee ís most comrnon in sandy areas (Eustard l97O), but is found in most habitats in South Australia. Field wori<. on the therrnoreguJ-ation of Varanus gor:J-C ii was carried out at ti:ree locations Cuning tire course of ihis stuoy. They wer.e at Flinders Ci:,ase, Celc,erum, aacì ,Ì
Ii6uJ-oorina Station. The ob-;ect of theee ot¡e ervations r^f as io deterrri-ne the ti'a i13' ¿¡¿ sê&scliral- move,'re::ts of tire aí!.ina]-s, tc non j,-tor their boriy temperature under natura]- cct:ditions, and to ooiain tlai;a c¡l ¡¡€' n:Lcrocii¡r¡atic coniitions wliicF.,. tiiey ericouili;er. Flin,1 ers Chnoe, v¡lrictr ie lccate
19.18 ) . B
Cal_perurn Station j-s locatet-i north_;.¡est of
Renmarl'-. Goanni,s ¡rere collected ancl observat ío¡rs ?Jere
made oÐ e series of psr,al-ie1 saird iiil1e wh-i cir are j_n tì.re
area descri-berJ by Greeri ( 1g6g ) , ai:d are covereci ¡.¡iti.:. l-tgh't n.rilee scr":b. ?he clilnate o:i ih.;ic area i-s semí- arid e.rrd r.Iarn,t, wi-El¡ mean valuee cf ev:Lporaiion e::ceeding rair:ie11 in every rreasûi1 (ûentilii |g¿i8). Mear¡ gnnual rainfe].l_ is Lû.311 inches.
. liul-oor ína s-tation i:Iomesteac ís locatec aÐp,rox- irnately õû inil-eo nortb-west of IiIarree. rt is iri an a?ea of l-ovi relíef anû srarso vegeËat ícn . obse ?vttions ;{ere madc in ârr ares approximately 2 ¡ni.les sor:t}:. of ;he hcmesiead in a region cf oandy soí1 which is tr_i-gi:üly covererl by 1cw Atr j, 1ex and iíccliia ¡¡i:i]-e Ínost animale t{ere r:oLLected on or íiear the sand dunes which border Lake tsyre sour,-h, apploxirnately 3c niies north of tire
hcmeste.g.d. The c1ímaie is 1e6s ) . 'Ii:e subspec-ies cf V. gouldii occul.r ing on each of theee arLrâG are: Flinil ers Chase V.g.rosenber ç-j 'ia lcerurn V. Ft . gou]-d i:'- iilul-oor ina V.g.ilevirufus I A.Sditional anima]-s were collected at a numirer of , othe¡ loca]-itiee in $otrth .A,usuralia anci the Northern Territory ( Figure X ) roor laborator;r studies . (2) Fi 1d Te ctrn ues è. Ca¡rture Anii'nals -r^¡ere generally capturec by one oro tlrree methocls during the course of ihe study. Tirese were: i. d i¿g !_ng out of burroi¿s ii. noosing iii. trapping Tire rsuccess of each of these method€ varíed on the dif f erent e tudy areas and àt sif f erent Lí¡nes ol. the year. i. For ,nucl¡ of t'ne year, inhabitec'r. burrorvs on Kaagarco rsland ar.e relativel-y co*spicuous anf, animals are easil-y dug ou'c o1' ther*¡. Th.is etas the nnain meÈirod, br,, r¡¡l¡iclr anj-lna1s were cat!turec or.ì Flinders chase . a,t calFerup.i and ÎiÍul-oorina;:urrows are cf'l;es êxtênsicris off rabbít r{arrer}s anõ are co;ls id erab Ly mcte d if f icult io locate than are those on :l'-arrgarco rsland, wi:ere no rabbits occur, ùoanna.l r^rere thua seldon caught by tiiis ¡n-ethod, on e i'Lt¿er of the rna inI.ai:C stud¡r areas . Figure I Localities at which Varanus souldií r¿ere c o ]-1ec ted during this study" o V.g.flavirufus { V.g.gouidii- ÈrV.g.rosenbergi c3 J-i-i. ii-. Afi.ålrra1s seen active in the fiel_C were cÍ,ten nocsed usi:rg Ê cectioned cr,ne.ocle 8 - l_5 feet in len.e,tl equi¡lqe.lt ¡rit.ti äou:ses m{.rde f ror,'i 1igi:r coËtcrr cord. Gcannas cf ten irecame i;nrno'':il-e at the approach oi tbe co]-lector a¡lc couJ.d be api?rcacired tc wi-bi':il: a iistance of 1 C' - L5 f eet . Oii¿ere were chesed on f cct ancl :aptured when they sought refuge in ciumg:e of vegetstion, trees or burrows . Tire nta jor ity of trre animels caþtureC in senni-erid and arié regions ani cof¡giderable nurnbers cf throse captured o:'r I(angaroo Is]-and r^rere obtainec in th i-e f ash ion . iíi. ?rairs r.Jere uced in a]-l three study areas, but generall-y with 1ow reteo of success. These were constructeC from. õ foot lengt?rs of 3 x 4tt rectangular metal pj-gles. Wire meeh. covered one end ci tne trap, and a rnetal door at the other encl irrcpped when an animal- Þressed a treadle upc.n enterinq tire balt chamber. Futre f iri-ng f isli was tììe ba it mcst comrí¡onJ-y ernpioS.s¿ . A .jiagrara cf the type of trap-' usei is presentec by Green (1969). I:: additicn-bc these net!:ode, a few a*ir'.rals !ùeFe caotured by band '¡¡1¡.en they r^rere observe¡l bashin6 or active during the Cay. J-l-. ¡,. Àiarking The i_niivièual- içarkinË fieilìoJ of ctri_¡;pin5¡ ciaws in various eoniblnations whicir r.,rrs use<1 1--:,r Green ( i.969 ) o* twc of these etrrr1y areas wae conti:iue<.i , In adéit ion, 6ome aní¡na1s were me,ti'-ed ;..;iuh acry 1í_c paint of one or r,?orc co1ours tc f ac iiitste shcri:te¡'m rcccgnition anó o'cserva.tion of indivicjual animal_s. c. Telerietry Cevices i-oçeÊ 19n ¿ Radic-transmitters Þtere tised tct iocating e number of e.nimaLs at intervaJ-s thitou5¡ilouË ti:e e;tudy. ?i:ese Þrere modif ied verÍlicns of th.e desi gn which vras descrit-¡es by Tester et a1 ( L90¿: ) and. 1"lne circuit tìiagram is sþ.own in Figure 2, The transr':lit. .¿.1G r.iere pcr+ereC Ðy twc [Iaìiory TrL32R mercury cells wh j-ch pro Cir¿-i:,iL Ciagrem ci= têJ-er¡retr.¡ devleee -"1 seC'cc reio¿ate il r-,4nn¿! -1 . c.r c/l i,r t) hú Fl) eñ Õ (o r-Þ 19 nc other restrictions on ti:e rnobiJ-S-ty cf the anirnaJ-s were observed, ïn the latter part of ti:e study, the sLze cf tlle transrnii;ters v¡ac reiuced sc the3r se1-CoÍ1 exceeded â treight c.f 2 .2 cr:ts . a::.d thi s d if f icuJ-ty was not säcûuntereC the reaîter . 1'-:¡.e -Eaiua]. we í6:;1:lt crf the iraircmiiterc and h.trnegses ra!-rí,8(l fror::: 1i-i - .:iíi grams, ar:rd ttre r-re1Ë?ìt of th.e animals to i.shich iliese tele:neir5' de','ices were fittei rangec'! ircn,rTL 13;1.û Ararìßs on Flinilers Chase en.l f ro¡r"' 3t5 649 Ërâms at Calperum. T.hey r,rere not used on lvlul-oorina Staf iori. d. Burror^l <1 ineneions aad conCíÈions. Burrow dime¡rsions were cieternineC usii-'g a neasuríirg tape, to the îrearest cent ineter . Lengttr r{as measured from the burrow mcuth to the 'ua.ck i.raij- cf the chanrber, and ieptir f rorn the soij- surf ace 'Eo the roof of the cham'oer . 9cil-:r,oisture content ctrt differ.ent areas of Flinders Chase was dei:er¡r,ånec frorn soil ea;npJ-es weigh-ing f rorn 2C - r',C gra.ms wirich v.lere ccJ-lecteC at t imes ti-rroughout the ),ear . Tirese ?vere obta izied lrom the roof of burrow char,rbers or fro¡n sarrp!-ee taken near pointG at v¡hícL occ"opieri i:urro-r¡s were 1-ocateC oa earlier trips tc tire study area oil Flinders Chaee, af¡C, at a depth which approximatert that of Varanus gouldii 13. burrows during thè summer (approxinûately 10 - LZ cm. ) Theee samples Þrere g3-aced ån p1-aetic e[,'ecimen tubes and se¿:1e,3 v¡ith contact cement . Upon returning tc Adol,a iele, the sa.nîpJ-es wcrre wei¿hed on a Mei,-t1êr i¡alance (t:¡pe I{i6 ) to t!:e ncare6'i . ûCi Êrarn anc¡ cven- dried aÈ lOSoC f cr a miniinurn cf' 48 hour.s ancl then reweighed. Soij. Ie'iEÊ!-3osg rnoisture was calcuiate,i ^u- Cry weight cf ecil- and expreueed ae & perceû'üâge. e. 9tornach ccntents Stcmacll contents of anima]-s which were accidently kill-eC on Kangaroo IsJ-and during ths couree of tne study, and of those found recently kill.ed on roads outside Flinders thase, were col-J-ected and preserved irr LO% f orrnalín. Ad¿itíona1 oanrpl-es r{ere obteineÕ from anima].s wbich i¡aC been co]-].ectee on Iíangaroc IsI-cnú az'-(t 1oéged i:¡ the reptiJ-e colJ-ection of the Soutli Australian l¡iuseurn. Facal sanrplee and reGuf,Éiitated fcod items were a1-so coll.ected. These rrere l-ater examíned and , wiiere poss ibl-e , ident if ied 'ic speciee . lriami¡r.a1ian reme.ins wer.e identif itrd -,;y ccriÞariilg heirs f rorn them wi-th tirose fro¡ir refereirce gpecimens, an',,-ì reptiJ-es ?{ere ke3.eä ûut to e pecies v¡i-ie::. possiL-1e. Ti:.o volur¡'ie of eaci'i iten vrac neasurec by water dispLacernent in a graduatec1 cylincler, enri expressed es a percentage ci ti:e total voiu¡ne. Percent 'aJ.sc f requency of ùccurrènce vras <-etermínecl . L.¿ . f Breeding cond it ion P.eprocluctive orgar¡s Í{ere collecteC from a nurni:efl of the enir"aale from whicil stornach ccntents were ob.tninecl , anC $rere rlso preserrzec'i in LA% formalin. vclume of testes was subsequentJ-y determirred '..r-v means o-f water displacentent, ailt-i ihe number oi develcpe ca lipers . ï-Iome range Locaticrnsofthepoinlgcfcaptureofarrimals at Flinders Chase and Calperurn eferre plotted cn tracing paper, using aerisJ- photo¡¡raphs with a sca1-e of I to l-OrOGC. The area of hcme ra$ge was calculeted usíng both tlr.e cÒnvex pclygon rne'f hoc ( t'iilstead "t-9'1l-) witir the coÎrecticn fcr recapture nunnber biae given D:{ Jennricir and Turner ( 1969 ) and b'"" tlie ellipsci-r1 tnethoú (Jennricir arr.d Turner l-969). These animal-s irad initial-J.Slbeencapturecbyoneofti:errret.'ircdsdigcussec ínItr(2)â.randwercrelccateöat:irreguf-arj-ntervaLs b:¡ tiìe sarne r,ethocls, par'cicuJ-arl¡r' by'the u'se of telemetrY ievices. 'n. Temp erature neasure nts Cioacal-úen?erctures of Varanus g¡uiCii in t-he f iel<'i anc â number cf environlïen'ta1 ternperatureS !nefte rjeter'-rrj-ne<1 b¡r tl;e use cî seVeral telïliDêrati:re ¿t . sens j-'ng devices. These ?rere: i.Quick-readj-n¡¡$ciiulth.eisthernnorneters}Íere .iire useC; f or ieterrnj-nin¡; 'Jeep ilo'J;' temPeratures ' t11erïnorêeters T^rere inserted i'l :' 'Je'çtil:' of-' 3 - 5 cn ' inmreCiaÈe1-y af ter the capture ci anirnals ' on a nurnber of occ¿rsions tirese ttrerr.^lorfleters arr,Í1 burrcw r{ere 31so ueec tc <1 e'üerrnine air, soil tenlleratules. Aif tet'nperatures vlere ta!:en at e h.eíght oî s.lliÐroxj-rí¡e'te1y 3O - õ5 cm' from the ground anc siraded f rc¡n tr'le sun. Scil temperatures I{ere nreasured at a del;th sucb that the 'i-herrnonieter i;u1Ï: i{¿lsjuctcover.e(lbysoil,wtiil-eburrowternperaiureS grere tatr'.en either in the wal-l 0f the burrcw chanber or in t]ne chamber iÜseli. íi. Ternperati¡res of f ree-ranEL{18 Êoarrilas ¡'{eîe raßge of trausmissj.on wae ]-ímited and transmitterc ofterr sl:orted out cr were reAurg it¿:ted , and th j_s meti:co t{as âbandcneC . FoLlowing the at,;ach.ment of .: teJ_ernetry device, ttle aninal -rlas released f¡êâp the poini of capture ¿1nd its location and <1eep bcdy te:T[ierature rvere rnonítored for periocls ran¿¡ing f ror¡. I 7 da¡¡s. observatiqrn of ani¡nal-s cucång efterllence and baclting r{as facilitated by ihe use of '.7 x 5r_j bi¡:ocsLars fron a aistance of 40 - 60 yards anð f of_iolvin¡1 the cecsatior¡ of be.sking they were located at intervals duriieg tile ée:{, when it was p'ossible to oo oo witl¿cut disiurbing tÞe animqls undu!.y, or if the si¿nal wirich vras received aI.tereC in unêx,Lrected f aeiiion, iíi. lernperatures cf burrows and other micro_ environmer,ãal. temperatures were meaeurecl using e 3 O-channel therrnistor ti:er¡-r¡c¡metgr congtsucted acccrciin¿ to the deoign of l,lcLean (J-gE4) . 'il:is cJevice r.rae al_eo used occasionally to determine the cloacal ternpsrature of goannas. iv. BLacl¡- bul_b temíi,êrattlres were tai:en to cb-bain Arl indieation of ihe extrer.*¡es cf sui.face ternpereiüfes, using a 1lcoc thermcmeter whicb r^ras ¡;l-aced in a partially evacuatec giass tube 1 inch in diameter, with a bulb 18. i.6 incheg in diameter. The bul-b was covered with fLat, black paint and coiLs oro braes wire held the thermorneter in place witliin tl,..e tr¡be. (3) General Ecology a. Burrow locations, dimensions, and riicroclimate. In comrnon vlith nany other opecies of terrestrial reptiLes, Varanu S ouldii spends a large amount of time sheJ-tering in 'ourrowe. These burrows ¡irovide relativeJ"y stable microc1.imatíc conditions and presumably aI-so protect their inhabitants frorn predators. A numÞer of factors lr,ave been reported to affect thê stability of the microclimate of burrows. These include depth (Schnidt-Nielsen and Schmidt-Nielsen 1950), vegetatíve cover and soiI- colouration (Geiger 1959)t so i1 texture ( Ha5nrard L9€'L ) and burrow o¡: ientat ion (i{arburg 1965 ) . Ðata were tl¡us co1-1-ecterl on burron locations, dimeneions and microclimate. i. Ðuring the perio Table 1. in which the entrances of the burrows of faced on Flinde¡rs Chase. I Or ientat ion Season Locat ion 'vfest Summer F]-ats I oÕ B 6 Sandh i11s îT 1 1, 2 Winter Sandh i1ls 27 L ït can be aeen that there is no selection for a particular orientation of burrows located on the tJ.at area, such as the paddocks and f irebreaksron Kanganoo Is1anri,. I{o differencee in temperature of burrows as related to their orientation were apparent. HeatwoJ-e (LgZO) reported similar finclings with the burrows oi Amphibolurus inermis. There does, honrever, seen to be a selection for burrows on elevâted areas to be located on north-facing sJ-opes, presumabl-y to rnaxímize the amount of sunlight which wiJ-J. fa11- on the soíJ- in which the burrow is dug and thue increase the temperature in the burrow. InitiaJ-ly, searching for burrows during winter was conducted ín an almost random fashion with regard to the direction in which slopes faced. In the latter part of tlre study, it was concentrated on the north-facing sJ.opes of a series of sand ridges which ran in a genera1ly east- I^re€t direction, as aJ.J. inhabited burrows had been locate' ¿J_. orl s1-opes which had a northern exposure. Thi-s area was a1-so searched in subsequent Eumrners to deterrnine the degree to which it was used bJ' V.gotl ]-d ii dur ing the surnrner . There is thus a biae j_n the arnount of tirne whicli was sÞent searching on north-facÅng elo¡res in sandhil-J-s, particularJ-y during the winter. Not enough burrows were located at Calperu:^n and I',{u].oorina to determine whether orientation affected burrow temperatufes there. There seemed to be no part icuJ-ar orientat ion wli:lch was f avoured during the summer, although one would bs expected if there was any noticabl-e effect o' bur¡ow temperatures resul-ting from a particular orientation, iii. The burro¡^¡s inlrabited by V.gouldii on Kan garoo trsland differ in ge'nera3- form and dim.ensions from those located at, Cal-perum. Those on Kangaroo Island are rel-ativel.y shalJ.ow (Tab1e 2), slightly curvíngr and have their deepest point located at an enlarged terminal chamber. On CaJ.¡lerum, summer burrows reached a greater depth than did those on l(angaroo Island, and aJ-J- burrows which r^rere excavated Tiad a rtpo¡l-ho1eil. Ttlís conoisted of a tunnel be¡rond the burrow chamber whj-ch extended to within several centimeters of the surface. Goannas use pop-holes as an avenue of excape when their burrows are Tatrl'.e 2. Ð ímens i nö of. t/ oú b to F]-inders Chaee and'C.a"lp-erum Statíon. AREA TOCATION s8A$ON NUÌ,ûB5R ÞtsPTTr ( cm. ) IENGTH (cn. ) g Flíndere Chase Fír ebroaks Summer :lo 10.AjO r Sandhitr]-e Summen t5 Ií,Ti!2.6 l¡l int er 22 18 . Ojl, ü g CaJ.perunt Sumrner þ 40.6ÏLA.7 L1.2 ,õj5. ¿¿. excaveted, and a1-so aElparently for thermoregulatory purposes (see IT (4)b). OnJ.y two inhabited burfows were dug up at Ìiluloor.ina, anC neither of them had a pop-hole, although the burrows of V.gouldii in arid and semi-arid regions of Australia genera1-1-y harze them (Bred1, pers. comm.). &iost goannas observed on Muloorina were eiüher active al{ay f rom burrows when seenr or took refuge ir' rabbit r{arrens, which accounts f or the l_ow Ítu¡îlber of burrows v¡hich r^iere located on 1cF'a1l- area. As Green (L969) found signifj-cant differences in the depths of burrows bc-tween those found at Renmark and on Kangaroo IsJ.and, and as both temgrerature and humidity of burrows become more stabJ-e with increasing depth ( Schmidt-NieJ-sen and Schrnidt-Nielsen, l-950) , f urther data on burrow dimensions were collected. These are presented in Table 2. Lengtirs of burrows in sumrner at both Flinders Chase and at Calperum were similar to those given by Green (1969) for both areas, and there was no significant difference in length of burrows frorn the two areas. There was al-so no significant diffcrence in lengths of bur¡ows on Kangaroo Is]-and beiween summer and winter. The depths of burrows on the firebreaks and pa on these areas (! in bcth ís.> .tl5), but depths of burrows o'Ír the f Lat ar¡eas and in the sandiril_ls dif f ere,j at the I% 1evel (F = 9.52, df = tr4-¿l). Burrows which were located on sandhiils i-n winter i.¡ere deeoer thaa those on the same areas during summer (F = ?.65, df = j-r56**), and both were deeper than those found on the flat areao near tÏrê F.ocky River liomes;teacl during the summer. While the difference in depth between burrows located in flat areas and on sandhil-ls rnay be due to ttre slope of the dunes into which the t¡urrows ?vere dug in the latter area, the seasonal_ dífference in depth of burror¡s in the sandhill-s cannot be expl-ained in this wayr and may be related to the fact that daily ten.irerature variations are larger in shal-J.ow burrows than in deep ones ( Schrnidt-Nielsen and Schmidt-i{ieJ-sen l-9gO) . Flayward (19 1) gives a value of g - A inches (7.6 LO,2 cm. ) as the depth of burrow at which the temperature stability of the burrow wi 1l- not be seriously affected, but this is also affected by the porosity of tbe soil. Goannas on Kangaroo Isl_anC may thus f ind it necessary to burrow deeper, and possíbly only into certain types of soil-, to avoid 1ow burrow temperatures iv. While the tem¡rerature within a burrow is rnuch more stable than either tnat of the soil surface or the air outside J.t (Figure õ), there is both daiiy and seasona1- variation a'r:out the mean temperature of the burrow (Figure 4), The niaximum variation of burrow temperature rneas¡¡reci on i"iangaroo Island at any time of year was B.4oC over a three .Ðai-l-y varíation in temperature within a burrow oi V.gouldii on Kangaroo IsJ-and.. T x...... ,x bu=row T x*¡ rnounÕ Tsol-I T Ì; {-\ t"""'t a ,i ii ii rl .lL 'J\ { l I I I Q I t g5 I Ér i:- J I ii .ti( :: f< f: 't õ tt:4 x 2J t a llà I tt) o6 l"Aar ch L Irtarch 2 iiiarchS Figure /i Se¿tsoaa]- var iation in tei'nÍ)erature v¡j-tL''in ti:.e burrows of V. cu].qi ii on 1í--a:ri':oroo Isl-and . A'f; 2B-l,{arch 5 il- 1-3-21 e 2-tr¡t " ,.." at, . r b Fl 't4 9 - X_X- () rì ;:" o Att o + É{ Þ .lr d Í¡ + e0) c) F X... ç a. "Í...'...... v- jx;. - - -xx- x-l å- rt-I* - - x 1r)" cj t ¿Li fr.9 1 2.:.! Rar¡ L Ðay 2 Ða3r õ 4ö ¿ interva ls thrcughout the ]¡ear, tempe ratures Ì{ere taken in inhabited burrows on Flindere Chase, and the resul-ts are shov¡n in Figures lt and 5. I_', can be seen ( Figure E ) that the mean difference which exists between the wínter and summer values obtaj-ned is verlz simi].ar to tÌìat reported by Eaudinette (L972), There was aJ.so a cl-cse sirrilarity between mean burrow tempebature and mean aír temperature, as vras reported by I{ayward (X96i_ ) , aJ.though the mean burrow ternperature wao slightly higher in winter and lower in summer than was tirat of the air. Maximurl burrow temperatu:ec were generaJ-l-y reached during the J-ate afternoon and evening (1600 - 22SO), and ¡ninimuyn temperatures occurred between the hours of 0600 - O9OO ( Figure 4 ) . Tire 1ag of 4 7 hours between rn_aximurn soil temperature anrJ that of burrows wae simil_ar to that reported by McNab (1-966), wj-th tire consequence that burrow temperatures were oftea still- increasing when V.gouldii took ref uge in tl-r er,r. ¡\s a resul1;, the durat ion cf the period of elevate SeasonaJ- Cifferences in mean temperatures of ii burro¡,¡s w-hicii wef'e duE uE) oi-r FI_inders Chase, lan6aroo Isl-and. :l ii al 3r]i 3AVAted U corLt int¡ous 2 b 25.a c j -jI l-if- I, I )-. (J o -i I b g 20.o 10 1 € 21 g 131 (Þ 1 E' l+ -1 10.0 5 5.O l+ L¡ 0.O ì ¡,IARCH ,SPRTT JUNE AUGUST SI,æT NOV DEC EDts }IAT I i I I I I Figure 6a. Ienperatures within a V..go,u]-dii burrow during February, Calperurn Stat ion . a ¡ burroç i"O inchee.t--d Çi ^^¿\) inchee ¡...¡ o I I 3C inches r-o ar I l:' 40 inches {-r( ii5 I c I i', T I T j) t coi]- o----e âl-f q 6 LJ t ç{ .J .,,r9-'.* (l) a @ fl, ?!.l I ra o x I a IU x. [-+ --x---+ -l(- 25 X- c \t ¡/ Ò 20 t": ü D e> .. 12 L2 ¿¿j 1.\ Feb.24 Feb.25 Feb .2.5 irigure 6b. Ternpenatures withín a V.souldii burror¿ duri ng November, Muloorina Stat ion. AI L¡ a I T t¿ ue r ol.r -ll- \-J I iirctrcc x:x t a a\, I , i:¡c;es *-x I a ó{, inches :*: ¿:.iû I I ']. l t S o i]. a----+ I I I I I a1r t I i5 I t I o I I ¡ I I tar I al , I t 1 I I ,¿b I I I '.. ì-* x- 1ia 24CO LztO llov. 2 26t Flinders Chase at the same time of tlre year (Figure 41 . Temperatures taken at, the oame time at dif f erent locations witlîin burrows at calperum varied by severa]. degrees. Greatest variation of temperature occurred near the entrance of the 'ourrow. ft has been suggesteci by lIoberJ,y (tg62) that decreasing soil te!"nperatures ¡ oF lessened variations in their ternperatures t flay result in the fai1ure oi Ðipsosaurus dorsaJ-is to emerge f rorn their wínter burrows. f'.ãayhew (l-965 ) has suggêsted that either a reduced photo- period or l-ower temperatures ír,âlz e1-icit a simí1ar feaPonse in Ftrrynosorua mlcaJ-1i. L{ean burrow te¡flperature a¡lproxiraates nteaÍr air temperatures at a given tirne cf year (Ilayward 196l-), and the mean air temperature at cape Borda (north oro Flinders Chase) and at Renrnarir during Jul-y is verlr simiJ-ar (Trumble 1948). As goanitãs on i{angaroo ïs1and are active ]¡ear round, it is unlikely ti:at declini ng soii terâperatures stimu]-ate 'I .E.gou]-dii and V.e. f ]-aviruf us to hibernate. v. l{umiCities of burrows on Flinders Chase anC at CalÞerum Ì{ere deterrnined by Green (j.969) to be at or near saturation during su¡nmer, and sir¿iIar to l-eveJ-s found by oÈhers (Baudinette i972, Kj-rr,íz L962, McNab 7_966, schmidt-Niel-sen and schmidt-Niel-sen 1g5o) in tlre burrows of a nuflìber of sFecies olo enirnals in diif erent areas. ivicNa'o (:1966 ) states ti:at burrows rernain sâturated in scile ;vith a moisture ccntent as ].ow r?.9 r%, and 'thus no rreesì¡re- menis of reJ-at ive huntidi-t1r rvere tai The soil part icle sízø on ti-".e firebreaks and paddocks was much s¡na1ler than that from tl:e sandh i]-j-s . The combination of low porosity and high rno isture cÐntent Figure -J , $ea s caa 1 variation in rncisture content in the soil in wiricir V.gculdii burrcvve were located on Flinder s Chase, i{angaroc IsJ-anC . a firebreak -ourro¡'lr¡ I range burro'rrc êA b sandhiil-s 30.o ¡, c c fire'¿reaLt samPles .-,TL rirêan 6 c 6 25.O 20.o G) f{ +-l c b ø t. c .rl 6 b o 5 15.O b .îl-l b o v) 6 \ar b 10.0 â 2 14 i lt a b a 1{ 6 '4 il ++ 5.o 4 5 ti I à .t +J- l+ -T i T ï o.0 rtsB MARCIÌ APRTL MAY JTJI{E JITTY JIUGUST SEP1 OCT NOV DEC 28. of the soil on these 1ow åreae resul-ts in irigir heat conductivity cf the soi1s. lleat flow by conduction from an ani:'nal to thre soil eubstraÈe would be rnuch gfeâter under these ccnditicns tl:an of¡ bette:'drained areas nearby, lr or cn tile same area durirrg sumnxer. v ¡É .rosenbergi do el-evate their bcdy temperatures on lnsny days during winter by basking (ff (4)'o)' and the soj-l i;as ir ccnductance several times higher tlian that of air (tsaudinetie 1-g'72), Animals rvirích hac burrop¡s 1oc¿:ted on ihe fireÞreaks and sirnilar areas durin¿ winter wouid thus lose heat rapidly through conductance to the soil uÞon entering s¡rch a burrow. Tttris melr elrplein why goannas are not generally f ound on i-irese s¡eas in vrinter' Green (1-9S9 ) d id locate two anirnal-s on this area in June of Lg67, 'out only O. ¿i5 inches of ra in irad f a llen on !(angaroc Islanrj during the previous t!ìree nionths cf that year, which was far bolow norrn¿rL levels of rainiall at that tirne of Year. b. Seaso¡a1 Activity Patterns Seasonal activity pat'üerns of monitor l.izards appeer ta be quite variabl-e for different sPecies, or f or me,'n ers of the sarre sPecies in Cif f erent areas. Several s¡recies ol varaníds have beer¡ reported 'f o 29. hibernate during ttre winter, whí].e others rernaín active througi:out the year. Since an understanCing of seasonaJ. activity patterns is important in understan Rocky River Homesiead Curing the Gumlner rnove artay frorn 'Ehem during tiie winter. Several anirnaj-e f rorn these areas r¿hich wef e captured during late eumînef and f ítted with transnnittLng devices were relccated Af rica (Cowles 195O ¡anci f rom sudan (Ciouclsl.ey-Ti:omÉ)con L966 ) , z1 Spec jmens of both V. g . gouid ii and V,g . f J.avirufus r^rere kept ín the laboratory through severaJ. winters anó ihey were active throughout the year. îirey are thereforre not obligatcry but f acultative hibernatoro (lr,{ayiievr Í-965 ) wT¡ich rneane tiiet theil winter retrea'U is srrf.',r â'oehavioural Te6pcnse ?¡ilict,'. enabJ.es then to surv:-ve tt.. or"inte" in a more f,avourabl-e microhabitât (ûioberLy 1962). The stir¡"uius which e]-icits t1ìis resÐone e ie rioi known. c. Þ-ooõ ldost references to the diet of monitor Liza¡ðs 6tate tbat they are general- ¡iredaÈors and scavengers, and l-ist the-types oÊ food which are taken by them (Cowles 193C, ÐeraniyagaJ.a 1931, Smitir 1930, Buetard 197O and cthers), In most ¡;ublications tbe gui contents of the animals have not actualJ.y been exar.lined, Exceptions to this are Ðryden (1965), a series of Faperc by Pianket (1968, 1959, L97Qa anC b, ]-97L) on six species of Austraiian '¡aranicle inc1-uding V.g.flavirufus, and rÌobertcon e';; e1 , (x962). The results of the exarilination cf' -iiie etomach contents of lJi- specimens of V. q . rosenber Ë,L from liangaroo Island anrl of f ecal. sarirples and regurg itateC Êood iteme of 17 specimens of V. g, gould íi anC 'ú. g . f la'¡iruf us f ron: semi-arid and arj-d regions of South Auetrai-is are presented 32, in Tables õ and 4. AJ,though f ecal- eampJ-es can over- emphas ize the importance of fcod iterns which contain mater ia ]-s whicil are not easily digeste % F,'l iirj,.r-IÐI]cY TO-'i¿i L % ctcup % ÛRÛUF FCOri t'ì-Ei,i :^i lì VOLUITlE % v¡Jlui:iri F¡iEQUlltiCli oF TCTAL ûCCURIìgHCl:i (c. ) OCCURiÌ;i.TilË VLìLUi:llE I,,/ianrma l-s 17 O' Ûia crol;)us ii û.ij -Ì1.¿i t tus l-J. r J-,4r . i., ¿'J . -i- äiîE--_ ð,2 ¿.J ñãOs3¡'i f -ì.ecÌ to 11e 3,2 .4t .¡.) ':, un:i-dentífieó 1, Arnph íb j-a du.'ner ili 2,7 Lvnlnodvnastes 3.2 rtebratee spirlere o o 7,7 !.J 5.O grâ s shoppers U /\É r oa ches ai. B o ]-es c, a.l . :) L,3 beet 11 ce'L p s j- k-j . s.ô eî i 1lar A ,l^ :l_ ¿. scorpions I ynant i-s r) 6 Û.4 cent ípede ì.] . /\ 2. 4 o.5 ants {). ¿ Trace snaiX 6. 4 i.,l . --, z fr otuü $p. ) 3. 1¿ .8 ..) . o ¿ Tra ce (JÙ.:7 Pl,an ù ira n'i s tr4 tJl 0 i-5 С¿ 1.eaves aiiil t;ligs п+. o .9 t74 ".j1. . u tl¡a L2.9 ().f_ Soil- !2.9 0.1 r{ r) tJ 11 'r. foil- tz a', o.3 lab 1e. z1 . Food items from feca]. samples and regurgitated_ nraterial f rom L7 V,g.gouldii and V.g.f l-avi,ruf us co]-lected at severa 1 l.ocalities % rnrquENCY FOOD IÎEI¡,I OF OCCURRENTB l{amma le Oryctolagus carrion 11.8 Bírd unident if ied 5.9 Rept i].es uniden-t if ied 29.4 Amphibia unident if ied 5.9 Invertebrates spiders L1,.8 grasshoppers 23,5 noaches l*J .6 beet ]-es 17.6 e corpion õ5.3 cent ipede 5.9 rnoth tro unident if ied 64,7 53. there was a smaller number of speciee of reptiles eÍrten by goannas f rom ilangaroo Island, and they comprised a smal]-er perccntage of their total diet than was reElorted for V.grfJ-avårufus ín central AustraJ-ía (Pianha 197Oa ) . This is probably a result of the great number of species and iedividual-s oÊ reptiJ-es which occur in the deserts of Âustralia. OnJ-y 7 species of reptiles r^rere f ound in 31 specimens of V.gou1-díi from tr(angaroo Tsiand, whereas Fianka (L97G) identif ied 77 species in the stomach contents of 48 specimens from arid regi-one. One specimen coJ-J-ected on Kangaroc IsJ-and contained remains of a smal-I- V. g. rose It is not known if this was taken as carr ion, or capiured a l-ive , but canniba l-ism ín other specieo of varanids has been reported by Flower (l-933) and Auf f enberg (l-97O) . d. Ereeding condition Although the gonads of only a smal-J- number of specimens were avail-able for exarnination, the resul.ts âre presented .in order to a1Low sorr.e comparison of the timing of tl-re ieproductive activity cf lt. g .rosenbergi from i(angaroo trsLand wíth that of other varaníd lízards. Ia a total of 19 males, the maximum testes volurnes which were obser.ved ( 6 B cc. ) occurred in November . This volume 3¿!, Cecreased in December, an of breeding activity ( Piai-rk.a 197OalIr'hras greater at that tirne than it wao in liovember. All five femaJ-es which were collected during Iatè l.Iovember December ,contained en]-arged ovarian eggs (6 19 rnm. in d ia,neter ) r and Green ( pers . corurt. ) observed a fernale preparing a nest charnber in a termite mound on Fl'inders Chase on Febi'uary 2|st' , 3.968, ar¡.d collected the clutch oi egge she l-aid there later that ciay. Pianka (797 @ ) coJ.lected f emaI.e v. . f ].av iruf ue la the Great Victorian Desert in late October and early December which containEd enlarged ovarian €ggs (8 tr5 rnm. in d ie-meter ) , and others wíth oviduc ia 1 eggs ( 5 25 mlil. in diameter) from late I'Iovemt,er to early December. Ï{e suggested that mat ing must have occurred Ln sePtember and earJ-y October, short1.y af ter the anin^al-s ended their period of winter ínactivit¡r,. Llat ing of two V.g.rosenbergi was observed on F]-inders Chase on January 4th and 5th, !967 (Green, pers. comm. ) . Ti:.e animals sheltered in separate burrows 55. apprcximateJ-y 5 meters apart overniglit, and were Geen to copulate several times during tire tv¡o days. The date of this cbservation suggestc that eiiher Pi-anka ( 197æ ) was in error in suggesting tiÌât rtating in i;he V. g. f l-aviruf us occurred in Sep+;sÍì6.. and Octoberr or that breeding activity occurs later or over a greater period of tirne on Ilanqaroo Is land than it doe s in ar id reg iono . É,s fertLt.i'zation in re¡tiles occurs foJ-J-cwing cv¡tlation (Bellairs 1969), which sèems to occür in Novenber Jaauary in V.gouldii, it l.¡ou1d be necessary f or slters¡r stofage to take place if the time suggested by Fianka (197Qa) for the occurrence of mating is correct. Fianka (79V@)stated that hatchlings of V.g.fl.avirufus emerga in late January or February, åt which time V.c.rosen.bergi are sti11 breeding aad laying eggs on l(angar.oo f sland. As -the incubation times etated for other speci-es of varanids range from over 4 moaths for the egg s of V.spen cer J. kept et llOoC ( Feters l-969 ) to 9 i-O months for T.niloticus eggs which '?¡ere ceposited in termite ne6te (Cowles.l-9SO), it a-ppeels that tliese hatchlingó m'.rsÈ be irorn eggs laid the previoue oumrner. Green (pers. cornm. ) estimatèd a development time of approximately six months for V rosenber t- based on the grovrth rates of ernbryos in a clutch of eggs 36. which ire colLected. This estimate is sirnij-ar to the length of tirne repor'ûed by DeraniyagaÌ-a (Lgri1) for the development of ihe embryos of V.bengal.ensis, Sma11 sif,ecirneÊs of V.g.roeenberg,i (37 grn. ) anC of V. g . goul-d ii (13 and 5l- gr'-. ) T.rere cauglri day and the renriaining tyrc embryoe were Cead. , The nurnbers of enlarged ova iiresenü in the ovanies of f evnale V.s.rosenbergi rvl-¡ich were exemined ranged frora i2 l-9 (Í = 15.5, n = 5), and a cl-utch of eggs of thi.s species whieh was f ounC on Flinders Chase cont ained !2 eggs ( Green, Pers . comrn. ) . T:rece are a 11 larger than the clutch oizes of 5 - 3 (l = 5.2, n = 5) found by Piani¡-a (197Oa ) for V , fLavirufus nhich is a smaller subspecies, 37. Clutch size of V.g.rosenber gi was sirnilar to those reported for otheÈ medium-sízed epecies of goannas (Peters j-969, Fianka 1,97i, Bustard 19zo). Larger clutches are reported frcm large species of varanicls (cowles 193t, Smith 1930). It thus ap¡lears that breeding in V.gouldii extends f or several mon'Lhs, and may ire sligirt ly later f or V.Ê,.rosenber ei than fcr V.g.ilavirufue. iiris rnay be related to seasoiral- nJif f erences in their habitats. Ðiffer€nces in the time of breeding ¿iven for v.salvator in dif f erent areas have been reportel1 by $rnir-h (1gBO) and Khan (f-969 ) . e. ï{orne range Varar:.id l-izards are generally reported to forage over large areas. These state,Tients are general_13' based on tire ¿istances over wtiich traciçe of ti'ïe animals irave been Êo1lcwedr râih,er than on actua'! obser*.¡ations of rnovements of tlle aaim4le of on iocations of recaptulres. As e number of specimens cf 1'I ,g.rosenbergi were recaptured on Flinders chase at varying intervals during t;:e course or tire studyr âû attempt was made to deterrnine the area of the home range of this s¡reciee orL Kangaroo Island. As wa6 Gtated earlier it was not possible to recapture 38. individuals of V,g,goul'dii or V . f l-aviruf uc over J-ong peniods anó eirnilar calcuLations could therefore nct be mai.e f or these goannas on the other stud¡r areås. There were 1_3 anirnals which wêre capiured at least 5 times {Table 5), and these recapture locations were used in the calculation of hone range areaa. The maximurn number oi captures for an individual was LV, an Ti:e techniqueG of the convex pc1-3'gon (Idilstead tg./1_I with the correctíon factor gívea by Jennrich and ?urner ( x96I ) and the ellipsoid calculation of Jennrictr ancS îurner (196 9 ) supposedly give sirnilar results i:cr areås of hone ranges. The results cb'fained h.ere using these two nethods varic-ii coneiderabJ-y f rorn one another. Ti¡e carculatec åreas of irome ranges cf incividual goånnas also varied eonsi'ierably withia both sets of results (Table .ã). The meau values ior area of 'nome range cbtained from using both methode exceeded tlre predicted area using the f ornaura of rurner et ai (lg69), based on the niean -iaLr1¡:5 1,ra¿r oi liome raírEIes oÊ V.ijoulcii on ian.c:a-toa Is j-a,.:r: BY ii{JM.-.lit 'iì::irï¡tj-l l\ ri,i'A È:í ¡iR.i¿), riil XIiA i, l: L' ,\ ,L \/ t/ _-':-'f t rLr.L f"'.'ìr'ìTiì, _i rJrJ L:¿ ,^l ir I r -.t / ll Fl CûÌiV-r,i -lti rIYCC)l,I (i{or{'iiii I - . -:: ..1-a\ .1. I. Il'1 \ :JÀP1'Ui]JJS ) (.i.iLlT'z\RE3 ) ({-'",,Î-;ri:,lS ) \.r:r\J!E:\¿-'JI _L ,; '.; .52 .! rJ z¡ 4 ./. :5 "t) yliu: .1 1=;, .? I r- f-' :- I {-::-- ' t: l_r' a" \-. .J.'..ì., !!_-.la:- -'- ., . L- lf J- / ':. t) a) 2l:., ,.j i: !1 P1 ,/!J :-' r¡ -!:i.:.: "' .: D ' .'J-L J ¿,J C_-a r\ 4 -11t' .:, '( ri î o:i.¿::: " -i- I -i \ t-ia n 1i;': ¡)â'1 C: ii . d"; i.: ,ì :) r, a. J' -L\-'. "' .l . 'i -'. J -uct) u(].:/J --j "J . -¡- .l 39. weigiri: (l-149193+ g) of the animals for which home rangeG r^ïêre calcrrlated. Tlleir f ormula is as iol]-ows: !¿. = i21 .1" WO'95 rrhere 1{ = }reight in glartts A = area in sqi¡are ¡ne1;cre. using this fcrmula, ilhe precicieJ. area for tire anirnals coneidered here would be l-3 . B 6j 1. OB lrectares . Ca lcu].ateci ar.eas weîe : Corre¡.11;êd convex polygon L9 ,44 ! i. öB hec't'ares Ellipsoid calculaticne 2¿,.,J õ ! 2 .L7 hectares Although J_arge a.nimals tended to have larger home ranges than did snaller indivi to fmile and 1 miJ.e respectively. I have also followed tracks of V. f]-avi¡ufr¡s for distances in excess of 55O meters before J-osing thêrfl. Tt thus appears that specimens of V.gouldii in arid 9rea9 fnaJ¡ range over larger areas thran do those on Kangaroo rsland. Movelnents in exceos of 7 kilonieter per day hs-ve been reported f or other s¡oe c ies of varanids , includ iirg v . komocl oens io (Ffeffer 1959, in Turner et a1 1969) and !.var_ius (Stebi:ins and tsarwick 1969 ) . f Ðens itw oit nonrr'! tions Little information is available on the deneity of populatione of varanid lizards. rn thic eEudy a number of s¡iecimens were found from one to several tímes on the area neer the Rock3' River Fiomesiead which was surrounded by firebreaks and paddockc. 1'he total anea of these open places and the patcìres of ecrub vrhich ûhey enclosed hras calculated to be approximately 59.5 hectares. During the period from February 196B to April 1gr2t a total of 26 individual specirnens of V..q.roGe WaS cap,tured on this area, with 3-3 of them being found Ëhele during 1969, and severa 1 of them be ing re loca ted tirere is sub.sequent yearc. These anirnals also ventured into the areås of scrub outside the firebreaks. Nevertheless, the minimum 4T, density oi the population of this species on tbe area concerned ( 1 per 4, hectares in l-969, i_ per 2 .3 hectares during the course of the study) is considerably greater than tllat for V.komodoensis (1 per 10.3 2L.6 hectares) reported by Auffenberg (1-97O). The calcuJ-eted mean síze of home rangec for goannas on trJ.inders Ch.ase would give densities sinilar to tlrat stated by Âuffenberg (19ZO) íf the horne ranges oi the animal.s did noi overlap. This ie not the case, however, as individuals 'rórere of ten located in burrows lêss than 2o meters apart, and dífferent anirnals have been found using the same burrow on clifferent days. Ðuring a fifteen day period in January, attempts were made to captr¡re as many Y¡-g*lgg-!!!È. as possible at Calperum on an area of approximately 60O hectares. The area was searched daily by two ¡reople, and 2b traps were set throughout this time. A total of 7 goannas eiras captured over tlis period. No otller goannas were seen on the area during tire subsequent 2 weeks. fn the unJ_ikely event that this represented a]-]- the goannas which inirabitei this erea, this would reeul-t in e density ot approxirnateljl¡ l- per Bb heciares. Even if onl¡i t of the individuals orr the area were captured., tiiis yrould stiJ-J. be a much lower density than that which wae found on Flinders Chase. 42, T-1t, thus appears that \/ onrrldii on F1 inders Chase heve smal-J-er home ranges tharr those which have been reported for other varanids. The population density is aJ-so very high in com¡;arison to varanid populations e lsev¡here . (4) Therr,.ra I Eco].ogy a Ðaily activ ity patterns i. Tirne of emergence The tines at which goannas emerged from their burrows in the morning varied consid,erably in any season on Kangaroo rsland (Fígure B). Bmergence occurred over an interval of up to tirree hours, and tended to be earlier in the summer than during ttie winter. cn several occasions, animals with low body ternÞe"atures were dug out of burrows at times l-ater than t;rooe at which the last anirrrals was seen to emêrge during that month. rt is Elossible th'at these a.nimals woul_ $eaeonaj- variation in tirne of rnorning emergcnce of V.gouldii on i(angaroo Isl-and. e4Tar-cB uaos,e' cIn ilnP pe3,:oura +ou pte-pt x a3.:eui¡o o+ uêo$ +; ..{ CJ . tle à-, '^o x x X q "JT-J fu\/' x X X o X e a X X x Ç a X X x ()^ a- X o OU X x a X ¡¡) â I a ö x * o X o û60 {f x@ ð I o a Ð ü (å a Ò X I X ï X a o a 0ð Ò .)OTT X x ooõT 43. Thère was a].so conside'r.able variation as to the time of ernergence of V. eou]-d ii whi-ch were observed at Calperurn and L{u1.oorina (Figure 9). In addition, animals on these areas often did not eäerge from their burrows for several days at a tirne. The earliest time at which an uninstrumented animal was seen active in the senri-arid and arid regions was 0925 during l,lovember, but few animal-s were located during the summer months in these areas. A few animal-s e¡îerged f rcn thei-r burrows during ]-ate af ternoon in the summer in the arid and serni-ari-d regions, but no data were obtained on tire preeise times at which they emerged. ii. Conditions at time of emergence The cloaca1. temperatures of goannas at the time of their morning emergence varied considerabl3r. This variation was recorded both during and between seasons ( Figure 10) , and was sir,tilar to the variation in cJ-cacal- tenperaturss in animals which 'o{ere captured by being dug out of their burrows during early rnorning (Figure 11). There was no precise reLatíonship between c1-oacaJ. temperature and air (Figure L2), soil (Figure 1õ), or burrow ternperatures ( Figure 14 ) a't the tirne oi' emergence. CJ-oacaJ. temperetures sornetimes dropped afier the emergence of the animals from their burrows, but erere generally at or close to their lowest point at the time of emergence. Figure 9. lime of morning emergence of V.gouldií during summer in arid and eemi-arid study afeas. a Seen to efnerge r( Ðug olit of burrow i-ooo a a cú o9--¡û a fl ô qn o o ú c) a t .i 1^)t il''l â o i-r t e a û7OO X e Oct. IJc"¡. Dec. .len. treb. Figure l-C. Seasonal varíation in cJ-oacal. Èemperatures of Y.g ouldii at the time of emergence, oi,t' Kangaroo ïsland and cB the arid and semi-arid study area6. & Arid and sc-n',i-ar íd afca s 30 X. Kangtrroo Is lanC (.J @ R, x 0) ó x Ér @ x +r xx N x Ê @ ^x o XxX (\ X x g ôi.r x c) @ +J rl rd X (Ú X o X rl X .v ^x ""Y 4 X ),ã X j\u¡; tr s t ùp-i. l-ì¡+ (f7. treb. ì1,. :¡ n r, h +\¡:ri 1 Ì'{ay June Ja i¡ Figure 1-3-, Seasonal variation irr cloaca]. tenifleratures of 1t ].dii which were du¿ out of lrurrcws on Flinders Chase, Kangaroo Islend. b 4 b 55 b a I-Iad not emerged ùo 3 b Frobably hr:d emerged -t racks (J30 (Samplo sLze shown ireJ-ow) I t o q L' 0) a û 7 ß{ T; I b 4 +) DK a b (ú r ^ ç{ I ,+ 4 t) :¡_ {)(\ É r CJ Ð ¿v a r{ ú d O d I 4 q o I a Fl t, Ç l_5 4 if' ï T F t t- i-o -t- Ç. Fel,¡ . Llar ch Airr i1 DiaY ,lune .3u ly r\ugus Sept. ov. Figure L2. Re]-ation of cl-oaca1 temperatures of lI.gouJ-dii to air tgrâperatures at time of ernergence, or¡ all- etu<Íy areas. O C]-oacal temp-rerature C lr j-,r c,ì c'ì {,) f_) or (:_) c) () O f) c) (.I1 (') Þ I Þ )< B xI x rT (J l-¡ ã<¡ x >( o a.) )< X t) þ Y cl ti (tl X X a FJ (: C'r. x r@ t) a tÐ >. o >( Õ t' V!' IJ [J a ts. ìJ (ä ta O 9J a Ê1 u ¡JO ry \i'1 o >( c) È1 ü1 t--{ UJ oû) c.) 3H x ts.ÞtÞ fD ca 6) u. Ê. Figure 1-3 , Relation of c1-oecal- tem¡reratures of \f ønrr'l rlìi 1;o soil teffipêra-fures at ti.ne of effiergence, on al-l- strldy areas. t)\J.'U x a @ o .) o X X x ß) {J X. v. Ê X -î ]r /Oì C\.t \3 tr c, f.I{ X ts- 6) lli 1\ /, .1.) I r-l X x (ú x X a) c( X rlC) Ç ,r ii'ancaroo -[s1and Ø ¿\rtd and semi=arid areas íì L o tr-5.C 2 .û 2fi.c 3c.c So j-1 -¡crrperti.-i'+re C Figure 74, Relation of cloacal temperature of V. gould ii to 'ourrow temperetúre at time of emergence, on alJ- siudy areas. x 2lr.t Ð o x 'Á (l 6d .Þ e $i Éa -1-'r . L C) +) J O X trJ O Ë ï(angaroo Island -i (_) 8t.årid aud serni-aríd äreas 5.ü r oL5 .o 2 .) o o Burr oi.¡ temPerattrrc' 44 Elack bu1-b temperai:ures whicll Frere taken near the burrows of enimal-s which were obeerveC aJ-so varied cons idera-ol.y at t irnes oÊ emergence, ranging f ro¡n X-2 .3 to 60.5oC (Figure :rg). On a number ot= occasionsr ffe direct sun was seeiì to f,all on the mound in fron't of the burrow prior to tlje emergence cf its occupant. Light intensity at tire tíme of emêrgence vlas not measured. iii. Behavicur u¡ìon emergíng Behaviour descríbed here is'oased on observations made on Flinders Chase. Observations wirich wêre made on animals which r,rere seen to emerE¡e on Calperum and Muloorine were simil-ar to lhose described here. It r^¡as often pcs$ib1e to anûicipate the emergence of, an animal which had been fitted vrith a transmitter because of a change in the i-ntensity of the signal received. This change is due io pcsitional changes by the animat- (Stel-.T;ins and Barvrj-ck X96B). SueLr charlges were observed on a number of occaeions, frcm 5 to 2A rninutes prior ta the ernergence oL= the anirnal. On five of seven occasione when j-t was possiÞle to see into the mouth cf the burrow, the hea¡5 gf the goanna coul-d be seen j-n the nouth of the burrow or just outside it Êcr periocis cf from 5 to 56 mi.nutes (X = 25.O j LX.2) before the animal moved its whole body out onto ihe rnound of earth in f ront cf tile b¡¡rrow. ûn a]-]- occasions when Figure 1'J. ReJ-ation of cJ.oacal- ternperatures of V.gouJ-dii tÕ bJ-acir buJ-b ternp'eratures at tir¡e of ernergence, on al-I study arees. !'í': I x Itìangaroo Tsland ø /i'rid and semi-ari-¿ afeas o o 4.û. E{ +r IJ Í{ & \-i . Ð '.) er û -l x q$ d .{ O ç ci (Ð x Fl )\ \ O ¡( ,\ I I x :{ n I 1-û. o U ,: 'JU o 50 oC tsl-ack bulb ternPel'lrture 45. animals which had nct emerged r"rere du8 out of burrows in the rnorníng, they were found to be in the terminal chamber of the Þurrow. rt thue 6eems that goannas may move fro¡n the chamber to the mouth of the burrow and rernain just inside tiie burrow for a varíable ¡leriod of time prior to emergence. Upon emerging, an animal genera].ly moved its entire body out onto tire mound and flattened itself to the soil. The legs were spreacl lateral1y, and the head and neck hlere generally resting oí1 the soi1, although tire anirnal- f requently raised its liead and observed ite slrrrounC j.ngs Curing the co.rrse of its basking. Thia positíon was generally maintained until a sufficiently elevated c]-oacal temperature (whicir varies considerably et different seasone) was reached, â| which tirne the animal noved off th@ mcund and away from the burrow. Ðuring basking¡ tro particular orientation to tlie rays of the sun !{as âssurûêd , exce}iË dur ing winter . Ður ing June and August, anirngls general]-y orienteC themsel.ves so that the Long axis cf the body was paral-J.eJ. to the rays of the sun. On three occasions during June and August, animals were observed to move off the mound çhortly after energing and with l-ow cloacal- temperatures ( 15. g t7 .4o ) , assurne 46. a baskiag pcsition on an elevated perch. rn alL cases, this perch was a pile of deaci bnanches within lo - 15 feet oÊ the burrowe. soil- temperatures on these occasions ranged from l'2,ooc tc r¿.ooc. cn two other occasicns, anivnals moved aw¿ìy from the rnound.s and reised t|ne front of the body by placing the front legs and head on sma1l rises of ground, thus increasing ttre amount of dcrsal surface which was presented to the sun, and baeked while in this posítion. No siínilar behaviour was observed durirrg the aummer months, If the anima1 was able to elevate its body temperatur"e to a sufficientJ-y higir level after a period of basking, it moved away into the scrub. on a nurnber of occasione during ttre winter mcnthe this did not occur because a change in weather conditions, such as rain or heavy clouds, caused a decrease in body ternperature and ín each case the animal re-ei:,tered its burrow (Figure l6). The animals ihen seldcni energed again for the remeinder of that day. on several occasior:s, goannas seemed to become aware of the presence of an cbserver and ren i:ack into their burrows. ?hey generarly re-ernerged aften ¡leriods of 45 7O rninutes and resumed basking. The heating rates of basking animals show a seasonal variation on l(angaroo rsrandr âs does the duration of basking. The values calculated for anima].s p¡hich Figure L6. CJ.oacal 'úernper,ãture of 4 f ree-ran EínE Y .n.rosenbersi û.ì äangaroo Islanri as Ceterr¡.ir:.ed b]r radio telernetry, Auguet 1-Lth 1-o LStir , i97Q, U Ternpe rature FÀ eñ ri: r) (l .Ö O a e tTJ ll Fj p lJ. H )i Ì> I'l Þð H urÉ ]*:,ìr., -. e t;,i o(+ll (i) b-J 5 <_- ,1 oÞ I FJ i.À I (} I H I (l I ¡ I I t iå l il I { o t ,Þt a'>O Ë tÐ ß] C¡ {.t-: tsj-l -i-+- ¿<- !: fr) Gr) €- Uel n 1- lJ. -..'- <-. t'd BJ I il I fr, , rj I ! (:r s I FJ ! Þl I I o .¡ I I lJ ¿_ r¡l H È- /^ ;\' w ø'gl LJ _t! Þ tsts.0 P <_..-a- Þ tsS F¡''J -*il gl CQ () l-¡ <- Ë t\' Íf c) cl 0 ¡ì' f¡ <- r't ei rrú' iì Q tJ t--\ f¡lJ (i.j \l (i e,J cli' fl f.J C +bJ ffr,N- rJçi çi' $ Èr-i Oo l-- cr 'Cr 3ÞJËFj ÞrJ Ca\ FJ i) I c)ri .Ë rJ OJ 47. carried transmitters ere shown in Table 6. iv. Feriod gf aciivity. The duration of the perior3 during which the animals are active r,Jas depencent upon the .r.nr.bient temperatures which prevaíIed and the time at wtiich the auimals emerged f rorn tlreir burrows. During summer, the animals nemained out of their bu¡rows for most cf the day cn Kangaroo rsland. The exact times of retreat into the burrows r^¡ere impossible to determine, aG the lizards were often fcund basking near ttreir burrows in the late afternoon and their moving into the burrows may have been a result of being frigtrtened in by the observer. The afternoor. retreat into the burrows generally occurs at about l-Boo during Nove¡nber Ðecernberr or approximately 3- 2 irours bef ore sunset, ai which tine ambíent temp- eratures are tenerally decreasing (Figure Lz). Goannas emerge nearly every day duri-ng sumfner, but may be f orced to retrear-- ber=ore becorning active because of rair:. of other unfavourable weather conditions. The perj_od cf activity wae generaJ-ly shorter during the winter than during tire eui.:rmer on l(angaroo Islsnd ( Figures l- 6 and I? ) . Cn a nur,.rber oi clays ti:e cloacal teffiperature of animals did not rise to nor;nal activity temoerstures ( Figure 1 6) ceslrite prolongecl Figure 1'7 . Cloaca1- temperature of a free-rarrg,íng V.g.rosenbergi on äangaroo Isl-andr ãs detenmíned by radic telerne'ûry, ßìoven¿ber 29th to lJecemì:er Let,, 197t. D Ierrper'..1csrc .j Þ N) C{ .i, ('-il ¡:i-í ü-i (-) e) cr) a) ei:-j ---rr-- - = I I l--! I ti UJ !J <,_ i1J "n þ!. i-.¡ u 0) a\ ¡ I ol -l'-' -7- i,l *¿ <_ rt o <- : c¿ì Õ Ir ) r.- L! (.r O I Õì {) L l:ì L _,) Ëè O c) \ I t_, I 1 t I l-ù <-- tTJ 48. pericds of basking (Table 6) and the aninnls ?rêre forced to retreat into their burrows to avoid decreasing femperatures durirrg lete morning end eariy afternoorr. Goannas seem to e:nerge aJ-mcet every day during winter on Kangaroo Island. O:r the 15 days on which animals which irad been f itted with transmitters wefe observed during the montirs of June tlrough Augustr oB only one day did any anima1 fai1 tc emerge frorn its burrow. In addition, during winter two ani¡¡rale which, on the basis of their clcacal temperatLrree and the absence of f reeh tracks into their burror^rs, i:ad not emerged that day, weré dug out of burrows at tirires well after the last anirnal was seen to elÌlerge cSuring that rnontl¡ (Figure s). NevertheJ-ess, mo6t V.gouldíi on Kangaroo IsLand appear tc ernerge almoet every day f or at least a brief tirne. Tn the arid and semi-arid regions, a rtifferent activity pattern occurs. During. sumnier , activíty ie mainly restríctec tc earJ-y rnornin¿; anci late afternoon and the anirnals do nct effierge every daSr (trigure iB). rn early Gurnmêr tlaere is a tencency f or Èhe aotivity of goannes in these areao to be active throughcut the dey ( Figure 9 ) . No Seaeonai vania-fíon in rnean ireetine ra';;ee durinri basir-ing of V.g.rooenbergi óit lianp,aroo Isl-anct. i:? ./" -t i-lT.lr: I t¡¡^xrt,iutu I :[t;i,j.REilSE 11 ?t t/ 1' t.f liloI.J"lt,r OË,SERVli?'IONS o/m j-n. Þ¡\üirLrlr;^ -t I\IIi ( ) ( t;lII{ïJTIJS ) TETdFEI'iI\:f TIIiE J. I ti ùia ¡r -Turr e tf, t . :i- 2- . í-')3'7 -r-Ù;.5--:¡r,,1 .v :i-s.20jt.39 liugus t t] tt,.1-{)4:.o'i7 i.5cì. 3!22 .'l l-5.,rsjo.zg l{ovenilrer a 9 rì¡,271 j. oss 6í .2¡-7 . 3 22 De ca'm"oer .AslL,24 + Iiia r c ir l:pri1 i-'),2g4!. o9û 6 .l.,a:22, .9 25,42!g.r.4 F igure 1-8 . CJ-oacaI- temperatures of a free-rangLng Y .e,.e ould ii on Calperum Station, as deterrnined by radio teJ.emetry, Februar¡r 22r.d ro 24t]]^, L971". NN Ì{ I-I jit'd f rl, 1n :lt I I I I v ,t] {, ù 'l,v ^t t' lt '$ü ! I ll3.A ("1 i C) ¿, I \ j 4\ :t \t Sl "3ü.C :l \ .Þ :t ñ I ,rt ç{ 't :, o .,1 ir,,' fl¡ il ,....1 E I i " /'l ¡-l 0) I t lt' 'l F1 2t,a i ,.¡ ljt¡ I :l , I 1A () 0600 j_.qOO 0600 t_80û 0oco LU ñry 24 Feb. 22 Fet¡ ¿t) Ircb. ï:urrov¿ êame c3rmbo 1o ¡1 s i;t Ëigure L6 , + N=neT,t ].ocation Ln. 49. May and Aggust. Attemats to relscate animals which had treen f itted with tr.ansm-ittere,and released in late summer gvere unsuccessf u1." v. Acti,vity areas Seasonal diiferences occurred in the size of tlìe area cver whic'h V.goul-dií were active. Data based on locatione of anima]-s which carried transmitters for periods oi up to 7 da¡re are shown in Table 7, Table 7, $easonal. variation in activity areas of V.rgoul.dii on Kangaroo IsJ-and. ' Í aiea /duV area lauy ( Hectares ) (Hectares ) Plonth Anima l-s Da¡rs' Corre cted tsLl.ipsoiC Fo1-y6on ô June Ê c' o.f.sj.os o. 14j. 05 Augr.rst 3 t4 a.77! .27 o. s5j.31 Ðecember 3 1,7 L.s7:.s4 1. B6j. g2 Lf ar ch ¿ o.ez! .L'l o. s4:.18 The ,JaiJ-y movenrents oË V.gou]-dii during summer on Flinders Chase and at CaJ-p,erum were compared, and the results are shov¡n in Table 8. Ti¡ere we*e no signif icant dif f erences in tire mean area per day used by gcannas at these twc localitiee during tiie summer using either rnethod of cal-cul.ation. Table I l'lean d aíl-v a ctivitv atrea of V-eou]-dii durinr.¿ summer a LOCAT,TTY MONTi:í ANIMAI,S ÐAYS + F1inders'Chase Ðecember õ L7 t .3'J - ,54 l-,8s! ,gz I CaJ-per.um January 5 56 1_.39: .48 'l-,4g!.n:i 5ù. vi. liscussicn idorning emerEence i:y 1-izards ie a!! ac-! Cictínct f ron the cnset ¡f dei]-y act-j-vltJ (Evans, 196./), It io necessârjr for the animaJ-e to bask fcr varj-abI-e período of tirne upcn e!?'¡ergence in or Ðrecì se conCíf ions under wiricir sorrrê ctÌ¡.er species cLo 1izards emerge . Iieat:ì ( 196 2 ) f ound tha¡; Fhr-¡nos orna i::âs temperat',ire-indepenCent rncrning erl.lergence and the aniyna1-s come tc ti:.e eurface within a narrclr range tif ti'ne each day regerdl-ess of '¿T,e ar¡?bient tempera'tures which rrere avail-able. Temperature-de¡enCent emergence wa€ f ound in An'.pir ibolurus crlletug , uiric?: vras cbserved tç, 51. emerge at different times cf dalr but aJ-ways under closely sirnil.ar conditions cf temflerature (Bradshaw and I{ain 1% I ) . The variaÞility cf tl:e tirte of etnergence of V. gouldii eG <íetermined in tir.is study is greater t!.ran that which is reported f or V.:vârj-us (Stebbins and Barwick 1968) or that implied but not cJ-early stated for V.komodoensis (Auffenberg 797Q), V. beng a ]-ens is (ÐeraniyagaJ'a 1931, l.4int on 19 66 ) or 'y' . gould ií (Green 1969 ) . SimiJ-ar seasonal differences in emergence time to those shown here kiave been reported in V.eremius (Pianka 1968 ) . These differences are probably related to the seaGonaJ- differences in ambj-ent temperature conditions which prevail in the habitats of these s¡lecies, and nay indicate that tliere is a del3ree of temperature-dependence invo1.ved in determining the êrrrêrgênc€ times of varanid lizards, but that it is not dependent on a specific temperature, but rather an acceptabJ-e ranEe of ternperatures. It is al-so possible that increaeing burrow temperatufes rnay provide the stimul-us required to caus€ emergence, and t'ie variation which occurs in these temperatures o-eceuse of the locaticn and dimeneions of the burrows may account for some of the variability of erûergencè tlmes which was observed. The burrow temperatures determined in this study r,rere a]-]. increasing at the tirne "")¿. of emers,ence of the goanîas, but had been for some time and were often stil.J- below tlie cJ.oacaf. temperatures of tlre animals which were sheltering in them. It may be that cloacal tempêrature is not as inportant as the temperature of cther parts of -the body in determining ernergence, as is the case in the initiation of other types of behaviorrr in this species (III (2)c). Heatwole ( 197ù) suggested thal; the rûorning emefgence of Àmphibolurus inermis was probably related more to either photic conditions or to a bioJ.ogical" rhythm than to terr,perature conditiong. The wide fange of black bu1b temperatures aÈ wlricn L.,tgg¿g¿+ emerged suggests that photic conditíons do not sti.ïulaËe êmergence in this species, as black bu1.b temperatures are a good meaeure of the input cf radiant enetgy (Geigor 1959). Tbe variation in tirne oi emergence of individual anirnals on successive daye sug¿ests that eirvíroolnental conditions rather than a bioJ.ogicaJ- rhythm deterr:ines €lhêrÊence times of V.gouldii. I{o c1 ata are avai]-ab]-e on tir.e factors which deter¡nine the time cf laËe af ternoon elnef. Sence of V.6ou1d¡-i in tite arid and semi-arid regions during cu¡';l:r{er, but thi-s activity ie probably related to decreasing soil tenPeràtur.eg which reacl;. valuec ín e]Ëcess of eÛ')C in carJ.y afiernoon 'Jrt. during summer in these areao. Tt has been suggeàted that some Li'zarðs warm thej-r bodies prícr to emerg€nce by exposing only the head (Bogert 1959, F.{itche11 L923), but Heath (196ô) has shown this does not cccur in other species. The small effect tÍiat warming only the head has on óeep body temperature (see III (2)d) in V. sould ii suggeets that, as was found by l-{eath (1964b)for GOfta , this behavicur serves to warm the head and thus to increase the coordinat,ion and inprove the function of the central rrervo¡ls €ystem. The postures assumed bV ]{,r6.ouldií, whil-e basking are sirnilar to th¡o6€ oi other species (Bradshaw and l{ain 1968). The use of elevated baeking oites, which ¡ninimizes the contact of the ventra]. suri'gce of tlie animal with a cold substrate and tiius decreases heat l-oss b¡r conduc-iion has been described by äeatwole (1970) for ancther species of Lízard. The ti-lting of the body by p1-acing; tlre forelego on elevations ic sir'rilar to the poeture descr ibecl ioor ].ate af terncon baoi':in¡; by V. varitre by Stebbins and Barwick (1968), and $erves io maintain the dorsal surface at ri¿ht angles to the rays of the suÍl. The orientation cf the body in relation to the rays oi the sun seems hapi:azard during the sunrnerr âE does the direction in which the burrow mouth opens. 54. In winter, however, the orientation of the ¿tnimaJ.s whíLe basking is such.as to m.axímize the amount cf radiant energy which will faI-1 orz thea, and tlrus maximize the' e]-evation of their body temF,eratures. The heating rates of ii during basking showed a seasonal variati-on. The rates of increase during Ðecember were greater than tiìose reported foæ V.variuç (.fao/mLn. ) at, the sarne time of year (Stebbins and Barwick 1958 ) . The difference in heating rate is probably a fuoction of the greater si-ze oE the V.v.ariue which was observed by $tebbins and Barwiclc ( 1968 ) than of the V.gouldíi studied irore, âe the air tempe:ratures in their 6tudy (rnean maximum air tempefatüfe as calculated from their data is approximately õl-oC) are above those which were obtaine body temperatures suf f icient]-]' and thèn L:e'come actíve . D-.rr ing surnmer , tire anima 1e ere genera 1J-y out ci the if, burrows for periods of 7 tc 10 hours when ccnditions are favourable, and active for the greater part of that period. The time of afternoon retreat is variable, as has been reported for v IUS (Stetrbins and Berwick i-968) and eo is the time of rnorning er:lergence. In the winter, goannas are J.ess active than in gumner, but nevertheless they èrnerge on rnôst daye and bask nêar their burrowg. The period riuring which ani¡naJ.s remained outside their burrows ranged from 1.6 to 7.5 hours, and on at least 6ome occasions during thíe seeson, cJ-oacal. ternperatureo reached normal summer values. The Geasorral act'ivity of V.niloticus in South A"frica (Cowles 19õO) is similar to that of V.g.ro senber I on Kan.garoo Ieland. In the arid and serni-arid regions, ï._ggJ¡Å$;LL are active onJ-y during the period fron Septernber to February (Pianka L97Oa), and for períods of only 4 5 hours in the morning (Green l-972, this otudy) and po6sibly during the late aÊternocn. During September and Octobe¡, the períod of activíty may be eor¡rêwiìât l onger ( Figure 19 ) . At tirat time ct jrear ambient ternperatures are generall-y milder than during summer. As ie coinrncn with desert- dwelling lizards, V.goulCii show a bir:rodr1 Cail.y activity pattern Cur in.3 Gltm¡ner . trigure 19. Seaso'c¿r1 v¿¡riation Lrt tirne s at whì ch act ive V.goulcii o¡ere seen in arJ-d and ser.ri-ar id regícne. 'i-trne cf day rjr t--"\ f.! Þ Þ r.) bt Ì1: c;-r a) C} e) o aj a Ç) .) o a ótt!o.! c Ò a oGers (.) rh ra a to t eÕ t o a o o I Êt a : oö I 56. During winter, V, ii in arid and semi-arid regions are inactive, remaining in their burrows tirrough- out the winter (Pianka L97Oa'. , Breól, pers. comm. ) . A Similar pattern occurs in some other varanids wttich inhabit theÐe areas, such as Y.ei'nenteus (Stirling LgLz), v. caudclinearus ( Pianka 196 9 ) , y-!-bf eI¿-gg-gg-g_ ( Fi-anka 197Ob ) , and V.tristis (Pianka L97L) Þut no'L in al-l speciec- V.ereraius shorvs a seasonal variation in ti'ne cf emergeflcet but appearÐ to be more active during winier than oummef (Pianka 3-968 ) . I,linter inactivity iras also been reported f or V. exantltenaticus ( Fitzsimrnons i9¿+3) and V.eriseuo (Auderson 1963, Flaggag er al 1965, hlinion L966) in areas whictr have cold winters. Ðif Êerences in the seasonal activi'Ey of varanids within the same species h.ave been re¡lorted previcus].y. The seasonaI. activity psrtternê of V^ni]-oticus in South Af r ica ( Cowleo 19 3C ) and in $udan ( CJ.ouds ley-Tirornpson 1966 ) dif fer rnar"kedly as do thcse of V.sr eus in fra 9r where it is rctive all day in winter and shows a birnodal daiJ-y pattern of actLvít;¡ in tlre summer (CorkiJ.J- 1928), anC in lran (/"nderson Í-953), EeyÐt (Ila6gag et aJ- 1965) and Pakistan (lúinton 1956), in all of wirich it is inactive during the winter. s7. Ðaily activity patterns of V.ì;engatrensis in desert re6ions cf Fakietan have been reported io differ from those of animals of the same speciee which occur ín areac of r'rarehlands (irlinton 1966). The dif ferences in activity petterns of animals in tiiese two regions are eimilar to those roound in the díffereni popuiaticns of Lr5gg it this €tudy, and in t¡oth cascs are protiably rel-ated tc the Ciffe¡ences ín PJ.ant cover and the protection rsitich iS thereb,y aifordêd i=rgrn radiant energy and elevated sci]- ten¡Peratures. In regions where seasonal ciif ferer:.ces in envifon- mental temperatures ar.e slight, Varanicìs such as V.ealVaÈof ( Iihan 19 69 ) and V.komod oens ¡-s (Àuffenbers 197O) remain active t!:rou,Shout the Year. The l.ow body ten-Eleratures and ohorter period oi activity of V..edtldii during winter on i(angaroo Istand accor¡nte for ihe Smaller area in which the animals at.e ectíve at that time of year. Of ten the anima:Ls moye but short distaqces from their burrows d'uriag these, months. Cowles (L930) reports that tl.¡qj¿g-g;þgg- al'so nrove ro-nly short distances during winter, often baslcing in front of their bur:rows. 58. b Therma]' regulatíon' i, Eccritic temPeratutres CloacaJ. teflìPeratures of active v u ii which were taken within one minute of the time at which the Lízatde were captured on l(angaroo Island and at several localitíes in arid and semi-arid areae during summer afe shown in Table 9, The values obtai-ned f rom anirnals captureC at Calperum, Ùluloorina and other localities in arid and semi-arid regions did not díffer significantly from each other, and have therefore been combined. Tb.e mean cJ.oaca1- tenperatures of animal-s from the two regions f^¡efe signíficantl-y different at the . Ol- level. Table 10. Analysis of variance of cloacal temperatures of V. ii captured at Kangaroo Island and at, other ]-oca].ities. Source GT Sg MS F q Retvreen l- go.4 õ o.4 *lÊ ^1 l{ithin 36 3,15 ,7I ,J . ¿¿ Tota 1 37 L46.25 I,Io active anirnal was caPtured olt either area at otlfer times of year. A small number (¿¡) of goannas were capturer-j just oute ide burrows on i(an.3aroo isJ-and Table o' C].oa ca1 temÐeratures of active V-pou].dii at time of capture T î T T,OCATITY MONTFIS NUHigER Fr c]-oaca r a J-r soil- Kangarco November 3-tt g5 .L¿t!.¿,O 2g .LtlL.2{) 3¿*.4L!3-.gt Is ]"and Apr i1 Aríd and Oct ober 24 96.99:.40 26.45!2,6L õ9.2ojo.94 semi-ar íd Febrnr¡ary 59. during rvinter and spring, but these wêre baeking at the time of capture. Their body tempefatures ranged from 19.O - 30.50C. Ey piacing temperaturè-sensitive'craûsmitters on goannas, it was possibl-e to monitor their bodY temperatüres at intervals over periods of severaJ' dayst and to locate the aninrals and determine their behaviouur duríng these Periods. The results of seveia 1 days of nronitor ing the cl.oacaJ. temperature6 of' v ou].d i i during summer an (Figure l'/ ) during winter (Fígure X'6 ) . AJ.though goannas on Kangaroo trsland rem-aín ou1- of their burrows for extensive periods of time during winter, cLimatic conditions at that time of year often prevent thern from elevatíng their cloacal temperatureg by more than a few degrees . 60. The seasonaJ- variation in cJ.oacaJ- temPeratures of goannas which were monitored whíle active is shown in Table 11 . lilean values of cloacal- tem¡reraturês were deternined ueing vaJ-ues obtained at a minirnurn of l-5 minutes apart, âs r^rere those of ambient temperatures. Maximum cloacal- temperatures ¡eached by índividuaJ. V,,gou]-dij- during a total of 15 Ca¡rs of monitoring during the monttrs May-August reached ttrose of surîrmer values on onJ.y two days (36.BoC or! June ll, maximum air temperature of l-6.5o and black bul-b temp- erature of 4A,4o, and on August 10, 3?,cio, 16.30 and 5O.40 rea!ÌectíveI-y). The mean maximurn cloacaJ- temPeratufe recorded for al-]- 7g days during winter was 26.67-1.53oC (19.20 37 .5o \ . Tha t during sumlner was 34 . 69-l- . OSoC (24.go 41.90) for 16 days. The diurnaJ., activity pattern,6 oi LrÁg!!!! on Kangaroo Island differ from those at Calperum and Muloorina during sumilrer (Figures tT and 18), and sc do the daiJ-y ranges of body ternPera-ture. Minimum daiJ-y cJ.oacal- terrrperatures are much higher in tlle ar id and semi-arid regions than cn l(angaroo trsJ-and, and activity perioda are muctl shorter and l-ess frequent on the former a.reas than on the latter. (ieasonal var iat ion in rnean cJ.oacaJ. tem efatures aî active v oul,díi on Kan aroo Is].alrd as determíncd b radio-te].errte-Lr' I{UI..'TEER NUT¿BER MEAII CLO¿\CAI MËAI{ ATR Ì,iÐliN BLAC:I BULIr OF LlCNTI-I OF TEMPERATURE TEIIIPgRATURE TET'TPERATURS ANIT,{ALS REAÐTNGS 27 51. Oôj1õ . 2C Htrar ch 2 40 29.74!3.06 ,ú2!5.2x 29 ,ï-Cj:j . ZS May June á 4L 27 ,¿i6!4.Ðg L6 ,28!A,22 3L ,22!'.J .6'.i August 3 79 22 .B elL .7 5 14.Erjo.,;s 59.5¿12 . Novernber !IJ LI 33 .tzlt,aø zj.2g!l-.il "12 De cernber 61. The mean cloacal temperatures of active V oôrl ]-d ií on Kangaroo Island and at Calperum and Muloorin.1, as cletermined by telemetry during periods of severaJ. days Mean cloacal ratures of actí eV otl ii under simi]-ar environme ta cond it ions o Kan aroo Island and in rid and semi-arid re ¡- ng MBAI{ TEt{PE¡RATURB IUEAN CTOACAL iyIEAN.ÂIR BTACK BULB LOCATION ANTMALS UAI U .fEMPERATURE TBI{PERATURÊ REAÐTHGS TEMSERATURE Kangaroo €rO!2 û B 98 35,53j.S1 23 .BOjr, ro Eg . .62 Is l-and Ca l-perum and rl 4 tI4 35.Ë.t4!.63 29,24!2,66 5g.6¿ù!6.77 l¡Iul"oor ina 62. The animal whose cl.oacaJ. temperatúre record is shown i¿ Figure 18 díd not emerge frcm the warren in which it was sheltering on February 23, yet its c!.oacal. temperature ranged from 33,7o to 37 ,goT during that dayr and the location of the animal in the r.rarren altered by distances of up to 10 feet during the day. It al-so failed to emerge from the warren on the three subseguent days until it t{as recaç}tured. Ðuring that time, its cloacal temperature remained relatively stable bet!.reen 30.60 and 34.6oC, with rnaximum body temPeratures being recorded between 21õO and 2230. ii. Ðiscussion The mean cloacaJ- temperature of active goarinas at the time of capture on Kangaroo Island was signifieantly lower thaa that of anima].s wbich were captured at the more arid localities (Table 10). The mean temperatures thus obtained f Or V.g.gor¡ ii and @were similar to those reported elsewhefe for these eubspecies of Y.gou t-l- . Bartholomee¡ aad Tucker (1964) give cloâcal' temperaturee of approxinately 36.Oo and 38.5o for two specimeas of v.g. u1dii , and Pianka (197Oa) r:eported a mean of õ8.13.42oc for 52 sPecimens of Y,g.f l.av irufus. Those of V. bergi are within the range of val.ues (34.4 36.2) presented by Licht et aL (1966) for this species, but ifr" range or the mean 63 value which they present is obviously erroneous aG the mean lies above tire maxifinum value which tliey report. Ðespite the large síze and cons¡)ícuous natune of varanids , there are t.eT{ other published f igures f or the cJ.oacaJ- temperatures of active specimens of ottrer species. The ve.1-ues obtaineC here are slight3-y below those of V. gr iseus (Andereon i.965 ), V. caudolineatus (Pianka 1969 ) and V.komodoensis (I{cNab and Auf f enberg L973\, Dífferences in the mean cJ-oaca1. temperatures, which r^¡ere determined in simiJ-ar faehion to tlìese, of l-izards of the same species at different J-ocal.ities have been reported Í)reviousJ.y ( Stebbins 1961, FIeatwoI-e i-97O) . The dangers of treating such valuee as the preferred temperature of a species have been stated by lIeath (196aa), whc poi-ntei. out that without having knowledge of the previous behaviour of the animals, the validity of using such values was suspect. By using telemetry devices to transrnit a series of body temperatures from individua1- animals and to all-ow the observer to relate the body temperature of the anirnaJ- to its glresent arrd previous behaviour and tlie microcJ.imatic conditions whicTt prevailed, this dif f iculty is J-argely overcome and the values which are thus obtained are more representative of the act'!¡a1 terflperatures over whích the animals norrnaJ-J-y function. 6a, The activity temperature€ of Y-dg¡1!!!! on Kangaroo IsJ-and r âs determined by the use of teJ-emetry, sho-r¿ a seasona]- variabi].i-ty. Seasona]- dif f erences in eccriüic ternperatures of l-izards have been rePorted previous1-¡z (t/ia¡rhew L95S, ûlcGianis L966, Bufns L97O), and appear to be primariJ-y due to the i-nability of tlre ani:zral-s to reach and rnaintain temperatures wíthin the norma1- preferred activity rangè at -a11 seasons due to [rreva iling amt' ient temPeratr¡res ( ]ûcGinnis 19 66) , The J-ow air amd soil- temperatures and iasol-atioa which occur on Kangaroo Is]-and f or much of the j¡ear (Table 11) prevent goannas from reaching their preferred activity temperatnres on many dayo there, including a number ot days duríng suírmef , llhen environmental conditions afe favourabJ-e, the animals reach and ¡naintain cJ.oaca!- temperatures which do not dif f er f ronn tiaose of V.goul.dii whích occul in the hotter and more aríd regions (TabJ.e L2). These values are very simiJ-ar to those of Y-:gJL¿¡Ls during sin"¡iJ.ar conditions, wh.ich vvere also determined usi-ng teJ-ernetry devices (Stebbino and Barwick L968. ). Similarities in the body temperatures of v. go u]-dii in different areas under suitab]-e conditions occur despite the differences in behaviour of the animaJ-s at these 1.ocal-ities. By remaining active for different 6 5. periods of tirne during the day ín summer, the animals expose themselves t,o relative¡.y sinila¡' conditions of, ternperature, and are thús abl-e to maintai¡ their body temperatures at similar values prinarily by behavioural means. It ha€ been shown that varanid LLzarde Poesess a considerabJ.e degree of physioJ-ogica1- contr"o1- over their body tem¡rerature (Earttrolomew and Tucker í964, Grenot 1968, Bennett t97L) br:t there do not appear to i:e eignif icant dífferences between species in theír physioJ'ogicatr caçrabil-itíes ior th-ermoregulation (Ðartirolomew and Tucker L964) or other functions (Greea 1969). Cow1ee (1939) gtated that desert reptiLes re1ied main]-y on behavíoura1 responses to avoid exceesive insoJ.ation an ( Figure 18 ) . Ey rnoving to dif f erent portions o'f the burrows and thus utilizing the differences in temperatufes whicTr occur along the burrow (see II (3)a)r the anima'ls are able to alter their body terìiperatures. In this wai¡ r an animaJ- can remain et or near its preferred body temperature and sti11- minimize water loss by remaining in a humid i:urrow, Goan:ias in these regicns Ína3/ er"¡erge only inf requentl"y, in order to f orage, durin.g suinrner. On tr(angaroo Is1d, ambient temperatures ere generaJ-J-y ¡irilder than dt t'{uloorina and CaJ.i>erum, and Ehe ctrense vegetation grovides stìe]-ter frorn the direct insolatíon. 67. This alJ.orrs goannas there to remain cutside theif burrows throughout the day öuring summer while maintaining body ternperaturee within thei-r normal actívity range, and still achieve ]-ow rates of water ]-oss " 68. ïIï Laborator Stud ies (1) Be viour and Freferred Tem eratures Introd uction The d,aíL3, activii;y periods and Þref erîed tem¡leretures of goannas from the Cifferent fieJ.d areas, anC tieose oi aninal.s coJ-1-ected on iíangaroo Isiand at different tirnes of year, were õe,terrnised in artificial therrnatr- gradients. E,y so doing, it ?ras possibLe to determine whether, under simiJ-ar condi'b ions, ]L€-911!|.i.i. from differeni: ]-oca]-ities. behave' in a simi]-ar fashion and ¡rhether their preierred temperatur'e€ wer€ the sane, or whether they differed. It ¡ras thus posoible to determine whether the behaviour of tt¡e animals, as it was oÞserved ín the field, e¡ae in response to the environmental- couditione which prevailed or riras due to innate differences in the behaviour of the animals. a. lÁete¡ials and l/lethods i. Gradients The temperature gradients wi¡ich t{ere used weae in an air-conditioned îoom and consicted c,t pens which were made of galvanised iron. The Elens were6 feet tong x 7+ f eet wide x 3 f eet deep. There r^ras a layer 69. of sand approxirnateiy 2 inches deep on the floor and an artiiicial. burrow (made of plaster of parís ) which was approxir*atel¡r 1E x 24 x B inches at one en f ed mice, young rato or minced .äeart. trlater w",.,g 'r€re generalJ-y avail-able. ?! l-L was not possib]-e to com¡:J-etel.y restrict accesD to lci;e roorn ia which tile gracliente were established, but a record T{as kept of times at wiric^: the roorn was entered, in case the beliavíour of the aniinal-e was a].tered e.û a resu].t of these distui.bances. ii . r\e c ord i-ng Temgieratures were recorded with lriuJ'l.ard Va SOOO P5K3 thermistors, (6.3K ohms at 25oC) which were connected by suitabl-e círcuitry to a Foxboro ¡node1 ERE lOmv 1-2 channeJ- recbrder (Yokogawa Eleciricaì. Work-s, Tolcyo, .Tapan). It was posaibJ-e to read tenperatures from 1C"o within O. 1cC. Outs ide this range ¡ cãJ.ib.rat ion char'cc were required.' The tirermistors f orned one arrú of a lilheatstone t'ridge, and Írere connecïec] to ít Dy lengths of light -í;winilex, The tips of the therrni€tor leads 'rrere encased in |tAra]-diterr epoxy resin and vin¡z]- tubing O. 5 críT. in d iameter . E4/L- Therrnístors were ínserted to a depth of 4 - 6 crn. into the cloaca oÊ the LLzatd and taped to the base of the teil rvith stripo of adhesive tape. The tirermistor leads ¡{ere taped to nylon cords which ran above the centre cf eacir pen at a iieight of ap¡>roxirnately 5 feet, l-eaving suÊficient slack to a3-1-ow the ani:nals to reach al.l- parts o'i tiae gradients easil¡r. Tb¡e leads occaeionaJ.J-y became tangl-ed, bu't were untangled at nighL when neceosary. AnimaJ-s were t(ept in the. gradiente f rom var1¡ri'ng lengths of ti¡t:e, generally f or periods of 7 to 10 days. $orne lizards were l-eft in the gradients for longer per iods, up to ,28 daYs . iii, [4eaeurement of pref erred body terí{perature and activi'by periods. The preferred body tenperatl:re of an anímal was estinat€d by calculating the mean of a11. cloacal- tenD- eratures measured at 15 mínute intervel-e during the period in which the animal- was expooed, fol-J-owing the initiaJ- dai1-y period of baeking. ?¿lhen animal-s were knovrn to have been disturbed by scmeone entering the roora, su-osequent tem1leratures $rere not Éced untiJ- ihey had risen 'Eo a.cproximatel-y theif value bef ore the distur-bance occurred . 72. It was possibl-e to deterrnine the ii¡".e at which tYLe goannas emerged torof,l their burrows bit the increaee in body temperature which occurIted at that time. Ïn addition, there v¡as a rapid and srnooth. rate of decline in cloacal temperature v,rhen the ani¡nal- retreated to its burrow, and the time of this retreat cotld therefore be determined. iv. Holding Aninrals whj-ch were not being used in the gradients or in other w,ork were heLd j.n a large Pen (g :,< 5 x 5 feet) in the safne room as that in which the ternileraËure gradients f"Iêre located. The f loor of tl-e pen Í¡as covered ¡iith seve¡al inches of sand, and heat was provided by heat lamí)6 and an e1ectric radiator. Food and watef were provided a'c tilc earne 1,irne ac f or those anirr..ale in the therrnaL gradients. Other anirnais ?vere h.e iü. f or varying p'er iod e of i inre in oPen Pens cír the rooi of tl¡.e zooLog;¡ Department buj-lcing, These pens were si.:ni1ar to thcse used f,cr the ttiermal gradients. v. Statistica].'üreatment. The difficulties involved in performing statistieal anaJ-ysis of preferred'oody ternperature data have been discussed by HeazeJ-J- (1972), The major difficulty in apolying statistÍcaJ- tests to pref erred tennperature data is tt.at. f or ti:e te,sts tû be strict].y vaLid it is necesçary to show that the individuaJ. measurements which are used are uncorreJ-ated, or independent. Correl-ation couJ-d exíst between the individua1. successive readingçr or between the rÍean cl-oaca1 temÐeratur€s of individual,s on successive days. The use of temperatures taken at 15 minute interva]-s is a compromise between theoretica]- require- ments and practical limítations. These intervaJ-s afe of sufficient duration to al-low a considerable change to occur in the cl.oacal temÍ)eratures of the J-izards under the conditions which lrere provided. In order to elininate correlations between dail-y nrean cl-oacaJ. temperatures, values would need to be obtained at lengthy intervaJ-s, and this would require much more extensive f aciJ-ities than r.rere availabJ-e, or would greatly diminish the amount of data which could be examined. In addition, it was necessary to obtain continuous recordings of deep body temÐerature in order to deterrnine whether corre].ations did exiet between succesGive measurements and rnean dai]-y val-ues to eva].uate the ef f ects of ttxe tf eatmeot s to which the animal-s wef e sub jected . The same comprornise between the conditions required for rigorous st.-a1.istica1- anaJ-yeis and th¡e demands irnposed by J.irnited f acilities as T^ras used by HenzeJ-l- (f972) was therefore al-so used in this study. Daily mean cl.oacal temperatures which were determined under these conditions were subjected to analysis of variance to deterßine whether differences in preferned têmperatures occurred between subspecies, individuals or treatrnents. Since analysis of variance assumes there is independence of readings, and since they are not independ- ent. in these data, the number of degrees of freedom in such an anaJ-ysis is overestimatêd. Observed differences between readings may thus be incorrectly judged to be significant by this analysis. This method of analysis ís, however, the best method' availabJ.e and was'therefore used riespite the problems invo.J.ved. b. Behaviour in gradients The behaviour of a1l three subspecies of V.g oul-d ii in tTre thermal gradients was si:nilar. Consid- erable variabiJ-íty existed in the times of emergence of 75. goannas frorn their burrowe, alttrough they generaJ-J.y emerged each da3' w6sr the heat lanps úarfle oû r or shor tly thereaf ter . The variation which occurred in times of emergence was both between individuaJ.s and within particular individual"s on successi./e days, With emergence times under norma]. conditions of light and tenPerature occunring over a span of up to 3 - 4 hours. Once they had ernerged, unless disturbed, the animals genera115' outside tlìeir burrows unti]. ""*"ined the heat lamps went off, and tilen retreated into the burrows. Some animaJ.e retreated bef ore tire lamps were turned off, however, and others rernained lying beneath the lamps for up to 5 - 6 hours after the lamps went off. There was no apparent rel-ationship betr^Ieen the time of emergonce, the time of retreat, or duration of exposuret and the preferred temperature of heaJ-thy animaJ-s. FreferreC temfleratures of animals which died while in the gradients generaJ.J-y dropped rnarkedI-y in the 2 days prior to the death of the anirnal. Sata obtained on these days were not incl-uded in the examination of exposure patterns or other as¡lects of tire l:ehavi-our of -ihe goannas. 1^lhen the T¡.eat larnps were swítched on continuousJ-y for periods of frorn 4 L2 days, the exposure patterns of the Lj-zards in the gradients became even more variabl-e. P'A Some animals f efltained oútsíde their burrows continuousl¡f for periods of up to Lì days, while others continued to re'treat ínto ti¡eir burror*s. The exposure patterns of; the J.atte¡ group became very eîlatic wj.thin 1- or 2 days of continuous heat. The 1izards ernerged at various tirnes throughout the day and rer¡ained outsíde their burrows for periods of frOnt 2 to L6 liours befcre retreating. They therefore shoí{ed some evidence of the voluntary hypothermia which was described for other speciee by Regal (í96?J, but thís pattern of beþaviour gsas not a con6istent oflê ¿ When extfa heat lamps were placed in each Pênr and tþe sand temperature at that end of the gradients rose to temperatures in excess cf 3SoC, the animal-s rema inecl outs ide the ir bur rolqg but were f urther a?'ray f ror,r the heated end of the gradient than trsual.. None of thern retrea¡ted into their burrows until late af ternoon, except on occasions when they lrere di-stur-oed by people entering the room which the gradiente were in. Postu¡es of basking animal-s were the same as those described for aninnals observed in the fie1d. Basking generall-y J-asted uni.'i1 cJ.oaca1- temperaturee in the range of approximate l-y 3õ.. oo õ7 . ooc were att,ained . Animals then becarne active and ¡itoved about the gradienL-s, 77. or shif ted their position in the graCien'Es slight]-y and continued to bask. Basking occurred at interval.s tirroughout the day, and occupied the rna jority of the time during which the animaJ.s were outside their burrows. Animal-s r,'vere not seen io pant in th¡ê gradienùs unless additional- heat gJas supplied and tire anímal-s were prevented from returning to their burrov¡s. At these times, the animaJ.s beca¡r,e ver3¡ agi-tated and showed obvious sigûs of distress. They dug at the corners of the Þens and ran along 1-lne side of iheín. Ðeep ¡:anting alternated with this behaviour, where the ani¡naL stood with its whol-e body aad tail raised of f the sand, with its feet cJ-ose 'r,ogeth.er benêa'rh the body aild i-is head ti]-ted i:Í) and tl¡e mouth' open. Fantíng rates ranged f rom approximete1-y 5C - 13O per minute. c. Freferred temperature L, ThE overa]-]- mean ierßperetuie of active Varanus soul-d ii which were nieasured in the r:hermal gradiente was 35.24j.O *o^ Th is valr:e was obtained fro:n a toia]- of 7L individuals of alJ. three subspecies over a total- of LA33 days of recordinge. Days oir which the air condition- ing unit failed are not íncluded, nor are those ior the f irst day on which animal-s were pl-acc.d in th.c gradients, 78, as body temperatures recorded from Lízards on tt^e first day have bèen shown to dif fer f ror'r those on strbseguent days in therma1. gradients (Henzell. L972\ - ii. frhen the mean temperatures which were determined Í^rere sub jected to an analysís of variance tc deterrnine whettrer differences existed in preferred ter,'rPeratures of ti:.e tl¡ree subspecies, a highly signif icant dif f erencg wa;e found (F = 2A.4i, df = 2rf-1õO ***). Ti:e summary oL' the analysis is gíven in Table 13. Table L3. AnaJ-ysie of variance cf the dif f erences in preferred ten¡perature of the three subspecies of V.e ou]-d íi. Ðai1y mean cJ-oacaJ- teraperatures of each animal are used in the calculations. Source of Surn of Mean var iat ion df squares squafe l< Subs pe c ie s z tío.87 55,¿i.4. 20.47 x.rf n Days L73A 3068 . 57 2.,J2 Dur¡can I g new multiple range tests'r^rere oerfo¡med on the data, and the mean va1''rês of V.g.rosenbergi and V.g.ilavirufus were founC to be not eignificaniJ-y Cif fere:rt frorr one another, while ti-lat of lrg--g-gt¿f,¡l;|l dif f ereci signif lcantJ.y f rom both other srrbspecies ( . OX ) . The mear: pfer"erred tempenatures of each subspecíes are shown in Table 1-â.. Table 14 Pre ferred temÐeratr¡res of the subeoeciee of V. pouldii as determined in thermal ¡adients SUsSPECIES V,. g. g,ou lid ii Y.F,,roeenbergí Y .9,. f laviruf us Numbor of 42 23 in,l iv idua ls 6 Says of 90 773 2,70 re c ord j.ngo Frefcrred 35.20j.O6 sb.a2!.LL t errperat ure 36,2?!.15 ryCl T'he irequency di.stribution of the meall daiJ-y cloacal- tem¡reratures of each subspecies is eirown in Figure 20. the borrndarie-e of ti-le dístribution of r¿O%, 7 rr% and 917' of tlre Caily meen cloacal tempeîa ture s se]-ected by individuaJ.s of, each subspecies are shovrn in Tabl-e 15. TabJ-e Lrr. Ternperature ranges within r^¡hich 5C%, 75% and 9t3% cf tt¿ê daiJ.y rnean cJ-oacal ternperatures of the three subsp ecies of, V. eoul-d ii occurred i-n therrna]- graõients. Subs pec ie s 6A7" 7 57" 957" T .9. rose :rber g i s4.0-õ6 .5 li5.2-37.L 32.7-37 .7 v.e.g ou]-d ií õ5.1-36.6 34,6-37 .2 32.ã-39,7 V,g. l:ra v ir uro tls 3õ .8-õ6 . 5 32.9-3',7 .L 30.9-58 . S iii. A srnal.l nurnber of Soannac of species other than V. oul-dii becarne available during'fhe course of this study, and their preferred te¡1lgeratures were *letermined in the ternperature gradients in the Game way as v¡ere those of V. gou ldii. Although the daËe obtaineC f ror'n them are very J-imíted, both in i;he nurrìbers of individual-s whicir were tested and t,ne num-¿ef of da;rs f or r,rhich va]-uee were obta ined , they are re¡ror{ted h.ere a.s tirere are ver]¡ f ew pubJ-ished val'¿es for the preierred teriiírerature.s Of Figure 2o-. Frequency distributions of the rnean daíly cl-oaca1 ten'lperatur e s of, the three subspecies of V. ou].d ii as selecÊed ín laboratory thermaI- gradients. V. A . ilavirufus (27o) 2t Ü) o 5 n]-d FI ii 6 Þ (eG) ç ñl o h -l.Fl d 2C, 4. 56 :t 3B o 40. &lean daily cloacal tempenature Õv¿ varani.ó species. An ErnaiSrsis' of variance was perf ormcd on the values obtained, and there wss a highly significant difference in the preferred temperatures between species (F = 23,.OO, df = 6rIO2 tt*åÉ), The results of the analysis are shown in Table 16. Table 16. Analysis of variance of the differences in preferred temperatures of seven species of Varanus. Daitr-y rilean c1-oacal temperatures of each animal- are used in the calculations. Source of Sum of Irlean var iation df sqüares Square F Spec ies o 218 . OO û . ú.J 21. OO *** Days LO2 1_7 ,42 r.73 Duncants new multiple raage test was performed on the valueo obtained, and the re€ul.ts are shown in Table L7. iv. The preferred body temperatures of V.s.rose berB i which were captured on Kangaroo Island at different times of year and placéd ín thermal gradients'as soon as possible after theír. capture (2 5 days) were determined, and subjected to an anaJ.ysis of variance. Tiie reauJ.ts of the analyeis are shown in Table i-8. Tabl-e L? Fr eferred tem raturea of 7 e ecies of Varanus as determined in the rma]- çradients. llXeans which are underlined b¡¡ the samo line are not signifi cent 1y different from one another at the O.Û1 l-evel. SFECfÊO V . s il-l.en! V. eremius v.t ist is V. serniremex 4 1 Number of D )- J. L ind ividua 1s Ðays of re c ord ings T2 5 \? I iPref erred sT,L2!,16 õ5.g,Âii-,oo 3s,44!,L9 34.8?j.50 t emPera t'.1r e V.vari,us V. sr¡encer i V.mertensi I 3 L 4 ¿4I 20 ¿ L') |JJ,¿¡ø!.2D tg.12! rz| s2.6c¡!.2s 41. Table 18. A.nalysi's of varianoe of Pfefeffed temp- eratures of V.e.Tgsenberei ca,ptured at diÊferent times of year and p1-aced in thermal ,gradients within 2 5 days of capture,, DaiJ-y mean cloaca1. temp- eratures of each anírna1 are used in the calculations. Sum hlean Source oe df of F var iat ion squares squalre ry Capture rJ 34,89 11.03 10.62 *** dates Days 108 119,36 x. 09 The mean c10aca1 tempefatures of anima1s which rdefe captured at different times of yeaf are shown in Table L9. Table Lg Preferred temperatures of V.e.rosenbergi captures at different times of year and placed in therma]- gradíents within 2 5 days of captufe. No. of Ðays of Preferred Month anima ls record ings tenperature March 5 18 36.LL!,29 Septernber 5 27 55.sgj..25 December 6 4t g 6. 28j.19 Apr i1 t: zo 55 . ogj.19 82, v. lr¡ an attempt to determine whether the differences which were found in iv. haC lesulted from acclirnatj-zation to low aml¡ient temperatures or from other fûctcrs, animals wh,ich were used in the Ðecember sarcple were pl'aced í.n the 1-arge holding pen and al.J-cwed ta tliermo- reguJ-ate Êo their preferred temPerature€t for a Period of approxinr¿rteLy 5 weeks and tfien ¡llaced in the thermal gradients O'nce agaín, where their preferred ternperatures were then determined again. Following this, the animals were put into smal-J- cages and kePt in a constant temp- erature room st lBoC f or 6 weeks, af ter whicl¿ tt¡eir pref erred ternperatures were detefrninod once more. Af ter another perio Tabl-e 20, Analysis of varíance of preferred tempe ratur:es of Y.g.rosenbergi acc]-imated to dif f erent ternpere'bures. Source of Sum of lutean variatioÊ df squares square F 'l r:, Trea tvnent s r) 6,47 t t.847 i{s Ðays x10 279.92 o t:.^ ' .83. There was no significant difference between the preferred tcnperatures oi animals in aîy of the treatments. Preferred temperatures of animaJ-s in,each treatment ere ehown in Table 2t. ví. ?he mean cJ-oacatr temperatul'es cf 1C indiviCuals which had beeß run in the therrnaL grarlieirts from 3 - 5 times at iatervals of. not l-ess than 1 nnonth , Êollowing periods in whicir they had. been keçt i:r Ëþe large holding pen f or ai least 3 week-s and during. wiiiclr f ood' and water had been provicledr ârê given in Table 22, Great individua]- variat íon oc,curred in , the mean cloaca1- temperatures which animals sel-ected '¿ri¡en ¡naintained under sirniJ.ar conditions during subsequent series of determinatíon s . vii. In order to determine whether or not feeding the Li-zarís ¡eeulted i-n an íncrease in their preferred temp- erature as has been reported to occur in some,other species of re¡rtil.es (Rega1 1966)r tlre neen cloacal- tenp- eratures of goannas cn tire du.y bef ore they r{ere fed while in the gradients r^rere compared to ttl.ose of the sa¡'tie animals the day after they had been fed. Of 'a total of T7occasions for which data are avaiiable, in ¿'7 (617") of them the qloacal- te;nperature was higlrer on tl:e day af ter feeding than it was on the day beforc the anim¡-ls were fed. Table 21- Preferred temperatures of V.g.fo senbereí acclimatsd t, ae al. te orat o€ CO}IÐITIOT{S OF NUMBER OF ÐAYS OF FRËFERRED THERMAL I{ISTORY ANIMALS RECORDINGÐ* TEI,ÁPERATURE Fie ld December 6 4L 36.28j.19 Allowed to thermoregulate to preferred temPerature 5 30 36'.O93.29 for 5 weeks. Acclimate Acclimated to 2aoC L? 36.6Oj.25 for 6 weeks. 3 Table 22. Mean cloacal terlr e?atures f v. ou 1d ii- dur in subse uent ser ies of determination at intervals of not less tb.an one month durin which nimals were ke t in hol-rlin ene n|¿ ?- ./i..J Ra F df SUtsSFECIES ii. _L *.2 ^'.) v.g.r. 3?.Oej.55 34,3.5! .38 3c.gz!.g¿t 34.5s! .vS 55.5g !,SZ 5 .99 4r29 tç át.tÉ j, It lt Jt v.g.r. 3ro.2Bj.L5 35.6 5!.ZA 33 .8e rg 35.44!,42 io.8B ù, ¿/ zJ ¿t'J 29 I{S v.g.r. s4.r¿2! ,zB 34.A?! ,52 t5.50j.39 34,5L!.4s . 3t 2t1-9 ',t lÉ -N v.g.r. 3B .5 t+ ,23 3? .53j.3S TEj .64!.33 1_9 ,.ó7 (>È) Cr O *lsåÊ V.g.r. 37 .761. rs 33.55j.40 s 6 .44j. 6X 2 rL7 ¿z î'tn * V,g,r. 35,s7!,33 3rÒ.27!,44 3s.3Y!.3-B 2 r33 j. (] Kq 4 lt l( tÊ v.g.f. S¿L.t-¡r*.2O 3s.62!,46 3¿'.,28:.28 37.ge e s 36.Ls!.L2 126 j.¿g 2 X-3- tt l( t( v.g.f. '36.20!.4s 3ç.57! ,Zt 3¿..gs 29 .69 , go gs /^. ¡Z 4 2rL2 NS '{.8.f , õ5, s 6!.zz 3lt,91-j. 34.Brj. l+ tç v.g.g. 36.7a j. gS s5.a5l.zo 34-.sSj. so 6.24 2,2t 8-i . I{hen analysed b¡r sign test, this dif f erence was not signíficant (71847 rP .2OO ). The mean increase in cloacal tennpêrature r^¡as .95i.14oC. Ilowever, in the remaining ,39% of cases, the mean cloacal temperature was lower on th.e day after feedíng than it had beèn on the day tref ore iood was given, and tlr.e Íiean dif iÐrence in ctroacal temperatufe on these days was .91i.|goc. When cl-oacal teÍìperetures on the da;v of feeding were comparecl with t i:ose of the f ollowíng daY, sir¡rilar results were obtained. Cl-oaca1 ternperature rose in 56.5% of tiìe cages, anti f e11 ori the remäining 4'i.E/,. The rnean d if f erences l¡cre .9gj,15oc, and .9oJ.19oc , respectivej--".-. In additíon, anirnaJ-s which Lad been accl.imat¿' NUMBER OF DAYS OF IúEAN CTOACAT CONÐITIONO AI{IMAtS RBCORDTi,IGS TEi.ãPERATURB Lz-Lg days after b 30 36.2.O!.20 water r"emoved. 1"9-24 days after 15 34.s4! .S? water removed. 4 After water províded 3 19 36.3'.7:,23 8A At the end of the period of deh¡rclration, the animals had ]-ost from 7L7" to 257, oi their ini-tia]- body weight. Some of this loss was regaíned during the week wherr wator was provided. Weight gains durinþ this time period ranged f rorn 2.A/" to 6.7% of the ïotaL body weight at the ij.ne when water was withdrawn .orom the animals, ix. As s'Ðated ín III ( 1)Trr Ðîima1s rrere maintained in gradienÈs with continual. heat provided by lamps for periods of frcm 4 - !2 days on several occasions. When the rnean cloacal terûperatures of animaJ-s wiricli remained outside their burrowe between the hours of 19OO - OTOO (during which the lamps were normal-J-y off) was compared to thcse of animal-s outside the burrows during the normal lighi period, ther.e were no significant differences between therß (F = .44, df = 7-r'Jg) , d. Discussion The simil.arity in behaviour of al.l tirree subspecies whil-e in the thermal- gradients indicates that the differences in daily activity patterns which were observed in tl¡e field e¡ere a result of the dífferent environme¡rta]' conditions which the anima]'s e nc ount e red in the areas where these observations were rnade and not a result of ínnate differences in tire Lìeraviour of the aninraLs fror''r th.ese ].oc,a]-it ies . 87, The most notable feature of the behaviour of V.eou].dii under the conditions which were provided was the ].ack of consistency which was st¡owß in such aspects of its activíty as the time of emergence, time of retreat', and the duration of expooure. The range of emergence iimes which occurred was similar to tirat which was observed in the field, and would seem to indicate that there are no precise environme'nta1 ccnditions which eJ-icit emergence in thi6 epecies. Insteatl, animaJ.s Êeem to emerge r^¡hen the conditíons faJ.J- within an acceptabJ-e range, and, the:factors which deternine the precise time within this period are not known. It is possible that tirey a,re,ralated to the hormonal or physiol-ogica]. state of the individua]-. There seeme to be no fixed daily rhythn or set exposure pattern in thís species. Instead, the animals remain outside their burrows f or varying periorJs r^rhen acceptable environmental conditions of J.ight and ternp- erature prevail-. ?iris ].ack of consistency is also evident in the pref erred'iemperatures whicb were selected by goannas in the therrna1- gradients. As is shown in Figurc 2O and Tahle LÉ, ti¡ere was a range of frorn l-.b^-a 2 ÐU-O^ in which 5O7. oÊ the mean daiJ-y c1.oacal temperâtures of each 48. of the. subspecies fell-. The upper limit of this rangel was very eimilar for alJ- three subspecies. trt may be that the higher mean ten,peratr¡re est imated f or V .e.sou]-dii r^ras a$ accidenta]- consequence of the smal1 number of individua]-s of this subspecies which were tested because there -y¡as considerab].e variability in ¡r.ean c]-oacal- temperature wirich wae f,ound both betriec.a and ¡r'ithj-n iridividua1-s of this species. The statietical tests wh ich r{e¡e used here .t end to overesti¡na te t i:e degrees of freedom invclved because of the correla'tion wtrich exists t¡etv¡een successive measuremen-!s of body temp- eratures. This, in combination with a rc].atively small and po6sibJ-y unrepresentative sample of goannas of this subspecies, could have resulted in the difference in mean cJ-oacaJ- temperatures between Y.g.gouldii and the other subspecies being sDuriously determined to l¡e signif icei:tly dif f erent . Ar, additionaJ- indication that this malr have occurred is thaË the frequency distribution curve for the mean dail¡r cloacal ternperatures of Y .e.e ou ]-d ií (Figure 2C) doee not show the range i.¡irich occurs in tir ose of the o-lher t-wc subs2ecíesr particularly ai the ]-ower tempefatures, îhe variability shown in preferred temperatures of individuals (TabJ-e 22) was also found by lienzeLL (7972) and may indícate t-utt the determination of nean vaJ-ues 8;9. oî aci;ivity temperatur'es oî Lízarðs requires that large numbers of animaJ-s b'e used when conä'¡ctíng such studies, or thai individual animals must bé run a nuntber of times to acc.urately determine the preferred terßperature or activitSr raage of the sflecies: Other studies of reptiles have found no difierences in the selection of preferred ternperatures of nor¡na1 aqtivity range between congeneric species even though they rnay occl¡Py dif f erent habitats (Bradshaw and ûîain 1968, Cowles and Bogert 7944, I{ea th 196 5 , Henze 11 1,97 2) In V.souldií , the simiJ.aríty of preferred temperature (as determined in the J-aboratory gradients) to eccritic temperature (as neasured in the fieJ- (2) Head-Bod Tem rature ÐiÊferences â ¡ Îúater ia l-s and methods . Thermistors were implanted in the heads of 4 spec imens of V.g.r osenbergi and 2 of u -tt - l- Iav airt rrr s ¡t¡ order to determine whethef head-body temperature gradients are maíntained in this species. Animals were anaesthetLzed with en interperitoneal injection of Nembutal (O.3 nL/Y\g) and a sn.a1J- hol-e was dri1-led thror:gh the cranium approxirnateJ-y 5 mm. ttehinC the pineal eye. A microbead tirermistor (I'ITC 2322- 27- 2L332) wh j-ch had been af iixed to a srn:ill- bloclt of PVC plastic with epoxy nesin was ímplante{ in tire craniurn of each anirnal- to a depth of apProximatel-y 3 ¡'nni. below the surf ace of ihe iread. The PVC bl-ock wac ce¡nented to the head of the aniynal with epoxy resin. Thermistor l-ocatione were deterrnined by autopsy foJ-lowing Éhe compJ-etion oÊ experiments. Tirey were found to be in contact with tþe surÊace cf tile brain in the region of the cerebelluni, between or s]-ightl-y bchin Observations of these animals were also made through a one-way mirror while they were being heated, and their aciivity was noted. Three animals which d ied during the course of these experíments r^tere heated and cooled in the sarne manner as they had been when t he y r^¡e re a l-ive , to compare the heat ing and cool_ing rates of ]-ive and dead anima l-s . J'¿ . In this waVr the importance and degree of physiological control over the heating and cool-irrg of the head and body could be determined " To determine the extent to which heat transfer from the head to tire body, and více versa¡ occured, three animal-s were pls.ced in an insulating box nade of poly- styrene foam and aluminiurn foil, with either the head or body protrudi-ng outside of ih.e box. Iíeat was supplied to either the head or rhe bcdy by s 2SOW heat J.amp, head and body temperatures anc activity of the ani¡naj.s was noted. b. Unrestrained animals Cranial temperatures of unresirained anímaJ.s in the temperatufe gtaöients were genera]-].y maintained at a temperatufe below that of the cJ-oaca, except during geriods of baskín|. 'dhen the heating larnps came on in the morníngt head temperatures rose more quickly than those of the cloaca for periods of apptoximately 20 - 40 minutes, untiJ. a mean craniaL terrperature of j. 33 ,6 õOoC (2E . O - 35 .1) was rei:ched . At t:nat poinr, the trace of cJ-oacal temperature crossed lhe trace of cranía1 temperature, and remeined above it for rnost of the rest af tlle activity period of the ani¡.-ia1 ( Figure 21) . Figure 21. FXead-t'ody 'temperatures of a T/. gor.ld lii over one day in a traboratcrSr thermaJ- graC ient . I CI.OaCA !*¿..1ñ. heat Tj heat T lam¡; on lamp of,f î t, t, i.) x ¡ lq .x x )( x l\) Çl O o Ê4 p X .f"ì Cì eS * l( "x¡ ..\ F¡ .J. Å-ra,^*'-x.. -xt&)l /\\/'a' {-x-*-N--x-{.r. } x' x. x o \r x \Y" .x.**__* t'lr x'-x. x' -x Y'Y rx=xà o F,l ÔB o 11) årJ 2 2,4 95 Both head and body temperatures l^Iere naintained we1-l above air temperature. The ranges of c.rania1- and c1-oacal teinperatures were very similar (Figure 22) and rates of cooling for head and boCy were similar following the end of the period in which heat was suppl-ied by the larips ( Fígure 2t) . There we1.e no significant differences between the fanges of head and body temperature for any of the four anirnals over the duration of the periods during which they were reco¡ded (Table 24). l{ithin the activity periods which followed the cessation of basking ¡ the range of hea.d temÍierature exceeded thst of cloacal temPerature on 2¿ù of the total of 38 days, the range of cloace1- temPerature exceeded that of head temperature on L! days, and on the remaining S days they were equal. The maximum head temperature recorded was 39.O-C,o and the mean daiJ.y maximum iicad temperature l{as 36.¿ß!,22cC (33.8 39.Or f, = 38) for unrestrained anímal-s in the thervnal gradienl;s. ff[aximum body temperature recorded for the sarne animals r^Ias slightly higher 'chan tbat f or the head (lÍ9.90û). Tire mea:! daíL;¡ maximun c]-oacal te¡ni¡efatllre w3'g a]-so 1r ighe r than ti,at of rhe head (3? .oL! .32, 32 ,5-3g ,9, l¡ 5B ) but the difference Table 24 Com¡rarison of dai]-y ranse of head and bodv ternÞeratures of V.eqU ldii in tbermal sradients WEIGIìT T df L ANTI,4AL (e) E n¿Ncs rhead X RANGE body rì 7t v.6.r. (1) L39e 3 . s].jO. 23 s.4BjO.30 L,L2 l.lS v.g.r, (2) 7LB rõ .24Io.5L 4,gú:o.24 27 O,lt$ I.]S V.8.f. (3) 565 6 . gojt. eo 6 .4oj1.92 9 o.22 NS V..g.f. (4) 355 5 .5g:1.02 s . Fsjl .2õ v o. o3 r{s Figur e 22 , lÁean daiJ-¡r head and body ternperaturee cf a V. gou]-cl ii in a laboratory therma1- gradient. 45.o a.-T c]-oaca l0.o b-T- nêa{l a b oÞ o Ér ã +Ð t5, E 0) 18 os # E.| 1B to 1B 25.o 't 2 3 4 5 6 7 I 9 ro 11 12 13 14 15 Day 96. wa.s not signj.ficant at the .05 level- (t--1 .573, d,f=75). i'ii-ni-lnum body temperature rerilained slightly higher than those of the head, anc1. both were above air teärperature while the heat larnps v'¡ere turned off. c. Restrai-ned animal-s Results obbaj.ned by resb::ai-ning goannas and placing them in teinperature cabinets Ìuere somev¿hat d.i-fferent from those stated Ín b. l,ïithj-n the temperature range for nornal activity, when anirnals were subjected to rapid changeo in aj-r teinperature their head temperatures altered more rapi-dly than d.id cloacal temperatures during both heating anC. cooling. liaxinnuin differences in head- body teärperatureei u.nder these conditions rúere greater thar those seen in goannas which had been placed in temperature g:'adients. The maximum dj-fference ì-n head and body temper- ature rccorded in a¡rimals v,¡hich hacl been held at tSoC and. then were placed ]-n a cabinet at 42aC rvas B"OoC, and the extent of the di-fference seems 'bo be related to the size of the animals, bein6 greatesi in larger specimens. During the initi.al peri od of heatin6, head and cloacal tenpera'bures of small animals rose tnore rapid.ly than those of large specinens (Table 25). Table 2l Ini a]- rat of chan e in hea nd bod ein ANIMAL ÈIEAD CTOAGAT croAcAr l.lEIGïfT TEMPERATURE TBMPERATURB : HBAÐ É5ea t ing l-Eo-3co t3r.tg o.79 o. 63 Lo¿ 4369 o,43 o.23 2.1 L4Q5,¿ o.4s o. oB 5.4 Coo 1-ing 3Oo-15o 1,3 5g () ,17O o. 52 7, r2 455g o.53 o.25 2.L L4Obe o.37 o. 09 4.7 )r.a'7 )urin; coJlir^r,, hc¡ ä teii*icri;tu,-res d.ccre¿rscC. nore ra,:lidlJ tha.;, ti.i,l cl-o¿lc¿r,-l- tci:,rg1¿,'5uÍ'1R il.-rc'1. tr"e nl;:linu¡r d-iffcrr,lcc ller,TiceiÌ tjtc iicrperature oí bl:c l:ea'1 ailC cioaca c.i ¿:.li ¿..,r.].ia-,'- l,i'.'c-lr, i:e.t cocliriq t.'aq 5,7''. ît:l,r: ei-ifere, ce 1-.eti,eett 'iìi e t¿te O_f C e"":;1O Oí '..ei d t0rr i.lef i:'-i;,tfe a:ltL ì-.od.y te:;re.it,-rrs ic .i:-:i1a:: ult1le cocling to tl-.¿t '*1;þi-g'r cccLirc ';ohil-c ar:.irral-s are lleatin:i (na¡te 25) . Goa.n;:las trlrich had- been held. in 15o ¿;.licl- 3Co cabj-nets ï¡ele pJ-i,ce,.L in ¿. 42o cabi;:et (relati..re humiJ-ity 25'¡;: - 3c,;). :-le¡d,, boi.y a-n,1 ilir teripetatures ïrere recorCeil. 1l:ccl'¡enr:e::attlrres rcse rìrore ra.:iil]¡r tl:lan cl-oa.ca-l- ter,rperatrïes (;iigure 23). I:Lespirltlon rate itrcreased vrith te:':rpe.rature ai:d. occu,.siona.l gula"r fl-utterirÌaj occurred as heacl. teriiile:. ¿.t,-lrG reaiclred. appro:'-J-iar-i;e1y 360 . lhis flutteri-ag is cor:lüonly, though no-1. v'ith strict âcc ,râcy, call-ecr parn'cing niren Ít occ-irs in reptiJ-es, a-ncl this 'berr:r has been r-,-sed 'rJo reÍer tc i'ü here. At approxi-t:ra-bel-y the tine at i'vtrich the ì:ei..ting cuîve of cl-oacal tenp.er'ature crossed tìlat cf lreacÌ tcnne.¡:c.tlìre, pa-irtinl: usr-rall¡r began at a rate oÍ 60 - 70 per ininutc. Sone a¡iinaJs occasionally str,":-ggl-ed. hrieflv at a slightly earl-ie: poin'r, tìr¿.¡¡ tlris. The rneair heaci te:"tperr,t',;re at r,:rh'iclr pantj-n.: bee:elt r'.ias 38.9È.30 (3t.t -+Q.3t rr = 13) iiiith êu ,r,3âr1 cl,o:,.cal- temp- erat re cÍ 3û . 9t.4o (37 ,9-4c; .2 , 11 = 1 3) . Figure 23, llead-body temperatures of a restrained V.gouldii which was ¡llaced ìn a ¿,2o C temperature cabinet. SPSP $t. I i *-a\o-¡-f*l-ç-f d !ï-c l. +.r-¡-x- -* + ¡. a-C-e-*-*- -û.¡ -þ -x *JL I -.x- , -¡-¡' q Èt T Jt * at |} '^ {.x,x x.¡ -x f a t I l x' T t !. ,'r a live dea 20 40 æ80 1O0 12O 1tÐ Tíme (minutes ) ¡ 98. Ðuring penting in V.gouldi-i the mouth is held slightl-y open and the gular region is fluttered rapidly. No differences in the depth of abdominal respiratory movernents were recorded before of, after the initietion of panting ín eíght animals where it was determined. I'Iead tempereture usual-J.y stai:iJ.ized or dropped sl-ightly when panting began, while cJ-oacal temperature coiatinued to rise until ít exceeded air temperature, and the pantirrg rate reached LzO - 1-3O per rninute. Occasion- a1ly, head temperature stabilized before the anirnaJ-s were seen to pant. On these occasions, breathing raEes become rapiC ( lOO - 13O per minute ) anC the mouth remained closedr or the anímaI had beer:. struggliag Once panting had begun, it was not always cont inuous . Anirnals wouJ.d occasionaJ-1y stoP panting foi. brief periods and at these tímcs neà¿ te:nperature wouJ"d increase elightJ-y unti1. the animaJ- resurned panting. Stabre head temperatures as rnuctr as 2.8o beiovr cloacal i;enperature eJere maintained for pericdo of o'fer 75 minutee by pantíng V.gouldii. i{o j-cwering of clcacaJ- teinpc.rature below air temPerature occurreri anC body tem?eraturc general-I.y rose above air temperature in the se c ir cul'lst an ces . 99 Head temfieratures of two specimens on which the rnouths were taped shut before being pJ-aced in the 42o cabinet sta-b íLLzed at ternperatures beJ-ow those of the cJ-oaca, but higher than those head temperatures which were previous1.y maintained by pantin6 (Figure Zri.). The dj-fferences between head temperai;ure lnaíntained by the two anirnals wben al.J-owed tc pant and r¡hen their mouths v¡ene taped shuË were L.Ao ancl O.BoC. Botli animal-s were abJ.e to maintain head temperatures beJ-ow clcaca1- temp- eratures b¡, very rapid breathing invol-ving deep thoracic movements for a pericd of 50 rninutes, but died shortly af ter the terminat ion of the experirnent . Efead temp- eretures l:.a¡1 stnbilized at 40.20 a:rcl 4O.Bc, with body telnperatures of 42,go and 42.7o respectively. The hc.ating curves af tire heed and cloaca of a dead V.gouldíi are shown in Figure 2!5. The head heats stea FIeacl-body ternperatures of reGtraine <1 uring ti.ie eecond they r^rere prevented fro¡n doing Go b-¿t taping their mouths shut. Moutb taoed. T--head. Pantir:g 1_ cl-OaCa-L Taar r""-'.""'¡ a ...... ---..- ) ..-.. -""o"""""" .¡..-...... "-r. ...."."..x x 25 20 tþ 60 BO 100 TÍue (uinutes) V.8. ¿p (2) I--- x {___ -Ð -- -3---- J' 35 3o 25 20 40 6o BO 100 ri-úe '(nÍrnrtee) d. ileat applied to l-imited parts of the anirnals, When the bodiee of V.gou]-d¿i were heated whíIe the head was shielded, a rise in head temperature occurred. The rate of increase was sinßilar to that of c1-oaca I temperature, trntil an intercraniaJ- temperat!:re of 5 6. Bo- 39.9n ,o.. reeched . At that point, head temperature began to decrease, while c1-oaca1- tenperature continued ta rise. Panting was not cbserved in an;; oi the f our anima 1-s used in th is cxper i¡nent , and scrne other means must i:avc been used to lower head tenperac'"lrê; Iieating the heaos of anim,al-s rshich lrad theír bodies siiie 1dc Effect of app J-ying heat to onJ-y the heac or onJ.y the body cf a r/. gou].ú ij- . C\¡ <;11 ilead heeteC: T cLoaca -'ts T! $ heac ...,..[...... , J.. a r-r -l(- - (") trugg ].izg r.. oa3 lieated.: T t Fody clolrca -*-- o l-am "äÍr i¡ off I head .. o...... '.... +) lamp d T f{t.f) ¡ â af .re --.: Oft l':l f,: o F ì( $ -t- .-tr- :-l- ':f - -** - *.- -r- -.x- ar- _,- - r{-_ _t ô¡ tl? -¡= :l-* :f --t_ ..:t .ìl- '-ll B t2 Oj- iirne ( rn ínrrie s ) 10r_. e. Ðiscussion The existence of têmperature graôients witt¡in tire bod ies cf reptiJ-es was reÞorted by Iieath ( l-964 ) and since that time has been the subject of a nurnber of studíes (ÐeWitt L957, HeatwoJ-e 197O, l,[ebb and ItreatwoJ-e i971,, Webb and Johnson L9?2, Crawiord L972, Spray and Belkin 1972 and t9'13 ) on a wide range of reptiles. The main area of interest has been in head-bo The existence of head-body tei-uperature gradíents is of possible importance in two waye. ïf, as was suggested b¡r Bogert (1959), e lizard can elevate its body ternperature by exposing only its ireaC r"rhen baslcing, there are po6sible advantages to be ¡;aineil in n'.inirnj"zí:'.g the degree of danger f rom predation. L?-e :-oir'dings of Heath (1954) in The rapid etrevatiorr of h.ead temperature to ihis optima1' range is achieved by a com.bination of f actors, f oremost of whici: are tlre large surf ace area : mass ratio of the heads oi most reÞtiles, and the tlìermo- regulatory shunting of warrn bJ.ood to the anterior port'íon of the body by the heart (Webb 3.972) . The subsequent rise oÊ cloacal temperature ibove head temperature in at least scme reptiles, including V.gouldii, LÐ a1-so a functi-on of severaJ. factors. Thesc include circuJ-atory adjustments in the shunting of blcod to various Parts of the botiy,and the evaporative cooling whicÎr Lìccurs f ront respiratory surfaces, either through normal evaporative water loss aB shown in Fíguro 24, or through hyper- vent j-J-ation or gular f l.uttering ( Figure 23) and f rorn the eyes. The latter seurce of evaporative 1oss, and thus of cooling, has been shown to be eíze dependent as to the amount of ¡¡ater i-ost f norn thst region (Green -r 9 69 ) r and cou1.d partial-ly explaín the differences in rnagnitude of head-body temperature difference fourir-i in anirnaJ.s of clif f ering eizes in this study. An :tCditionaJ. f actor in ti: is explenat ion woul-d be the degree of 1;he rn:ra I LaF, involved ín tl:e heatin¡1 of bodies as a resul-t of tt¡e surface area : rnilss ratios of the animal-s which are Johnson (L972) suggestsr or very limited datat that a narrohTer rnnge of head temperature tirân that of cl-oacaf iernperature exíste in active 1'/.gouJ-dii , simi1-ar to that whict¡ has been reported for other species of l-izarCs (ÐeI{itt 1-9.7 ; ûampbe 11 19 69 ) , Dat¡r presented here dc not suppoft tiiis suggestiorr. The control cf head temE) erature b¡r V.gculdii withir^ ti¡eir norína1 range of activity ter'"rperstures is no more preeise thaa is that of bod¡r terlperature. Spnay and BeJ"kin (19'73 ) suggest thau physiological- contro]- of head terìiPerattlre in Iguana i6:luana is al-so lacking at cl-oacal- tenperatures $? to 32oC. The only situation in which âreater control of hea6 terÌ?[]erature seems to occur in V.gou1dii ie when cloacal temÞerature rises above the noriïe1 ¿rctivity range, at which tírne head temPerâture is actível.y maintained at a temÞerature below that cf the bodS' by increased evagorative cooJ-ing resul-ting frorn gu1-ar fluttering by ihe anirnal; Th.e nean clcacaJ- te:n¡rerature at which pantin¿;' began in 1;1:is str:dy is similar to thcse reported previouel.-,r fo¡ severaJ. species cf varaniCs including V.gou]-diå, whicli range irom 38.Oo 1.{1 .5oC (E.artirolomew an<3 Tucher l-964, Benneti L97L, Green 1969, Grenot Í-968, iohnson 1.972, Langlois 1902, lfciÏab anú Auf fcrrberg 7973). 105 Etread teriperature at the init j-ation ( Figures 23 and 24) was higher than thai recently reirorted by Jchnsoo (L972) f o r tr^ro spec irnen s cf V. goul-dii (36.xtC) . Var j-ation in the c]-oaca]- iernpcratupes at whicit panting begins in V. gculdíi has also been reported by tsenriett ('197I) , Green ( i959 ) and Joìrnson (L972) . ler:rpl-eton ( LgTO) f ound that in iii:,soûaurue dorsaLie tile rate c¡Ê heating affecied tlnø terrlpeu'ature at which panting began, Ð.'.u.t -ihere al-so seeff.s to be sonre individual variaiicn in ti:,e'ce;:r¡-rorature ( e ither iiead or bod ¡t ) u.t wh ici: ilani ini:; ì:e j ílto in V.goul.dii as al-l- animal.s were ireated at the €ane rate in thís study. The range of !¡ead temperatures over wi''ich Johnson (1-972) repcrted the initiation of panting occurreð Þrac ¿:reater than in t?re preeent study, but tire eite oi inpiantaiion which:'iê ciiose (outsíde the craniuin) r"ras ¡-'roiiai:1y mcrc subject tc -iemperature fluctuation EliaÊ tire intercranial irrpJ-ants l.il:ic?r i{ere used liere. The lact ti-iat rio chan¿e in tJre depth of abdo:r"'ina1 respiratÐry rnovelnenis was recc,'r'decl before and ai'ter anirnaLs be6an panting ís consistenr r"¡ith the view tiret the functicr: c;i p,ar:ting is a t;:.errnore¡;ulatcry rather -ühan respirator3r cne. Be nnett (J-9'7L) etates th.at it appearÐ that the increased dernaad for oxyõen during activity in reptiJ-es is ri¡êt only wi-tii iircreaseC tidal volur,re, -r-vJ. ûnd reports a decreased tidaJ- volurne durirlg hyperventil-ation in V.gouldii. f n ti1 is study, the decreased c1-oe caj- terflÍ)erature r^¡hich rvas sugp;ested far this spec,ieo as a resuLt of panting 'oy C.z'een (1969 ) and Johneon (1372) was not observed. Neither auÉhcr ¡rrcvides Cat¿i on reJ-ative irurnidity va]-'¡es nt tire ti.rne ci' the j-r exiieriffielìic, s.J it ie poss il¡ 1e t ha'i: rel-at ive huraid it y ili ti rs s'tuc1;rr (257" - 3G%) r^rao iríghe'r than during tireirs, rnii lras toc liiEh to a1lo¡^l gcannâe tc lcwer their body ten:persturee belovl arnbient by thís method, but this seerrs :rn1ike1¿"'. the restrj.cting of head tc;iirerr.tures to a def inite ma:.:imurn limi-t apElears to be necessery to prevent heat darnage to the brain ancl gular f luttering ís an enaergeacl' rnethcd by whicir this can be acccr¡ifrf_isi:ed, al.tiiogh it greatLy increases the ratê of water tross f ro¡n the animai. Green (1959) found that t'nc l-,ul:noaar-,/ water loss of a penting V.,qou1di i increases to ,7 - 6 timec tiiat of a nLril.-i)antin¡; individual- at the eârî:ê teni¡lerature. ït iras been i-e¡;orted that two tyiÐeri of ¡iiiyeiological- adjus';- ment occltr ciuri-ng per ioCs of ireat strecG irr at J-ea,st some gLrecies cf l-izarcls . îirece are a circul-atory aC just- rneni, rrhicl: ijreced,es panting and is ¿-.ssoÐiated with vigorouo activity "zncl a r¡arked incre¡rso in heart rate, !47, and a respiîatory adjustment which. folJ-ows the onset of pantiag (Webb et a1 L972). 'ihe drop irr head tê¡rperature which fcllows the circul-atory adjustment hae been attributed to an increased fJ.ow thrcugh tire head of cooler blood frori the bod3r. Strug¿iing b]' lizarCe whictr have liacì tlleir body teraperatureG elevated a'oove ttie ncrmei activity temperature ranp.je has ¿?eilerÊl]-y been consiCerei tc !;e an escape reection, t¡u'; ít appeare to also have an adCitional tJ.:errnoregulatory f'¿nction. 'ilue higi: rate of, water 1-oss whícT: occurs úuriag panting can be hazardous f or arl anLrnal- whicir lives in the arid and semi-arici regicns which occripy much of tfre range of V.gcul-dii. 'Ihe discontinr¡ous panting whicir r^ras observed in r.ost of tire anima1e used ir:. this study may --ùe a meci¡aniom to lower tiìe nate of water ]-oss belol^l that whích would resul-t from contiiruous pantiü,ry, or rnay sirnpl-y be due to muscle f ati¡7ue. Tiie r3i-e of rvater l-oee whict: occurs ¡'rhil-e penting j-s such that the rosultant coolin¡; ef f eci nrüGi be ?estricted to naintainin,g a stable head temperature whi'le boCy tenrperature is aliowod to riee. Pant ing by V.gouldii has been cbserve'i i:i ihe field ( Cooke, ijers . coinm. ) but is apparent 1;r s1"ornffion as Aoannac generall;' ¡utouot to a ti:ermaL rei=u6e wher^ environnentai conditions 1;ecome tac extreme. 4 rìQ ( 3) I\asa1 Ternperatures a. l''IasaI morphoJ-ogy Casts r^¡ere made of the nasal sacs of eevera]- \{ Cead specimens of V.gouJ- V . benga lens is I âs shown by lisllains (l-9.i9 ), but bctÏi the sp ecírnens wh ich i:e exanined were ;uven il-es . The possibi-l-it¡r that interspec j-f ic clif f ererices in tlre dinensions of porticns cf the nasal sac l¿ave an acraptive signì f icance re1üteai to tl:e irabitat of th.e e ¡recies has been suggested by r,t{ertens (1-942) . Variaticns iir the j-og. extent oi the lateral recess of t-þe nasal sec r{ere found in the species of Varanus exarníneC by BeJ-l-airs ( 1-92,19 ) anC it was sugljested brr him l*hat these too miglrt'¿e related ta d if,f erences in the h¡r'oits cf the species . I".Io reJ-ative differences i-rr length oi anterior nasaJ- iubes or laterai recesses (exoressed, âs a Þercentage of head J.ength) were found !:etween eubspecies of V. ou l-d ii or between thern a.nd V.Aiganiel¡s. Tire dierneter of tlte anterior nasal- tubes in the speci-"nens examined here ranged irorn CÌ.9 L..o m'r.. ín silecimens of V. gouldii wh ich ranged f rorn 27A - õ55 rryrt. snouL-vent length, aÉd l'rom 1.O - 2.1- rnm. in V.giganteus (snout-vent lengih 605 77O mn.), whil-e in t',ro specimens of V.acanthurus which were examined, the dj-arneter was A.4 mfi. The tu'oe is ovoid in cross- section. The nasa]- gl.an'-1 duct enterg the nasal sac at the juncr,-ion cf the antericr charnber and the ol-factory charnber, rs cccurÍ] in the other sr¡ecies of varanids whicli have been ex:mined (Eel1airs, i.949). ?he nasal capsul"e occupies al-most the eûtire anterior region cf the chondocraniu:r, an.l the anterior nasal tube e¡ao Þ¡itirin C.8 1.5 mÍn. =î the surface of the snout in aJ-J- specimene of V.gouldii whicir v¡ere exannined. l,iicr obead tìrermíst ors ( l{TC 2322 627 21"332 ) we.re used tc deterr,rine the te.mperature of insi: ír ed and expired aír. The thermistcrs elere solde¡ed on tc air¿ltt, L10. &avge copper r^rire and mounted on the tip of a ¡lrobe rnaCe f rorn poJ-3r;¡sn. tubing with an inside diameter of O.8 ¡?nr., wliích was f il-I-ed with clear epoxy resin. The respcnoe tirne of tl:ese ther:iristors cou]-<1 not ì-€ de'bermined fro:ii the 1 itere.ture ¿rvail-ai¡l-e on them. 'Ii:e t1-.er¡n:_stor prcbe f crmed one arir of a trlheatstone bridge, v¡i:ich i^¡ae connected io the F'ox'oorc ER Seríes recorderr âs i{e-o rJeecribed in IIï (.tr- ) cr. Resp j-red air ternperatures r^reîe ¿eterrnined in a rcoríi where air temperature r^ras reguJ-ated at \BaC, and witir a rel-ative hurnídity of 6C%. Coils of copper wire, ore ead cf which extend.ed alongsiCe the snou-L of the animal. past the externa1. nare wiril-e the otiror pro3ected a¡lproximatej-y 2 crì. above the hesd of the animal, vJere af f ixed to tiie heads of tine exper innental- animals with êpoxl/ res in . A thêrrnistcr was pl-aced in the cl-oaca of tiie anil¡lal s and taped in pgsition, anc the anin¡al y¡as ttien secr:reJ-¡r tieó oî ta a r"letal griC, witÌr a sTree-i of X inch t1:-¡ck ¡lol¡rstrrrene f oa:n betvleei: 4t an,j ì;he metaL. A 'Chermistor probe T"ras taped to tire v¡ire l+hich extended -oeside thc- s1lout and the tirermistor vtas then positicned J-n the nare tr;,2 manipulation cf the wire. ånother ti:em- istor çqas taped tc ti¡e wl-re abcve the head, and was used to measufe air temperature near the head oi the anima1-. ++¿4.1 a Recordings of resp j-red air temPeraturê, cl.oaca1. te!"flÞeratúre, an'd air ternperature 't{ere taken for 1O - 20 ¡ninu.tes ¡¡ith the animals at equiJ.ibrj-um with air ternp- efature, and the body of tne lizsrd was then hea.,-ed by placing a 25O9.T jteat lamD aì:-cve tl:e pelvic regicn of the animel-. A siriel-d of pol-ystyrene f oam anrl alui'niniun f oil .,,^¡as placed ovef the head of tiie enimal to Prevent heatiirg of ti-:e t1'¡errnistcr -oy the Í-amp. Ðue tÇ tl:e J-ag Ln f,esponse of the ti:ermistors ancl recorder, the fårlge oi t1ìe respired air tenperaËufes f or eny given period couid iiave been Efeater tiran that incicateci by the reccrdingo obtainecl . Yelues wefe corrected when necessar]¡, actLng on ttre assurriPtion that inspirei air was a,t the sanÌe temçlerature as that recordecl just above the l:ead of the animal and that the truncaticn cf the values which were thr:s rjeteririned Þfas equeL at 'ooth extrenes, Thus, wi1elte necessarir, values l^¡ere adjusted in this fashicn in crder tc ceter¡nine actual terfilrerature of ex¡lired air. c. Ìrasa1 tera eratures Irieasurements cf reepiratory ternperature were taken on specilnens of V.eoul-dii, LJglillg_ an of their externaJ. neres, , which f acilit¿rted rßeaGurment of inspired an<í expired aín ternperatureo inside the nares. l¡11- animel-s had init ia1 cloacal_ ternperatures sli6htly above air temperatures despi-be havinE; -oeen hel-cl in the experiraental room for a rninimum oi' 4 hours prior to takini; reccr'Cinge. The sJ-ightJ-y elevate<1 cf-oacal_ ternElerat'Jres are pro'oably the resul-i of raetabolj-c ther.rnc- genesis (Bsrth.clomel,r and Tuclcer t96t') and ti-rey rarig:e.J f:'ori-¿ O.5o 2.CcC above ambi-ent temperat..lre. Tenrperature of inspired. air duríng this tirne was the same ae the air temperature readings r¡hictr were obtained, and that of expirecl air was C.20 O.4oC below air tem¡lerature,, anC o f roni C. f 2.2cC bel-ow that of cJ.oacal terirpenaiure. Ciianges in respiratory tem.perature giere observed ¡.¡hicir correlated witi: the respirator;r movements of the animals. Tlie calculated range of these f l-uctuations is shown in Figures 26, 27 anC 2g which ehcws the course of tlie tem¡lerature changes experienced 'c5r a A..65 I(g V. varius a i-.595 I(g V. spenceri and â .",55r. Kg V.F,jou]-dii which r{ere run i.n tlie manner pnevic,"Jsly described. îhe resul-ts obtained from a].l_ aninal_s whicl--. r{ere exa.mined were simil-ar, although Che m_¿ignitude of <Í if f erences between the rieep body- ternpenature anC t,ha-t Figure 26. CJ-oacal tenì[]erature and nasaJ. Ëemperature of a ¿, .65 "v"g V . var,ius - t lcl-oacal 41.o xx o 'Tti" r( J"rrespLratory t9.o I { I x x x 37.O x x T x T x rJ t5.o x o $r o oÉ çto *x ä t + g B cÈ (d x ql t{ o 33.O t-l F{ È +> {, Ê (tt d o o E{ # 37.O I t. I f xt( 29.o t f ¡1j .L ,lr?-? , { a I T T'l + i t 27,O o 20 40æ 80 1o0 12o: rl+o t& 180 2æ 22O rine (ntuuteÐ Figune 27. Cloacal- temperature and nasa1 tefl?perature of a l-.595 i(g r'/.spenceri. ç Ê çt o o x È $' H r} 4o lå È t {,T x r 38 I I x t6 I ¡ (, x o' f g 34 s d Í{ Cù f¡ E 12 x o H T. þ x' I + -r 1 - t 28 :::ii++rttïir+b ïl 26 20 IrO 60 BO lirne (urinutes) Fi,";ure 23 , Cl-oacal -temperatüre, intracranial ternperat úre and nasa l- -terlperature of a C.3511 íg V.gor:ildíi. T ttt x c 10a ca to Í o thbad ., i N a ? 'rr ¡:l t""=piratory f f ¡l) x Ì-{) Ð I o ov) e ${ t'f s f +) r{ o f{ O-l .É gr{ rC o € x c) þr o Ol c\ì .ç f-!tGi-i i I Il.b ¡\ c\ 2ô do do 89 r-OO Tirne (minutes ) aa|a of the expired air did vâry beiween anirnal-s. å.s cloacal ternilerature roser expired air temperature also increaseci, but at a slower rate, and it rel¡18ì íneci r^rell below bcth cloacai and intracranial- temperat'rres (Figune 2'rB ) of the anim,a1o. 3i>. specirnens cf V ií wl:rich vrere cpeneC uP by ¡1 mici-ventral incision while ur.dQr aneesthesia had J.ung têrrepêrâtures wirich tÆere equai- tc or sJ-ightLy }-igher l;han cloacai tem¡leratures. Sprai/ and Re1-i:in (L973) f cuad that lunq ten'.perature rose rncre rapidl-y than heart, head, or closca 1 tern¡rerêturea in Ïguana i ÉJdllq r The difference'cetween clcacal temperature anC temperature of thg expired air is thúe probabLy l'ess than that rvhich actual]-y exists between thet of expired air and air in the 1ungs, The ¡:raxirnurn clifference between the cl-oaca1 tern¡-rerature and the ternperature of expired air which was observec rangecl from 5.8o íl 1.I-oC, ârrd; occurred at cloaCatr ternperatures of 3'J .4Î õ9.9oend air tennpef atur es of 28 .60 29 ,2o. The iemperatirre cf expired n ir rcse ac cJ-oacal telTrperature increa.sed, but at a sl-ower rater' snd it exooeded inspired ai¡ te;nperature'uy as müch as ¿,..8ÐC,. Èlaxinum expireci air ten^peraturê occurreü sligìrt 13i af ter t-::e tleat lamp haá been turned of i=, 'D]t i"¡hictl tinne L7t). cJ-oacal terßperature had already be¡;un to drop. Spray and BeJ.kin (L973) founC -u}.at a nasa1--cJ-oacal- ten'iperature difference can be rnaintained in reptil-es for severa.l hours during the disaipation of a therrnal- 1oad. The greatest difference betvreen cl-oaca1 temperatüre and expired a ir temperature ( 11- . loC ) wae seen j.n an ind i,¿idua 1- cf V.spenceri (Figure 27) which weighed i-595 grans, but tiie magfli tude of; ihe Cif f erences couX.d not be consistently reJ.ateC -¿D the size of the animals uced cr to thê aridit:¿ of their natura-1- habitat. l{o attemE}t v'ras lîtade to deterinine tho temperature gradient which oxisted a1on6 the nasa1. passaÊ,er.raVsr due to the sna]-l- diameter end rhe curvature of ttìe anterior na sa l- tube , Å TJ Ðis cuss ion The functi-or'Lno, of the nasa]- .passageways as temDcral counter-currelt iieei exchangers 1¡as been discusseC by Sctunidt-I{iel-sen et s1 ( -'1970) . Brief LV, the¡rr r"rfr'c1;ioa as f crJ-l-ows. Ae inhaJ.ed air i.'asses along the nasaJ- tubes, hest an.d water are removed from t,';e ira 1ls ¡f thc tr-:bes and tbe air is war¡ne$ eitd humidif ¿ei1. Upcn exha Lation, tlie warm air frcm tl::,e Lungs passes b¿'. ck thnou¡3ir the r¡asal Pass¡lgeÞfâyc r¡i.lici.: were cocl-o<1 -! I i: by the ínco;ning air, and heat is then transferred back to the tissuee and noisture is al-so regaineC by the animal-. ï-ieat exchange is faciJ-itated Ì-r¡r a large surface area, ehcrt distance r,o the v'¡a11 j-n the nasal- []agsateÞ¡a]'s r and by a low air vel-oci-ty. The relatively elongated s¡iout, antericr nasaJ- tr:bes ì anterior nasal cirarnber "r of varanids, aild the sma1l dia.meter cf tne tui;es and chanber rro -lhus cE benef íÈ in heat excLrange betv¡een ti'le respired air arC he iissues of; the nasal sac. i.Io measurements of the r:ie olo air f l-ow wefe obtained. The sensory cLîaci"ory e,Dittreliurn in varanl-ds is lj-mited in extent (EeJ-1airs 1 949 ) and much cf iiie sac is i-ined witÏr stratifieC sqrråmous epitheiium whicir appeûrs -r'o aid Ln Ëhe conditíonin¡¡. of inspt.íed and expired ai¡ ( Stebbins tr-9.18 ) . úco1in,3 of exçiired air íc i;ri1.:ortant i::. tire conserva.tion of water, which con,Jenoes cn to the cocl-ed surfaceo cf tit.e nasal ÐaesageG, Aii ocÍi'tional eaving cf watef .lccr.rrs Ln anirnaj-s which irÐsseso il t,,t'çtctiona]- nasal- sait r;J-ar'..], whicir Green (19e9) has shoçvn 'C. occuÍ' irr V,rZcui-3ií. l,icsË i¡unldifying of inepiled air in r€p1;í]-es oceuro in the i;rincipal, or clfaoto:y, chnnnber (Stebbi::s 19,'.,ô ) . Irs¿lired ¿r i-r ÞacseG ovc-r tlie ;'l-ui 1oç¡ rate cl ¡:uI-rnonar-J¡ ;^rater loss f cund ín V..qoui- ( Green l-9 69 ) . Tlre r¡aximurr, differences observed between cl_oacal_ tern¡:erai;ure anC expired air -tea.?ersture in thie study exceed i;i:ose cited fcr Ðípso6auruG dorsa J-is (ifiurr-: da and Schrnídi-llieJ-sen L97'í.l- ) anC are s i.-rilar to 't,hosê af the iíangaroo ret, ÐiPodont¡,ts t-rrêrriarni an Canr?ylorhynchus brunneicapí1lum , dt o imll¿rr a ir ¿rnC lrod¡i tem¡-r6¡¿¿ures, and tc those of Ïguana uena ( 3pr"ay and tsel-kin 1-973]r . No incicatic;n waç f cund cf a 1ov¡er .fenìperature of expired air in cleseri as opp,csed -!c non-desert species of birds or man".;-'ra1€ (lìchnidt-I{ieJ-sen e-i a1 L97Q), so it was uniil¿.e1;¡ that suclì a difference r¿c.uj.d occrir':etrreei¡ Ëhe species of varanids examiired ilere, airC none r"ras f cund. i'he ireat which is recla ined b5'tl:e cocj-ing of expined a i:. ce:r a lso 'oe of bene f it t o ]-izarcis. An a'.¡.iiina1 whicia t'as r¡-isecl its bcdy tern¡;erature Lir besiting wi]-l- be abl-e to extercl à-ts perio.i cf elevsteil -uoi¡r tem¡;ere.tui'e wlrile foreging in shaCeC ârets r cr af ter returnin¿ 'r'-r 4 4Fl its burrow by retarding iis rate of heat j-ces by this nßeens. The cooling cf expired air is thus cf consid- ereble benef it to i;i:e animals. ( ¿)) Skia reflectivity There Le colÍsiderat:le vari-atj.cn in tire dor.sal- col-ouration of V.gouldii frorn different parts of the wirie distribirtioa of the s¡iecies. Tiree e S;limadzu QR-5,-Í) spectro¡-rhotoi;reter vlith a refI-ecüance Âttûch:nent. 'r-he reiLectivity cÉrveo obtained &re pJ.r:tteC 44ñ I-!-(/ ¡ ín Figurec 29 and 3C. There is consialerall-e variability irr. refl-ect'ivity witirin each subspecies ( Figrrres 2ia t L, c. ) anC tl;e intergrad.ation which occ'ùrs fcr dersal cll-curation between subepecies, with V..r¿ . goulCií in';êrrnediate -f o the otber tçlo substr)ècies, was al-ec found'io occur for tlis characteristic ( Figure 5O:. ) . Scne overlap in tf¡e reflectivity vaJ-ues of the different suboÞeciee dces occur, par t icu J-ar J.y between V.iZ.gouldii- ani V.g.flavirur"us in the vis j-ble portíon cf tlr,e spectr-trñr. T'his may be reJ-sted to the reguirments of ¡;ro-iective colouratioa of the se aní:nals . The dif f erences v¡hich occur ii¿ refJ-ectivity veiues excend beyonC the visiDle range, and afe greatest in 'Ehe flear inÊr;-.i-red, prhere tire higheet va]-ues ererê oi:tained f or e1l eâr.,rÞlee. I'Iorrís (1-967 ) s-i;a tes that J-arge lj-zerdc têncl to liave hi¡tT-er refl.ecti-vity values in tile near inf¡a;red prtriicn of the sí)ectrurn, ï,..here tiiermal- re].atir:nsirips 11 o t;,îoteci;íve col-cura'lion, ti:ar di; sv,".a1l-er sÐecies. When tire va1¿es obtained i:.ere ere conpare,.i wi'i;ir those given by S;_;e1j-er-oer¿ (L972) for Sphe irr:raorpltuG s?ec'i êsr i;-:is re1¡rt i-onsl:ip exists . That this geneîa \L';7 r-ioec not always irci Reflecti-vity va lues of excised skin e a:npJ_es of : (a) three V,g.fl-av (b) three V.g,gouJ.díi % REFLECTIVITY 20 U $j 5 2C, õC' 60 T x ù + fr I x I t(. t + (Þ g't Y I x + a l( { t f,t l + o * ts * t t + \x o I þ '+ (r 4l t .tl. cl co I *ö oo t x. x l. \ x\ :li I t'. + + x -a \ t¿. \(,, o + + \¡ o l-¿ ¡-¡ \ ,:l \ o ix {t x\ Ë \ o x + x\ T \ x -l-l' x\ x +." þ x\ o x + O \x O Figur e 29c , Ref lectiv ity val-uee of exc ised slcin salipJ_es of thre'- Y .6. rcsen'oerga. Fi-gure 50. I,{eae rellectj-vLtyr vz.1¡res of excised ei..in o arap le s of three sÊecimens of each subspeciee of V. gould ii. x 0 -* r9 +' \z zX- X¡ x .+7- .X' + \z + l-ax z* + + + C) x' -l 4¡ ç --b''x...... 1$...... t ù"' oû + c O o a h*{ ¿j 0 Á Ð ô 3_ (-i; L¿¿ +¡ '.ì .F{ +) O C) r-l c!.¡ O orn -¡- i4 +0 + Èe + g. ,+ V. r. + a V. g" g. V. g. t.4 ö {I + a + a o r' t ¿X I x-x + a rf. -* r i{ C) -r- (\ x x s-x x 2',x -x /¡ ç- 3_ Wave 1er:gth. rfl-ält-CT On S 1_3_9. trere for indivi Specinens of V.i;,rcsenbergi , w!:ich rea ch a inucl: J.a rger s ize tlìân do tirose of th,e otlrc.r tr^7û s',..if species, have lower dorsa l- rel']-ectivities than ,f c tn-()se o? V.g.gouldií or V.s.flavirufus. No dirêct vaJ.ues for the reiJ-ecSivity of tire integunient oi other varaniri species i:ave L¡een publj.she'J. ?ercafs (1963) presenteC a transrnission curve fcr tlie shed skin cf V. lonrodoerrsis , løhich transmits Less tTran tC:/' of the radiant energ;r at all wave l-engths wi:icir were rneasüreC be'üween 4CC - 2OCO rn-nicrcns. If , as Norris (A93'Ì ) etates, tlìe-transniissicn.l-css of radiation ¡>assi::g ti:rcugir tr:e skin i:f diurnal re¡itij-es is of essentía1-iy no i,-nportance, tl:ís ieúicates e very high ref l-ectivity val-ue f or tiie kerat inor-rs layer of the skin of th.is very I-arge varanid. Ref lectivity values of the exuvium Ciiiered corì€iderably frorn ihose or: excised skin, but those ob'Laíned f cr tile three s-úbsi.,e'Jie5ì of V.gould j-i (Figure 31) âre cons j-dera!:¡tr-y be-i-ow th.cse vlhicir can, be esrinated f or V.komodceäsio. Tercafs (i9C3) h:s suggeeced that the iow trarrsrnissiou of ra,iiar:.t energy b',i tl:e e>cuviu¡a cf V. ilo¡nocioeasic is d':e tc its qreater thici:i:,ess ( 5C rnicrons ) in co-i;iÐ;iFiscn 'Lo '5;hat c,.f the other speciee of rept il es rrnich were :;iêasureii . The thícir:iees of ttie scrnpl-es of sired. s!',-in trûrr, V. ¡c ul,jii wh icir r,Jere ti-ie;r. eur êd hera ran e ed f r cm ii . ti : . i; micrcns . Figure 3i-. Ref J-ect ivity values of samples of sired skin from the three subsireciee of V.gouldii. % re f l-e ct ivity r:n ¿\) ll\ (f \-/ 7{J xl + x /a x +l x o + c¡a 0'o Gq FJ )a I t+ F.Þ CA l, x c o F o X Õ + Þ m! xr ¡ i.) X c + x ,tt + I X c -t- F¿. o x\ l| l'r'-J r¡ .+ o \x X + L¿W. The highest refJ.ectivity vaJ-ues obtained here are from specirnens of V. . f ]-avirtrf us r^ririch occurs in the iro'u, arid regions of centraJ- Âustral-ia, and tire l-owest vaJ-ues are f or tfie specímei:s of V.9.. rosenbergi Êrorn i(angaroo Isl-and. Ðíf,f erences in the dorsaJ. ref 3-ectivity between ccngeneric si:!ecies, wiiich are correlated. witli th.e arisity and tertperaiure cf the habiiats of the anirn"ale, have been s;h.ci,¿n for other species of J-izards (FÍutchinson anC Lariner L960, SpelJ-erber¿; t9'12). Theoe lìavê cbvious aclvantagee il. increaeing, -i;lie heating rates of the lizards f rom cootr habitats, ald lor¡ering those oi the anirnal.s f ron hot, arid re6icr's. In thie walf r activity perioüs oi anirnals in both typoe of areas are extended. ,N D.1 Meneral Ðiscussion ii is a speciee which is widel-y distributed throughout Australia. lts physiol-ogy io uniquely adapted to its mode of existence as an active predator whicii ltray occupy a large home range (Bennet'E L97I), It is also well adapted to living i-n arid environments (Green 1969), as it Possesses severaJ- physioJ'ogical and behavioural. ada¡:tations which enable ít to overcome the problems of maintaining water and electrolyte balance and to therrnoregulate in a wide range of habitats. Ðespite the wide distribution and considerabLe age of the fanily Varanídae, there is 1itt1e morphoJ.ogicaJ- variation within the species of the genus E:3-!gt except for body size. There is also strong sinriiarit3i in the general- habits of these rather unspecialized predators, and in their eccritic temperatures, despite the wide range of habitats which the;"' occuly. The value to aninal-s in such a- grouP of possessing fl-exibl-e behavior.rr pat terns is evident. By adopting Patterns of behaviour anJ activity whictr suit tire 1ocal climatic conditions, a species rnay occ'Jpy a wide range without evolving nuílrerous physiological ancl nrorqhoJ-ogica1- 122. adaptíons to a particular type of climate which rnay restrict its distrj"bution to that climati-c region. The irnportance of behavioural- thermoregulation to reptilee ws,s ernph.asized b¡r CowJ-es and l3ogert ( l-94¿I ) . Since that tirne, a number of etudies of tirenrnoregulaEion of reptiles ín ihe field have been made, but Ðawson (1967) suggested that studies or¡ the preferred temperatures of I-izards required more deta:lled inforrnaticn on the behaviour and ecology of Lízatds in nature than was then available for most species, The use of telemetry devices can make such .etudies easier and more t,roductive. Ðata obtaintd in this study provides cuch information on 1/. eou]-d ii r¿ft¡en combi-ned with the recent studies of Green ( lgAg , L972) , Pianka ( 197Oa ) , Bennett (1,9? íl , Webb et aJ. (a971) and h?ebb (L972\, it provides a more compJ-ete picture of the behaviour, ecology and physioJ-o¿y of V. gou1C ii in t lie f iel.d and in r:he l-aboratory ttran is kr¡.own f or r*cs I cther .A,ustralian ]-izarcle . An in'rportant asÞect of the behavictrr of Lízerds in ariC and semi-arid regions ís th.e use of burrows by these animals. The use of burrows as thermal refuges is common in non-tropíca1 species of reptiJ.es, and V.gouldií s pend a Large amount of ti¡ne si:eltering in burrows which vÍlry ir, depth and general f orm in dif f erent i23. parts of the range of the species. The microclimate within these burrows in different regions is very simiJ-ar at a given time of year, despite the dífferences in air and soiI. ternperatures which occur outside the burrows. Mean daily burrow temperatures vary by approximateJ.y LzoC from sumrner to wínter oil Kangaroo Isl-and, and a simil_ar seasona1- variation probabJ-y occurs in the burro;^¡s in other Þarts of the distribution of tire speciee. The duration and tiraÍng of the periods of activity by goannas outside theee burnoyrs is dependent oa the 1oca1 environ- mental conditions, which al-so show a seaconaJ- variation. By being.active only within a certain ranse of ambient conditions and speading the rernainder of its time in the reJ-ativeJ.y stable microclimate of its burrow, a goanna can avoid thermal extremes and thus encounter sirnilar ambient conditions despj-te the variations in climate which occur in different parts of its distribution. 0n Kangaroo Island, V.gou]-dii emer g¡e almost every day throughout the year and when suffi_cientJ-y high ambient temperatures occur, they remain out of tlie burrows f or ,leriods of 8 - l-O hours per day. In the arid and semi-ariC regions, the same specíee is ir¡active during a period of approxímately 5 - 6 rnontiis oio the year, ann generaJ-J.y emerges onj-y for short periods on L24. those days on which energence does occur during summer. TiÌose animals which remain in burrows ori Gumiiler. days in the arid ancl semi-arió aîeas are ebl-e to thermoregulate by moving to diif erent parts cf their bureo¡.re, and are thus abÍ.e to maintain elevated temperaturee ar:.d yet reetríct their rate of water loss by rernaining in humid burrows. Tire reason f or the winter inactiví-ty of goannas is not known, but Pienka (1-9'/{}a) h"s suggested that it rnay be related to the thermore6i'rlatory require- ment s cf the species . Simi1ar diif elrerìces in the da il_y and seaeo;1a j- a.c'¿ivity of other species olo varanids b.ave been reported previousJ-y for V.gris eus ( CortcilJ. 1928, Anderson L963, Iiaggag et a1 X965, and túinton l-956 ) and V . ni].ot icus (CowJ-es 1950, Cloudsle3r-Thompson X966 ) . Green (L972) has shown that V.gouldii which emerged infrequentJ.y fror*, tireir burrows in a semi-ari animals in tire f ie ld , and the preierred terrperatures and behaviour of gcar'r.as from these areas ín the laboratory r.Íe?e similar. Green (í969) found no difference between the rnean values of water loss in dj-rferent subo¡:ecies of V. ¡;ouJ-díi urlclen J-abcra iary cond it j_ona , an.d there hTere ,Åc apparent dir"f,êrêírcês between the suL"s¡recies in the labora'i;cry in ti,is stud;¡, v¡ith ttre ezceÞticn cf the irigher ref iecti vity values f cr the skin sarnpies f rom goannas f rorn tlie semi-arid and arid regicns. rt Ehus âppears that tile adaptations wnicjl a1'!ow this specJ_es tû exist i-n ania regions ere a]-so foilnd in,>c¡;uI_atiüns wh.ic1: exist in niesic areas, and are probabl;r characteriotia of the r/aranidae in generaJ,. Eerrne'{;t (L97'f) has stated that V.gouJ-dii is not a metabolic intermeciate between tire riamrnals and other rept il-es , âs llas suggê6ted b3r Brrtiiolomew and T'"¡cker ( 1954 ) , but is instead a rj,zarti wllicli is able to rnaintai-n hígh levels of aerobic resiriration during pericds of activj-ty bj'stretching the aerobic capa'oilíties of re¡:ti1ían physioJ-ogical orgeni.zation to theír ¡rrobabl_e limíts. Tirese adaptati-ons include an imprcved Gxygen transpoft sj¡stem, ãî ela1¡irate J-ung s-fructure, anC a high myoglobin content in muscles. It is ab]-e t<_r recover rapid 1y f cllowing activit¡r, ciue ''"c ti:e l-a-cl: crf iiig,.r l.ai-'r J.evels of l-actete accrtmulation . l-t j-s thus hzV,l:Ly adapted to Lts rnode of existence as an active ¡:redator. ?-he iriportance to d.eseri dweJ.l.ing aninials of restricting water loss, a:id the close associaticn between L{ater loss and ti:e rrnoregulation .ras beer^ established in a number of etudies on a wide raÊge of opeciee ( schrnidt-Nielsen 196â,, E[eath ig6g, Green 1g6g ) . varanids Ilosseos a number of ph;reiologica1- ada ptetions which functian to decrease their rate of +¡ater loss. rncluded annong these ane the posGession of f u¡:ctional nasai g.lands aní a ior.r rate ;f cutaneous water loss ( Green i-g 69 ) , tine absorption of w,rter frorn the cloaca (Braysirer and Green 1970), 3 nasaL n'orphology lrhich reeults in a cooling of ex¡ired aír and contri-butes to their 1ow rate of pulmonary l¡ater loss, and the use oÊ eva.oorative cocling by gular fluttering for cooling cnJ-y the heacl during short ¡.,eriods cf heat stress. These atlaptat ions are f cund in goannas f rorn reesic areas as wel1. as from arid regions, and tire addit ior:.al- decreeses in water loss which are attained by desert-dvroJ-iing individual_s are accornÍ¡I-ished b)' behavicura I lnearts . in tiiese regic,ne , a restr iction cf time sFent outside t1:e ttrerynel refugc ic necessary, whereas the ¡ni¡naig in *iore rriesic areas have mucir 1on,qer 1t)r1 actívity periods. SeasonaJ- differences in actívity between goannas f rom tlrese areas rr".a5r be deterrnined by thermoregul-atory requirements r 8s was sugu.aested by Fianka (i97aa') or'oy ct?¡er fectors suci.t as tire seasonal_ availabj-Lít.y of f ooC. V.go_r4 those sel-ecÈed by v.gouldii in artificial therfüra1 gradients as they do within tire preferrêd tem¡:erature range of the f arnil.y Varanj_dae (l:,iacl{ay l-963 ) . Other physiological- processes sucn as hear-t rate and recover]/ time are ternperarlure deoerrdeirt in thic trou.Ð (Eennett L971,), I-t tTrus appeare that varanids can funetion ef iicienti.3r cvúr a range of deell bcdy temperatures, rather than at a precioe temperature, and this ability is of o}¡vicus arivantage to such a wi'Je 1¡l d isi;ribtr ied group of re¡:tiIee. An irnoortan:! ¡_oeature of this species, and of varanids in general, is the behavi-oirr-a1 fle:rj-bility which is sirown in r.êsponse to 1ocal conditione. This lLøxíbi1ity, Ln co¡nbination with tlne pir;rsioJ-cgical capabitr-ities of the family, l"l'ae enabi-ed V.6;cr:ldii to successful-1¡r occup]¡ a wide range oi habita';s throughout most of Australia. J,IPEIÍDIX Add-itional records of tÌrc cloacal temperatltres of free-ranging sgo ii at l,Íul-oo;ina Calpenrin¡ âírd- on Kangaroo Isl-and ¡ âs d.etermined. bJ. rad-io telcmetry. E= cmcrged. from bu''.rrow B= animalrs locati-on dctcrmincd as bcing in a burrow. I\T = a:iime.lrs l-ocation v\iithin a burrow has altcreô from that of the prevlous dc-bcrninatlon. O= alimal had not shcltcr'cd. in a burrovr¡ overnilht. D= obsenred. to bc alternatoly cli,1ging et a burrow e-i:d baisking " P rain. cr'-oec€Ll- tcmpcrature " air tcmpcraturc. bl-ack bul-b tcmp::-rr:-b *-¡;: " soil tcmpcri'tirrc. l I I I l R I N I \ J I \ i FIGURI:I 18 .E'Cr: 4o S-iE FEBIIUJ\RY 22 T) 2+ C) o t-] tli 5O È) EJ* t-ì:r F¡ Pr HÉl 20 00 0 1 0 00 FEBRU/iRY 25 FEBRUJ.RY 26 ChIPERUIvI V. Ao i-i ldo. 1 1 \ t \ E B N \ rt t L t, t; \ 40! I I \ I I \ i,' \. I \ I .'t C) I o :i F'f 5o g tH I L gF'l gtrt 20 o6 0600 1 BO0 0600 FEBRUARY 25 FEBRUARY 26 IEBRU¿RY 27 CAIPERUT4 Lr_A. Âo_Eldij. No. 22 EBE B EBNE B N .f.l$ ,f t, [¡ I { I \ l \J l I I I ! I I I I I \ I I ¡ I I I \ \ I \ I l I I I i \ 40 \ I ¡ I I \ l.' I \ '-:ìii () it \ :/ i '#d Fí Þ H .Ff,d \ \ Ê{ \ i E20 j I 0 01 00 06 0 18 U 1 OCTOBER 26 OOIOBER 27 OCTOBER 2B l{UlO0RIN1À V. A. f]-avinrfus No. 2 OC TEI'iPER¿.TURE f\) vi + o o O a 3 o, ¿\ L¿J -"" :+ l-f ?r¿ ¿1 N)r -l é È oH o FdH z O Þ Ot <'- o Ld O c) È 4- td O bJ E a Ð lq lú -. a @@ o ts. r-J É Fù aÉ z o o o N) Er ¿ DJi.D STUSK IÙHIIE PI,SSING UNDER X, FDVCD . 40 I () o l-.ì Ê.j )v .tEI Ë f.ì P.t F H 20 o6 0 1B MÀRCIT 2 KJNGiII?OO IS]J/'ND V. . rosenber No. 11 3t E LI I I I I I I \ i I \ 4o \ \ t) o \ 7O äü "----.' , : r 1 1 o0 o 1 T,T¿,RCH 5 I{ARCH 4 MARCII 5 KA.LÁROO ISIAND V. s. rosenþers:L No. 72 R R E RB 3 I i I { û ,J It v I I. \ I I I I i () o Ér-E 20 Þ trr F-l Ê{ trt Ê 10' 1B 0 1 JUN]] JÏ]NE 4 KÂ]TGAROO' ISTAND V-:__9.:_ros_gnþ_q-rgj- N o, þ 1 E I E ,t t" ù 5O I I \ O \ o 20 \ l-qÐ Þ H \ tsl_Ë ê{ H Fl f-r 10 1 0 18 I o0 JUNE 3 JIJND 4 JriNE 5 I&NG,4,Iì00 IS'I.¿IITD V. e.. ros enbersi No. 22 oc TEMPERATUn-E r\ wl c o o\o o Þd <-84 ç) a4. a) Ê @ ftJ @ +td o Þ{ tr ç) F ooo HA Ol u)o ì . L{Þ -- <-.84l ÞcZÇ) e---t ) bJe CNË (o o) a o )q a o Þ d o o Or r-j o lÞ o H. Þ >.*-H d H z i. -\ o I :l a a) Ê lo ,/ <-;-{, O* r--cc R RR E RDB R E DB ,t ,ft t ,[], ,f J ,t ,f 3O C) o 20 H Þ H -4 ^=J rìl-Lr Pi iã H 10 06 0 i8 00 1800 0 00 1 AUGUST 12 ÄuGUSr 15 /iUGUST 14 K/i1[GÍ.ROO ISI/ND V. Ao rosenbersi No, 54 E E B ,[l I I I ! I +o i Lr SEE FIGUR.I] 17 o tr'OR NOVEIÎBER 2 g / \. trt TO DECEIVIBER 1 frj 30 Þ EI É f-q P.t H I F 20 06 1 0 0 00 0 NOVUqBER 2 DECJil4BER 2 KA\IGÄROO. fSIA$D .V. gr_::roeB!þergi No. 15 E E B ; I I I it I I i I I I I I I i I I I I I I I :l 'I I I I 40 I I l Í l l l :r I ì I I I L) I I o í. I I I r-.ì I rr'Í 3o I Þ I H ; -t -l r :\ c,ì I \:\ I fjì : Ê.t ê¡ [.ì f-l 20 NOVEI\TBER 70 DiìWEI{BER 1 DBC]üUB.1R 2 KJ'\IG¿,ROO ISLND I1.-S'**I-qF94þ*egg! jn4,. 21 oC TEM?XRiTTIIPC N) \_ñ è F U (- t.J I C) '1... H xrù I Þ bEl +Ð ()zÐ ,1 Þr Ð u.l o t" o ,l H CN H L4 U U L.J +- L*J C) !- _l : 6 )q a o Þ L*rIA d .>ì.ìì_::ì t- o U H L'l lÞ c) l-, f-J Ë=tÉ td o ÞJ a F \ñ tu \t] e- td l3 B J'BEt, i Itl I 4 () o l=l 3 0 rË Þ r--{ ',Í" 1..-l Êr Ér f--{ 2 06co 180û 06ö0 1 SbO o Dlì3,T,tBEiì 17 DJICNMBER 18 DECIÛIBEiì 19 K/NG¿,.IìOO I'JliJ[D V. a" ï'oserrb erEj- lÏo. 35 BftsLIOG Y Ânderson, S,C. i-963. Ampi:ibiane and reptiLes frorn fran Froc , Catr.if . Acad Sci. 3f-( 15 ) : 4L7-498 Auf f en-herg, ''.1. L97Q. Fepcrt oÍla sl;udy of tire Ko.nodo inonitor . Anir¡.. {=Lng Bej-J-a:-rs, A. d t ^d. L949. Cbser.¡ations oi1 ti:e snout oLo Varanus,, aFrC a comiieriscn witir tiiat of otirer lizartis ffi-snãkes. J. Anat. e3(2): .,a€'-L46, EeiLairs, A. d r A. 1 969 . Tire 1if e of re¡:tiles . Weidenf e1d and I"licol-soir, Lozrdoir. 59C pages. Ee'cnett, A. F, 1e71. Oxygen transpor-i and energy netabo]-ism in tv¡c species cf i-Lzards, Sa¡.rroma lus obesus anö Varanue l_4. ?h.Ð. t?.ie6is, U. of ffigan. Bennett, å.F. , ârrd Licirt , ? . 1E72. Arraerobic met¡:.boJ.ism dur i ng act ì vity in lizarCs . J. Coläp . i.hys iol-. Bi-z ñnn z¿ J-¿OO.-oÔ Boge rt , C ,'tX , i9 59 , I-Ior'¡ rept ij-es reguiate thc i:: f:oCy ternperature . Scient . Amer . 2OO: 1C5- j-2û. Èradshar'l , S.9., anC L{aì n, A.R. 1963. Beliaviourai attitudes and reguì-at ion of tenpere-tule in .Arnpir i-o c luruo LLzarðs. J.ZooL., Lona. L1542 193-22L. Braysher, Il'i., anrl Greeri, B. i97O. Abocrplt-¡oi: o'Ê water anC e-l ecirol-ytes fronr tire cloaca of aì1 Ausiralian J-Lzard, r/alanus gou ld ii ( Grrr y ) . Conr:r . l3 ic ch em . Fhrrs íc'l . :55: 6. a? -61¿:, . Brcdl, J. L977. Fersonal commr¡nication. Burns, T.A. 197O. Ternperature of Yarrogr, rs s¡li1'1-¡ 1izard SceJ-oporus jarrovi at high aJ.titudes. Ilerpetoiogica, 26(r) z 9-16. Bustard, I{.R; 797A. Âustra1ian 1-izards. l^1il-1iarn ColJ-ins Ltd,, Brisbane ¡ Campbe1l, H.W. 1969. The effects of te¡nperature on the auditor¡r sens it ivit3' of l-izards. thysioJ-. Zoo1. 42 z !83-23,4. Cloudsl.ey-Thompson, i.L . 1965. Seasonal- changes in the éaily rh¡rthms of an ima ]-s . ïnt. J. tsiomet. 10(2): !t9-L25. Cooke, E. 1975. PersonaJ- communication. Corki11, N.L. 1-928. I{otes on the desert monitor ( Varanus gr iseus ) and the spíny tailed Li.zarö. ( Uro,'na st ix microl-epis ): j.Bornbay ra{at. äíst. Soa. 322 6O8-6LC. Cow1-es, It.B. l-93O. the l-ife hiotory of Varanus niloti-cus ( Linnaeus ) as observed in I'latal- South Africa. J. Ent. ZooL. 22(L)z X-SL. Cowles, !R.8. i-939. Fossible implications of reiltil-ian thermaJ- to1.erance. Science, il.Y. 9Û: 465-466. Cowles, P..8. aítc Ëogert C.M. 7944. A pre1-i:'ßinary stud3r of the thermaJ- requirements of desert reptiJ-es. tsu11. .Am. Þius. i"Iat. I{i.st. 852 26i-296. Crawford, E.C. 7972. Brain and body -bemperatures in a panting Lj-zard. 5cience, N.Y. 3-77 : 431--4'ð""5 , Dawson, Til.R. !967 . Interspec i-:f icr Vâr iat ion in phys io1-ogicaJ. resÍ)onses oî lizards to ternpenatlJre . in I4ilstead, l{.'l^1, (ed.) Lízard ecology: a syrrrposiurn. Univ. of i,4issouri Fress. lerani]'aga1a, F,E.F. 19ill-. Some Ceylon lizards. Spo1ía zeyLan, L6zt39-i8Ù. Seran íyagaLa, :J.E.P.'L958. Reproduction in t Tre mon it or LLzatô Varaflus bengalensis (Saudin). SXro1-ia zeyl.art. 28: L67-3.66 . Ðe1{itt, C,.8. L967. Frecision of therrnoreguJ-at ion and its re]-ation to envi::onmenta]. flctors in t}:e Evans, I(. J . A967. Observa-tions on the da j-1y ei-,'lergence of Col-eonyx vari-egatus and Uta stansburLane. IJerpeto1.ogica 26 : 21-7 -222 . Fitzsímmons, V.F. í943. The i-izarde of SouËh Africa. Transvaal Huse'dm, Fretoría. Flower, S.S. 19õ5. Notes on the rêceni reptíles and amphibians of Egypt, with a list of the sç,ecies reccrded f rorn that kingdon. Proc . ZooL. Soc. Lond. 1953: 735-85'L. Geiger, R. l-959 . The climate near the ground . Iiarvard U. Press t ¿r94 PP Gentill-i, J, 1948. Two climatic o]/ste,ïs app].ied to Austra ]-ia . Aust . J . Sc i. 1-l- : 13-L6 . Green, B. l-969. f'later anC electroJ.yte balance in the sand goârÌna Varanus gould j-i ( Gray ) . Ptr .D. Thesie, Univers it5r cf Ade 1a ide , South A¡¡stra J-ia . Green, B. A972. I{ater losses of the sand goanna ('/aranus g.ou1d,ii ) in ite natural. environrnents . Ecology 53(3) : 482-457. Green, B. L973. PerscnaJ- communj-cation. G¡enot, C. L968. Etude comparative Ce 1-a reeistance et ä].a Chale'ur dt Uromastix scanthin .urus et de Varanus griseus Terre Vie 1,968: 39O-4O9. Ilaggag , G., Raheem, K.A. and Kha1i1, F. í96í. IIi-cernaticn in reË)ti]-es: changeo in bj.ocri el-ectroj-]'tes. Ðonnp. Biochem. Firys io1. 16 : 457 -461, . Ilayward, J.S. i-961-. Tire abil-ity of the wil-d ral¡bit tc survive conditions of water rec¡triction. C.S.I.R.O l.lild'l . Res. 6: 161)-t'i5, I-Ieath, J.E. t962. Temperature-independent rnornLn'g ernergence in ].izarcs of the gerlus Fhrl,rnosoma' Science, N.Y. i38 : 89!-892 . I-Ieath, i.E ¡ 1964a. Ë.eptiti¿n thermorêgulationi evaluation of f ield studies . Science, I{;Y¿ 145: '18¿;-78ú Head-bod3r temperature d if Êerences i ¡1 Heath, J.E. i.954b. -tjniv Ijiornecl ]-izarde . . Ca l-if . Pub Is ; ZocL.64: 97-r.3 6 IIeath,J.E.l965.Te,irpere'ureregulat:.onandóiurnal ectivity in leorneõ lizards. Univ; Calif . Pu'o].s. ZooL. 54t 32-1t29. FIeatwole, i{. 1-9?t. Ti:.ermai ecolcgy of the Ðeseit Dragon An',gh ibo l-u¡ us i;:errnis . EcoJ- lvlcnogr . 4Ai 425-r¡37 . HenzeLL, ìì.F. ig72. AC:.gttatLon to af i<1it¡r in .lizards of tile Egernia whitei species Ë19"p' *Þh'D' Thesis' Univ. oildelairlé, $outh AustraJ.ia ' ilutchinson, V.II., an Sihoernaker, V'li' anci I¡1.a in r\ . R . Licht, - Ê., Dawson, W'R., , 1966. Observeit ions on the tlierma]- re].ations of Westera ¿lustralian lízards. Ccpein 79662 97-LLt, j-nn -i966. i\'1c'3 ig , S . i[ Sce].ooonus occidental-is: í]referre ., d body temgerature of tiie ilestern Fence l-izard. Sci-ence, Ì{.Y. i-52: i-O9t-l-O-ôi. irfa cKay r R.S . !961t, Gt-i apngoe tor loise and marine iguaria deep bod¡r tern¡ìsi'a;';re r,rêâsurêd by radio te]-erßetry. Ida'Lure, Lond . 2.'!)(z:95,5 ) : 355-55E. i'iacIia5', R.S. 1958. Cbservat icns cn perisi¿r1tic actj.vity vefsuG ternperzi-ú:ce and cir.cadian rir1rf,¡i,n" in uncisturbed Iu/arríi=JG f ]-avesceïìe ¿riid Cterrosaiirg pectinata. Cope ia , .1-968 | 252-259 . LicLean, .I .li. 195/+. A r¿etl:o.i for cci-rs¿-ruciut-n6 direct reading ti¡.ermistcr il:er:riorneters . J. Scrent . Inetrum . 3!; 4rjrj-,!,57 . irlcl{ab, Ð.Íi. 1956. '.ihe rnctabol-isrir of fossori::1 rodento: e st:tdy cf ccnvergerìce. .9co1ogy, ¿)7 (5): 't'3-2-733, i{c}Ia'o, l.l.-. aäc Auf f en'rerg, ''¡1. !97 3. The ,bod;r ten.:p- erature of the tiornodc iïonitor, Vara:rus ko:nodoens is IìIö¡tñ it{a yirew, ri.l{. 'J,96õ. Te;lrperature p;'eferences of Sce loporus orcr¡tti. Ìieri>etoJ-ogíc¡ 78.. 2L7-233 . Ìäirynew, W.W. l-965. Fliber.nat:-on in the oÌ{ornea Li,zard, Phrynoooma ¡n t call-i. ComP. Biochern, Physiol. l-5: j-o3-r_r_9. 1¡lara¡:e I.,4ertens, R. L91i2. Dre Fa.rriJ-ie der ( Yaranidae ) . 'L-1-JL6 Abh. senckenb. niìturf orsch. Ges . 452: . l\'trertens, R. 1956 . -r+emerlcu-ngen uber d j-e Warane Austra].iens . Senckenberg bio1.. 39 (5/5 ) z 229-26,:;. i'rîertens, R. 1966. Ein neue¡ ztrergr^raran aus liustraJ-ian. Sencicen'berg biol . a? ( 6) t 43'J -¿l!,i . lúertens, R. 197L. Ubec eine WaranSsrr-,rin1uí¡¿j auS d ern ost ].ichen I{euguinea. Senckenberg bio1, 52 (î/2) t IK lì{i1steed, rf .I^l . L977, Oi-. t'te problems of home rsnge meas'rrement and iadìvidua]- recogniÈion i-n. LLzatd ecol-ogy studies. Iïerpet . Rev, 3 ( l_ ) : t7 . Minton, S .4. l-965. A contribut ion to the herpetology of r¡olest Pakistan. Eu11. Am. Ii{us. I{at. Hist. L3¿-¿ 27 -iB4 . tr{itche11, F.J. L97:3. Studies cn tlie ecoj-og3r of the ag e¡nid 1 izard Ar:',ph ibo ].urus rraculosue (iiiitcheJ.J-). \. Ar, r7€. 'irans. R. Scc. S.Aust. 97(L ). ¿;a-. a. I{oberiy, l.T.R. l-962 . i:iiberna-r. ior: in t]ee esert .Lguana, -r,)ii,:so. ¿irrue Peiere, U. l-'ii:9. Zum ersten rnal i."r ,aef angeil.schai'i: eibI-age und sch.lupf vûä Var¿rnus spê-r=rceri-. Aquar . - U. Terrat.-2. 1,5(9): 3O5-3A7. t'-feffer, ?. i-959. iibservations 6ur l-e và1.3r: de l-ic;nocl c Varanus komodoensig Ouwens 4 a4 c: T'erre Vie i-SS: !95-2>i3. Pianka, E.iì. j.968. i-{otes on the i;icf-og1' of Varauus ererriue . tf .¡\us'l . i'Tat . Li(2) z fli-i..:], -I;zranug Pianka, Ìi . R; 1 959 . Iio'ces on th.e biolo¡;y o 'î caudo ]-ineatus and Vara-irus S;ilJ-eni. W . Aust , irlat . l-tz 76-'ò2. .bio1-cgy ?ianka, !.R. 1-9'lQa.. Ì{otes on t1:e of Var:nus 8o u1C i-i f l-aviru f us . 'l.I ..\ust. ilat. l-l-(6) :'I41-L44. Fian!r-a, E.F.ì. L97Ob. if otee oïì Varanuc Lrrevicai:'ia. W.llr:et. l{at. 11-(5) : :¡-i3-1-i6. Fianl... , f . R. i97 i. No'lee Ð:t ¡fie L-: io1-c¡ji¡ r.;f Yaranus tristiG. 'yl.Aust. l{at. il-: :r.¿lü-f-85. Pian'l.a, E.Ll . i9'1 2 , ZaogeoEralüh¡,' r-;llli e Deciation i.-f Austral-ian desert LízarCs: a:ì ecclog j-c¿r1 irersL)ective. copeia 7972(!-) z 1-27-:L,i1. F.ega 1, P J. l-965. TirermophiJ-ic resironse iol-lar¡ing f eeCing l-fr certain Í'eptiles. Copei:. 1-966 (3 ) : 589-59û. Rega1, ?,--r. X9î7. Voh^ntary liy¡;otb-ernzia ín îepti1es. Science, N.Y. -155(15769 ) : 15Li"-1-555. Robertsori, Í.*\.Ð., Chapnianr 9.1r1 . r C.napnr-aa, F..F. 1962. I,Iotes on solne re.piil_es in ti:te tì*kr,ls Vaj.le¡r, g.l{.Tanganyilca. Ani'r . l[.a3. Hat . i.]ist . Ser. i3 ( 5 ) : .1ta^ ';â_L-r.¡ùv.^^4 Saint Girons, Ii., and Saini Ciro:s, ii,i.C. L959. -sspace viiai domcine et ierr.itoirc czez l_es vL'rtelrreO terrestres ( reptiJ-es at mar.niif c,res ) . ii[amna_1ie 23 : 4tj8-¿"7 t;3 . Schrridt-i'lie.1sen, 1{, L9ô4. Ðesert ar:. i-m;l 1s : pir]'s io't o,g + ca l- pr ob l¿rns of heat aad T.Ieter . C l-a rea C.. rr Fress. Cxf crci 277 Ðp , Schi-rric¡;-I{ielsei:., !!,., Í:ainsworth, F.lì. ané L,;ulrrsn, Ð.E. 7S'7 A. Counter-current ireat excha':ige in th e nespiratcr¡,- ps,ssa,ges: ef iect on wi-ter an(i l:ea'i brl-ance. Res;. Pl:.r'sio1. 9: 253-27õ, Scnrridt-Nieisen, 8., and Sch¡nid-t-liieJ-sen, Íi.. -'¡-950. Evapci-ati-ve'*¡atèr J.oss iti desert rodents in their natu¡a1 hahi tat . Eco]-ogy 3L: 'J5-3ú , Sr::íth, Ii.C. l-93'O'. The :r'ionitor lLzarÕs of Burmr.. .1. Eombay ltr:t. Iiist. Soc. li4: l5 67-3'73. Spe11-erbor.Et I.F. !ç72. ?lrermai- eccJ-o6v- Di a1-3-cp,atric lJ-zarc e ( Sg;!ienomorphus ) in Scuth. East Atiri'iraiia. ir. ?hysi ol-ogi-ca1 aspects of tir-ernrorcguJ-ation CecoLcgía 9(.4) | 325-398. $.ore¡¡, Ð.C. ei:.C Eelkin, D.E. 1t972. rate c]-oacal- teínperature bysteresis in {5q+;+"Jeari i_s 3 reoufi of thernnal lag. I'iature, Lond . 27,9( S371_) : 33j-33S. Sprayr D.C. arrd tse1kin, T).3. 797 3. Tireri,ra 1 pat-lerns in the heatin6i and cccling of I,3uana iguana and Ctenosaura heir.iJ.opha. Comp. ¡iioch eÍi , Fiiys io 1 . aa(31') z 83it-&92 . Stebbins, R.C. 19¿-8. liasal stru¿ture in j-i-zar,.:e witir reference ta ol-faction anó crrnd zt,ionLng. of irispired 4.1F2 ¡^.r a ir , A:ir. ,T. ¡\na-i . û 3 : J-V¿-á¿L. SteL.bins, R.C. l-96i. P.cdy ternperature st-i:d ies oto South African ].izards. Kcedce t,z l'¿--6-=! . Stebbins, ì?.. C . rnd Bar.wicl*:, R. E . i96[t. Ììariictelemetric study cf 'Lherr.qoregulation in a Lace rlonitor. Oope:-a '9íj3. ti41-5t17 . Stir1ing, E.C. LgAz. Observations on the habits of the ie.rge Central AustraJ-ian rnonitor ( Varanus g iganteus ) r"'ith a noÈe on the trf at bodiesrr of tlris species. Trane . Eoy. Soc. S.A. 55: 26-33. Storr, C.&i . 1964. Sonîe aGpects of the geogr.a¡.ihy cE A'¡stra'! ian repÐij-es. 0encirenber.g bio]-. .4S.. 577-589. Stcrr, ç..li. n966. Redisoover.J¡ anC taxono;itic ctatus of the Australian ij-zarc Varair.us pri$orûius. Copeia 19,.15 : 58 3-534. Templ-e-f on, J . R. 1 '97C. irant i::;; and its coniroL ín ¿-he desert i-p"rta:-a, Ðips csa urirs C orsa l-ic . Ámer . ZaoL 1-û( ): '¿2'r. Tercaf s, R.R. i96.3. lransmiseicn of ultla-vioJ-et, visi'bI.e and ínfra-red rariiatior:. -ihrou;l; the keratinous 1ayei. ci rep,t iJ-e skín (te::pentes a-nd Saur ía ) . Eco 1-og;y aA( i) : 2i./;-218 . Tester, J . R. , llarroer, ¡ .l.l . and Coch.rair, "FI .W . 196¿1 . A, radio-trac;.-ing systerí fo¡ stuCying';he rfloveineiìts of ceer . J. ,iikl1 " l,lgmt . 2¿F): ¿t2-45 . Trunbl-e, 1,9/"8. .1.ì.rirai'a11, everporation anC drought- frequency iri South Austraij-a. J. Deí.,. ltgric. S.Aust, 52:58,-64. Turner, F.8., Jenirrich, R.I. and i.le i-ntraub, J .D. l-969 . äoi'ne ranges and body s izes of J-izards. Ecology 5O(6): x076-1-081, I{arburg, l'ri.R. 1965 . Gtudies on the e nv ir on:nen t a I physiology of scrÍie Australian lizards fron arid and eení-arid r-:abitats. Aust. J. Sool . l-3: 565-578. leleathers,'hl.tr^f . and Ì,ior6areidge, I'l.lR,. i.977. Cutaneous vaecuJ.ar respoilses to iemper.ature ciranges in the Spiny-tai1eö iguana, Ctensaura .aeniiopha. Copeia 1-E7iz 548,-55ü. Webb, G . J.!^I . i-972 . A. nel^r hypot,'les is ci'ì. the p€ìttern of bJ-ood f 1ow through the sq"Jamate hec.rt. Search 3 (a): L58-L/;C,. trJebb , G, and i-Ieatwole FI. L97I. Patterns oro heat distri-bution wittiin tl¡e bodies of soíße .Austra l-ian pyth.ons . Copeia J.971,2 2O9-22C-. Web¡, G., I-ieatwole, Il. and ÐeBavay J. 1971. Comparative cardiac anatom;t of the reptiJ-ía 1 , ?he c¡1crn'Ðerc and septa of t-rle varanid veniricle. J. ii{orph. 134(ö): t i] ð-.i 3U . l.le¡U , û. and .Tohnson, C.R. 7972. ileail-1:'od3' te:nÐerature dif f erences in turtl-es. Co:n¡:. Eiochen; P}.:ysio1. /.3ì,t 59'ó-5.1.l. I,lebb. û., johnscri, Ü.R. ariC. Ilirtil , È.T. 1972. i{ead- body te!'írÐerature dif f erences ir; lizaris. Fh5'si.1. ZooJ- . 45 (2) : 13C-t/-¿2 . Wegner, R.I\T. 1-922. l-ler siutzknocirenr os naria1.e, in den nasenirohl-e bei ëer, Gurteitiere:r, Dasypotiidae, und seirre ho:noJ.cgen gebiide bei /rrnphib j-en, Rep f iJ.ion und l.{oilotremen. l'-{orph. Jtr. 5l- : /'"-r3-ð'92 . 'øli1J,iams, I{. i-959 . Sor¡th .åustraJ-ia f rom tiie air . i{e}-bourne -U. fress . t29PP,