Biawak, 3(2), pp. 57-60© 2009 by International Varanid Interest Group

Introduction

In1992, thefirsthatchingof theKomododragon,Varanus komodoensis,outsideofIndonesiaoccurredattheSmithsonianNationalZoologicalParkinWashingtonD.C.,USA,where13youngdragonswerebornfromwild-caughtparents(Walshetal.,1993).In1995,inagreatgesture of international cooperation, the managementof the zoo inWashington D.C. sent several of theseoverseastoKomododragonkeepinginstitutions,amongthemthezoosofBerlinandRotterdam.TogetherwiththefewV. komodoensis that were already in European zoos,thisbecamethenucleusofanewpopulation.

Breeding Program

Afteraninternationalzoomeetingin1998attheZooofThoiryinFrance,itwasdecidedtostartaEuropeanStudbook for the V. komodoensis in the European zoo community, under the umbrella of the EuropeanAssociation of Zoos and Aquariums (EAZA). AninternationalstudbookaswellasanAmericanstudbook,werealready inplaceat the time.Twoyears later thisEuropean Studbook evolved into a so called “EAZAEEP”,astandardizedbreedingprogramforendangeredspecies. The program was and still is, coordinated by the

A Third Captive Generation of Komodo Dragons (Varanus komodoensis)

at Rotterdam Zoo, The Netherlands

GERARDVISSER¹,²,SANDRABIJHOLD¹andJUDITHVANDERKOORE¹

¹Rotterdam Zoological and Botanical GardensPO Box 532

3000 AM Rotterdam

²E-mail:g.visser@rotterdamzoo.nl

Abstract - At Rotterdam Zoo, Varanus komodoensis has been bred to the third generation. Four off-spring hatched in the enclosure of the parents. Total length and weights of the hatchlings are tabu-lated. A short discussion on imbreeding of this species in zoos is presented.

RotterdamZoologicalandBotanicalGardens(RotterdamZoo,TheNetherlands).TheseniorauthorofthispaperbecamethespeciescoordinatorforEurope.In2000,thepopulationconsistedof17animalsineightinstitutions(VisserandBelterman,2000).

The First European Births

In 1999, Rotterdam Zoo was one of the zoos toreceivethree(1.2)youngdragonsfromWashington.Fouryearslater,itwasdecidedtosendoneofthosefemalesto Reptilandia reptile park on Gran Canaria, CanaryIslands,Spainfor reasonsofavailablespaceandmostofall, for theclimaticbenefits;ontheCanaryIslands,V. komodoensiscanremainoutsideunderalmostnaturalconditionsformostoftheyear. In 2001, Reptilandiamanaged to obtain a pair ofcaptiveborn,F1V. komodoensisfromGembiraLokaZoo,Yogyakarta,Indonesia,andsoanunrelatedpotentialF1breedingpairwasestablished.Thisresultedinaclutchof32eggs inFebruary2004and, inSeptemberof thesame year, the first hatching of F2V. komodoensis in Europe,andwithintheEEP.Atotalof17younghatchedsuccessfully(PetherandVisser,2007).

Further Births in Europe

Following Reptilandia’s breeding, several birthsoccurred in Europe. At the Zoological Society ofLondon’sLondonZoo inGreatBritain, one sexually-conceived F2 hatchling was born in August 2006.However, the event that had rocked the internationalreptilecommunityprior to thishatching,wasthebirthof 4 parthenogenetic dragons in March 2006 (Wattset al., 2006; Sunter, 2008). In 2007, a further eightparthenogeneticV. komodoensishatchedatChesterZoo(Great Britain). Meanwhile, Prague Zoo (Czech Republic) hadreceivedanadultF1pairfromIndonesia(borninTamanSafari,Indonesia),whichlaterproducedthreehatchlingsin April 2007 (Velensky, 2007).

The Rotterdam Situation

In order to get the best possible results, animalswithin the EEP are placed in the most potentially

favorablecircumstances,which implies that in severalcases adult V. komodoensis were moved around todifferent European zoos and replaced by subadults oreven hatchlings that were born elsewhere within theEEP.This isdone tomakeup for the“loss”ofaniceadultspecimenandwithittheattractionvaluesuchananimalhasforthepublicofthezooinquestion.Inthatrespect, the cooperation between zoos in this EEP isexemplary. ForRotterdam,itmeantthatwehadtosendourlarge,andthensolitarymaletoGreatBritain,tobepairedupwithfemalesatChesterZoo.Inreturn,RotterdamZooreceivedayoungsiblingpairfromGranCanaria(bornSeptember2004)forexhibitionpurposes. In July 2008, matings were seen, but since it isgenerally accepted that V. komodoensis reach sexualmaturityatfiveor sixyearsofage, theseeventswereregarded as a formof “play” behavior, and no resultswereexpected.Thefemalewas3.5yearsofageatthetime.Asitisrathereasytoover-feedtheseanimals,theywerekeptonastrictdietandthereforetheanimalsgrow

Fig.1.ThesiblingpairofV. komodensisonexhibitatRotterdamZoojustaftertheirarrivalin2007.PhotographbyGerard Visser / Archives Zoo Rotterdam

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slowly.Hence,thepairissmallcomparedtowhatwascustomaryinthepast.Thisrathersmallishfemaleindeedshowednosignsofbeinggravidatall.

F3 Generation

We were of course greatly surprised to first findtwo, and then another young V. komodoensis in the 120m²,fully-plantedKomododragonexhibiton10and11March 2009.Aswe had noticed the “copulations”in July, the eggsmay have been laid inAugust 2008.Whenwefoundtheyoungdragons, theyolksackhadbeenfullyabsorbed,sowebelievetheyoungmayhavebeenadayortwoold.Theeggshadbeenburiedintheexhibit’ssubstrate,whichwascomprisedofhard,loamysoilapproximatelyonemeterdeep.,inwhichtheparentshave dug several burrows and tunnels. Thus, in thissoil, the eggsmust havebeen incubating for ca. eightmonths.

After the young were found, we searched for thenest,furthereggs,oreggshells,butnothingwasfound.Tofindthenestwouldhavemeantatotaldemolishingoftheentireexhibit,whichwas,andstillisnotfeasible. Two months later, onMay 10, we found anotherhatchling,addinguptoatotaloffouryoungsters.Thisisanindicationofaprolongedhatchingprocess.Sincethese hatchlingswere born to anF2 sibling pair, theyrepresentthefirstcaptiveF3generationofV. komdoensis everproduced. Themeasurementsandweightsofthesehatchlings(Table1.)fallintothelowendoftherangeofweightsand lengthsknownfromothercaptivebornhatchlingsthat were artificially incubated. The animals show nobirth defects. Additionally, the estimated incubationperiod seems to be rather normal. This would implythat theconditions in thesoilof theexhibitwerewellsuitedfor the incubationofmonitoreggs,evenduringtherathercoldwinterof2008-2009whentheambient

Fig.2.AnF3hatchling,twoweeksafterbirth,feedingonalocust.PhotographbyMarten van Dijl / Archives Zoo Rotterdam

59 VISSERETAL.-ATHIRDCAPTIVEGENERATIONOFV. KOMODOENSIS

temperaturesdropped toas lowas25ºConcolddays.

Inbreeding Allowed?

AlthoughcaptivebreedingsinvolvingsiblingpairsisnotrecommendedwithintheEEP-breedingprograms,these animals can still play a significant role in thepopulation.Theymay serve as “exhibit only” animalsforzoosthatjustwishtokeepV. komodoensis without further breeding goals, or as replacement animals foradultssentouttobegroupedwithotherstoformbreedingpairs,and,incaseofanemergency,theycouldstillbeusedforbreedingpurposesinthefuture.TheaimoftheEEPistokeepgeneticvariabilityatamaximumlevel,sohopefully inbreedingwillbea last resort.Ourgoalremains that the EuropeanV. komodoensis population will develop without further inbreeding. For thatpurpose,theEEPhassoughtandfoundcooperationwiththezoosofPretoria(SouthAfrica)andSingapore.Atthemoment,severalpairsareinpositiontobreedandthreeinstitutionshavereceivedeggsin2009.Atthemomentthere are 19 participating zoos (in comparison to 8 in2000),withafewmoreonthewaitinglist.ThenumberofV. komodoensis inEuropeancollectionshasrisento42specimens,fromjust17in2000.Hence,thefutureof

the European V. komodoensispopulationmaynotbeasgloomyasitseemedtobejustafewyearsago.

References

Pether,J.andG.Visser.2007.TheFirstBreedingof KomododragonsasaResultoftheEuropean EndangeredSpeciesBreedingProgramme(E.E. P.).Mertensiella16.AdvancesinMonitor ResearchIII:430-440.Sunter,G.2008.Managementandreproductionofthe KomododragonVaranus komodoensis Ouwens 1912atZSLLondonZoo.London.International. ZooYearbook42:1-11.Velensky,P.2007.BirthsandHatchings.EAZANEWS 59:23.Visser,G.andR.Belterman.2000.EuropeanKomodo dragonstudbook.Rotterdam.RotterdamZoo.Walsh,T.,R.RosscoeandG.F.Birchard.1993.Dragon tales:thehistory,husbandry,andbreedingof KomodomonitorsattheNationalZoologicalPark. Vivarium4(6):23-26.Watts,P.C.,K.Buley,S.Sandersson,W.Boardman,C. CiofiandR.Gibson.2006.Parthenogenesisin Komododragons.Nature444:1021-1022.

No. Snout-ventLength(cm)

TotalLength(cm)

Weight(g)

1 17.5 41.1 852 18.0 40.3 853 17.5 42.5 904 14.5 39.0 70

Received:3 June 2009 ; Accepted: 8 June 2009

Appendix

Table1.Hatchlingmorphometrics.

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