University of Tennessee, Knoxville TRACE: Tennessee Research and Creative Exchange Masters Theses Graduate School 12-2003 Object introduction, exploration, and play behavior in Black- throated monitor lizards (Varanus albigularis albigularis) Jennifer Diane Walton Manrod Follow this and additional works at: https://trace.tennessee.edu/utk_gradthes Recommended Citation Manrod, Jennifer Diane Walton, "Object introduction, exploration, and play behavior in Black-throated monitor lizards (Varanus albigularis albigularis). " Master's Thesis, University of Tennessee, 2003. https://trace.tennessee.edu/utk_gradthes/5259 This Thesis is brought to you for free and open access by the Graduate School at TRACE: Tennessee Research and Creative Exchange. It has been accepted for inclusion in Masters Theses by an authorized administrator of TRACE: Tennessee Research and Creative Exchange. For more information, please contact [email protected]. To the Graduate Council: I am submitting herewith a thesis written by Jennifer Diane Walton Manrod entitled "Object introduction, exploration, and play behavior in Black-throated monitor lizards (Varanus albigularis albigularis)." I have examined the final electronic copy of this thesis for form and content and recommend that it be accepted in partial fulfillment of the equirr ements for the degree of Master of Science, with a major in Ecology and Evolutionary Biology. Gordon Burghardt, Christine Boake, Major Professor We have read this thesis and recommend its acceptance: Accepted for the Council: Carolyn R. Hodges Vice Provost and Dean of the Graduate School (Original signatures are on file with official studentecor r ds.) To the Graduate Council: I am submitting herewith a thesis written byJennifer Manrod entitled "Object Introduction, Exploration, and Play Behavior in Black-throatedMonitor Lizards (Varanus albigularis albigularis)." I haveexamined the finalpaper copyof this thesis forform and content and recommend that it beaccepted in partial fulfillmentof the requirementsfor the degree of Master of Science, with a major in Ecologyand EvolutionaryBiology. Gordon Bur C4.-u�f>� C�) Christine Boake, Department Head We have read this thesis and -n I _, Object Introduction, Exploration, and Play Behavior in Black-throated Monitor Lizards (Varanus a/bigularis albigularis). A Thesis Presented forthe Master of _Science Degree The University of Tennessee,Knoxville JenniferManrod December 2003 DEDICATION This thesis is dedicatedto my husband, Matthew Manrod, greatsupporter and friend, my parents, RobertWalton and Gwen Walton, wonderful role modelsand guides, and the rest of my family,friends and coworkers, for always encouraging me, believingin me, and inspiring me to reachfor the stars, achieve my goals, and accomplishfeats I couldhave never imagined. ii ACKNOWLEDGMENTS I wish to thank all thosewho helpedme complete my Master of Science degree. First of all, I would like to thank Dr. Burghardtfor his guidanceand his effortin makingme familiarwith the scienceof animal behavior and the utilization of the Observe!® program and for chairing my thesis committee. I would alsolike to thankDr. Neil Greenbergwho helpedme beginthis journey and gaveme adviceand insightinto ethologyas well as servingon my thesiscommittee. Dr. Lou Gross was always available and patientand helpedin statistical and computingissues as well as servedon mycommittee. Dr. Sandy Echternachtprovided helpful editorial suggestions and alsoserved on my committee. Finally, I would like tothank Mike Oneil,of the StatisticalConsulting Center at TheUniversity of Tennessee,for his insightand guidancein the statisticsthat furthersupported this thesis. Lastly, I would like to thank the Dallas Zoo, especiallyRuston Hartdegan, whose dedicated staff made this workpossible. iii ABSTRACT It is widely accepted that providingstimulus enrichment and opportunitiesto play is an important partof the development and maintenance of behavior and well-beingin mammals. However, extending this idea to non-avianreptiles has barelybeen explored Observationsreported by scientists, zookeepers, and others,however, have suggestedthat non-avian reptiles can and do performsome formof play and explorationwith novelobjects and maybenefit from enriched environments. Varanids display several · advanced mammalian-likecharacteristics (i.e. physiology, life history, and prey discrimination) compared to other reptiles, and it is plausiblethat higher cognitivebehaviors are also present. It was hypothesized thatplay and exploratorybehaviors would beexhibited in the thesetrials and thatthe monitorswould react differentlyto eachstimulus. This study, basedon systematicvideotaped trials, analyzedthe behaviors of eight juvenile Black­ throatedmonitors, Varanus albigularis, in responseto an enriched environment. Two objects(food ball and food tube) and one social stimulus were introduced. Thefood ball allowed the monitors to see and smell, but not attain, the prey while the food tube allowedthe monitors to attain the prey through hinged doors. In the social introductions the monitors could seeand smell, but had no physical contact with, a consj:,eci:ficplaced in their home enclosure. After constructing a behavioralinventory based on the videotapes, the mean duration and mean occurrenceof various state and eventbehaviors were analyzed. There were many significantdifferences in the amount andtype of behaviorpatterns elicited (p<0.009)by the differenttypes of stimuli introduced. Responsesto the food ball exhibited the most change over time and primarily consistedof exploratoryand play-likebehaviors afterthe predatoryresponses decliined. However, this stimulus was presentedthe most times (10). Responsesto the foodtube were primarily predatorybehaviors and the lizards showed learning in openingthe tubeand capturing the preyby the second trial. Finallythe conspecificelicited social behaviors that were not seen in the other two treatments such as a rocking seesaw behavior. These results suggest theseanimals are interactive, discriminating, and exploratory. Thisstudy provides further evidencefor the needfor morein depthenrichment, specificallyobject introductions, in captive non-avian reptiles. The responsesseen in captivitycan lead us to reassess behavior reportedin wild monitors, as well as to lookfor more affiliative social behavior and novel foraging tactics. Due to the results of this and similar studies, serious consideration should be given to providing enrichment in captivesquamate reptilesin general, and large long-lived species in particular. iv TABLE OF CONTENTS Section Page I. INTRODUCTION 1 ImJ>Ortance of Enrichment ............ .......................... .... ............... ...... l Histocy ...... ......................... ...........-.. ..... .......................... 1 Previous Studies and Definitionof Enrichment ...... ... ............ ... ..... 2 ()t)jectIntrochictions ... .................. ......... ............ .................... 3 DefiningBehaviors ()t)served When Providing Enrichment .......................... 6 Criteria for Exploration and Play in CaptiveAnimals ..................... 6 II. NON-AVIAN REPTILE BEHAVIOR, EVOLUTION, AND PHYSIOLOGY 9 Non-avianRei,tile Play ............... ......... ........................ ............ ..... 9 Monitors .................................... ........ � ...................................... 9 Evolution and Life Histocy.. ................ ........................ ........ 10 SensocyCal)3bilities ... ........................ ...... ... ............... .. ...... 10 Physicaland BrainSize Variance .......................................... 11 Physiology ............ .. ....... ............ ... ................................. 11 Natural Histocy ... .................. ... ......... ...... ........... ............. 13 Current Study and GeneralPredictions .. .... ........... .... .. ............. .. ...... 14 CaptiveEnvironment ... ..................... ...... ...... ............... .... 14 Si:,ecies .:...................... .................................................. 15 Summacyof ExperimentalProtocol .......................... .............. 15 GeneralPredictions ....................................... ................... 16 Ill. METHODS .......................................................... ... ................. 17 Subjects ............ .................................................................. ..... 17 Housing and Maintenance.. ............. ............ .................................... 17 Procedure .......................................... ... ...... .............................. 18 ExperimentalDesign ........................... .. ............................ 18 ()l)jects Introd.uced ............................................................ 19 Data Analysis ...... ... ......... ... .. ............... ..................................... 22 Ethogram .................. ............ ............ ......... ...... ...... .. ... 22 Analysis.. ............................... .................. .................... 26 IV. RESULTS AND DISCUSSION ................................................... .. 29 ResJ>Onseto Different()t)jects .. .... ... ..................... ......... ... ... .............. 29 C>verallResJ>Onse ... ............................................. ............. 29 Comparisonof Behaviors Elicited ... ............ .......................... 32 Predictability ................................................................. 45 Habituation and Learning.. ... ...... ......... ........................................