Orangutan Behaviour in Captivity: Activity Budgets
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O R A N G U T A N B E H A V I O UR IN C APT I V I T Y : A C T I V I T Y BUD G E TS, E N C L OSUR E USE A ND T H E V ISI T O R E F F E C T C H O O Y U A N T IN G B.Sc. (Hons.), NUS A THESIS SUBMITTED FOR THE DEGREE OF MASTER OF SCIENCE DEPARTMENT OF BIOLOGICAL SCIENCES NATIONAL UNIVERSITY OF SINGAPORE 2011 A C K N O W L E D G E M E N TS Just as I was thinking that my affair with the hairy creatures would never end, I finally found myself having to bid them farewell. The following thanks are kept brief, as no words adequately express the relationships between people. I had fun and much chance to grow during my research, and to everyone listed here, I hope I have made just a bit of difference in your life as well. As with any routine done regularly over time, one starts to develop what I call specialized quirks. Some people call them occupational hazards. Being in the unique situation of watching apes in a zoo setting, where I have both hairy as well as hairless ones to watch, I cannot help but draw comparisons between the two. During the first few months of watching orangutans, I started seeing orangutans everywhere I went. The way my dad sat with his leg up on the sofa looked like an orangutan. The way a stranger on the street scratched himself reminded me of a certain old orangutan in the zoo. The crowning touch came one day when after exiting the zoo washroom, I passed through a crowded restaurant on the way back to the orangutan exhibit. To my horror/amazement, I saw Bento, one of the 2 year old (orangutans) rolling around on the floor! How on earth did he get out, and there he was, frolicking in the midst of humans! I was stunned. But on taking a second look, I realized that it was actually a very tanned human child in an orange singlet, rolling around on the floor. That incident proved really hilarious, even to myself. Other humouURXVµVLGHHIIHFWV¶RIZRUNLQJLQWKH]RRIRUH[WHQGHGSHULRGs of time include hearing the zoo show jingle, IRUVRPHUHDVRQZKHQ,¶Pin the toilet. And once, I thought I heard the mating/territorial call of a mature male orangutan in my house. I wondered: Why is Charlie long-calling in my house?? The following thesis is a summary and analysis of my past months with these apes. They have brought me only fun, laughter and constant opportunities to self-introspect. On the other hand, the heartache and sweat came solely from the efforts of this human, to want to watch them in order to write a long report that humans call a thesis. For all of this, I am grateful, and would like to thank the following people. ii Dr Li, my ever present source of advice and support. Thank you for taking in the young and inexperienced girl back then, and nurturing her into the competent, confident researcher she is today. Dr Todd, my grammar master. Always ready to pick up where I have left off, and pushing me that extra step to do a better job. Thank you. Of course, with any captive animals, come their ever faithful keepers. Jack, Kumaran, Gabriel, Prakash, Md Noor, Arshad and Marzuki. I sincerely thank you for all you have taught me and I hope your lives have been at least somewhat enriched, E\WKHJLUOZKRLVµDOZD\VORRNLQJXSLQ WKHVN\¶7R&KDUOHQH6DPDQG-RKQ7KDQN\RXIRUDOOWKHVXSSRrt and advice you have given me, I have really enjoyed knowing you! Eunice. I felt that choosing to go on with Masters, rather than working after my B.Sc, was made in part worthwhile because I got to know you ^^ My labmates ± with them, I understand why humans are truly social creatures. Even the intensely focused task of analyzing data or writing a thesis reTXLUHVFRPSDQ\VRPHWLPHVDQGZKR¶V company better to revel in, than those of my ever fun, ever game fellow researchers. Thank you Huishan, Diego, Stanley, Junhao, Seok Ping, Shichang, Mindy, Joelyn, Ganison and my other Spider Lab colleagues who make me look forward to going to lab. Giam, Dr Chan Yiong Huak, Kia Chong, Yangchen and Lainie. Thank you for your invaluable statistical advice and comments on my project. My father, who paces me both in life, and as a researcher. He, who I must attribute much of who I am today to. My family, always supportive, despite my regular crankiness. Thank you. And last but definitely not least, myself. ,GLGLW<D\*RRGMRE<XDQ7LQJ\RX¶YHGRQH\RXU best and grown lots through this experience. Well done. And to you, dear reader, I hope you enjoy the following account of my time spent with the hairy, as well as not so hairy apes of the Singapore Zoo. iii T A B L E O F C O N T E N TS Page Acknowledgements ii Table of Contents iv Summary vii List of Tables ix List of Figures x Chapter 1: General Introduction 1 Orangutans 1 Zoos then, and now 4 Singapore Zoo 6 Study objectives 8 Chapter 2: Activity Budgets of O rangutans in Two Naturalistic 11 Enclosures and Comparisons to Wild O rangutans Introduction 12 Materials and Methods 15 Results 23 Overall activity budgets and activity budgets across age groups 23 Comparing activity budgets across enclosures 27 Comparing captive to wild activity budgets 28 Discussion 29 Comparing activity budgets across age groups 29 Comparing activity budgets across enclosures 31 Comparing captive to wild activity budgets 33 Recommendations 37 iv Chapter 3: Use of Enclosure Structures and Vertical Space 39 in Two Naturalistic O rangutan Exhibits Introduction 40 Materials and Methods 44 Results 50 Overall structure use 50 Structure use across age groups in both exhibits 51 Behaviours at each structure type 53 Use of vertical space in enclosure 56 Discussion 57 Use of enclosure structures across age groups and exhibits 57 Behaviours at each structure type 61 Use of vertical space in enclosure 64 Limitations of study 67 Recommendations 68 Chapter 4: Visitor effects on zoo orangutans in two novel, naturalistic 71 enclosures Introduction 72 Materials and Methods 76 Results 82 Effect of visitors on orangutan behaviour in the Boardwalk exhibit 83 Effect of visitors on orangutan behaviour in the Island exhibit 83 Discussion 87 Effects of visitor number 87 Effects of visitor activity 88 Effects of visitor proximity 90 Other influences on the visitor-animal interactions 91 Limitations of study 92 Recommendations 96 v Chapter 5: General Discussion 98 Common factors across the three chapters 99 Recommendations on enclosure design 102 Recommendations on husbandry routine 104 Other considerations and recommendations 106 Study limitations and future directions 109 References 111 Appendix 124 vi SU M M A R Y Orangutans are great apes that are found in the forests of Borneo and Sumatra. In the wild, they live in complex rainforest habitats, and travel great distances daily for food. As a result of habitat destruction and poaching, these apes are now endangered. In captivity, orangutans become obese if not provided with sufficient arboreal stimulation. They are also known for their intelligence, and keeping them mentally occupied is a challenge. For captive orangutans, little is known about their activity budgets, enclosure use and how zoo visitors affect them. Hence, more knowledge is required to maintain the welfare of these intelligent apes. In zoos, there is a current and ongoing interest for naturalistic exhibits, as such exhibits may provide greater stimulation for captive animals. Using features such as vegetation and rockwork, naturalistic enclosures are designed to increase species-specific behaviours by simulating wild habitats. Such exhibits have also been found to improve visitor appreciation of captive animals. In Singapore Zoo, the presence of two naturalistic orangutan exhibits provides the chance to study the behaviour of this ape in such enclosures. Hence, the activity budgets, enclosure use, and visitor effects on Singapore Zoo orangutans were investigated. The results showed that captive orangutan activity budgets were age-specific, differed across enclosures, and were not dissimilar from that of wild orangutans. Exhibit use was influenced by both biological and environmental factors. Biological factors included age and dominance hierarchy in orangutans, and environmental factors included the availability and arrangement of structures within an exhibit, as well as features surrounding the exhibit. For visitor effects, large crowds, visitors with food, visitors who were looking or taking photographs, and visitors who were close by, all affected orangutan behaviour. On the whole however, the effects of visitors on vii RUDQJXWDQVLQ6LQJDSRUH=RR¶VHQFORVXUHVZHUHOHVVHUWKDQK\SRWKHVL]HGInterestingly, possible sources of visitor stress appeared to be alleviated by the large, naturalistic enclosure designs and the unusual husbandry routines implemented at Singapore Zoo. Being the first study on structure use in a naturalistic orangutan exhibit, and amongst the few existing studies on orangutan activity budgets and visitor effects, this research provides useful information for zoo management, and sets possible direction for future studies. viii L IST O F T A B L ES Table 2.1. Individual details of study animals. 20 Table 2.2. Definitions for orangutan behaviours. 20 Table 3.1. Individual details and age groups of study animals. 49 Table 3.2. Definitions for orangutan behaviours. 49 Table 4.1. Individual details of study animals. 78 Table 4.2. Definitions for orangutan and visitor variables. 79 Table 4.3. Definitions and levels of variables for multinomial logistic regression 81 Table 4.4.