View metadata, citation and similar papers at core.ac.uk brought to you by CORE provided by Kölner UniversitätsPublikationsServer SOCIAL RELATIONSHIPS IN CAPTIVE BORNEAN ORANGUTANS (PONGO PYGMAEUS) Inaugural Dissertation zur Erlangung des Doktorgrades der Mathematisch-Naturwissenschaftlichen Fakultät der Universität zu Köln vorgelegt von Dorothee Claßen aus Düsseldorf Köln 2011 Berichterstatter: PD. Dr. Thomas Ziegler (Gutachter) Prof. Dr. Ansgar Büschges Tag der mündlichen Prüfung: 20.10.2011 “…when you look into the eyes of the orangutans there comes this moment when you get goosebumps, when you realise you are looking into the eyes of a person” (Dr. Willie Smits) Front cover: female orangutan Lotti, Cologne Zoo; this side: female orangutan Sandy and her newborn Samboja, Stichting Apenheul (FAQ: drawings by Dorothee Claßen) Contents i CONTENTS 1. Introduction ...................................................................................................................1 1.1. Social life in primates ...............................................................................................1 Social structure and social relationships ..............................................................2 Social organisation...............................................................................................3 1.2. The orangutan, Pongo spp. .......................................................................................5 Status and distribution..........................................................................................5 Ecology ................................................................................................................6 Ranging behaviour ...............................................................................................7 Mating system......................................................................................................8 Social life .............................................................................................................8 Inter-species differences in social organisation .................................................11 Captive orangutans.............................................................................................12 1.3. Aim of the study .....................................................................................................13 2. Animals and Methods .................................................................................................15 2.1. Animals and keeping conditions.............................................................................15 Chester ...............................................................................................................16 Apenheul ............................................................................................................17 Cologne ..............................................................................................................18 2.2. Methods ..................................................................................................................20 2.2.1. Data collection.............................................................................................20 2.2.2. Ethogram .....................................................................................................22 2.2.3. Data analysis................................................................................................24 3. Results...........................................................................................................................27 3.1. Activity profiles......................................................................................................27 Non-social activities in proximity......................................................................28 Aberrant behaviours...........................................................................................30 3.2. Social behaviour .....................................................................................................31 3.2.1. Overview .....................................................................................................32 3.2.2. Dyadic interactions......................................................................................36 Female-female relationships ..............................................................................36 Male-female relationships..................................................................................42 Male-male relationship ......................................................................................47 Adult-juvenile relationships...............................................................................47 Juvenile-juvenile relationships...........................................................................55 3.2.3. Triadic interactions......................................................................................57 3.2.4. Long-term observations – Cologne .............................................................59 3.3. Spatial behaviour ....................................................................................................66 3.3.1. Interindividual distances..............................................................................66 Group average and sex-classes ..........................................................................66 Long-term observations – Cologne....................................................................68 3.3.2. Patterns of neighbourhood...........................................................................71 Nearest neighbour distance ................................................................................71 Proximity index..................................................................................................73 Sequence of neighbourhood...............................................................................75 Contents ii 3.4. Long-term sampling of behaviours.........................................................................76 3.5. Summary of results.................................................................................................81 4. Discussion.....................................................................................................................84 4.1. Sociability...............................................................................................................84 4.2. The structure of social relationships .......................................................................88 4.3. Fission-fusion tendencies........................................................................................93 4.4. General conclusions................................................................................................95 4.5. Future work.............................................................................................................97 5. Abstract ........................................................................................................................99 6. Zusammenfassung.....................................................................................................100 7. References ..................................................................................................................102 8. Appendix ....................................................................................................................113 9. Danksagung................................................................................................................123 10. Erklärung...................................................................................................................124 Contents iii TABLES AND FIGURES Tab. 2.1: Keeping conditions overview ................................................................................15 Tab. 2.2: Orangutans Chester Zoo ........................................................................................16 Tab. 2.3: Orangutans Stichting Apenheul.............................................................................17 Tab. 2.4: Orangutans Cologne Zoo.......................................................................................19 Tab. 2.5: Ethogram - behavioural categories and included elements ...................................23 Tab. 3.6: Frequency and duration of aberrant behaviours ....................................................31 Tab. 3.7: Interactions within female-female dyads...............................................................36 Tab. 3.8: Sociopositive interactions within female-female dyads ........................................38 Tab. 3.9: Agonistic interactions within female-female dyads ..............................................39 Tab. 3.10: Interactions within male-female dyads................................................................42 Tab. 3.11: Sociopositive interactions within male-female dyads .........................................43 Tab. 3.12: Agonistic interactions within male-female dyads ...............................................45 Tab. 3.13: Interactions within the male-male dyad...............................................................47 Tab. 3.14: Interactions within female-juvenile dyads...........................................................48 Tab. 3.15: Sociopositive interactions within female-juvenile dyads ....................................49 Tab. 3.16: Agonistic interactions within female-juvenile dyads ..........................................50