Assessment of Abnormal Behaviour and the Effect of Enrichment on Captive Chimpanzees in Aalborg Zoo

Anne-Marie Olsen, Henriette Gamborg Kristensen, Kasper Weidick Iversen, Nicklas Halby Pedersen, Cino Pertoldi, Aage Kristian Olsen Alstrup, Trine Hammer Jensen, Sussie Pagh


Studies have suggested that chimpanzees and other primates in captivity tend to develop abnormal behaviours if they are housed without proper enrichment. The purpose of this study was to get a better understanding of the behaviour of chimpanzees in captivity in Aalborg Zoo, Denmark. This was done by examining whether the individuals displayed abnormal behaviour and whether the enrichment provided would affect the display of abnormal behaviour and other examined behaviours. Furthermore, it was assessed whether the age of the chimpanzee would affect the amount of time spent on enrichment. The assessed behaviours were abnormal, passive, play, climbing, walking and/or running, foraging, food and water ingestion, grooming another, receiving grooming, mutual grooming, and self-grooming, while enrichment included a mirror, televisions, toys, and balls. The chimpanzees were recorded for 20 hours over the course of 5 days in the control week, and 20 hours over the course of 5 days in the enrichment week in autumn 2019. The results showed that the enrichment provided did not lead to any significant change in the behaviours observed in the four chimpanzees. The results also showed that all chimpanzees displayed abnormal behaviour, but also that none of the observed chimpanzees interacted significantly more with the enrichment, based on age. It could be concluded that none of the four different types of enrichment had any significant effect on the observed behaviours. The study shows that it is important to evaluate the effects of new enrichments.


chimpanzee; Pan troglodytes; behaviour; enrichment; captivity; behavioural instability

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