Regurgitation and reingestion in zoo-housed orangutans
Abstract
Regurgitation and reingestion (R/R) is when an animal voluntary moves food from the stomach and back to the mouth, hands, or floor. This is regarded as an abnormal behaviour in captive-housed orangutans. This type of behaviour is more extensively researched in gorillas and chimpanzees, there is however a paucity of studies on this topic in orangutans. This knowledge is important to improve health and welfare in captive orangutans and is therefore crucial to study and extend our understanding about this behaviour. This study aimed to find individual, dietary and stress related factor that may influence the amount of R/R seen in zoo-housed orangutans.
The methods applied included a combination of observations by me, the zookeepers at Kristiansand zoo and a survey sent out to multiple zoos around the globe. Direct observations were done in both Kristiansand zoo and in Toronto zoo over a live streaming. The results of this project show no association between age, species and R/R. Male orangutans did however exhibit a numerically higher amount of R/R than the females. Activity or foraging were not associated with occurrence of R/R either, similarly to browse. When the orangutans had access to the outside exhibit there were significantly less regurgitation, than when they only had access to the inside exhibit. The effect of diet is usually the most discussed trigger of R/R, my results did however indicate no association between the different diets and the number of R/R. This study did find a correlation between R/R and the number of visitors, where more visitors resulted in less R/R. In conclusion, during this study the only factors that seemed to influence R/R were individual preferences, sex, number of visitors and outside access.