A case study of orangutan and siamang behavior within a mixed-species zoo exhibit

This empirical case study assessed the behavior and welfare of 2 orangutans (Pongo abelii) and 2 siamangs (Symphalangus syndactylus) within a mixed-species zoo exhibit. The study used instantaneous scan-sampling to record behavior, location, and interspecies proximity over 174 hr and all-occurrences data for any interactions between species. Results revealed frequent affiliative interactions between the female orangutan and siamang pair and an absence of agonistic or aggressive encounters. All individuals used the majority of the exhibit without segregation by species. Both orangutans spent most of their time on the ground (above 70% of all scans), and low levels of foraging were identified (1-4% of scans for all individuals). Overall, the findings support the notion that mixed-species exhibits may be enriching to the species involved through increased stimulation and opportunities for interaction. A poststudy incident also highlights the need for careful and continual monitoring of mixed-species exhibits over time.