Predatory behavior of crowned hawk-eagles (Stephanoaetus coronatus ) in Kibale National Park, Uganda

Abstract

Evaluating the nature and significance of preda- tion on populations of wild primates has been difficult given a paucity of data regarding the phenomenon. Here we addressed this problem in a 37-month study of the pre- datory behavior of crowned hawk-eagles living at the Ngogo study site in Kibale National Park, Uganda. We collected prey remains underneath the nests of two pairs of eagles and census data on potential prey species to in- vestigate prey selection and the ecological impact of predation on the Ngogo primate population. Results indi- cate that primates form the vast majority of all prey items. Eagles prey selectively on monkeys according to sex and species. Male primates were taken more often than fe- males, while two species, redtail monkeys and manga- beys, were captured significantly more and less, respec- tively, than chance expectation. In addition, there was no bias in the age of prey: adult and non-adults were killed in numbers roughly equal to their proportional representa- tions in the forest. Further analyses indicate that a non- trivial fraction of the entire primate population at Ngogo succumbs to crowned hawk-eagle predation each year. These results reveal both parallels and contrasts with those reported previously. Some of the parallels are due to simi- larities in prey availability, while contrasts are likely relat- ed to methodological differences between studies, inter- individual variations in predator hunting styles, and differ- ences in prey abundance, demography, and behavior.