Slow loris (Nycticebus borneanus) consumption by a wild Bornean orangutan (Pongo pygmaeus wurmbii)

Abstract

Vertebrate predation and consumption by wild Bornean orangutans (Pongo pygmaeus spp.) is rare. In contrast to recorded observations of slow loris consumption by Sumatran orangutans (Pongo abelii), no cases of this have been previously published for Bornean orangutans in the wild. In 2017, we observed the capture and consumption of a slow loris (Nycticebus borneanus) by an adult unflanged male Bornean orangutan at Tuanan Orangutan Research Station, which is located in the Kapuas region of Central Kalimantan. The unflanged male was together with an adult female and her 3.5-year-old offspring throughout the event. However, despite the mother and her offspring watching the male closely and occasionally begging while he consumed the loris, he resisted all food-taking attempts. This study reports, to the best of our knowledge, the first documented case of slow loris predation and consumption by a Bornean orangutan, and thus provides an important data point for understanding primate predation on other primate species.

Slowly Making Sense: A Review of the Two-Step Venom System within Slow (Nycticebus spp.) and Pygmy Lorises (Xanthonycticebus spp.)

“…Both birds of prey and orangutans are known but infrequent predators of slow lorises. There are only 15 documented predation events of Sumatran orangutan ( Pongo abelii ) in the Gunung Leuser National Park, northern Sumatra, Indonesia on N. coucang [ 121 , 122 , 123 ] and one record of predation by a Bornean orangutan ( P. pygmaeus ) at the Tuanan Orangutan Research Station, Central Kalimantan, Borneo, Indonesia on N. borneanus [ 123 ]. These attacks all occurred in the day, when slow lorises sleep curled up tightly in a ball.…”