New ecological information on the little-known Sumatran endemics Black-and-white langur Presbytis bicolor Aimi & Bakar, 1992 (Primates: Cercopithecidae)

Abstract

Black-and-white langur Presbytis bicolor Aimi & Bakar, 1992 is a rare endemic leaf-eating monkey that occurs only in a limited distribution between the Indragiri River and Batanghari River, Sumatra, Indonesia. In this paper, we summarize historical records of P. bicolor, put the distribution records into the map (including new localities, but still in geographic range), and provide new additional pieces of information on its ecology. We collected all published and unpublished of our observations on P. bicolor from January 2016 to April 2022. Our findings suggest P. bicolor can tolerate and survive in the degraded forest habitat, particularly in areas where rubber plantations are present. It was confirmed that P. bicolor fed leaves of Para rubber tree Hevea brasiliensis (Euphorbiaceae) and Mango Mangifera sp (Anacardiaceae); and it was reported that they also fed various plants. No indications of hunting or illegal collecting for the pet trade, but the mortality due to electrocution from power lines and road accidents have been detected and confirmed for this species