High flexibility in diet and ranging patterns in two golden monkey (Cercopithecus mitis kandti) populations in Rwanda. Issue 1 (23rd November 2021) - Tuyisingize, Deogratias
Abstract: Many primates exhibit behavioral flexibility which allows them to adapt to environmental change and different habitat types. The golden monkey ( Cercopithecus mitis kandti ) is a little‐studied endangered primate subspecies endemic to the Virunga massif and the Gishwati forest in central Africa. In the Virunga massif, golden monkeys are mainly found in the bamboo forest, while in the Gishwati forest they live in mixed tropical montane forest. Here we describe and compare the diet of golden monkeys in both fragments. Over 24 consecutive months from January 2017 we used scan sampling to record feeding and ranging behavior of two Virunga groups and one Gishwati group totaling ca. 240 individuals. We also examined the phenology of bamboo and fruit trees, key seasonal food plant species for the monkeys. Golden monkeys fed on more than 100 plant species. The Virunga groups were mostly folivorous (between 72.8% and 87.16% of the diet) and fed mostly on young bamboo leaves and bamboo shoots, while 48.69% of the diet of the Gishwati group consisted of fruit from 22 different tree and shrub species. Bamboo shoots and fruit are seasonally available foods and were consumed regularly throughout the period when they were available. Despite being the smallest of the three study groups, the Gishwati group had a larger home range area (150.07 ha) compared to both Virunga groups (25.24 and 91.3 ha), likely driven by the differences in availability and distribution of fruit and bamboo in the habitats. Like other blue monkey subspecies, golden monkeys appear to have a flexible dietary strategy enabling them to adjust diet and ranging behavior to local habitats and available food resources. Additional studies and continuing conservation efforts are needed to better understand how variation in feeding and ranging ecology affects reproduction, population growth, and carrying capacity. Abstract : Great dietary flexibility enabled Endangered golden monkeys to adapt to the different foods available in two remnant isolated forests, the Virunga massif where they are mainly found in the bamboo forest and Gishwati‐Mukura National Park, a mixed montane forest. Research highlights: Great dietary flexibility enabled golden monkeys to adapt to a folivorous diet dominated by bamboo leaves and shoots in the fruit‐scarce forest of Volcanoes National Park, and a frugivorous diet in Afromontane forest of Gishwati, in Rwanda. Golden monkey ranging strongly related to diet: the smaller, mainly frugivorous group in Gishwati forest had a larger home range size than both larger groups with folivorous diets in Volcanoes National Park. Conservation efforts for this Albertine Rift endemic and Endangered primate are essential to protect both populations in Rwanda, where habitat loss and illegal human activities persist, and a reduction of bamboo regeneration has been documented.