High flexibility in diet and ranging patterns in two golden monkey (Cercopithecus mitis kandti) populations in Rwanda

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.

Diverse diets and low‐fiber, low‐tannin foraging preferences: Foraging criteria of Tibetan macaques (Macaca thibetana) at low altitude in Huangshan

“…found that they also adjust their diet based on habitat and food availability (Tuyisingize et al, 2021). Previous studies have defined Tibetan macaques as folivore primates (Thierry, 2007;Wang, 2008;Zhao, 1996), but the findings of the current study provide a different perspective.…”

Distribution and conservation status of the golden monkeyCercopithecus mitis kandtiin Rwanda

“…Group sizes and densities in each study population probably reflect differences in resource availability at the different sites. The Gishwati population is mainly frugivorous, whereas the Volcanoes National Park population is mainly folivorous (Tuyisingize et al, 2021). Differences in the spatial and temporal distribution of key food types may drive the differences in group sizes and densities between the sites (Clutton-Brock & Harvey, 1977; Twinomugisha et al, 2007).…”

Food availability influences birth seasonality at a small spatial scale in endangered golden monkeys (Cercopithecus mitis kandti)

“…The VNP bamboo zone hosts larger groups compared to the Gishwati forest (Tuyisingize et al, 2021). In particular, the density of the terrestrial herbaceous vegetation in the Gishwati forest is lower than in VNP, which likely translates into a higher detection of mating events in group G compared to groups M and K. Our personal observations also show that the terrestrial vegetation is denser in group M's range compared to group K's, which could also explain why our estimated relative mating rate is higher in group K than in group M. However, this detection bias may not explain all the differences in relative mating rates that we observed among groups.…”

“…Both VNP groups had relatively small home range sizes of 0.25 km 2 for group M, 0.91 km 2 for group K, and a narrow elevational range (235 m for group M and 120 m for group K). The Gishwati group had also a narrow elevational range (264 m), with a home range size estimated to be 1.5 km 2 (Tuyisingize et al, 2021).…”

“…Overall, the forest cover was reduced by 50% in VNP and by 98% in the Gishwati forest (Nyandwi & Mukashema, 2011; Plumptre et al, 2001; Spinage, 1972). Golden monkeys have a flexible diet, which allows them to use different types of habitat and food resources (Tuyisingize et al, 2021). In VNP, golden monkeys range almost exclusively in the bamboo ( Oldeania alpina ) forest where fruit trees are absent (Stapleton, 2013; Tuyisingize et al, 2022).…”