Habitat loss is one of the greatest threats to extant primates, with effects that are immediate and time delayed. Identifying how habitat loss affects wildlife, particularly vulnerable populations, is important to understand the mechanisms that can lead to population decline. Golden monkeys are a subspecies of guenon with two extant populations: one larger (> 4000) on the Virunga Massif, and the other smaller (~200) in Gishwati Forest. Once connected, deforestation over five decades separated the forests of Volcanoes National Park (VNP) (on the Virunga Massif) and Gishwati Forest and decreased the total forest cover by 25 and 90 percent, respectively. It is likely that the golden monkey populations also decreased during that time. We examined how location (VNP vs Gishwati) and human contact (low vs. high) affected infection using records of parasites identified morphologically from feces. We assessed the effect of population or human contact (via crop foraging or distance to forest edge) and used a mixed model to explore if there was an interaction effect between population and human contact (i.e., distance to forest edge). Both populations had the same richness. Overall, the VNP monkeys had A higher prevalence of infection and higher rates of multiple infection and groups that foraged for crops or were near the forest edge had a higher prevalence of Capillaria infection. These results suggest that population density, forest edge permeability, and human presence outside the forest increase infection risk in golden monkeys. Further, they provide initial insights into parasite-based health risks for this endangered primate.
Johnston et al. (Fri,) studied this question.