Variability in habitat, diet, and social structure ofHapalemur griseus in Ranomafana National Park, Madagascar

Abstract

This study investigated the effects of habitat on the diet, population density, and social structure of a small-bodied folivore, Hapalemur griseus. Three groups of H. griseus were followed at two study sites (Tala and Vato) within Ranomafana National Park in southeastern Madagascar. These two sites differed in degree of habitat disturbance, forest composition, and forest structure, as determined by botanical plots (50 x 10 m) which were monitored twice monthly in the home ranges of three study groups (group T, n = 4; group V1, n = 4; group V2, n = 2). Tala has experienced more habitat disturbance compared to Vato, and this appeared to influence population density and group size. The H. griseus that inhabit Tala occur at much higher densities and in larger social groups than the H. griseus at Vato. These results may be attributable to: 1) a greater number of potential food sources, 2) a more dense resource base, and/or 3) higher-quality resources at Tala for this folivore. In general, dietary diversity for all groups was low, and groups exploited similar plant species. However, within this small range of food sources, each study group specialized in food sources found in the highest abundance within their home range. This resulted in dietary differences between groups within sites, as well as differences between sites. Introduced tree species such as Chinese guava (Psidium cattleyanum) may have greatly impacted the diet and social structure of those groups at Tala, whose home ranges included this food source. In contrast, Vato group 1 ingested more new and mature leaves of Ficus spp., and Vato group 2 primarily ate spider bamboo (Nastus elongatus). In conclusion, it seems that microhabitat differences, which may be related to habitat disturbance and/or other factors such as topography, influenced the food species ingested by H. griseus. Overall habitat quality, which is likely also affected by habitat disturbance, influenced general diet, population density, and group size.

Maximum ingested food size in captive anthropoids

“…Propithecus and Hapalemur have relatively short faces, short jaws, partial symphyseal fusion, and dental features associated with breakdown of highly-resistant foods like leaves, stems, and seeds (Richard, 1978;Beecher, 1979;Ravosa, 1991;Grassi, 2006;Irwin, 2006;Vinyard et al, 2008). These features likely represent an adaptive suite for processing tough and/or high-yieldstrength foods that require great bite forces and/or many chews to process.…”

Plant foods consumed by Pan: Exploring the variation of nutritional ecology across Africa

“…If consumers experience equal gains in spite of variation in ecology, one would expect to observe differences in population density and resource competition. Evidence for habitat-related variation in the social behavior of neighboring groups with overlapping home ranges comes from studies on lemurs and colobus monkeys (e.g., Curtis, 2004;Grassi, 2006;Harris and Chapman, 2007). Comparing data on social organization, activity budgets, and diet composition from a large number of savanna baboons, Kamilar (2006) found that variation of diet composition among geographically separated subspecies did not exceed variation within subspecies.…”

Variation in diet and ranging of black and white colobus monkeys in Kibale National Park, Uganda

“…Species that show high dietary variability within or between sites, e.g., blue monkeys {Cercopithecus mitis; Lawes 2002), might be able to cope better with habitat alterations than species with a narrowly focused diet (e.g., bamboo lemurs; Grassi 2006). Documenting such variation can help identify which food species or nutritional components are most and least essential•information that may be useful for decisions concerning conservation strategies, including reforestation.…”