Responses of Primates and Other Frugivorous Vertebrates to Plant Resource Variability over Space and Time at Gunung Palung National Park

Identifying patterns of primate diversity and abundance over space and time provides a window into the ecological processes that influence species distributions and community composition. Long-term studies of primate communities across multiple habitat types at small spatial scales are rare, yet can improve our understanding of habitat and resource use. Within primate community ecology, there has been recent interest in studying primate species in the context of the broader faunal communities of which they are a part because interactions with ecologically similar but distantly related species may influence habitat use. We present the results of a 64-mo study of 10 vertebrate frugivore species with highly overlapping diets inhabiting seven distinct forest types at the Cabang Panti Research Station, West Kalimantan, Indonesia. We used survey transects and phenology plots to measure variation in vertebrate population densities (four primate, three hornbill, two squirrel, and one pig species) and fruit resources over space and time. We found little evidence of habitat partitioning or specialization. Densities of all 10 frugivore species, however, varied spatially, due largely to elevation and forest structure. Ordination analyses demonstrated that forest types differed in their structure, floristic composition, plant phenology, and frugivore communities. We also documented substantial temporal variation in orangutan densities, reflecting movements over large spatial scales. The densities of other mammalian and avian frugivores, particularly other primates, varied comparatively little over time. Our results demonstrate the importance of forest structure for determining frugivore community structure and highlight the importance of lowland forest types for the conservation of tropical frugivores.