The seasonal feeding ecology of the javan slow loris (nycticebus javanicus).

OBJECTIVES: To describe the strategy employed by exudativorous primates during seasonal shifts in food abundance using the Javan slow loris as a model. Males and females may cope differently as well as exploit fallback foods in different proportions.

MATERIALS AND METHODS: Observing 15 free ranging Javan slow lorises over a year, we quantified their seasonal diet and nutrient intake using intake rates. For gum intake rates, we conducted a trial with 10 captive Javan slow lorises measuring the length of time it took for them to ingest 10 g of gum. We monitored phenology in our field site over five plots that were assessed monthly. We weighed our free-ranging animals every six months. We analyzed all food items slow lorises ingested for macronutrients using the nutritional geometry framework.

RESULTS: The slow loris diet consisted of eight food categories, with gum and insects being the major food sources in terms of wet weight intake. The captive gum trials resulted in an intake rate of 0.021 g/s. All food items eaten by wild Javan slow lorises were available in the wet season and were restricted in the dry season. Males and females reacted differently to seasonal abundances with females ingesting more protein, gum, fruits and flowers and males ingesting more fiber.

CONCLUSIONS: The strategy used by the Javan slow lorises during periods of lower food availability were similar to folivorous primates and included increased dependence on lower quality foods. The reproductive costs of gestation and lactation may place a burden on females that requires them to alter their foraging strategy during the dry season to ensure enough protein and overall energy is ingested. The overall strategy used by these exudativorous primates is one of nutrient maximization as no nutrient was clearly preferred over another.