Distribution of a folivorous lemur in relation to seasonally varying food resources: integrating quantitative and qualitative aspects of food characteristics.

The goal of this study was to assess the relative importance of food availability and its quality for the spatial distribution of a folivorous lemur species, Lepilemur ruficaudatus, from the highly seasonal dry deciduous forest of Madagascar. Males and females of this species showed opposite changes of body mass and body condition during the dry and the wet season. Male body mass declined during the dry season that coincides with mating, while female body mass remained constant. During the wet season that coincides with lactation, female body mass declined but male body mass increased. This indicates that changes in body mass are not linked as much to environmental seasonality as to mating and reproduction. The distribution of L. ruficaudatus was most significantly related to the spatial distribution of leaf protein during the wet season. Neither the availability nor the chemical composition of leaves eaten during the dry season affected the spatial distribution of L. ruficaudatus. These findings are consistent with hypotheses that constraints are most severe during the times of lactation and weaning and that distributions of primates reflect their food requirements in order to optimize their reproductive success. They are inconsistent with the idea that the lean dry season is the most stressful time of year for lemurs in energetic or nutritive terms.