Food partitioning among Malagasy primates.

Food partitioning among lemurs was studied in relation to food patch size and plant chemistry in the eastern rainforest and a western deciduous forest of Madagascar. Patch size (i.e. crown diameter of food trees) is significantly correlated with group body weight of different lemur species. But intraspecific variability is high and prevents effective species separation. Chemical analyses of more than 400 plant parts eaten by seven different lemur species revealed major differences in their food choice with respect to protein concentrations, condensed tannins and alkaloids. Among the leaf eating lemurs discriminant analysis segregates three groups à two species based on chemical characteristics of their food. Whereas differences in food chemistry are pronounced between groups they are lacking between the two species within each group. The two species of each group avoid interference competition by different activity rhythms. Actual competition for slowly renewable resources such as leaves and fruit, however, can not be reduced by different activities. Here interspecific differences in gross categories of food, food species composition and different habitat utilization due to other constraints may contribute to the possible coexistence of species. Thus interspecific differences in food selection in relation to primary and secondary plant chemicals is an integrated part of the mechanisms allowing several primate species to coexist in sympatry.