Primate species richness in relation to habitat structure in Amazonian rainforest fragments

Abstract

Factors affecting species richness in fragmented habitat are often of interest to conservation programs. Groups of red howler monkeys Alouatta seniculus, white-faced sakis Pithecia pithecia and golden-handed tamarins Saguinus midas occurred in five small (approx. 10 ha) fragments of Amazonian rainforest. However, not all of these species occurred in every fragment. The purpose of this study was to identify some of the factors affecting the number and distribution of primate species among these areas. To determine whether habitat structural diversity influenced primate species richness, height, diameter at breast height (DBH) and number of trees, DBH and number of lianas (woody vines) as well as height and number of palms in 15 20 × 20 m quadrats in each fragment were recorded. Also, height and number of secondary growth plants surrounding reserves were sampled. Structurally 'complex' reserves had high mean number of trees, high mean number of lianas, low mean percentage large trees (> 10 cm DBH) per quadrat, and streams. These characteristics were correlated with high species richness. P. pithecia occurred in the most structurally 'complex' fragments, S. midas in fragments surrounded by relatively tall secondary growth and A. seniculus in all five fragments. The relationships between the habitat requirements of the three species and their occurrence in these fragments are discussed. © 1989.