Population density and vertical stratification of four primate species at the Estação Biológica de Caratinga/RPPN-FMA, Minas Gerais, Brazil

Abstract

In 2003, we carried out a line-transect sampling for all the primates (Alouatta guariba clamitans, Brachyteles hypoxanthus, Cebus nigritus, and Callithrix flaviceps) at the Estação Biológica de Caratinga (EBC) to estimate the sizes of their populations. Our goal was to examine whether the trend in population growth observed in the northern muriqui population was accompanied by similar trends in the other three species, or if there was a decline which could indicate the possible effect of competition with northern muriquis. In addition, we studied stratification to verify if the different species use the forest strata in different ways to avoid direct competition. We registered a total of 78 sightings of primates: 33 for A. guariba clamitans, 23 for C. nigritus, 18 for B. hypoxanthus and four for C. flaviceps. Our results indicated that A. guariba clamitans continued to be the most abundant primate at the EBC. Cebus nigritus and B. hypoxanthus occur at almost the same abundances, being half of that of brown howlers. Callithrix flaviceps is the least common primate in this forest fragment. Compared to previous studies, our census shows a decline in the abundance of howlers. This study confirms the prediction that larger primates use higher strata of the forest while smaller species move in the lower strata.