Size groups and population density of primates in the Crystalline region, Southern Brazilian Amazon

Abstract

The Cristalino region is located in northern Mato Grosso and it is a priority area for conservation in southern Amazon. Our goal was calculate the average size of the group of primates and estimate population density of primates in the conservation units: the Private Natural Heritage Reserves Cristalino, Lote Cristalino, and the Cristalino State Park, totaling 184,900 ha. Field work took place from May 2008 to February 2010 using distance sampling in line-transects, totaling 361.3 km. We recorded seven species of primates, three of them had their densities estimated. The Tuffed capuchin Sapajus apella (Linnaeus, 1758) was the most abundant species (density - D = 5.27 groups/km2; confidence interval - CI = 4.11 - 6.75), but there was not difference between the densities estimated of the groups of White-cheeked Spider Monkey Ateles marginatus É. Geoffroy, 1809 (D = 1.39 group/km2; CI = 0.91 - 2.11), and White-nosed Saki Chiropotes albinasus (Geoffroy & Deville, 1848) (D = 1.03 group/km2; CI = 0.62 - 1.72). The biggest average sizes of groups were obtained for White-nosed Saki (12.14 individuals; standard deviation - SD = 4.00), Tuffed capuchin (7.67 individuals; SD = 5.48) and White-cheeked Spider Monkey (6.86 individuals; SD = 3.63). Our results demonstrate that Cristalino’s region is an important refuge area for primate species in southern Brazilian Amazon.