Behavioral modifications in northern bearded saki monkeys (Chiropotes satanas chiropotes) in forest fragments of central Amazonia.

We investigated behavioral differences among seven groups of northern bearded saki monkeys (Chiropotes satanas chiropotes) living in five forest fragments and two areas of continuous forest at the Biological Dynamics of Forest Fragments Project study area, located approximately 80 km north of Manaus, Brazil. We collected data in six research cycles from July-August 2003 to January 2005-April 2006. When bearded saki monkeys were present in a study area, we followed the group from dawn until dusk for three consecutive days. Every 5 min, we conducted behavioral scans of all visible individuals. There was a positive relationship between forest size and group size, but animals in the small forest fragments lived at greater densities. Bearded saki monkeys in the smaller fragments spent more time resting, less time traveling, and less time vocalizing, but there was no relationship between forest size and the amount of time spent feeding. Our results indicate that the main behavioral differences among the groups are related to the amount of forest resources (e.g., fruit trees, space) available to the monkeys in the smaller fragments, as well as the resulting smaller group sizes. We stress the need to preserve large tracts of forest and provide connectivity between forest patches.

Home range estimates vary with sample size and methods.

Accurate estimates of a primate's home range are important, yet methods vary greatly. This paper examines the accuracy of minimum convex polygon (MCP), adaptive kernel (AK) and fixed kernel (FK) estimators by comparing home range estimates of northern bearded saki monkeys (Chiropotes satanas chiropotes) living in forest fragments and continuous forest in the Brazilian Amazon area. MCP was more accurate than AK and FK in calculating home and day range when sample size was small, and AK overestimated range most frequently. It is important to consider the various home range methods, as the appropriate method may depend on sample size and the species' behavioral ecology.