Abundance, use of space, and activity patterns of white-faced sakis (Pithecia pithecia) in French Guiana

White-faced sakis (Pithecia pithecia) are among the least studied neotropic al primates. The combination of shy and quiet behavior, their ability to mo ve silently, and the extreme difficulty of capturing them may explain why v ery few field studies have been undertaken in undisturbed habitats. During the course of a wildlife rescue in French Guiana, six individuals were capt ured and translocated to a safe area of primary rainforest. In this area, b ased on the observation of 35 groups, the average group size was 2.3 animal s (SD = 1.2) and a density of 0.28 group/km(2) (0.64 individuals/km(2)) was estimated from transect censuses. Our study focused successively on three radio-collared animals (two males and one female) over a 287-day period, st arting from release to the loss of the animal. From the study start, the tr iangulation method was used prior to habitutation to human presence, follow ed thereafter by 1,327 hr of visual monitoring. The translocated animals se ttled down, and two of them had a stable and compact home range. Two of the m merged in association with members of the resident population. A resident group had a much larger home range than previously reported: 148 and 287 h a, using grid cells and 100% minimum convex polygon techniques, respectivel y. A group composed of two translocated individuals (one male and one femal e) had a home range of 68 and 135 ha using the same techniques. Additionall y, two solitary animals used 152 and 162 1-ha quadrats. We observed animals (translocated and residents) moving quickly in one direction up to 11.5 ki n. The mean daily path length of resident animals was 1,880 m. Sakis used t he lower strata of the forest more when in group, and the intermediate stra ta more when solitary. Allogrooming is fairly common in social groups. On a verage, the activity period ranged from 7:17 to 15:59 hr. (C) 2001 Wiley-Li ss,Inc.