Distance influences the foraging decisions of emperor and saddleback tamarins


Júlio César Bicca-Marques, Pontifícia Universidade Católica do Rio Grande do Sul, Faculdade de Biociências, Av. Ipiranga 6681 Pd 12A, Porto Alegre, RS 90619-900, Brazil. Tel: 55-51-3320.3545 ext. 4742, Fax: 55-51-3320.3568


Studies on great apes, Old World monkeys, and New World monkeys suggest that anthropoid primates may retain a detailed spatial representation of the distribution of important food resources in their home range. This is evidenced by selecting the shortest travel routes between sets of feeding sites. In this research, I tested whether distance influences between-patch foraging decisions of free-ranging social groups of black-chinned emperor tamarins Saguinus imperator imperator and Weddell's saddleback tamarins Saguinus fuscicollis weddelli living in a 100-ha forest reserve (Zoobotanical Park of the Universidade Federal do Acre) located in Rio Branco, State of Acre, Brazil. Four artificial feeding sites (feeding stations) were established within the home ranges of one group of each species. They were distributed in a diamond configuration and located from 58 to 256 m from each other. Each feeding station was composed of eight feeding platforms (two of which baited with one banana). Data collection was conducted from 3 October to 28 November 1997 (54 days). To determine whether distance among feeding sites influences tamarin daily between-patch foraging decisions, it was recorded whether a group visited the nearest, intermediate or farthest station after departing from a particular one. The emperor tamarin group visited the feeding stations 207 times (average=3.8 visits day−1) and the saddleback tamarin group visited the feeding stations 265 times (average=4.9 visits day−1). After arriving at a feeding station, both species tended to choose the nearest station to visit and to avoid the farthest one at a frequency greater than chance, supporting the contention that these tamarins know the distribution and spatial relationships of their main food resources.