Laurence Fedigan

Field methods for capture and measurement of three monkey species in Costa Rica.

A total of 54 free-ranging monkeys were captured and marked in Santa Rosa National Park, Costa Rica, during May 1985, and an additional 17 were captured during March 1986. The animals were darted using a blowpipe or a CO2 gun. The drugs used were Ketaset, Sernylan and Telazol. Ketaset was effective for Cebus capucinus but unsuccessful for Alouatta palliata and Ateles geoffroyi. Sernylan was successful for A. geoffroyi and A. palliata but is no longer commercially available. Telazol proved to be an excellent alternative capture drug for both A. palliata and A. geoffroyi.

Post-weaning resource competition and sex ratios in spider monkeys

In this study we examine the applicability of the resource competition hypothesis to explain both the existence of a skewed sex ratio in the spider monkey (Ateles spp.) where females disperse, and the variation in sex ratio among geographically separated sites and neighboring sites of varying productivity. The resource competition hypothesis would predict that when females disperse, animals should attempt to reduce the effect of intraspecific competition by limiting the number of male offspring produced by the community. This prediction is in agreement with the observed female biased sex ratio in spider monkeys. The observed variability in sex ratios between populations suggests that when the potential for post-weaning resource competition is high (i.e. in habitats with low productivity), the community will limit the production of the non-dispersing males more than in highly productive habitats. C. A. Chapman and L. J. Chapman, Dept of Biology, McGill Univ., Montreal, Quebec, Canada H3A IB1. L. M. Fedigan, Dept of Anthropology; and L. Fedigan, Faculte St. Jean; Univ. of Alberta, Edmonton, Alberta, Canada T6G 2E1.

A Demographic Model of Colonization by a Population of St. Kitts Vervets

Two sets of censuses by enumeration (1971, 1981) of an isolated population of vervet monkeys on the island of St. Kitts were used to construct a model of the population history of the group. From a co

Ecological and demographic influences on the pattern of association in St. Kitts vervets

A group of St. Kitts vervets (Cercopithecus aethiops) were observed to have an association pattern which involved the formation of spatially separated subgroups which were unstable in composition. Five types of subgroups are described which account for 94% of the associations observed. The size of the subgroups changed when the abundance and distribution of the available resources changed. Based on this observation and on an analysis of the diurnal patterning of subgroups, we suggest that the association pattern of the vervets is a response to the distribution of food resources and that it arose under specific demographic conditions.