This grant permits Dr. Robinson to continue his study of wedge- capped capuchin monkeys (Cebus olivaceus). For the past eleven years Dr. Robinson and his colleagues have collected data - some with NSF support - on groups of capuchin monkeys which inhabit the dry tropical forest of central Venezuela. Over a two year period Dr. Robinson and a student will collect a wide range of data on four of these monkey groups. Because of past research all individuals have been identified and their maternal geneologies are well known. The team will continue to collect demographic data and monitor reproductive success, mortality patterns and dispersal of individuals among the groups. They will also focus on social interactions and note both positive behaviors (such as social grooming) as well as antagonistic actions (threats, chases etc). They will also note relationships between individual animals and determine the extent to which actual genetic relatedness serves to explain observed variation. The goal of the research is to understand the factors which determine capuchin social structure. This particular field situation is an interesting one because the four groups under study vary greatly in size and a protocol of between group comparison offers a potentially valuable approach. As a species wedge-capped capuchins are interesting because they provide a unique comparison with similar studies of Old World species. Like them, it is arboreal and groups have a single breeding male. However its demographic patterns are strikingly different: mortality rates are low, fecundity rates high, sexual maturation is very delayed in males and patterns of dispersal ensure significant inbreeding. This research is important because it will increase our understanding of how social groups are organized and maintained. Scientists have proposed a number of theories: some are based on demographic factors, others on kinship and genetics. Cross species comparison offers a powerful tool to approach this question and it is within this context that the significance of Dr. Robinson's work lies. Also, it is only through long term multi-generational studies that such factors are most clearly revealed and it is important to continue Dr. Robinson's longitudinal work. Many tropical primate species are endangered and it is important to do such research now.
