摘要:

Most cercopithecines reproduce on a seasonal basis, but the proximate mechanisms influencing birth periodicity are often unclear. We analyze 10 years of data from the Gilgil Baboon Project (Kenya) in order to examine the relationship between annual birth patterns and rainfall. Savanna baboons at Gilgil copulated in all months of the year, and births did not occur on a seasonal basis. Annual rainfall patterns showed no association with annual birth patterns, but the chances of conception were significantly greater following the end of the long rainy season than at other times of the year. Nonseasonal reproduction is a general characteristic of savanna baboons (Pαpio cynocephalus subsp.) throughout Africa. The extreme dietary diversity of baboons enables them to utilize a wide variety of resources and facultatively manipulate the timing of different stages in the reproductive cycle in accordance with resource availability. We predict that nonseasonality of reproduction will be more likely to occur among species with a large dietary diversity than among species with a more restricted diet

ISSN:0015-5713    

DOI:10.1159/000156738

出版商:S. Karger AG    

年代:1993

数据来源: Karger

摘要:

Data are presented on group dynamics in a wild population of the common marmoset, Callithrix jacchus, in northeastern Brazil. Three marked and habituated groups were observed, and composition noted, for at least 5 days a month over 12–18 consecutive months. Group sizes ranged from 5 to 15 individuals, and changes in group composition were the result of births, emigrations, and disappearances. No immigrations into the main study groups were observed throughout the study period. None of the three known emigrants was known to join an established or incipient group for up to 10 weeks after their departure. One group contained only breeding individuals and their offspring. Observations of recruitment and loss in the other two groups suggest that they, too, were extended family groups. The group dynamics described in studies of other populations of Callithrix suggest that extended family groups, or at least groups consisting of breeding individuals and their close relatives, may be characteristic of those population

ISSN:0015-5713    

DOI:10.1159/000156739

出版商:S. Karger AG    

年代:1993

数据来源: Karger

摘要:

Habitats, population densities and group sizes of 5 primate species (Callithrix flaviceps, Callicebus personatus personatus, Cebus apella nigritus, Alouatta fusca clamitans, and Brachyteles arachnoides) were estimated, using the method of repeated transect sampling, in an area of montane pluvial forest in eastern Brazil (Atlantic forest). A. fusca and C. apella had the highest densities in terms of groups and individuals per square kilometer, respectively, while B. arachnoides was least abundant. The highest primate densities were observed in areas of secondary vegetation. Both group sizes and population densities for the 5 species were generally lower at the Reserva Biologica Augusto Ruschi than those reported in other areas of Atlantic forest. Hunting pressure and the different carrying capacity of the habitat are suggested as possible causes for the low number of sightings registered for these species.

ISSN:0015-5713    

DOI:10.1159/000156740

出版商:S. Karger AG    

年代:1993

数据来源: Karger

ISSN:0015-5713    

DOI:10.1159/000156741

出版商:S. Karger AG    

年代:1993

数据来源: Karger

ISSN:0015-5713    

DOI:10.1159/000156742

出版商:S. Karger AG    

年代:1993

数据来源: Karger

ISSN:0015-5713    

DOI:10.1159/000156743

出版商:S. Karger AG    

年代:1993

数据来源: Karger

ISSN:0015-5713    

DOI:10.1159/000156744

出版商:S. Karger AG    

年代:1993

数据来源: Karger

ISSN:0015-5713    

DOI:10.1159/000156745

出版商:S. Karger AG    

年代:1993

数据来源: Karger

ISSN:0015-5713    

DOI:10.1159/000156746

出版商:S. Karger AG    

年代:1993

数据来源: Karger