Group size and composition of black-and-gold howler monkeys (Alouatta caraya) on the Upper Paraná River, Southern Brazil

In social mammals, group size, sex and age-class composition are important parameters that are required to understand population dynamics and determine conservation strategies. These parameters are known only poorly for the black-and-gold howler monkey ( Alouatta caraya ). Here, we studied groups of...

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Bibliographic Details
Published in:Primates 2009-01, Vol.50 (1), p.74-77
Main Authors: Aguiar, Lucas M., Ludwig, Gabriela, Passos, Fernando C.
Format: Article
Language:English
Subjects:
Age
Age Factors
Alouatta - physiology
Alouatta caraya
Animal behavior
Animal Ecology
Animal populations
Animals
Behavioral Sciences
Biomedical and Life Sciences
Brazil
Comparative studies
Evolutionary Biology
Gender
Gold
Habitats
Infants
Life Sciences
Monkeys & apes
Observation
Population Density
Population Dynamics
Rivers
Sex Factors
Short Communication
Social Behavior
Zoology
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Summary:In social mammals, group size, sex and age-class composition are important parameters that are required to understand population dynamics and determine conservation strategies. These parameters are known only poorly for the black-and-gold howler monkey ( Alouatta caraya ). Here, we studied groups of A. caraya on islands and adjacent banks of the Upper Paraná River of southern Brazil, to examine variability in group size and composition. This location is important for this species because of the high density of howlers. Group size was large, varying from 6 to 18 individuals (average = 11.5, standard deviation = 3.3, n  = 13). Groups were multi-male, and adult females outnumbered adult males. On average, groups had the following ratios: 1 adult male: 0.5 subadult male: 1.9 adult females: 0.9 juveniles: 0.5 infants. The ratio of 0.2 infant: 1 adult female is less than that in other species, but typical of other studies of the black-and-gold howlers. Here, we discuss environmental and social pressures that may impose structure on large groups of howlers in terms of strategies for living in high densities. We also compare these data with those of the area of sympatry shared between A. caraya and A. clamitans , and suggest that competition may occur between the two species and that reduced fitness may be a consequence of mixed groups.
ISSN:0032-8332
1610-7365
DOI:10.1007/s10329-008-0115-0