POPULATION-DYNAMICS OF MACACA-SYLVANUS IN ALGERIA - AN 8-YEAR STUDY

The demography and dynamics of two groups, one living in an evergreen cedar-oak forest (Tigounatine) and the other, in a deciduous oak fores t (Akfadou) in Algeria, were studied from 1982 to 1990. Group size fel l within the range of other wild groups except for the Tigounatine gro up when it reached 88 individuals before splitting into three new inde pendent groups. The structure of the studied groups, except one which was temporarily ''one male,'' was comparable to that of other groups o f Barbary macaques. There were 43-50% of immatures on average dependin g on the group. The sex ratio (M:F) of the sexually mature animals was relatively balanced (1:0.9-1.2). The mean age of primiparous females was 5.5 years in Tigounatine and 5.3 in Akfadou; the rate of reproduct ion of sexually mature females was 0.56 and 0.63, respectively, while the infant mortality rate was 0.23 and 0.38, respectively. Great inter annual variations occurred at both sites. The differences between nata lity and mortality induced a higher intrinsic mean annual increase for the Tigounatine group (14.6%) than for the Akfadou group (4.8%). The rate of intergroup transfers was not correlated with the increase in g roup size. Integration of male immigrants did not lead to the departur e of resident males. Conversely, fission process promoted a substantia l increase in the number of transfers in Tigounatine. The period prese nting the greatest risk of infant mortality was the summer dry period, in both habitats. Wide interannual variations occurred in the availab ility of two staple foods for monkeys: caterpillars and acorns. The cu mulative effects of a low acorn supply during the gestation period (au tumn) and a low caterpillar supply during the beginning of the followi ng nursing period (spring) led to a temporary increase in infant morta lity.