Population dynamics of Macaca sylvanus in Algeria: An 8-year study

Area of Science:

• Primate Ecology
• Population Dynamics
• Behavioral Ecology

Background:

• Studied Barbary macaque demography and dynamics in Algerian forests (Tigounatine and Akfadou) from 1982-1990.
• Compared group structures, age at primiparity, and sex ratios to other macaque populations.

Purpose of the Study:

• Investigate factors influencing population size, growth rates, and survival in two distinct Barbary macaque habitats.
• Analyze the impact of environmental variables and social dynamics on population trends.

Main Methods:

• Monitored two Barbary macaque groups in evergreen cedar-oak and deciduous oak forests.
• Collected demographic data including group size, age structure, sex ratios, natality, mortality, and intergroup transfers.
• Assessed food availability (caterpillars, acorns) and correlated it with reproductive success and infant mortality.

Main Results:

• Group sizes varied, with one group splitting. Immature percentages ranged from 43-50%, and sex ratios were balanced.
• Reproduction rates were 0.56-0.63, with infant mortality at 0.23-0.38. Tigounatine showed higher annual population increase (14.6%) than Akfadou (4.8%).
• Infant mortality peaked during the dry summer, linked to low availability of acorns and caterpillars during critical reproductive and nursing periods.

Conclusions:

• Habitat type and resource availability significantly influence Barbary macaque population dynamics and survival rates.
• Environmental fluctuations, particularly food scarcity during key periods, directly impact infant mortality and population growth.
• Social factors like group fission can increase social interactions but do not solely drive population changes.