Male residence and association patterns in Costa Rican squirrel monkeys (Saimiri oerstedi)

Area of Science:

• Primatology
• Ethology
• Evolutionary Biology

Background:

• Squirrel monkey (Saimiri oerstedi) social structures vary geographically.
• Costa Rican males display unusual residence and social patterns compared to Peruvian populations.

Purpose of the Study:

• To model and interpret the evolution of male residence and social structure in Costa Rican squirrel monkeys.
• To understand the ecological and social factors driving these unique male behaviors.

Main Methods:

• Field observations of a wild population.
• Analysis of male spatial associations, social interactions, and troop dynamics.
• Comparison with social structures in other squirrel monkey populations.

Main Results:

• Males form strong cohort bonds, exhibit low aggression, high vigilance, and cooperative female investigation.
• Males reside in natal troops, with some cohorts migrating to usurp other troops.
• Female non-philopatry is proposed as the driver for these male social adaptations.

Conclusions:

• Long-term male reproductive cooperation is advantageous in Costa Rica due to female mobility.
• Reduced inbreeding costs and enhanced predator defense likely shaped male social systems.
• Higher genetic relatedness is predicted among troop-resident males compared to females.