Social organization of captive monandrous squirrel monkey groups (Saimiri sciureus)

Area of Science:

• Primate Social Behavior
• Animal Sociology
• Behavioral Ecology

Background:

• Squirrel monkey social structures are complex and hierarchical.
• Previous research has explored female dominance hierarchies in squirrel monkeys.
• The impact of male introduction on established female groups requires further investigation.

Purpose of the Study:

• To investigate the social dominance hierarchy in a mixed-sex group of squirrel monkeys.
• To compare social dynamics before and after male introduction.
• To assess the effect of prior deafening on social behavior.

Main Methods:

• Observation of a mixed-sex group (1 male, 4 females) of squirrel monkeys.
• Evaluation of social dominance through dyadic interactions (food stealing, grasping, sexual behavior).
• Comparison of social hierarchy with a prior all-female group and a second mixed-sex group (no deafening).

Main Results:

• A linear rank order was established among females prior to male introduction.
• The male squirrel monkey assumed the highest rank after introduction.
• The female hierarchy remained largely intact, with the highest-ranking female's position challenged.
• Heterosexual interactions increased, while homosexual behavior decreased compared to all-female groups.
• Deafening in females had no apparent permanent effect on social behavior.

Conclusions:

• Male squirrel monkeys integrate into existing female hierarchies, typically becoming dominant.
• Female social structures demonstrate resilience but can be influenced by male presence.
• Sensory impairments like deafening may not significantly alter established social behaviors in squirrel monkeys.