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Group size and aggression: 'recruitment incentives' in a cooperatively breeding primate
Animal Behaviour
|July 1, 1997
Summary
In cooperatively breeding marmosets, larger groups exhibit increased aggression towards strangers, particularly females, potentially limiting immigration. Smaller groups show tolerance, possibly aiding recruitment of new members.
Area of Science:
- Primate behavior
- Social structure
- Cooperative breeding
Background:
- Group size often correlates with reproductive success in cooperatively breeding species.
- Helpers are crucial for offspring survival in marmosets and tamarins.
- Breeders may employ social strategies to regulate group size.
Purpose of the Study:
- To investigate the link between group size and aggression towards strangers in Wied's black tufted-ear marmosets (Callithrix kuhli).
- To understand how group size influences social strategies related to immigration.
Main Methods:
- Comparing aggression levels of breeders from small (no helpers) and large (helpers present) groups.
- Exposing resident marmosets to male and female stranger presentations.
- Observing proximity, agonistic displays, aggressive behavior, scent-marking, and partner proximity.
Main Results:
- Breeding females in large groups displayed significantly more aggression and proximity towards strangers than those in small groups.
- Breeding male behavior showed minimal variation based on group size.
- Females in large groups increased scent-marking and partner proximity post-intruder exposure.
Conclusions:
- Small group breeders are tolerant of strangers, potentially facilitating recruitment.
- Large group breeders, especially females, are intolerant, potentially inhibiting immigration.
- Findings shed light on immigration regulation mechanisms in cooperatively breeding animals.
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