Dynamics of intrafamily aggression and social reintegration in lion tamarins

Intrafamily aggression poses a critical problem in the captive maintenance of callitrichid social groups. Group cohesion and individual health is threatened by aggressive altercations. This paper discusses several aspects of lion tamarin aggression. To investigate the demography of intrafamily aggression in golden lion tamarins, we reviewed instances of family‐group aggression from our facilities and we solicited data from facilities around the world. The sex and reproductive status of tamarins that initiated and received aggressive attacks and a description of the nature and severity of injuries inflicted during aggressive altercations are documented. In lion tamarins, aggressive interactions between members of a social group are severe: 20.5% of such encounters resulted in the death of an individual. Juvenile males were found to be the most likely targets of injurious aggression (50.6% of all attacks), and juvenile females also accounted for a significant proportion of attacks (38.5% of attacks). Juvenile males, adult females, and juvenile females were most likely to initiate attacks, while adult males rarely initiated attacks on family members. A protocol for managing intact family groups by the successful reintegration of expelled tamarins back to their natal group is also described; this method requires direct and progressive contact of an expelled individual with their family group. This procedure has not proven successful for reintroducing hand‐reared infants to a social group.