Intergroup food transfers in wild golden lion tamarins (Leontopithecus rosalia)

The transfer of food between adults is uncommon in primates. Although golden lion tamarins (Leontopithecus rosalia) are unique among primates in the extent to which they transfer food, reports of food transfers between adults have so far been restricted to captive or reintroduced individuals. Here, I report the first recorded events of adult–adult food transfers in golden lion tamarins between individuals belonging to different groups in the wild. Given that individuals emigrate from their natal group to find reproductive opportunities, I suggest that intergroup food transfers could be a way for individuals to estimate the quality or availability of potential mates or social partners. I propose an additional function of food transfers in wild golden lion tamarins: that they create and strengthen social bonds with individuals outside of the family group.