Data from: Homophily around specialized foraging underlies dolphin social preferences

Individuals often associate socially with those who behave the same way.
This principle, homophily, could structure populations into distinct
social groups. We tested this hypothesis in a bottlenose dolphin
population that appeared to be clustered around a specialized foraging
tactic involving cooperation with net-casting fishermen, but in which
other potential drivers of such social structure have never been assessed.
We measured and controlled for the contribution of sex, age, genetic
relatedness, home range, and foraging tactics on social associations to
test for homophily effects. Dolphins tended to group with others having
similar home ranges and frequency of using the specialized foraging
tactic, but not other traits. Such social preferences were particularly
clear when dolphins were not foraging, showing that homophily extends
beyond simply participating in a specific tactic. Combined, these findings
highlight the need to account multiple drivers of group formation across
behavioural contexts to determine true social affiliations. We suggest
that homophily around behavioural specialization can be a major driver of
social patterns, with implications for other social processes. If
homophily based on specialized tactics underlies animal social structures
more widely, then it may be important in modulating opportunities for
social learning, and therefore influence patterns of cultural
transmission.