Data from: Determinants of hyena participation in risky collective action

Collective action problems arise when cooperating individuals suffer costs
of cooperation, while the benefits of cooperation are received by both
cooperators and defectors. We address this problem using data from spotted
hyenas fighting with lions. Lions are much larger, and kill many hyenas,
so these fights require cooperative mobbing by hyenas for them to succeed.
We identify factors that predict: when hyena groups engage in cooperative
fights with lions, which individuals choose to participate, and how the
benefits of victory are distributed among cooperators and non-cooperators.
We find that cooperative mobbing is better predicted by lower costs (no
male lions, more hyenas) than higher benefits (need for food). Individual
participation is facilitated by social factors, both over the long term
(close kin, social bond strength) and the short term (greeting
interactions prior to cooperation). Finally, we find some direct benefits
of participation: after cooperation, participants were more likely to feed
at contested carcasses than non-participants. Overall, these results are
consistent with the hypothesis that, when animals face dangerous
cooperative dilemmas, selection favors flexible strategies that are
sensitive to dynamic factors emerging over multiple time-scales.