Data from: Ecological tradeoffs drive a power-law relationship between group size and population density in social foragers

Foraging animals have been documented forming groups in wide range of
environments and taxa. Benefits of group foraging include reduced
predation risk while costs include increased resource competition among
group members. While the relative strengths of these factors are known to
vary with density, it is unclear whether forager group sizes should also
vary with density. Here, we model how the costs and benefits of group
formation drive density dependence in group size when including the
impacts of improved vigilance and increased intragroup competition. Our
model predicts that forager group size will exhibit a one-third power-law
relationship with their abundance when predator abundance is independent
of prey abundance. We tested this prediction using empirical data of
group-foraging birds and ungulates and found clear support for our
theoretical predictions. Our results contribute to a growing body of work
highlighting the importance of group formation in maintaining stability in
predator and prey populations.