Collective self-assessment in banded mongoose intergroup contests

Contests over resources are widespread in nature. To optimize outcomes,
animals assess fighting abilities, deciding to escalate conflicts based on
their own strength (self-assessment) or comparing their own strength with
that of their rival (mutual assessment). While most research focuses on
one-on-one (dyadic) contests, the assessment strategies employed by groups
remain poorly understood, even though animal groups from ants to humans
engage in intergroup conflict. Mutual assessment is frequently assumed, as
more information is thought to improve decision-making; however, this
assumption has rarely been tested. Here, we used a dataset spanning 21
years and 633 intergroup contests in a banded mongoose (Mungos mungo)
population in Queen Elizabeth National Park, Uganda. Our results support a
model of self-assessment: groups with many males tend to escalate
conflicts regardless of the rival group's strength, thus contrasting
the commonly held assumption that decisions during intergroup contests are
made by mutual assessment. We suggest that assessing rival group strength
during conflict could be disproportionately costly, compared with
assessing own group strength, which can be done over longer time periods
and is easier to obtain. Greater understanding of these dynamics can shed
light on the drivers and escalation patterns of intergroup conflict across
social species, including humans.