Data for: Kinship, dear enemies, and costly combat: The effects of relatedness on territorial overlap and aggression in a cooperative breeder

Many species maintain territories, but the degree of overlap between
territories and the level of aggression displayed in territorial conflicts
can vary widely, even within species. Greater territorial overlap may
occur when neighbouring territory holders are close relatives. Animals may
also differentiate neighbours from strangers, with more-familiar
neighbours eliciting less-aggressive responses during territorial
conflicts (the “dear enemy” effect). However, research is lacking on how
both kinship and overlap affect territorial conflicts, especially in
group-living species. Here we investigate kinship, territorial overlap,
and territorial conflict in a habituated wild population of group-living
cooperatively breeding birds, the southern pied babbler Turdoides bicolor.
We find that close kin neighbours are beneficial. Territories overlap more
when neighbouring groups are close kin, and these larger overlaps with kin
confer larger territories (an effect not seen for overlaps with unrelated
groups). Overall, territorial conflict is costly, causing significant
decreases in body mass, but conflicts with kin are shorter than those
conducted with non-kin. Conflicts with more-familiar unrelated neighbours
are also shorter, indicating these neighbours are “dear enemies”. However,
kinship modulates the “dear enemy” effect; even when kin are encountered
less frequently, kin elicit less-aggressive responses, similar to the
“dear enemy” effect.  Kin selection appears to be a main
influence on territorial behaviour in this species. Groups derive
kin-selected benefits from decreased conflicts and maintain larger
territories when overlapping with kin, though not when overlapping with
non-kin. More generally, it is possible that kinship extends the “dear
enemy” effect in animal societies.