Abstract and Summary
Four species of gulls (Larus occidentalis, L. livens, L. atricilla, L. novaehollandiae) were studied in captive and free-living situations to determine which sex of paired gulls is dominant, if either, with respect to pair-bonded behaviour. Aggression against a mate was rare (all four species). Conflicts during nest reliefs (L. o. occidentalis) or feeding (all four species) were not resolved by dominance but by egalitarian mechanisms: access to the nest was decided on a case-by-case basis and food was shared (large items) or acquired on a first-come-first-served basis (small items). Analysis of the use of vocal signals (Head Toss, Mew, and Choking) during nest duty interactions suggests that reduction of signaling occurred when a pair's priorities were most in agreement. Egalitarian conflict resolution is defined and selective factors favoring egalitarian behaviour patterns are proposed.