Turn-taking ceremonies in a colonial seabird: Does behavioral variation signal individual condition?

Abstract

In species with biparental care, pairs share a cooperative interest in offspring survival but may be in conflict over their relative investments, as reported in recent turn-taking studies of chick-provisioning birds. Turn-taking in Common Murres (Uria aalge) involves the foraging bird returning to the colony to provision the chick and the brooding parent departing. We examined whether Common Murres in poor condition had slower or more irregular turn-taking behavior, as has been documented in Common Murres equipped with geologgers. Irregularities include the brooding bird not trading parental roles with its returning mate or a bird returning to the colony without a fish. Irregular turn-taking sequences generally took longer than normal turn-taking sequences and differed in the rate and synchrony of allopreening, the main interactive behavior between mates. There was a delayed onset of allopreening when nest reliefs were protracted, whereas returners that did not bring a fish started allopreening sooner than either their brooding partners or other returners that brought a fish. Common Murres in better condition (higher body mass and lower lipid metabolite levels) left the colony sooner after their returning mates fed the chick compared to Common Murres in worse condition. Birds with higher chick-feeding rates brought fish back in more visits, which suggests that these were higher-quality birds. When birds vary in their turn-taking ceremonial behaviors, they may be negotiating by providing their partners with cues about their condition. Since Common Murres have long-term pair bonds and both parents are necessary to raise offspring, mates should respond to information from their partners if they can do so without compromising their own condition beyond a critical threshold.