Do parents coordinate their efforts while caring for offspring? (#472)
The amount of care parents devote to joint offspring is affected by a conflict of interests between the sexes (‘sexual conflict’). In turn, on a behavioural time scale empirical evidence also shows that parents negotiate over parental care, modifying their efforts in response to the effort provided by their mates. Although theoretical explorations suggest that sexual conflict and negotiation should reduce parental care, and as a consequence parental and offspring fitness, a recent model (Johnstone et al. 2014; Behav.Ecol. 25:216-222) proposes that alternation of the provisioning visits as a negotiation rule can help to overcome this and lead to a cooperative and more efficient level of parental care. This turn-taking mechanism implies that each parent monitors its partner’s behaviour. We investigate the spatial and temporal coordination of the foraging activity as a behavioural mechanism mediating negotiation. We studied great tits (Parus major) and analysed i) the sequence of provisioning visits to the nest by the male and female, and ii) the nest departure directions, to investigate whether parents coordinate their activity more often than expected by chance. Furthermore, by carrying out a short-term brood size manipulation we also investigate whether alternation of the nest visits and spatial coordination vary in response to brood demand. This work points at the importance of studying the behavioural mechanisms underlying negotiation rules to provide new insights on how sexual conflict over parental care is mediated and resolved.