Seabird parents provision their chick in a coordinated manner.

Pair collaborative behavior may play an important role in avian reproduction. However, evidence for this mainly comes from certain ecological groups (e.g. passerines). We studied the coordination of parents in foraging and its effect on food provisioning rate and chick growth in a small seabird, the Dovekie (Little auk, Alle alle). The species exhibits a dual foraging strategy, where provisioning adults make foraging trips of short (mean ~2 h; to provide food for the chick) and long duration (mean ~ 13 h; mainly for adults self-maintenance, although the food is also brought to the chick). We expected that offspring would benefit if parents coordinate their foraging patterns: one making short trips in the time when the other performing the long one. We examined this hypothesis using Monte Carlo randomization tests on field data collected during observations of individually marked birds. We found that parents did indeed adjust provisioning, making their long and short trips in an alternating pattern with respect to each other. Furthermore, we found that a higher level of coordination is associated with a lower variability in the duration of inter-feeding intervals, although this does not affect chick growth. Nevertheless, our results provide compelling evidence on the coordinated behavior of breeding partners.