The ecology and energetics of chick provisioning by Black Guillemots

I studied chick growth and parental provisioning behavior of Black Guillemots (Cepphus grylle) in Hudson Bay, Canada. Chicks received benthic blennies, principally Stichaeus punctatus and Eumesogrammus praecisus, which parents caught in water less than 40 m deep close to the colony. Chick feeds were more frequent in the morning but feeding rates did not vary with age of young. Size of prey items increased during the nestling period, and energy intake peaked at about 780 kJ/day/chick when chicks were 25 days of age. Black Guillemots can maintain higher reproductive rates than offshore-feeding Alcidae because their short foraging range and the temporal and spatial predictability of their benthic prey permit higher rates of chick provisioning.