Intraspecific fledging mass variation in the Alcidae, with special reference to the seasonal fledging mass decline

A dynamic programing model of fledging in alcidae, based on the advantages and mortality costs in habitats before and after nest departure, suggests the variations in growth with hatch date to be the cause of the seasonal fledging mass decline. When the development of the nestlings is nearly complete, they fledge. As a result the fast-growing and the later-hatched nestlings fledge when they are young.