MAXIMUM DIVING DEPTH IN FLEDGING BLUE-FOOTED BOOBIES: SKILL DEVELOPMENT AND TRANSITION TO INDEPENDENCE

Abstract

We evaluated maximum diving depth and time spent at the nest of fledging Blue-footed Boobies (Sula nebouxii) at Isla El Rancho, Sinaloa, in the Gulf of California, Mexico. Within three consecutive 10-day post-fledging intervals, maximum diving depth was highly variable, but was not affected by sex, weight, or body condition. During the first days of post-fledging flight, maximum diving depth increased rapidly. By the second week after first flight, the plunge-dives of juveniles were almost as deep as those of adults. Parental care and attachment to the nest lasted several additional weeks (up to 40 days after first flight). Although their diving capacity rapidly reached a level similar to that of the adults, it appeared that juvenile boobies took much longer in acquiring other foraging skills.