Incubation Biology and Nestling Growth of Bulwer's Petrels on Manana Island, Oahu, Hawaii

Abstract

Data were gathered on incubation of eggs and growth of nestlings of Bulwer's Petrels nesting on Manana Island in the Hawaiian Islands. Mean incubation period of five eggs was 45.2 days. Duration of pipping period of six eggs, which began with star-fracture of the shell, was 4.5 days. Daily water loss from unpipped eggs was 62.6 mg/day; water loss from pipped eggs was much higher, and 36.3% of total water loss occurred from pipped eggs. Mean nestling period (hatching-fledging) of four nestlings was 62 days; body weight of eight nestlings increased to a maximum 21.2 days before the nestlings fledged and then declined. Body weight of adult Bulwer's Petrels declined over the breeding season.