MORGAN, S.M.*; ASHLEY-ROSS, M.A.; ANDERSON, D.J.: Incubation in Masked Boobies

Lacking brood patches, masked boobies (Sula dactylatra) incubate eggs with their webbed feet. No studies to date have examined incubation temperature in masked boobies. Incubation temperatures were tracked for individual masked boobies nesting in a colony on the island of Espanola, Galapagos, Ecuador. Plastic Easter eggs, identical in size to actual eggs, containing water and a temperature data logger to record egg temperature, were sealed with white acrylic paint to more closely resemble natural eggs. Natural eggs in four, one-egg clutch nests were replaced with data logger eggs. Birds were allowed to incubate the logger eggs for 3 days. This procedure was repeated 13 times for a total of 52 nests. All egg temperatures remained above ambient temperature during incubation. Over the 3-day interval, mean egg temperatures were 37�C (range: 2 – 3�), while ambient temperature fluctuated cyclically throughout each 24-hour period from 22�C to 35�C. Preliminary data with isolated thermocouples suggest that boobies added heat for incubation through the webs of their feet.