Ecology of Audubon\u27s Shearwaters (Puffinus lherminieri) at San Salvador, Bahamas

The Audubon\u27s Shearwater (Pqffinus lherminieri), nearly pantropical in distribution, remains a poorly studied species. The subspecies P. l. lherminieri is endemic to the West Indies region. An estimated 5,000 pairs inhabit the Caribbean, but there has been a substantial decline with many colonies becoming extirpated. It is thought that as many as 3,000 pairs (60% of the West Indian population) nest in the Bahamas. In May and June of 2000, I collected data on shearwater demographics, colony site selection, burrow microhabitat, chick behavior and the effect of moonlight on the onset of calling of the Audubon\u27s Shearwaters nesting on the satellite cays of San Salvador Island, Bahamas. The population of nesting shearwaters on the cays was estimated at 107 pairs. The size of the rock over a shearwater burrow and the percent of rock within a one-meter radius of the burrow entrance were two factors that distinguished between the burrow microhabitats of the different cays. The size of the colonies on individual cays was proportional to the availability of rocky habitat. Chick behavior varied ,significantly with time of day and age. Adults returned from offshore foraging areas to feed their young on 70% of the nights. Measures of chick activity were greater at night than by day and increased during the three weeks of the study. The amount of ambient light on any given night did not significantly affect the time shearwaters arrived at the colony (i.e., started calling). The detailed behavior of chick feeding bouts was described, and data on morphometrics are also reported. The information gathered in this study is integral to understanding the biology of the Audubon\u27s Shearwater and aiding in the development of an effective conservation plan