Survey of pigeon guillemot colonies in Prince William Sound, Alaska: 1993

During a survey of 98% of Prince William Sound's (the Sound) shoreline in May and June 1993 we found 184 pigeon guillemot colonies, most of which were previously unknown. There were no guillemots at 14 former colony sites, but we found new colonies within a few km of eight of these sites. The southwestern Sound, with 41% of the shoreline surveyed, had 62% of the guillemots, the eastern Sound, with 24% of the shoreline surveyed, had 10% of the guillemots, and the Naked Island area, with only 2.5% of the shoreline, had 27% of all guillemots. We found concentrations on Jackpot, Fool, Pleiades, Seal, Evans and Bligh Islands, and in Passage Canal, Port Bainbridge, Harriman Fjord, and Blackstone Bay. In general, half of all guillemots were at 22 major clusters of colonies.

We counted a total of 3028 pigeon guillemots, including 1012 that were unassociated with colonies. Our count is within the range of a Sound-wide estimate of 3000 to 4900 guillemots from pelagic and shoreline surveys by another project in July 1993. These figures reflect a continuing depressed population compared with a
1970's high of about 15,000.

Guillemot counts at oiled Naked Island continue to decline, but numbers have also declined in nonoiled areas of the Sound. Reasons for this decline are unclear, but besides the oil spill killing birds outright, reduced food availability and increased predation are possible factors.

Studies of guillemot productivity, food availability and predation at several key locations would help clarify reasons for the guillemots' population decline. These studies, coupled with monitoring colonies every two to five years, would help evaluate possible restoration measures.

These data were originally collected by Gerry Sanger with Mary Cody.