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Some bird populations soaring down.

Following the Exxon Valdezoil spill in 1989, wildfire biologists succeeded in surveying from boats approximately 100 different types of near-shore birds in Alaska's Prince William Sound and compared their findings to tallies made at similar times of the year in 1972-73 and 1984. Overall, postspill estimates indicate, at least 11 species - from murrelets and loons to crows and cormorants - have undergone a sound-wide population decline, reports Karen K. Laing of the U.S. Fish and Wildfire Service in Anchorage.

When she and her colleagues compared the 1984 estimates to the 1989 through 1991 surveys, population declines at oiled sites appeared to exceed those at unoiled sites among loons, harlequin ducks, scoters, black oystercatchers, Arctic terns, and mew gulls. Among the most significant declines: Loon and scoter populations at oiled sites were 86 percent lower than expected and harlequin ducks 76 percent lower than expected. A few studies by other researchers of individual species especially harlequin ducks, oystercatchers, and guillemots -- indicate that the spill played a direct role in depleting these and presumably other marine bird populations.

Laing says the "statistically rigorous" sampling design employed in her analyses has rarely been used for estimating marine bird populations. "This study served to demonstrate its feasibility," she says, and to identify species at special risk.
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Title Annotation:Alaska's Prince William Sound following 1989 Exxon Valdez oil spill
Author:Raloff, Janet
Publication:Science News
Article Type:Brief Article
Date:Feb 20, 1993
Words:212
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