Components of breeding productivity in a marine bird community: key factors and concordance

Canadian Journal of Zoology
By:  and 



We estimated components of annual breeding productivity for eight species of marine birds on the Semidi Islands in the western Gulf of Alaska. Mortality of eggs and young, caused primarily by avian predators, accounted for most of the annual variation in productivity. Failure to produce eggs, clutch size variation, and the hatchability of eggs were generally less important. The stage of breeding at which annual productivity was most strongly regulated differed among species. In murres, chick-rearing success accounted for the largest share of annual variation in overall productivity, whereas incubation success was the key factor in fulmars, kittiwakes, and puffins. Although avian predators were the dominant proximate cause of egg and chick losses in some species, food supply seemed ultimately responsible for variation in all the major components of productivity. Concordance of productivity among species was low for the marine bird community as a whole, but selected pairs of species exhibited a greater tendency for high and low productivities to occur in the same years. Compared with the same or similar species outside Alaska, Semidi Islands birds were in one of three categories: (i) species whose productivity was about the same as reported from other areas (fulmars and gulls), (ii) species with comparatively low productivity (murres, puffins, kittiwakes), and (iii) species with similar mean productivity but greater annual variation (cormorants). These patterns suggest that specialized consumers of forage fish experienced food shortages at the Semidi Islands and that surface feeders were more severely affected than divers.

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Additional publication details

Publication type Article
Publication Subtype Journal Article
Title Components of breeding productivity in a marine bird community: key factors and concordance
Series title Canadian Journal of Zoology
DOI 10.1139/z90-248
Volume 68
Issue 8
Year Published 1990
Language English
Publisher NRC Research Press
Contributing office(s) Alaska Science Center, Alaska Science Center Biology MFEB
Description 11 p.
First page 1680
Last page 1690
Country United States
State Alaska
Other Geospatial Gulf of Alaska, Semidi Islands