Climate Fact: Pacific Brants and Climate Shifts
The rich waters in Alaska’s Arctic and sub-Arctic estuaries provide the Pacific Brant, a small goose that travels in flocks of as many as 500 birds, with a steady supply of eelgrass (its principle food source) during the summer months. Traditionally (before the late 1970’s), almost 90 percent of the population would spend their summers in Alaska, retreating south to Mexico during the fall and winter months. Since the North Pacific “regime shift” of 1976-1977, a phenomenon that featured noticeable changes in ocean circulation and species distributions/concentrations, the waters in the North Pacific and Bering Sea have been warming. In Alaska, this warming has corresponded to more eelgrass and more favorable conditions for the birds. The regime shift has also corresponded to weakening of the Aleutian Low, the low pressure center that lies near the Aleutian Islands. As the low has weakened, the number of days each autumn when there are favorable tail winds for the migration has decreased. These trends may account for the increase in the number of Pacific Brants spotted in Alaska during the winter. Counts before 1977 would rarely detect more than 3,000 birds. In recent years, the counts have found as many as 40,000 birds.
To view and download a public domain image of a Pacific Brant family, visit the United States Geological; Survey: http://gallery.usgs.gov/photos/09_09_2009_hlc5Fsq11Y_09_09_2009_0.
Seasons: Fall, Winter
Source: U.S Department of Interior, U.S. Geological Survey. “Opting Out of Migration: As Climate Warms, Arctic-Nesting Geese Elect to Winter in Alaska Instead of Mexico.” 9 September 2009. Accessed Online 11 September 2009
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