Monday, January 19, 2015

Common Eider (Pacific)

On Friday, Erika and I finally drove up to Duluth, Minnesota, to search for the Common Eider that has been seen since 10 November 2014. The bird was within a large flock of Mallards, Black Ducks, and even a few Pintails. Despite its different-shaped bill and pale color, the bird could be difficult to spot among the other ducks. (When first reported, there were two individual eiders in the area, representing the first winter records for the species in St. Louis County.)

Last November I posted a photo of one of the Atlantic races of the Common Eider and concluded, as have most observers, that the Duluth bird is a Pacific race. The distance between the eye and the back extensions of the bill is much greater in the Duluth bird than in the Atlantic one (fide Ken Able). The extensions are more pointed in the Duluth bird. Finally, the Duluth bird is much paler brown. Sibley suggests that birds of the western Arctic are so distinct from other Common Eiders that they “seem to be good candidates for splitting."

One may be surprised that an inhabitant of the north Pacific would show up on Lake Superior. Perhaps not coincidently, a huge low-pressure storm, the most intense ever reported in the region, blew up the Pacific and into the Bering Sea and Alaska. Barometric pressure reached near record lows and winds approaching 100 mph. The low pressure area spun clockwise, bringing warm weather to Alaska, but pulling frigid Arctic air into the continental United States, including Minnesota (Accuweather.com). This weather system may also be responsible for pushing Pacific Common Eiders to our region (fide Peder Svingen and Matt Dufort).

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