Wednesday, July 13, 2011

Northwestern Crow

Another perplexing bird of the Pacific Northwest is the Northwestern Crow. This small crow historically was restricted to the tidewater from Alaska to Puget Sound. Deforestation has resulted in the Northwestern Crow's expanding its range, meeting up and hybridizing with American Crows moving into cleared lands from the east. It is a common bird in coastal, agricultural, and urban landscapes. (The last photo in this post is of a Northwestern Crow perched on the back of a pickup truck parked at a fast food parking lot.)

Local ornithologists will tell you that, as a result of this hybridization, now no such thing as a Northwestern Crow exists. They will wink at listers who check small Northwestern Crows, ignore intermediate birds, and identify larger crows as American Crows. If you want to list a Northwestern Crow, the bird must be small and next to the ocean.  They are about 10% smaller than American Crows, have smaller feet, faster wing-beats, and a lower pitched voice (Verbeek and Butler 1999). These authors warn, "A small crow seen in coastal Oregon is not necessarily a Northwestern Crow; it is more likely to be a small subspecies of American Crow, Corvus brachyrhynchos hesperis." They continue, "Successive editions of the American Ornithologists’ Union Check-list have listed Northwestern Crow as a full species (1910), a subspecies of American Crow (1931), and a full species (1957, 1983, 1998)." Not even ornithologists have been consistent, and many now once again consider the two to be subspecies.
I found the bird above in the tidewater of the Olympia harbor.  When I first spied this individual, I thought it was a large grackle!  I was surprised this by this juvenile bird's blue-gray eye--but young Northwestern and American crows are reported to sport this color eye. Finally, Northwestern Crows store food that they capture during low tide.  They retrieve it later, usually during the next high tide.

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