Wednesday, June 8, 2011

Odd Brown-headed Cowbird

On a recent stroll in the Carleton College Arboretum, Erika and I flushed a male Brown-headed Cowbird.  Knowing that I have more photographs of female cowbirds than of males, I focused my camera on the bird, which had perched atop a nearby bush.  I immediately realized this cowbird was odd--it sported a golden collar.  I am not sure of the cause of this abnormality.  Perhaps it is attributable to xanthochroism, where birds have unexpected yellowish plumage caused by genetic mutation or by diet.  This condition, however, is usually seen in red-plumaged birds.  Another possibility is that this odd color was caused by abnormal feather ware, either due to feather mites or other damage. (I've previously posted about Brown-headed Cowbirds in May 2010.)

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