Sunday, January 16, 2011

Rough-legged Hawk

Rough-legged Hawks breed across the high arctic of both the Old and New Worlds.  North American birds mostly winter in the northern United States.  Their numbers tend to fluctuate from winter to winter, perhaps as a result of local rodent populations.  The species is a treat to see as individuals gracefully hover over snowy fields before plunging toward their prey.
Rough-legged Hawks, like this one photographed near Nerstrand Big Woods State Park (on 14 January), can be remarkably tame  (often to their detriment).  Because of its relatively small size, I believe this hawk is a male; its pale head indicates a young bird.  The dark vest and dark underwing spots at the wrists (not visible in this photograph) leave little doubt as to the hawk's identity.  (This photo was taken without the aid of lures--just dumb luck; the white backgrounds are due to cloudy skies.)

None of my field guides, however, illustrate Rough-legged Hawks with such bright rufous flank feathers or with such a white tail.  The photos of the perched bird only suggests its dark subterminal tail band.  In the flying bird, the band is hardly visible.  Is this a case of partial albinism (leucism)? Rough-legged Hawks are famously variably plumaged, and range from being almost completely dark to very pale. Look at the legs of this hawk.  Above their bare, yellow toes, the legs are clearly feathered.  This feathering is why the hawk is called rough-legged.

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