Sunday, November 14, 2010

Sharp-shinned Hawk

Because this forest-inhabiting hawk subsists almost entirely on small birds, this Sharp-shinned Hawk was probably attracted by the activity at our feeders.  I banded it on 8 November.  The hawk flew up from our water feature, where it may have been drinking.  At the time, no small birds were evident.

Male Sharp-shinned Hawks are much smaller than the females.  The size of the sexes do not even overlap.  This bird, with a wing chord of 203 mm, is a female.  Her yellow eye and brown back indicate she is a young bird.

Several hypotheses exist to account for female hawks being larger than their mates. Perhaps females need to be larger to protect themselves from dangerous, aggressive males. Alternatively, perhaps to reduce competition between the sexes, males and females specialize in different sized prey. Apparently, for whatever reason, the more a raptor specializes in taking small birds, you expect to see a larger difference between the size of the sexes.

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