Monday, February 27, 2012

House Sparrow

Looking through my bird photographs, I was surprised I lack the ubiquitous female House Sparrow. Last summer I set about to remedy this situation, but I failed to obtain a good photo. The closest I got was this male, molting into Basic Plumage.

The plumages of juvenal male and female House Sparrows are similar as they leave their nests. But soon thereafter they begin a post-juvenal molt. As time progresses, their bibs, due to feather wear, become more extensive. The bib on the bird in the photograph indicates this House Sparrow is a first-year male.

House Sparrow numbers have been declining in North America. The Breeding Bird Survey indicates declines of almost 3% a year in most regions. One reason for this trend may be that House Sparrows thrived when we humans depended on horses to get around. (They fed on grain, both before and after it passed through livestock.) But with the advent of automobiles, the sparrows shifted to more rural environments. Lowther and Cink (2006) explain that "changes in farming practices in the 1960s--towards larger farms and greater degree of monoculture crops--have probably contributed to a general decline in continental populations of House Sparrows...." (I have previously posted an account of the introduction and subsequent evolution of House Sparrows.)

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