What’s with the Crows?

by Carl Strang

Ever since the arrival of West Nile virus several years ago I have grown accustomed to seeing few crows in DuPage County. Urban and suburban areas supply plenty of habitat for the species of mosquitoes that most often carry the virus, as opposed to rural areas, which do not. Consequently I have come to think of the suburbs as a population sink for crows. The mosquitoes carry death to crows in the late summer. New crows appear in the winter or spring, apparently having immigrated from rural areas. Some of these may nest, though most apparently are young birds not quite ready to do so. Thanks to the virus, they don’t get a chance.

This fall has been different. I am seeing crows regularly. The most remarkable case came on one of the very windy days we experienced last week (cue wind shot).

As I stopped by forest preserve district headquarters in the afternoon, I saw a flock of at least 30 crows. They perched on the HQ roof, but spread out before I could get the camera untangled.

A few remained on the roof.

Others went to the lawn, or to nearby trees.

I was away from the county for most of the crow nesting season, so now I am asking myself: are these locally raised birds? Have they at last evolved a resistance to the virus to match that in our other avian species? Can we look forward again to easily finding great horned owls?

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