Crow Question

by Carl Strang

Lately I have been seeing the occasional crow flying around in central DuPage County. It may not mean much. Maybe they’ve been lucky and not been bitten. Maybe they are recent arrivals from a rural area. But my hope is that, at last, we may be starting to see some crows with a resistance to West Nile virus.

American crow

This has been an uptick year for the virus in Illinois, thanks to the drought, which favors the mosquitos that spread the disease. According to the Illinois Department of Public Health, 179 people have been diagnosed with West Nile this year, and 6 have died in the state. This compares to the corresponding numbers of 34 and 3 last year. In DuPage County, survey traps monitored by forest preserve district staff have found at least 23 infected mosquitos in locations scattered all over the county. My memory is that in years like this, crows are absent from late summer until well into the winter, when dispersing or migrant crows move in. That is why seeing a crow in early autumn, as I have done lately, is cause for at least a meager hope.

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2 Comments

  1. dfg said,

    October 9, 2012 at 12:29 pm

    I didn’t know that West Nile killed off the crow completely! Are the dispersing crows you refer to coming from a Northern population in Canada where West Nile isn’t present due to the cold? or is DuPage county particularly bad for West Nile and the dispersing crows are coming from other counties that don’t have a serious West Nile problem?

    • natureinquiries said,

      October 10, 2012 at 6:00 am

      The mosquitos that carry the virus breed in the kinds of small murky bits of water that can be common in urban and suburban neighborhoods (catch basins in storm drains, discarded tires, gutters, litter, etc.). Farmland, and even small rural towns, have lots of crows, so healthy populations can be within a few counties’ distance from urbanized areas.


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