Crows Die in Winter, New York State (3) (Modified by Environmental Risk Analysis Program)

I would take issue with the second statement [made by Dominick
Ninivaggi]. We still are seeing no evidence of any resistance to WNV
in crows in central New York. Of several hundred American Crows tested
for WNV antibodies over the last five winters, only a couple of
positives have been found each year, with no increase in occurrence
over time. We just sent off this year's batch to be tested, but we're
still pretty pessimistic about the appearance of resistance. When the
mosquitoes are out, the crows seem to die.

I will be very interested to know the whole story on these recent
positives. I'll still bet that they either were bitten by emerging
mosquitoes or picked the virus up by carrion feeding.

Kevin

> [1] Dominick Ninivaggi <Dominick.Ninivaggi@co.suffolk.ny.us>

> It will be interesting to see if WNV was the cause of death. As the
> report notes, there is now evidence that WNV is no longer nearly 100%
> fatal for crows, as it was in the early years of WNV, so the birds
> could be positive but something else killed them. Crow-to-crow
> transmission of WNV is known in the lab, so that is possible. I
> suspect we are seeing resistance in the crows, since the same strain
> of virus (NY-99) continues to circulate. Evolution in action. Crows
> may be losing their usefulness as sentinels for WNV.

> *****************************************************
Kevin J. McGowan
Cornell Laboratory of Ornithology
159 Sapsucker Woods Road
Ithaca, NY 14850
607/254-2432
fax 607/254-2111
kjm2@cornell.edu
http://birds.cornell.edu/crows/

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Received on Tue Feb 22 15:36:22 2005