Bird Watcher's General Store

West Nile Virus - 06/27/03


Dear Bird Folks:

For years my area has been inundated with nasty, raucous, big black birds. Two years ago the West Nile Virus was reported in our area. Now suddenly there isnít a black bird to be seen. Could this have something to do with the West Nile Virus?
- Phyllis, W. Stamford, CT

Crows Phyl?

Are the black birds that you are talking about crows? Crows are big and raucous for sure, but I wouldn't call them nasty. Crows are fascinating birds. If you want to see nasty, stop in the local DMV (Department of Motor Vehicles) sometime. Even crows are afraid of those people.

The West Nile Virus was first diagnosed almost seventy years ago in, coincidentally enough, the West Nile region of Uganda. It didn't appear in this country until 1999 when, like most immigrants, it arrived in New York City. Its arrival surprised almost everyone and seems to keep surprising all who have been following its progress. As with all new situations, the information on WNV is based on a combination of current knowledge, speculation and a good dose of hysteria. Somewhere in that mix lies the truth, but who knows where.

The West Nile Virus is spreading with amazing speed. It is pretty clear that our pals the birds are a major player in the spread of this disease. Birds, along with those lovely creatures mosquitoes, have teamed up to move this virus across most of this continent in less than five years.

The chain of command is something like this: An infected mosquito passes the disease on to a bird by 'biting' it. The bird flies away where it is bitten by another mosquito. That new mosquito is infected by the unknowing but now sick bird. That mosquito flies off to infect other birds and on and on the fun goes.

For the last seventy years WNV has had little serious impact on the birds overseas. However, the jury is still out on what long-term effects the disease will have on the birds of North America. Many species of birds have been affected by this illness, but the corvids have taken the hardest hit. (Corvid is a family of birds and not an ethnic group) Crows, ravens, jays and magpies are all members of the corvid family. They appear to be dying more than other birds and we are not sure why. It seems odd that, of all birds, crows should be affected. Crows have thrived for centuries, despite countless attacks by farmers and by people who like to sleep late. You wouldn't think that a bird, which loves to eat rotting road kill and stinky garbage from dumpsters, would be sensitive to a mosquito bite, but it is.

Sadly, people are also dying from this illness. Now before you jump on the hysteria band wagon, keep in mind that people are infected from mosquitoes not birds. And that very few healthy people have had trouble with the WNV. Most folks recover without even knowing they've ever had it. It is people with compromised immune systems or those who have fed the dog their broccoli under the kitchen table, instead of eating it, that are the most at risk.

As usual, Phyllis it has taken me 600 words to answer your question. And my answer is no, I don't think the sudden drop in your "nasty black bird" population is related to West Nile. The spring, and especially this subzero spring, is basically a mosquito free time of year and thus no virus can be spread to birds to cause any sudden reduction in population. If there ever was a noticeable population drop, it would most likely take place in the warmer months.

I have no idea what could have caused the disappearance of your wonderful crows. There are many reasons why birds suddenly avoid an area. Perhaps some threatening thing like a hawk has moved into your neighborhood or even worse, an employee from the DMV.

Artwork by Catherine Clark



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