MICHELE NORRIS, Host:
This is ALL THINGS CONSIDERED from NPR News. I'm Michele Norris.
ANDREA SEABROOK, Host:
NPR's John Nielsen reports that a new study says it had a big impact on some well-known species.
(SOUNDBITE OF BIRDS CHIRPING)
JOHN NIELSEN: Peter Mora, an ornithologist with the Smithsonian Institution says that's when the West Nile virus arrived.
PETER MORA: There weren't as many crows. There weren't as many robins for a while there. Chickadees seemed to have disappeared and many people were noticing this. My neighbors were noticing this. Where did all the crows gone? The question was: How large a scale the impact was there actually?
NIELSEN: Mora has been trying to gauge that impact ever since. And in a new paper in the journal Nature, he and some colleagues say they now know which bird species were hardest hit. To get these answers, they sorted through a national census of breeding birds that's been done every year since 1966.
SHANNON L: Where census and scientists go out in the first week of June and count all the birds they hear.
NIELSEN: The study also showed that the virus hit harder in some places than it did in others. Around Washington D.C. for instance, it killed off 90 percent of the crows. Perhaps most intriguingly, according to LaDeau, this study shows that in the places where the virus killed a lot of birds, it also killed a lot of people.
DEAU: The bird impacts and the human impacts moved as a common wave across the continent.
NIELSEN: John Nielsen, NPR News, Washington. Transcript provided by NPR, Copyright NPR.
