West Nile Virus Decimates Black-capped Chickadees

A study by Audubon and the Bird Conservation Network (BCN) in October of the effect of West Nile disease on songbirds throughout the six-county Chicago region found that the black-capped chickadee, a common bird of our woods and towns, appears to have been completely extirpated in large areas.

"The data gathered by 74 trained monitors tells a dramatic story," stated Judy Pollock, Audubon project manager for the Chicago region. "In three areas of our region — parts of eastern Lake County, some south suburbs, and a large area of northern Chicago and nearby suburbs — chickadees were almost completely gone."

The study, the first that focused attention on the effect of West Nile disease on songbirds, raises questions about the effects of chemicals used to control mosquitoes. The pesticide spray kills fish and many species of insects, disrupting the chain of life that birds and humans depend on. Audubon recommended carefully weighing the needs of birds in developing the next season's pest control strategies.

The area where chickadees were missing in the north suburbs coincided with the area of the highest incidence of human West Nile Virus cases.

Twenty-two chickadee searches totaling 81 hours turned up only two birds in an area of approximately 120 square miles extending from northwest Chicago through west to Des Plaines, north to Northbrook, east to the lakefront at Winnetka, and south to the northernmost neighborhoods in Chicago.

"One hundred and twenty-four species of native birds are known to have been affected by the virus," added Pollock. "We still don't know the fate of many of the birds that breed here in summer and which were preparing to migrate when the disease hit."