The Cornell Lab of Ornithology reported yesterday that last winter, in West Nile virus-afflicted parts of the United States, American Crow counts dropped to a 15-year low. Other species, including Black-capped and Carolina Chickadees, were also scarce, while still others appeared in record-high numbers.

The Midwest, which by far showed the most dramatic drop in American Crow and chickadee numbers, was a West Nile virus hotspot for birds and humans alike last year. However, West Nile virus may not be solely responsible for the declines in bird populations. Wesley Hochachka, assistant director of the Cornell Lab of Ornithology’s Bird Population Studies department, observed, “Chickadee declines were not limited to states with West Nile virus outbreaks. This suggests that the drop in numbers might be attributable to more than just West Nile virus.”

Species on the rise over the last year include Red-bellied Woodpecker and Northern Cardinal; both were at an all-time high in the Midwest, even in the presence of West Nile virus. Downy Woodpeckers and Mourning Doves were seen in slightly greater numbers throughout their ranges. Both Cooper’s and Sharp-shinned Hawk counts also reached new highs, still rebounding perhaps from the now banned use of the pesticide DDT.

The study is based on data from Project FeederWatch. Last year, more than 16,000 people counted the birds that visit their feeders and sent this information to the Cornell Lab of Ornithology, where it was collated and analyzed to determine the status of North America’s feeder birds. What an excellent example of citizen science at work!