Ups and Downs
Project Feeder Watch data reveal avian population increases and declines
Roger Di Silvestro
KENTUCKY, Illinois, Indiana and Ohio—Midwest states hard hit by West Nile virus—have seen counts of American crows drop to a 15-year low, according to data compiled by Cornell Lab of Ornithology’s Project FeederWatch. Crow numbers nationwide continue to be stable, but other species are not so lucky. Black-capped and Carolina chickadees reached 15-year lows throughout their respective ranges, but Wesley Hochachka, assistant director of the bird lab, says the virus may not be the cause of the decline, since the drop occurred also in states that have not experienced a viral outbreak.
House finches also have declined, according to FeederWatch data, as part of a decade long fall blamed on a bacterial infection that first hit the birds in the early 1990s.
But some species have increased, including Cooper’s and sharp-shinned hawks, which were at an all-time high for Project FeederWatch, possibly as a rebound from declines caused by the pesticide DDT during the past 50 years.