The count has been going on for 114 years, making it the longest-running citizen science survey in the world. Washtenaw County birders have taken part since 1940, but the volunteers didn't see a single turkey until 1989. Last year, they counted forty-three.
"There are a number of species that you think of as common that really didn't used to be," says Gelderloos, such as northern cardinals, southeastern birds which were rare in the 1960s and are now seen in the hundreds during the CBC, as are red-bellied woodpeckers and, in much smaller numbers, Carolina wrens.
What birders are seeing in Ann Arbor reflects national trends. Based on CBC data from the past forty years, 200 North American bird species have shifted their range northward an average of thirty-five miles due to warmer temperatures. Helped by a reintroduction program and their ability to live near developed areas, wild turkeys are now found 400 miles north of their former range.