The United States is home to over 30 million American Crows with frequent sightings across every state. But the birds flock to Ann Arbor in unusually high numbers during the winter, roosting throughout the city and around the University of Michigan campus. But why exactly are there 20,000 crows here, and how do they impact students? 

Juliet Berger, president of the Washtenaw Audubon Society, told The Michigan Daily crows travel in large flocks and nest in central locations so they can watch out for potential predators. Berger said that’s why crows are frequently drawn to urban areas. 

“In the fall and winter, crows group together in large flocks,” Berger said. “They tend to nest and roost together in urban areas because it’s warmer — there’s a five to 10 degree (Farenheit) increase in temperature in urban areas. Also, in these large groups, there are more crows to watch out for predators.”

Natalie Hofmeister, assistant professor of ecology and evolutionary biology, told The Daily that crows tend to return to the same “roosts” that they have used for long periods of time. It’s not clear how the crows know to come back to the same spots year after year, Hofmeister said, but it’s likely that the Ann Arbor crows have been roosting in the same spots on campus for generations.“

They are returning to a roost that often has been used for a really long time,” Hofmeister said. “(Crows) are very social birds. Exactly why do they do this roosting behavior? I don’t think we really know. It’s hard to know for how long different parts of campus have been roosts for these birds, but they might be returning to it year after year.

”Hofmeister said in addition to this behavior, crows often participate in complex and emotional rituals, such as holding funerals for fallen members of the flock. 

“Everybody’s got feelings about birds in general,” Hofmesiter said. “Crows have this association with death. For example, there’s an ornithologist who has been studying crows for a decade and she videotapes crow funerals … For people who already associate them with death, maybe that’s not what you want to hear, but they have a lot of fascinating behaviors that we can try to interpret and not really ever know exactly how a crow sees it.”