On the Midway and in Jackson Park, it’s hard not to come across a flock of Canada geese, with their sharp, hissing beaks and black, white, and gray feathers. The birds are unfazed by humans, but don’t get too close—they can be harshly territorial.

Now, they have more of a presence than ever, ruling over Chicago’s parks with their loud honks and hisses. In recent years, observations from scientists suggest that these migratory geese are wintering farther north than they have historically, contributing to an increase in the overall Canada goose population in the Chicago area and impacting the human Chicagoans as well. The wild goose chase to understand the city’s geese pulls in all sorts of people, from scientists and academics to facilities managers and professional goose chasers to even student journalists.

Michael Patrick Ward, a professor of natural resources and environmental sciences at the University of Illinois Chicago, began studying Chicago’s geese after Midway International Airport encountered the problem of too many geese staying in the winter. Ward is a well-cited academic authority on geese, although he does do research on other birds, too (in our interview, he also told me about his work for the Cuban and Mexican governments). His goose research focuses on understanding the birds’ behavior and why their habits have changed.

“There are some birds that leave Chicago in the winter, but the [number] of birds in Chicago has greatly increased to the point where there’s lots of concerns about air traffic and running into geese,” Ward says. Geese are capable of flying in the way of planes, which can cause damage and even be deadly to plane passengers. Ward’s team reported that geese were responsible for 1,403 recorded bird strikes to civil aircraft from 1990 to 2012. One such incident in 2009, in which a flock of Canada geese forced down US Airways Flight 1549 onto the Hudson River, was even dramatized in the 2016 film Sully.

The Past and Present of Canada Geese

Although they’re now a fixture in grassy areas across the country, the Canada geese we see today wouldn’t be there without successful population restoration efforts. In the early 20th century, hunting, egg-collecting, and habitat destruction nearly drove the giant Canada goose, one of the most common subspecies in the Midwest, out of North America. In the 1960s, a small flock was discovered in the Midwest, and a program was launched to bring them back. Their…