URBANA, Ill. – Canada geese collide with aircraft, intimidate unassuming joggers, and leave lawns and sidewalks spattered with prodigious piles of poop. They’re widely considered nuisance birds, and municipalities invest considerable time and money harassing geese to relocate the feisty flocks. But new University of Illinois research shows standard goose harassment efforts aren’t effective, especially in winter when birds should be most susceptible to scare tactics.

“Harassment is part of an energy equation. If a bird is hanging around Chicago in winter, it's probably not in good shape. It’s cold and doesn't have a lot of food,” says Mike Ward, professor in the Department of Natural Resources and Environmental Sciences (NRES) at Illinois and co-author on the study. “The goal of harassment is never to hurt the geese, but to get them to use up energy during an already tough season, forcing them to migrate to warmer climates. Unfortunately, we found that doesn’t happen in practice.”

The study isn’t the first to find harassment doesn’t work, but it is the first to explain why. The researchers used GPS transmitters with Fitbit-like movement trackers to learn where Canada geese go and how their behavior changes when they’re harassed.

Ward’s doctoral student, Ryan Askren, now a postdoctoral researcher at the University of Arkansas-Monticello, worked with USDA-Wildlife Services personnel to harass Canada geese at Marquette Park near Midway Airport in Chicago. During the winters of 2017 and 2018, members of the research team walked or drove toward geese while clacking boards together.

Most harassed geese either moved elsewhere in the same park or were back within the hour. Those that did leave went to commercial rooftops, railyards, other parks, water treatment ponds, and sports fields; not exactly migrating long-distance and away from the urban environment.

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The Department of Natural Resources and Environmental Sciences is in the College of Agricultural, Consumer and Environmental Sciences at the University of Illinois Urbana-Champaign.