Canada Geese have shifted their winter range northward in recent years by taking advantage of conditions in urban areas--but what specific features of cities make this possible? A new study from The Condor: Ornithological Applications suggests that rather than food, geese are seeking safety, congregating in areas where they can avoid hunters and be buffered from the coldest winter temperatures.
Heath Hagy of the University of Illinois at Urbana-Champaign and his colleagues captured 41 geese in the Greater Chicago Metropolitan Area between 2014 and 2016 and fitted them with radio transmitters to track their movements. While the geese used a remarkable variety of urban habitats, they preferred deep water and rivers over green space such as parks when temperatures dropped enough to tax their ability to maintain their body temperature. For geese that remained within the metropolitan area, winter survival was 100%, but this dropped to 48% for those that emigrated out to forage in surrounding agricultural fields, countering expectations that the proximity of agricultural habitat may be a factor in geese's winter expansion in the area. Together, these results suggest that sanctuary may be a higher priority for wintering geese than good foraging habitat.
Better understanding how geese use urban habitat in winter may help reduce human-wildlife conflicts such as collisions with airplanes. "The growth of urban areas and northward expansion of row-crop agriculture have changed the way geese migrate. Unfortunately, some of our large cities have become goose sanctuaries, where resident geese and migratory geese congregate during winter to escape hunting pressure," says Hagy. "Although additional research is needed, our data will be useful to guide goose harassment efforts, which may offset the benefits of remaining inside urban areas during winter and open hunting seasons."
"This work offers comprehensive insights into the biology and behavior of a large wintering population of Canada geese that inhabits a major metropolitan area in the mid-western U.S. Appropriately grounded in an energetic context, the study thoroughly describes how Canada geese utilize the urban environment under varying weather conditions and demonstrates the survival benefits of urban adaptation," according to The Ohio State University's Robert Gates, a wildlife management expert who was not involved in the research. "Findings from this study provide a firm biological grounding for the development and implementation of management actions to alleviate human-Canada goose conflicts in urban areas."
"Survival and habitat selection of Canada Geese during autumn and winter in metropolitan Chicago, USA" will be available October 11, 2017, at http://www.
About the journal: The Condor: Ornithological Applications is a peer-reviewed, international journal of ornithology. It began in 1899 as the journal of the Cooper Ornithological Club, a group of ornithologists in California that became the Cooper Ornithological Society, which merged with the American Ornithologists' Union in 2016 to become the American Ornithological Society. The Condor had the top impact factor among ornithology journals for 2016.