Southward Departure of Urban-Wintering Canada Geese From Two Major Metropolitan Areas

Wintering distribution of both subarctic- and temperate-breeding Canada geese (Branta canadensis) abundances have increased while wintering distributions of Canada geese have shifted northward in the Mississippi and Atlantic Flyways. Abundances of geese remaining north of traditional wintering areas and in urban areas has resulted in decreased hunting opportunities further south. These shifts are likely due to a combination of changing climate and adaptation to urban areas that provide necessary resources and safety during mild winters. However, severe weather events may push geese from these urban refugia to huntable areas, leading to increased harvest and hunter opportunity. Our goal is to better understand resources that facilitate remaining in urban areas during winter and weather conditions that force geese from these areas by examining southward departure of Canada geese marked in the Toronto and Chicago Areas. We GPS transmitter-marked 153 Canada geese in the Toronto and Chicago Areas between 2014 – 2018 and tracked geese until death or transmitter failure. We quantified timing and weather conditions associated with southward departures and modeled effects of weather, breeding status, and breeding region on the propensity to depart. We recorded 32 departures from the Chicago Area (n = 153 birds/seasons) and 48 departures from the Toronto Area (n = 81). Mean departure was 6-January ± 22.3 days from the Chicago Area and 14-December ± 20.6 days days from the Toronto Area. Minimum daily temperatures on days of departure were similar between Toronto and Chicago Areas (-8.9° C ± 7.3, -12.6° C ± 7.8 respectively). We are continuing to model the effects of weather, breeding status, and resource use in urban areas on southward departure. A clearer understanding of the relationship between urban land uses, weather, and winter departure can improve management of goose abundances and harvest.