Last Friday’s autumnal equinox officially marked the arrival of fall, and with it the beginning of the seasonal migration of Canada geese. Living in Canada, hearing the unmistakeable honking of the geese, and seeing their characteristic V-formation signals a turn in season. Even in the busy city of Montreal, it is hard to miss the geese overhead. Fall wouldn’t be fall if it weren’t for the flight of these birds.

However, changes caused by global warming affect the migration of the Canada goose. The freezing of northern waters, where the geese nest during the summer months, triggers them to begin their migrations south. Able to fly up to 1000 kilometres in a single day, these geese are usually seen as far south as the southern United States and Mexico during the winter. Yet with warmer fall and winter temperatures, some populations will find it unnecessary to travel as far south in order to find open water and adequate food supplies.

Milder climates, combined with increased farmland (which provides a comfortable food source and shelter from predators) may render the need to migrate unnecessary. This has already happened in areas of California and the Great Lakes. What’s more, geese populations have started taking residence in parks, golf courses, and even near airports, which could easily change the birds’ reputation from harbinger of seasonal change to pest.

While these shifts do not threaten the size of populations, they do affect the relationship between the birds and their environment. The timing of events in nature is intricately linked: chicks hatch and find caterpillars ready to eat, which had been feeding on the available spring-time buds. A disturbance in this sequence means drastic change. If the geese’s temperature-change-trigger occurs earlier or later in the month, by the time the birds arrive at their destination the insects and plants they rely on may have blossomed or hatched too early—or failed to do so at all.

In addition, global warming will affect the wetland shorelines of the St. Lawrence River, an essential habitat for migrating geese. The cumulative effect of global warming therefore will change many of the areas suitable for breeding, feeding and nesting. If Canada geese no longer need to migrate to escape an inhospitable environment, we might not see many V-formations in the sky. While the effects of global warming may seem distant for many, they are a pressing and tangible threat. For Canada, to lose such a distinguishing feature like the flight of the Canada goose seems unimaginable. Let’s hope that we continue to see more than just Canada Goose jackets as a marker of winter.