As high temperatures loom, they’ll pack up and fly north once again to enjoy the gentle weather of the Canadian summer. Many birds follow some variation of this pattern, driven by a pre-programmed instinct that allows them to thrive by traveling to where conditions are best for any given part of the year. Migration, after all, is a biological imperative. At least, that’s how it used to be. What happens, though, when climates change? What do birds do when habitat alteration provides new options, besides the yearly trip south? They adapt.
Changes to local ecosystems, whether immediate through human development or gradual through climate change, have made it possible for larger numbers of birds to stay put, rather than migrate. Urban areas provide year-round sources of food and shelter for birds capable of adjusting to life alongside people. Milder winters, as a result of climate change, mean that the food supply in many areas is less taxed than in previous generations, making it feasible for more birds to remain yearlong residents. While some birds have always stayed behind, this is now more prevalent. Besides increasing the size of non-migrating subpopulations, climate change has also altered the list of acceptable destinations. American robins, American goldfinches, and other traditional migrants have been recorded wintering in areas further north than their previous ranges due to changes in temperature averages for those areas.
Some birds take this kind of adaptation to new levels. Canada geese, for instance, have become yearlong residents in warm states like Arizona, where they have found the perfect habitat for themselves on artificially landscaped golf courses. The birds are simply following instinct; nature drives them to seek circumstances best suited for survival, and as humanity increasingly transforms the makeup of the world, necessity dictates that they capitalize on it however they can.
The age-old problem hasn’t changed; winter still means colder temperatures and scarcity of food. What’s is different is that, for better or worse, there are new solutions, and birds, being nothing if not adaptable, often follow whatever path seems most likely to ensure survival. For most, the answer is still a mandatory journey that takes them far away from winter’s wrath. Others, though, have made the most of what humans have done to the world, by altering their own behavior to suit urban environs or climate shifts.
Regardless of the method, survival is ever the only goal, and adaptability remains the means to achieve it.