Bird Movements Mirror a Changing Climate

The purple finch winters far to the south in some winters and farther north in others. These birds did not go as far south as wintertime temperatures increased during recent years. Audubon says their overall northward movement has been about 433 miles since 1968.

A network of volunteer bird-watchers across North America has documented a significant northward and inland movement of the continent’s bird species in response to global warming, according to a new report by the Audubon Society.

Analysis of 40 years of bird sightings reveals that more than half of 305 bird species in North America — including robins, owls, gulls, and chickadees — are spending the winter about 35 miles farther north than they did 40 years ago, the report says.

While shifts in population among individual bird species have been known to occur due to a variety of factors, Audubon says the shifts in wintering territory of around 177 species coincides with long-term winter temperature increases where they have occurred.

"Birds provide some of the best evidence for species' responses to climate change, through their population size, distribution and timing of breeding and migration," said Stuart Butchart, Audubon's Global Research and Indicators Coordinator.