Fall has arrived and in the northern climates it’s time to say goodbye to summer flowers, fresh strawberries, and some of our wildlife friends. Many birds leave Wisconsin each fall for warmer temperatures of the south. The most well known in Wisconsin might be the Sandhill Crane or the many waterfowl that can be found in our lakes. The cold temperatures during Wisconsin winters mean that vital food and water resources are gone or frozen so birds must either face harsh competition for limited food or leave until spring time. But how do birds know when the right time to leave and fly south is? How do they manage to appear during those first few chilly days of spring like the American Robin always seems to do?
A new study from scientists at the University of Oklahoma demonstrates how birds may know when to migrate at the precise time of year. Using observations from citizens along with radar and satellites these researchers found evidence that birds likely use temperatures and (to some degree) seasonal changes in the landscape, like bud formation on trees to adjust migration timing each spring and fall.
This precious balance in timing can mean life or death for the millions of birds that make a migratory trip during the year. Arrive too early or too late in the spring, and there either isn’t enough food yet or the nesting territory may already be taken. Leave too late in the fall and a snap of cold weather could be dangerous! The environmental cues that help birds make the trip are important to understand since climate change has resulted in milder seasonal temperatures but with occasional erratic weather. These warmer temperatures may ‘trick’ birds into migrating too early or staying too late.