It happens every fall: The days grow colder, the nights grow longer, the birds grow restless and then they take flight. In North America alone, billions of birds fly south for the winter, sometimes in enormous undulating flocks. It is one of nature’s great spectacles as well as an athletic feat: Some birds regularly migrate thousands of miles or stay aloft for days at a time.
And yet, for a large-scale, annual event, migration remains surprisingly mysterious. Scientists are still seeking answers to basic questions about the costs and benefits of these avian journeys and what it takes to survive them.
“How do you get a bird like a godwit that can fly over the entire Pacific Ocean?” said Christopher Guglielmo, a biologist at Western University in Ontario who studies the physiology of bird flight. “How do they have enough energy?”
And, perhaps more to the point of his own research, he added, “How do you study what’s going on inside a bird?”