A huge flock of migrating tree swallows are seen in the sky during an Audubon Christmas Bird Count in New Smyrna Beach, Florida. When Logan Parker first sees a male, black-throated blue warbler near his Maine home each spring, two things strike him about the tiny bird – its stunning appearance and the thousands of miles it traveled from its winter home in Central America or the Caribbean. The birds, with their striking black masks and contrasting midnight blue and white feathers, “look so delicate,” said Parker, a birdwatcher and an ecologist with the Maine Natural History Observatory. “It’s hard to imagine they make these long-distance movements to come here to raise young.” For centuries, these birds and many others completed long-distance migrations in tune with other ancient spring rhythms, such as the trees budding out into leaves in myriad shades of green. But that’s changing. Spring – with its “pulse of food and pulse of life” – arrives earlier than it used to, driven by warmer temperatures, said Ellen Robertson, who co-authored a recent bird migration study while doing post-doctoral research at Oklahoma State University. The study found a mismatch between earlier spring green up and the timing of migration for some long-distance travelers, leaving birds such as the black-throated blue, “out of sync.” For example, they might arrive in their spring nesting locations after the peak period for insects to emerge. Robertson is one of many scientists working to unravel more of the mystery around migrating birds and their potential long-term survival as climate change multiplies the threats they face. To do so, they are using a growing body of information that offers the most complete picture in history of when, where and how birds migrate. Recently published studies have tapped more than three decades of data […]