Scientists made seabirds fly harder. Only 67% returned next year

Researchers clipped a few wing and tail feathers of wild black-legged kittiwakes in Alaska to make flying more energy-intensive and tracked them for several years. The birds struggled to raise chicks during that breeding season, and fewer survived to return the next year. However, those that did return migrated farther and were more likely to breed successfully, showing how energy spent in one season can affect the next.