<p>Every year, billions of birds migrate thousands of miles from their summer breeding ranges to their warmer wintering ranges and back. However, the question of where these birds stop to rest and refuel along the way has long stumped ornithologists. Princeton Ph.D. student Fengyi Guo and her colleagues from Princeton and the University of Delaware address this question in a newly published <a href="https://www.cell.com/current-biology/fulltext/S0960-9822(23)01583-X">paper</a> by using weather radar imagery to map the birds’ migratory stopover sites in North America. </p>