Last summer, biophysicist Douglas Warrick spent eight hours each day patiently sitting on the fence of an Oregon cattle farm. Pointing an alienlike metal wand toward a field, he waited. The rod was a special antenna designed to listen for very small radiotags. Earlier that week, Warrick and his team from Oregon State University had glued these tiny trackers, weighing less than a third of a gram, to 120 barn swallows (Hirundo rustica).
“These birds are the absolute extreme when it comes to flight performance,” Warrick says. “They're at the cutting edge for what can happen with an avian body plan in terms of flight, yet so much of their behavior remains unknown.”