Birds Fled Area Before Tornadoes Appeared 99
A reader sends a report from scientists who were tracking a group of birds — golden-winged warblers — in the Appalachian mountains. Just a few days after the birds completed their seasonal migration, they did something odd — they picked up and moved again. Shortly thereafter, a series of storms swept through that area of the U.S., which led to a destructive tornado outbreak (abstract).
After the storm had blown over, the team recaptured five of the warblers and removed the geolocators. These are tiny devices weighing about half a gram, which measure light levels. Based on the timing and length of the days they record, these gadgets allow scientists to calculate and track the approximate location of migratory birds. In this case, all five indicated that the birds had taken unprecedented evasive action, beginning one to two days ahead of the storm's arrival. "The warblers in our study flew at least 1,500km (932 miles) in total," Dr. Streby said. They escaped just south of the tornadoes' path — and then went straight home again. By 2 May, all five were back in their nesting area."