A tiny backpack revealed a songbird's secret 6,800-mile journey

Yellow-rumped warblers, the small songbirds that bird-watchers call "butter-butt" for the yellow patch above their tails, have been hiding a much longer commute than anyone realized. Smithsonian researcher Stephanie Szarmach and her Ph.D. adviser David Toews fitted dozens of the birds in Anchorage, Alaska, with Tic Tac-size geolocator backpacks, then waited a year to recapture each one and read the data stored inside. The tags record air pressure during flight, letting scientists reconstruct the route. The warblers did not take the short hop south to California, as a 19th-century ornithologist once guessed. They flew east across Canada's boreal forest before dropping to the Gulf Coast, a 6,800-mile round trip for a bird thought to be a short-distance migrant. To catch one wearing a backpack, Szarmach played its own song through a speaker. The bird, convinced a rival had arrived, flew straight down into the net. The data helps pinpoint stopover sites worth protecting.