4,660 miles in just 13 days

Tiny songbirds such as martins and thrushes can travel as far as 311 miles a day in their annual migrations between the Americas -- three times as far as researchers had previously believed -- biologists found in the first study to track the birds to their wintering grounds and back.

The birds fly two to six times as fast heading north in the spring as they do heading south in the fall, perhaps in a competition to reach the best breeding sites and attract the fittest mates, ornithologist Bridget Stutchbury of York University in Toronto reported today in the journal Science, which released the study online Thursday.

One industrious female martin flew the 4,660 miles from the Amazon basin to Pennsylvania in only 13 days -- with four of them spent on stopovers.

The new data were obtained using miniature geolocators, about the size and weight of a dime, attached to the birds' backs much like a schoolchild's backpack. The same technology was used in 2006 by Scott A. Shaffer of UC Santa Cruz to demonstrate that shearwater gulls fly a huge figure-eight over the Pacific Ocean during their migration, traveling as much as 46,000 miles in a year.