After flying more than 10,000 kilometers from South America to the Arctic, male pectoral sandpipers should be ready to rest their weary wings. But once the compact shorebirds arrive at a breeding ground in Barrow, Alaska, each spring, most keep going — an average of about 3,000 extra kilometers.
Scientists thought males, which mate with multiple females, stayed put at specific sites around the Arctic to breed. Instead, in a study of 120 male pectoral sandpipers in Barrow, most flitted all across the region looking for females. One bird flew a whopping 13,045 kilometers more after arriving, researchers report online January 9 in Nature.
“We had no clue that they range over such a wide area,” says study coauthor Bart Kempenaers, a behavioral ecologist at the Max Planck Institute for Ornithology in Seewiesen, Germany. To track the birds, the researchers placed satellite transmitters on 60 males in 2012 and another 60 in 2014.
“It doesn’t seem to be very tough for them to do these flights,” Kempenaers says. Competition for a mate, however, is cutthroat. In Barrow, just a few males sire the majority of offspring each year. The new work shows males visited as many as 24 potential breeding sites over four weeks, perhaps to boost their chances of reproducing.
Some had better stamina than luck. Kempenaers told of one male’s 2,000-kilometer Arctic odyssey: Once the bird reached Barrow, it flew north over the Arctic Ocean before turning around and landing just 300 kilometers from where it started. “There’s nothing northwards. There is only the [North] Pole, no land,” he says.