In a new study, scientists have discovered that great snipes can complete a transcontinental flight across Europe, from Sweden to sub-Saharan Africa, in as little as two days without resting. The birds traveled up to 4,200 miles (6,760 kilometers) at an average speed of 60 miles (97 kilometers) an hour.
To track the birds, biologists captured and tagged ten great snipes with geolocators at their breeding grounds in western Sweden in May 2009. Tracking data for three of the birds was retrieved after their recapture in Sweden a year later.
At first glance, great snipes don’t look especially speedy or well equipped for such an arduous journey. Their bodies are small and chubby, not aerodynamic, and in the autumn the birds get so rotund that, when shot, “their skin sometimes ruptures when the shot bird hits the ground,” according to one 19th-century account.
But it’s these ample fat reserves that allow the birds to fly such long distances without stopping, said study leader Raymond Klaassen, a biologist at Sweden’s Lund University.
“They almost double their body weight before the flight,” Klaassen said. “And all this fat will be burned during the flight, and they will arrive lean and exhausted in Africa.”
Fast Flyers a Rarity
It’s a rare bird that can fly both far and fast. For example, the Arctic tern racks up as many as 50,000 miles (80,000 kilometers) during its yearly migration from the Arctic to the Antarctic and back again. However, the animal spreads the flight out over several months and fishes along the way.
At the other end of the spectrum, peregrine falcons can reach speeds of up to 200 miles (322 kilometers) an hour but only in short bursts to catch prey.
The only other bird that comes close to matching the great snipe’s abilities is the godwit, a wading bird. In 2007 scientists recorded a godwit flying more than 7,000 miles (11,500 kilometers), from Alaska to New Zealand, in nine days at an average speed of about 35 miles an hour (56 kilometers an hour).
“[One] difference between the godwits and the snipes is that the godwits travel over the ocean, and thus have no possibilities to stop,” Klaassen said. “Hence, their amazing flights are not their choice.”
By contrast, snipes have several rest-stop options during their autumn migration to Africa but choose not to take advantage of them. The reasons for that are unclear, especially since the birds make several stops during their return flights to Sweden in the spring.
Bird Migration “Revolution”
As with other migratory birds that fly long distances, it’s unclear how great snipes can apparently fly for such long periods with little or no sleep.
“This is one of the unsolved mysteries of long-distance flights,” Klaassen said. “We now believe that half of their brain sleeps at [a] time, alternating between the left and the right side. Or they do not sleep at all, but this seems impossible regarding the importance of sleep in general.”
Klaassen says so little is known about bird-migration strategies that he wouldn’t be surprised if the great snipe’s record is broken soon.
“Generally we know rather little about the performances of different species, as many have not yet been tracked,” he said.
“I foresee many surprises in the nearby future, due to the recent development of minute tracking devices. The field of bird migration is currently going through a revolution, and these are certainly very exciting times for us.”