Arctic tern’s extraordinary pole-to-pole journey mapped
Researchers have mapped the extraordinary pole-to-pole migration of the Arctic tern, the bird world’s ultimate commuter which flies the equivalent of three return trips to the Moon during its lifetime.
Tracking devices attached to the bird’s legs have revealed new details about their annual journey from their breeding grounds in Greenland to the Weddell Sea on the shores of Antarctica.
Far from heading directly south, the tracking devices revealed that the birds spend around a month at sea over the North Atlantic before following the the coast of north-west Africa.
Half of the birds then continued south down the African coast but researchers were surprised to discover that the rest crossed the Atlantic before flying south down the coast of South America. Some of the birds had flown more than 50,000 miles by the time they completed their journeys.
“They’re the ultimate commuters,” said Carsten Egevang of the Greenland Institute of Natural Resources in Nuuk whose work is published in the Proceedings of the National Academy of Sciences. “This is at the edge of the capacity of any living creature.”
Egevang said the birds’ circuitous route was to allow them to take advantage of prevailing global wind systems in order to preserve energy.
“They paused in their southward migration to spend time in highly productive waters in the middle of the Atlantic Ocean,” he said. “Clearly, Arctic terns have learned to ‘fuel up’ before crossing areas of ocean with limited foraging options.”
But Egevang warned that climate change, which could devastate both poles, could undermine the Arctic tern’s survival prospects in years to come.
“Climate change is happening most rapidly at the Poles and the Arctic tern is one of the only species that spends significant amounts of time at both extremes. There is no doubt that it will be affected.”