Record-breaking Arctic tern migration secrets revealed

A ground-breaking study of birds that breed on the Farne Islands in the UK reveals Arctic terns travel 96,000 km – the longest recorded migration in the natural world

The Arctic tern is an incredible traveller. Look beyond that jaunty black hat, the lipstick red stockings, and a fame for pooping on tourists visiting their summer residence, and you will recognise an intrepid explorer that spends much of its life chasing the trajectory of our sun.

Thousands of these birds nest on the Farne Islands, just off the coast of Northumberland, and although scientists knew they headed south at the end of the summer, no one knew exactly where they went or what route they took to get there.

Already some exciting broad conclusions can be drawn

To try and solve the mystery, last year the BBC Two series Springwatch teamed up with Newcastle University to launch an ambitious year-long study, which involved fitting tiny transmitters to 28 Arctic terns (Sterna paradisaea) nesting on the Farne Islands. These ingenious devices weigh less than a paper clip and record both day length and temperature.

All of the arctic terns analysed so far have headed south via the West African coast, then east to the southern Indian Ocean

Dr Chris Redfern is one of the project's lead scientists and has had an anxious wait for these precious travellers and their "black boxes" to return to the Farnes this spring. But his patience has paid off and to date they have successfully re-captured, and retrieved information from 15 individuals.

"This data is in the very early stages of being processed, yet already some exciting broad conclusions can be drawn," explains Dr Redfern. “All of the Arctic terns analysed so far from the Farnes, have headed south via the West African coast, then east to the southern Indian Ocean, continuing south into Antarctic waters."

 

In 2013, a similar study was undertaken in the Netherlands, where birds were also found to follow a zigzagging route, this time bouncing from West Africa to South America on their return to the Arctic.

According to Dr Richard Bevan, part of the team from Newcastle University, the previous longest recorded trip was one of the Dutch birds that flew 90,000 km. One of the birds from this study in collaboration with Springwatch flew 96,000km, making the overall distance longer than that of any other migratory species on record. 

So why do they take such a circuitous route? The answer is surprisingly simple; it is thought the birds are simply following huge, spiralling wind patterns in the atmosphere, and so avoid flying into the wind. 

Unexpectedly, it seems that a number of the "British" Arctic terns Dr Redfern is studying have a serious case of winter wanderlust, and once within Antarctic waters they drifted widely, some as far west as the Weddell Sea. 

 

On the return leg, it is thought these birds took the same route back via the coast of West Africa, and as the data continues to be extrapolated, it is hoped that further details of this extraordinary journey will finally come to light.

You can watch a wonderful update about these magnificent birds on Springwatch, which continues on BBC Two at 20:00 BST, Monday to Thursday until 16 June.

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