By BBC News Online's Julianna Kettlewell
Tiny transmitters have been attached to migratory swans so their epic journey can be tracked for the first time.
The swans were fitted with tiny transmitters
One whooper swan and five Bewick's swans are being tracked by satellite so their progress can be followed online.
The researchers hope to reveal where the swans stop to rest and their exact flight path, along with many other trials the birds face on the journey.
The study is being carried out by the BBC and the Wildfowl and Wetland Trust, who hope it will aid conservation.
Shrouded in mystery
Of the three species of swans that live in Britain, two - the Bewick's and the whooper - fly thousands of kilometres each year, to and from their breeding grounds.
The reason these birds migrate is to make use of a productive but very short summer in the Arctic tundra, where they breed. Many of them then return south to over-winter in more forgiving climates.
Until now, their long-distance flight paths have been shrouded in mystery.
The migrant swans have yellow and black bill markings
Previous research has focused on the swans at the beginning and end of their journey, but this is the first time individuals will have been tracked along their whole route.
Scientists travelled to Arctic Russia in August to find the stars of this project - the Bewick's swans Alexei, Andrei, Anatoli, Kostya and Pechora, and Huc the whooper.
"We found the swans in the Pechora Delta, which is about as far north as you can go before the land runs out," said Julian Hector, Editor of the BBC's Natural History Unit Radio. "They are all non-breeding adults, who were hanging around in sort of teenage gangs.
"At that time of year they are flightless, due to the moult, so we were able to catch them with giant butterfly nets."
Researchers hope that the transmitters will also reveal which lakes the swans stop at to rest and replenish their energy reserves.
Information like this will be helpful in conservation efforts.
"Detail is very important when designing conservation strategies for migrant swans," said Tony Richardson, WWT Director.
The project will reveal where the swans rest and refuel
"Knowing that they put down in Estonia is not enough. We need to know what lakes they use to feed en route. Something like the size of a lake we can conserve and manage, not something the size of a country."
Biologists know that thousands of Bewick's swans spend the winter in Britain and Holland but virtually nothing is known about where whooper swans from the Russian tundra migrate to, or their flight path.
"It had been assumed that they travelled directly south to winter in places like Kazakhstan, but Huc is heading this way, which is a real surprise," said Mr Hector. "As we speak, he is on the Russian/Finnish border."
The transmitters fitted to the birds are very sensitive, conveying their position within a square kilometre, their speed and even temperature. But, sadly, the news is not always good.
"Kostya flew 1,700 miles and landed in a lake in Estonia. Then his signal suddenly stopped," Mr Hector told BBC News Online. "We are very worried about him because we know a lot of shooting goes on around there."
The remaining swans' progress can be tracked online from the BBC Radio Four website, and the Today programme will give daily updates from Monday.
Julian Hector said: "We are not only finding out their route for the first time, we are unpicking the event to reveal a huge amount of information and surprising facts."