Twenty critically endangered spoon-billed sandpiper chicks have been successfully bred in captivity in Britain and released into the wild.
A team of British and Russian ornithologists collected the eggs from remote breeding grounds in the Russian Far East and brought them back to the Wildfowl and Wetlands Trust in Slimbridge, Gloucestershire, for incubation.
Nine spoon-billed sandpipers were also successfully reared in the village of Meinypil'gyno, in the Chukotsk peninsula.
All the birds were then released as fledglings to make their 4,971-mile (8,000km) migration to Burma.
The conservationists hope their work will ensure the survival of the rare species, which is unique in the animal kingdom for being born with a spoon-shaped beak.
There are thought to be fewer than 100 breeding pairs of spoon-billed sandpipers left in the world.
In recent years they have been declining steadily and it is thought they could be extinct within five to 10 years.
During the trial, the team, which consisted of WWT aviculturist Roland Digby, Juriy Bragin of Moscow Zoo, and Liza Tambovtseva of Birds Russia, perfected the methods needed to rear the birds in captivity on the remote Russian tundra.
It paves the way for eggs laid in the UK to be flown to Russia, hatched and released into the wild.
Mr Digby said: "We worked round the clock to keep the chicks alive and healthy. It was wonderful to release them and watch them as they found their way in the wild, but it was definitely tinged with anxiety, knowing the terrible threats they face.
"I just have to remind myself that we'd given those particular birds a far safer start in life and that as a result we've learned so much that is going to be critical to the future of their species."
The rear and release methods, known as "headstarting" within the conservation world, effectively protects the young birds from predators and sudden bad weather.
In the wild, only three out of every 20 eggs laid survive long enough to migrate away from the breeding grounds.
Mr Digby added: "Predation by skuas, foxes, dogs and even bears has a massive effect on the birds, but it is small beans compared with the effect of land reclamation along the coast of the Yellow Sea, which has wrecked the main place they stop to feed on their long migration.
"The other major threat they face is in Myanmar (Burma) and Bangladesh but, thankfully, initial reports indicate that measures to discourage hunters there from targeting shorebirds like spoon-billed sandpipers seem to be working."