Spoon-billed sandpipers on display at WWT Slimbridge
Thirteen of the world's rarest birds have been moved out of quarantine as part of a project to save the species.
The spoon-billed sandpipers are settling into purpose-built quarters at Slimbridge after hatching en route to Gloucestershire earlier this year.
Experts are using CCTV to monitor the birds and footage will be included in a daily film showing at the centre.
It is believed there are fewer than 100 pairs of the birds left in the wild, with numbers dropping 90% in a decade.
The hatching of the critically-endangered chicks in captivity is a world first, according to the Wildfowl and Wetlands Trust (WWT).
Roland Digby, from the WWT, said the spoon-billed sandpiper was "one of the holy grails of birdwatching".
He said: "This tiny little bird has got everything against it and it is just so important that we do something to not only halt its decline but prevent it becoming extinct."
Hunting and the destruction of stopover sites on the birds' migration route have caused the drop in numbers.
Experts feared that, without intervention, the spoon-billed sandpiper could be extinct within ten years and so the mission began.
A conservation team travelled to Chukotka, in Far East Russia, in June where they spent weeks searching 100 sq miles for nests.
Eggs found were then were hatched in special facilities before beginning the 4,970-mile (8,000 km) journey to the UK.
After spending some time in quarantine at Moscow Zoo, the chicks were flown to Heathrow and transferred to WWT Slimbridge where they are now.
It is hoped the 13 juvenile birds will establish a captive breeding population.
Andre Farrar, from the RSPB, said: "It's clear that success, ultimately, must be judged in boosting the wild population.
"But for now, we should celebrate a very significant milestone."
The breeding programme is a collaboration between the WWT, Birds Russia, Moscow Zoo and the RSPB working with colleagues from the BTO, BirdLife International, ArcCona and the Spoon-Billed Sandpiper Task Force.
In the wild the birds breed on coastal tundra in North East Russia and spend winter 5,000 miles (8,047 km) away in the tropics of South and South-East Asia.
Populations of young birds are being hunted in places such as Myanmar, Thailand and Bangladesh which has devastated the species' numbers.
As well as that, farming and development has destroyed stopover sites on their migration-route, such as the Saemangeum wetland in South Korea where a 20-mile wall was built in 2006 to dam and reclaim the land.
Nigel Jarrett, head of conservation breeding at WWT, said the birds had done "very well" despite being held in unnatural surroundings.
"It is crucial we keep it warm because at this stage in the birds' lives they'd normally be in the tropics," he said.