The young bustards were hatched from eggs saved from farmland near Saratov in Russia.
They were flown in on 2 August by a group of conservationists who want to reintroduce the Great Bustard to Britain, more than 100 years after it died out there.
The Great Bustard can grow up to a meter tall and weigh 20 kilograms
"Do I believe it will work? Well I think the answer to that is that we know enough to give this a try," says Stirling University's Patrick Osborne, who is one of the leaders of the project.
He calls the Great Bustard -- which can grow up to a meter tall and weigh 20 kilograms -- "the most dramatic and spectacular of all the grassland birds."
The project, which aims to boost Russia's bustard population as well as return the species to Britain, has taken years of preparation. It has also made unusual demands of the conservationists.
They've had to wear specially made costumes and feed the bustard chicks from a glove puppet to prevent the birds from getting used to humans.
But it's bureaucracy that posed the biggest challenge -- and Osborne says it almost made the bustard enthusiasts abandon their project.
"We went to Russia about a month ago, had the birds ready for transport to Britain, but then found that the paperwork wasn't actually complete and that it would take an unknown length of time to resolve the difficulties. So we had no choice but to leave the birds behind in Russia and to return to Britain and try to sort things out at a distance. Young bustards grow very rapidly, the real spurt of growth does happen in this first couple of months of their lives. So we're talking now of birds that could weigh around 2-3 kilograms and maybe standing as high as 40 centimeters. So these are really quite large birds to put into boxes, to go onto aeroplanes to go to Britain," Osborne says.
Now in Britain, the young bustards will now spend one month in quarantine, before being moved to temporary holding pens.
A few weeks later, the first birds will be released into their new home on Salisbury Plain in southern England, where the Great Bustard used to roam.
If all goes well, more bustard chicks may follow in the coming years -- with the eventual hope that they'll start breeding.
"They're not going to breed in the first few years, they simply don't breed, and the males certainly don't until they are three or four years old, so we won't expect there to be any offspring in that time. The intention is to repeat the process year on year for a five-year period initially," Osborne says.