Great bustards being reintroduced to Britain on Salisbury Plain are now reared from eggs brought here from Spain instead of Russia.
And conservationists are hoping that 33 birds will be released on at two secret sites on Salisbury Plain this year.
The world's heaviest flying bird was hunted to extinction in the UK in 1832 and Wiltshire's Great Bustard Group was set up in 1998 by former policeman David Waters with the aim of reintroducting the bird featured on the county crest and flag.
Under the reintroduction scheme, great bustards have been released on a Ministry of Defence-owned site on Salisbury Plain since 2004.
Eggs were being taken from great bustard nests on farmland in Russia where they would otherwise be destroyed by agricultural machinery, being hand-reared from behind a curtain using a puppet to prevent them getting used to people.
They were then brought to the UK, where they are put into a large enclosure until they are ready to fly away of their own accord; some even headed off as far as France in the first year.
Although the first successful hatching of wild chicks happened in 2009 the population of birds on Salisbury Plain is not yet big enough to survive in its own right.
Today Mr Waters said: "The Great Bustard Trial Reintroduction has entered a momentous new phase.
"Up until this year the project has used only birds sourced from Saratov in Russia, and the UK Government restricted this to birds hatched from eggs rescued from destroyed or abandoned nests.
"The difficulties in rescuing the eggs, combined with the huge distances and logistical challenges of working in Russia meant that the number of birds the project was able to import into the UK was small – often as low as six birds a year.
"The Great Bustard Group received a tremendous boost last year however when Dr Paul O’Donoghue, of the University of Chester, undertook a genetic comparison of European great bustard populations.
"He discovered that, contrary to the previously held belief, the great bustards in Spain form the closest living population of great bustards to the original UK population before its extinction.
"The Great Bustard Group is very grateful to the museums and private collections that allowed genetic material to be removed from their specimens."
Spain has two thirds of the world’s great bustard population, with over 30,000 birds, and that number is increasing.
"The density of birds and nests are higher than in Russia, therefore the birds are easier to find and, of course, the potential numbers which may be released in the UK are much higher," said Mr Waters.
"Having been granted the appropriate licences from the regional and national governments, a team of four GBG staff with two specially trained dogs and two staff from the RSPB collected 56 great bustard eggs.
"The eggs were exported in partnership with Madrid Zoo and transported by ferry to the UK to specialist bird park, Birdworld in Farnham, Surrey, home to the only public captive great bustard enclosure in Britain.
"Here park curator Duncan Bolton and a team of incubation experts undertook the incubation and hatching of the eggs with excellent results, achieving a hatch rate of over 82 per cent of the viable eggs.
"The young chicks were then taken from Birdworld to the GBG project site in Wiltshire and reared by Great Bustard Group and RSPB staff.
"The first birds are now at the release sites - a total of 33 great bustards will be released this year at two secret sites in Wiltshire.
"The use of Spanish birds promises to be a major step forward for the project. The previously released Russian birds have demonstrated a tendency to disperse in a south westerly direction, often to their detriment."
It is thought that Russian birds instinctively head in this direction to avoid the worst of the Russian winter. Many of the birds released on Salisbury Plain have dispersed, some reaching France, and although many have successfully returned others are thought to have perished.
The cost of collecting the eggs and importing them to the UK from Spain was covered by the Rural Trust, whose support for the Great Bustard Group goes back to the beginning of the project when the first UK licences were being applied for.
Since 2010 the Reintroduction Trial has been assisted by an EU LIFE+ grant which is coordinated by the RSPB. The LIFE+ programme covers up to 75 per cent of eligible expenditure.
More information about the Great Bustard Group at http://greatbustard.org/