Dickon Hooper BBC News Online Bristol

The bird is normally found in Spain, Portugal and Russia

The great bustard is the heaviest flying bird in the world, but has not been seen in the UK since the 1870s.

Six Russian experts are working with the UK Great Bustard Group, the Zoological Society of London and Stirling University in an ambitious plan to return the bird to the country.

David Walters, head of the Great Bustard Group, told BBC News Online that the bustard was the most impressive bird he had ever seen.

"It is very handsome and quite tall: a male can reach the waist of an average person.

"It is the missing part of Wiltshire's natural and cultural heritage. On the coat of arms it is the county bird."

The chalky grassland of Salisbury Plain is the bustard's natural habitat

The Russian visit was the latest part of a four-year plan to bring 25 chicks over by the end of the year, and release them onto Salisbury Plain.

The plan still needs Defra backing, but Mr Walters is confident he will hear from them in the coming days.

"The science of Salisbury Plain - the habitat, the food and the geography - were all perfect and the next stage was to source the birds.

"They are found mainly in two places - Iberia and Russia. We chose Russia because there are more birds there, and they are genetically more appropriate for our plan.

Natural habitat

"We will work now with the Institute of Ecology and Evolution in Saratova who will supply us with the chicks."

The plan is to bring over 40 a year.

"A huge area of Salisbury Plain was never subjected to modern agriculture, so there has been little change there since the days of the bustard."

There are only about 50,000 great bustards remaining globally.

If all goes well, Salisbury Plain will have its own bustard population back within five years, and the bird will have been introduced again to some of its most natural habitat.