Conservation groups, including the Royal Society for the Protection of Birds, have approved a plan to shoot ruddy ducks in their British breeding grounds in an attempt to protect white-headed ducks in Spain.
The problem is, scientists say, that male ruddy ducks can breed with white-headed ducks and produce fertile hybrids.
And the growth in the number of hybrids threatens to make the white- headed duck extinct.
''Almost certainly shooting will be the preferred option'' said Chris Hubbard, an RSPB member of the UK Ruddy Duck Working Group, which has approved the culling plan.
Ruddy ducks, first introduced into Britain from the US, have grown in numbers to about 3,500 since first nestings in the wild in the early 1960s.Now the population is going up by 10 per cent a year. The bird has also found its way into 20 other European countries and is found as far away as the Ukraine and Iceland.
But it is its amorous activities in Spain which have caused the greatest problems as it mixes with Western Europe's most important breeding population of white-headed ducks. Conservationists discovered the first hybrids in 1991 and, thanks to the " highly aggressive" American immigrant, numbers have increased every year since.
According to the working group, the ruddy duck, along with its hybrids, dominates other waterfowl within a breeding site. ''A strategy of waiting to see what happens could result in the extinction of the white-headed duck,'' it says.
Mr Hubbard said marksmen will be recruited to shoot ruddy ducks during the breeding season whenthey congregate and present the best targets. He said that some people may object to conservation groups such as the RSPB, the Nature Conservation Committee and the Wildfowl and Wetlands Trust deliberately killing wild creatures.
But the ruddy duck had spread very rapidly, "and we have a responsibility for international conservation. There are 600,000 ruddy ducks in the US - and that is where they ought to be''.
More work along these lines is yet to come for scientists: the Arctic char, an ice-age fish that has lived in Scottish lochs for millenia, is mixing with Arctic char that have escaped from fish farms; and the Scottish wildcat is known to be interbreeding with domestic cats.Reuse content