Sir: The working party on the introduced ruddy duck, whose advice Environment Minister Michael Meacher has accepted, are not thinking clearly ("Ruddies to be shot for mating with wrong ducks", 2 February). They advocate exterminating this duck in Britain as a way of protecting the white-headed duck in Spain. But if male ruddy duck interbreed with female white-headed duck and produce fertile young, surely they are one species, and all that would be at risk is the genetic purity of a sub-species - perhaps not such a big deal.
And if the ruddy duck genes provide a more robust cross in the Spanish environment than unadulterated white-headed ducks, that will assist the species to flourish in Spain. If, on the other hand, the ruddy duck genes are disadvantageous to the species, they will hardly persist in the population.