Conservation of the globally threatened white-headed duck,Oxyura leucocephala, in the face of hybridization with the NorthAmerican ruddy duck, Oxyura jamaicensis: results of a control trial

The North American ruddy duck, introduced into Europe in the 1960s, threatens the globally endangered whiteheadedduck with extinction through hybridization. A regional control trial, conducted in three areas of Britain, killed over 2,600birds and led to a significant regional reduction in ruddy duck numbers. Control using firearms was effective but trappingineffective. Population modeling suggests that the ruddy duck population in Britain can be reduced to fewer than 175individuals in four to six years using year-round control if access is available to the principal wintering sites. The likely cost ofthe program is between