Many of Britain's bird of prey populations suffered major declines in the 1960s and 1970s. In some species this decline has been the subject of detailed case-history studies: falling numbers of both the Sparrowhawk, Accipiter nisus, (Newton 1986) and the Peregrine, Falco peregrinus, (Ratcliffe 1980) were shown to be directly attributable to the use of organochlorine pesticides in the environment.