The Cereals and Gamebirds Research Project: Overcoming the indirect effects of pesticides.
Many examples of the direct poisoning of wildlife by pesticides, the bioaccumulation of residues within food chains, and the sub-lethal effects of pesticides on wildlife during the 1950s and 1960s were drawn to our attention by Rachel Carson in her book, 'Silent Spring'.
Throughout those decades, and earlier, The Game Conservancy was monitoring the abundance and breeding success of one of Britain s native gamebirds, the grey partridge (Perdix perdix L.). In fact, monitoring began in the early 1930s and has continued to the present day. Since the 1950s populations of wild grey partridges have been reduced to less than 20% of their pre-war densities (Potts, 1986).
The grey partridge is predominantly a species of Britain's lowland arable landscape especially cereal fields. The most important changes that have occurred on farmland coinciding with the partridge decline have been associated with the management of cereal fields and the intensification of grain production. Intensification has involved increasing field size (hedgerow removal), better drainage and increased use of fertilisers, improved plant breeding, and the increased use of pesticides . Since the 1950s, both increases in the numbers of pesticides used (Table 1) and increases in the areas of cereals sprayed (Table 2) have occurred (Rands, Hudson and Sotherton, in press).
Pesticide use may have been responsible for the decline of grey partridges in three ways.