The environmental benefits of conservation headlands in cereal fields.

Abstract

In 1984, The Game Conservancy's Cereals and Gamebirds Research Project began working on the problems associated with wild gamebird production on intensively farmed arable land. The Project started after studies on the grey partridge, Perdix perdix, identified the problems encountered by stocks of wild, breeding birds and the factors that had contributed to the observed 80% decline in the national population of partridges monitored over the last forty years (Potts, 1986).

Blank et al., 1967 had found that the key factor causing changes in a grey partridge population in Hampshire was chick mortality and linked the observed national decline and the increasingly poor chick survival. Chick survival was shown to be related to the availability of sufficient quantities of the preferred insects that are essential in the diet of young birds. It has been suggested that Iow densities of these insects resulted from the increasingly intensive nature of cereal production over the last forty years and the use of pesticides appeared to be a major contributory factor.
The list of preferred food items of young birds include beetles (leaf beetles, small diurnal ground beetles and weevils), larvae of Lepidoptera and sawfIies and many species of plantbugs. Many of these insects were found to be more abundant at the edges of cereal fields where wild gamebird chicks forage.

It is now known that the use of various types of pesticides (insecticides, insecticidal fungicides, herbicides) can affect detrimentally these non-target species (Vickerman and Sunderland, 1977; Sotherton et al., 1987). Herbicides have probably been the most important single contributory factor because they remove from cereal fields weeds that are the host plants of many of these phytophagous chick-food insects (Southwood & Cross, 1969; Sotherton, 1982).