Spatial changes in Grey Partridge (Perdix perdix) distribution in relation to 25 years of changing agriculture in Sussex, UK.
Numbers of grey partridges Perdix perdix in a study area in Sussex, U.K., have fallen by 72% since 1970. They have remained constant, however, on the only farm in the area that has maintained a traditional mixed farming system with rotational grass established by undersowing spring crops. On the other four farms, rotational grass has disappeared and winter cereals have replaced spring cereals. Under the Environmentally Sensitive Area (ESA) scheme introduced in 1987, farmers have been encouraged to switch out of cereals and into grass ('arable reversion'). Autumn densities of grey partridges on ESA arable reversion fields before reversion averaged 33% higher than on surrounding areas. After reversion, densities averaged less than half as high as on surrounding areas, and the relative proportion worsened with time since the scheme began. Another major change in agricultural practice was the large-scale use of summer insecticide, starting in 1989. Chick survival rates averaged a third lower where insecticide was used intensively than on areas of little or no insecticide use (22% v. 34%). By extending the ESA scheme and the Countryside Stewardship scheme to include a low-input mixed arable option, the Ministry of Agriculture, Fisheries and Food could benefit partridges and other declining farmland animals and plants.