Preliminary results from using GIS to examine spatial variation in grey partridge demography over 30 years in Sussex, UK.
Grey partridges Perdix perdix have been monitored annually since 1968 on a 33 km2 area of the South Downs, Sussex, UK. Incidental observations of predatory birds and mammals have been recorded as well. Using a geographical information system, we subdivided the area according to level of productivity and of overwinter loss, for each of six five-year periods. Spatially, productivity increased with spring partridge density and decreased with corvid density. Spatially again, overwinter loss increased with productivity, but increased also with densities of raptors and predatory mammals. This is the first time that a correlation has been found between raptors and increased losses of grey partridges in Britain. The basis of the correlation is as yet unknown.