The magpie is an omnivorous species that is encountered frequently on lowland farmland. It tends to forage for insects, but will take bird eggs and nestlings too. They may be shot and trapped year round by landowners, occupiers and other authorised persons to conserve fauna and flora under an annual general licence, issued under the Wildlife & Countryside Act (1981). We collect information on the numbers culled.
There was a spectacular five-fold increase in the bag index up to the early 1990s. Since then the index has stabilised, but at a level far in excess of that recorded during the 1960s. The stabilisation may at least in part be due to the deployment of Larsen traps by gamekeepers from 1990 onwards.
The explosion in numbers during the 1970s and 1980s parallels the trend in fox bags. Both species have increased significantly in urban and suburban environments, and both species take advantage of the availability of household refuse and bird table offerings. The national population trend estimated by the British Trust for Ornithology identifies a doubling in abundance from 1966 to 1990 and stabilisation thereafter. This pattern suggests that perhaps use of the Larsen trap may have had more than just a local effect on magpie densities.
Index of magpies shot per km2 from 1961 to 2009 (see statistical methods and interpretational considerations). Error bars represent 95% confidence intervals.