Pheasant release in Great Britain: long-term and large-scale changes in the survival of a managed bird

The release of artificially reared pheasants is a widespread practice in Great Britain, used to increase the number of birds available for hunting. We examined the spatial and temporal patterns of release and shooting between 1960 and 2014 using data from a self-selected sample of 1195 sites. We examined changes in the efficiency of release, the contribution of birds that were not released that year to the numbers shot, and the form of these relationships through time. An annual estimate of the efficiency by which releasing increased the numbers shot was 50% over the period 1960–1990 declining rapidly to 35% by 2005 and reducing more slowly thereafter. There was no obvious regional pattern to this relationship. It has been hypothesised that the efficiency of releasing is lower on sites that release higher densities of pheasants; this study does not support this hypothesis. Annual variation in the density of birds shot in the absence of releasing (1960–1990) was closely correlated with a measure of annual gamebird chick survival. After this date, the relationship was no longer significant, consistent with a decline in wild pheasant stocks and coinciding with the declines in other farmland birds. We highlight increased fox abundance, genetic and behavioural changes arising from the rearing process, and increased shooting in late winter as possible causes for the observed decline in releasing efficiency. We consider the general increase in rearing, habitat changes, increased disease or losses to protected predators as unlikely to have been important causes of the changes in releasing efficiency. Pheasant releasing results in increased numbers for shooting, but has not prevented the wide-scale decline of wild pheasant numbers.