Seasonal densities of released Common Pheasants (Phasianus colchicus) and Red-legged Partridges (Alectoris rufa) on land used for shooting and on nearby non-release land in southern England

Abstract

Capsule
During autumn and winter a small proportion of summer-released Common Pheasants or Red-legged Partridges disperse beyond the release/shooting area and occupy nearby land in the following spring at densities of between 5 and 60 individuals per km2.
Aims
To compare densities of released Common Pheasants and Red-legged Partridges on land used for shooting and on non-release, non-shooting land nearby.
Method
Released birds were surveyed along walked transects on ten large release sites in southern England, and on eight non-release sites within 2 km of a release site, every three weeks for 19 months and over two summers. Proven spring count methods were used to adjust long-term survey data to estimate approximate densities.
Results
In early spring, after shooting had ended, there were 100–450 Common Pheasants per km2 at release sites, and 50–250 Red-legged Partridges. In early summer, before the next release, there were up to 100 Common Pheasants and 70 Red-legged Partridges per km2. Non-release sites always had significantly fewer birds: in early spring there were 20–60 Common Pheasants and 5–25 Red-legged Partridges per km2; in summer there were fewer than 20 Common Pheasants and ten Red-legged Partridges per km2 on all but one non-release site. Following the next summer release and initial dispersal, we documented a circa 50-fold increase in densities, with 300–2,500 Common Pheasants or Red-legged Partridges per km2 on shooting land in autumn. On the non-release sites, a modest and delayed response to dispersal from release sites involved a 50–100% density increase over winter.
Conclusions
Our proportion and density estimates can help conservationists to understand the potential ecological effects of releasing Common Pheasants and Red-legged Partridges for shooting, and support modelling work that can predict distributions of released birds in different scenarios to help guide release policies.