Pheasant productivity in relation to population density, predation and rearing: a meta-analysis.

Abstract

Studies of pheasant popuIations in Europe and North America were reviewed. From 27, we obtained estimates of hen pheasant numbers in spring. Of autumn chicks fledged and details of game management for 32 sites over, on average, 2.8 years per site. Only studies with no significant change in pheasant density through the period of study were included. These data were used to investigate the relationship between spring densities and productivity, as measured by the autumn counts.
For the dataset as a whole, we found that pheasant productivity was not dependent on spring density. We then attributed all studies to one of three management categories, either wild bird studies in areas with no predator management, wild birds in areas with reduced predator popuIations, or areas where hand-reared birds were released. Investigation of these relationships identified differences between groups. In particular, for wild popuIations with no predator management, we found evidence of a density dependent effect of spring hen density on individual productivity. For wild pheasants with few or no predators, we find that productivity is higher than with predators, and is either not affected by breeding density, or weakly so. Where releasing was undertaken, productivity was low.
We discuss these results in the context of the analytical methods used, density dependent effects found in other gamebird species and the role of predation and releasing in population regulation.