Grey partridge population dynamics: comparisons between Britain and North America.

Abstract

Information from 15 studies of the grey partridge (Perdix perdix) in the U.S.A. and Canada was examined to estimate nest densities, brood production and chick survival rates, and annual adult 'survival'. After allowing for the effects of nest density, the brood production rates were found to be much lower than in Britain. On the other hand, chick survival rates were higher, and unlike in Britain, have not declined. In both continents annual adult 'survival' is lower following high breeding success, partly because of emigration of first-time breeders prior to nesting. In Britain such emigration is reduced as theproportion shot the previous autumn increases and, in general, there is a dynamic equilibrium established between productivity and emigration around a population density set by the habitat. From these results, it is concluded that top priority should be given to the provision of more and better quality nesting cover. A synopsis of the requirements of such cover is given; hedgerows of the kind often found in Britain are ideal.

The basic idea of a blueprint approach to management has been pioneered by the Agricultural Extension Services in Britain. Their aim has been to provide an idealized plan which integrates all the existing research findings. Costs are secondary considerations which can be pruned according to individual circumstances or as various parts of the blueprint are proved redundant or counter-productive. The method has been useful in several crops, notably winter wheat, where yields have far out-stripped the maximum predicted on theoretical grounds.

The recently published blueprint for  the survival of the grey partridge in Britain (Potts 1983) concentrated on the provision of nesting cover, predator control, careful use of pesticides in cereals, and correct rates of shooting. The aim of this short paper is to examine whether the blueprint can be applied to North America.

I am very grateful to the International Foundation for the Conservation of Game for their travel grant which enabled me to attend Perdix III, and to K. Church for his help in many ways.