Factors controlling the population of the partridge (Perdix perdix) in Great Britain.

Abstract

The subject of this paper forms part of a scheme of research into the ecology of game populations carried on, with the aid of a grant from Imperial Chemical Industries, in the Oxford University Bureau of Animal Population. This work consists of a study of game populations, particular attention being focussed on the partridge, on privately owned estates in different parts of the country. On some of these estates I have been able to take censuses and make field observations since April 1933, while statistical data for previous years have been obtained from records and diaries kept by estate owners and their gamekeepers. My thanks and acknowledgments are due to all those who have placed their data freely at my disposal and are giving me exceptional facilities for research on their estates. I am particularly indebted to Mr. W. J. Barry for allowing me to use the records which he has kept at Great Witchingham in Norfolk for the past thirty years; his deep knowledge of the life of the partridge, the facilities for study, and the help given by himself and his keepers are proving of inestimable value to these investigations.

This analysis of records I have obtained up to date on the partridge is made with the object of showing the normal mortality which occurs in the population at various stages in the life of the partridge from egg to adult. From the data available it is possible to trace, with a fair degree of accuracy at most points, the typical production and losses of a standard population in a hypothetical  "average " year. In drawing up this balance sheet for the partridge population over the period of one year it is important to remember that no such average year exists, since the numbers are subject to violent periodic fluctuations (Middleton, 1934), and in any one year the number is nearly always greater or less at the end of the year than at the beginning. The " average " balance sheet is therefore an attempt to smooth out these fluctuations by using data which cover a considerable period of years.

All the data I have been able to obtain refer to partridges on estates where gamekeepers are employed for the preservation of game. The partridge is, however, essentially a wild game-bird, and as there is no reason to believe that game preservation seriously affects the interpretation of the figures given, many of them would be equally representative of a strictly natural population. The losses due to predators and other causes would undoubtedly be greater on land unpreserved, this loss saved being the extra margin that can be shot as a return for the protection given by the preservation. Up to the present little attention has been paid in this country to the artificial propagation of partridges for augmenting the natural production as is generally practised with pheasants, so it need not be considered with regard to these population statistics.

I have referred to different estates in this paper by the index letters used in the files of the Bureau of Animal Population, with the name of the county, as in many cases owners do not like having the names of their estates published.