Observations on a decreasing population of Red-backed Shrikes.

Abstract

One of the last relatively densely populated breeding outposts of the Red-backed Shrike Lanius collurio in Britain was to be found until recently on large areas of heathland in Hampshire. Over 60 pairs still bred there within the last ten years.

The great decrease in this species, formerly widespread in the southern two-thirds of England, has been reviewed by Peakall (1962) and Parslow (1968), who showed that the Hampshire population formed the largest remaining concentration. This decrease is part of a wider one affecting Red-backed Shrikes throughout north-west Europe (Durango 1950, Peakall loc. cit.). Quite fortuitously in 1954 1 came upon a pair feeding nestlings in a shallow valley containing gorse brakes and scattered hollies and thorns. As this site was typical of much of the area, a wider search revealed a total of four pairs within a square mile. In subsequent years, as far as spare time allowed, the area of search was increased and many more pairs were located. The main aim throughout was to plot the distribution of the pairs in the area - a total of approximately 162 square miles with the most intense study concentrated in 23.2 square miles of this - and to obtain other information which might be relevant to population changes in the little time remaining. The interest of many other observers was aroused, which added to the numbers found and in some cases provided additional information on nests. In 1961 and 1966 co-operative surveys were organised with C. R. Tubbs of the Nature Conservancy and a team of voluntary helpers covered the area. Their observations have been incorporated with my own and the people concerned will be acknowledged individually at the end of the second part of this paper.