Raptors and red grouse populations overwinter: a comparison between three studies.

Abstract

Whilst there is argument in the literature as to the main regulatory factor controlling Red Grouse Lagopus lagopus scoticus populations (parasitism in Potts et al. (1983); Hudson et al. (1985) or social behaviour in Jenkins et al. (1963); Moss and Watson (1985)), studies have agreed that predation by raptors played only a minor role in their study areas. These investigations however, have been carried out in areas of high grouse density and low predator density. Over the last 20 years, Scottish grouse populations have experienced a major decline (as much as 80% from bag records) and predator numbers have increased Barnes (1987); Hudson and Moore (1986). The effects predators may have on population dynamics may have altered considerably.

Here the preliminary findings of a study investigating the effects of raptors on red grouse populations overwinter (from September to April) are presented. Results are compared to those of two other similar studies: one in Glen Esk. Scotland from 1956 to 1961 (see Jenkins et al. 1963 and Jenkins et al. 1964) the other led in northern England by David Newborn.