Population Fluctuations in Red Grouse: Analysis of Bag Records and a Simulation Model

Abstract

(1) A time-series analysis of numbers of red grouse (Lagopus lagopus) shot per annum was carried out for fifty-two moors in northern England where data were available for at least 20 consecutive years during the period 1870-1977. Correlograms were constructed and auto-correlation coefficients were tested for statistical significance. (2) In the most representative sub-sample of moors, 83% of the series had significant negative coefficients at T + 2 or T + 3 years or both. A mathematical model was fitted to the fluctuations to describe their quasi-cyclic nature and the average 'cycle-length' was found to be 4.84 + 0.086 years. (3) Field observations and data from trials with captive grouse were combined to construct a simulation model of a red grouse population; its main features were: