Dispersal distances of juvenile radiotagged Red Grouse Lagopus lagopus scoticus on moors in northern England.

Abstract

Radio-transmitters were fitted on 146 juvenile Red Grouse Lagopus lagopus scoticus (116 hens, 30 cocks) to study the timing, frequency and distances of dispersal on managed grouse moors in northern England between 1999 and 2002. A third of the radiotagged birds were shot. Disturbance on shoot days meant that radiotagged birds were shot at points more than twice as far from the catch location as the points when they were last recorded alive. For birds that were shot, the distance from the catch location to the place they were shot was more than twice the natal dispersal distances of the survivors. Therefore, shot birds were excluded from the dispersal analysis. Juvenile hens dispersed significantly further (mean 861 m, range 50-4,660 m) than juvenile cocks (mean 343 m, range 90-660 m). Dispersal distances were not related to pre-dispersal Grouse densities at the catch area in summer or to Grouse densities in the following spring. The mean date of dispersal for juvenile hens was 6 October ± 4 days (se), with only one record of spring dispersal (14 March) of 1,490 m.