Territorial status and survival in red grouse Lagopus lagopus scoticus: hope for the doomed surplus?

Abstract

A previous study of survival in territorial and non‐territorial red grouse Lagopus lagopus scoticus conducted between 1957 and 1967 found that territorial status in the autumn pre‐determined over‐winter survival. A very high proportion of territorial birds survived and virtually all non‐territorial birds died or emigrated. We tested the hypothesis that over‐winter survival was dependent on territorial status within four grouse populations in Scotland between 1986 and 1993. In contrast to the previous study, 66% of non‐territorial birds survived over winter compared to approximately 70% of territorial birds. There was no significant effect of territorial status on the survival estimates. Moreover, some of the birds considered to be non‐territorial during autumn went on to successfully raise a brood. We suggest that on our study sites, territory ownership in autumn did not greatly influence over‐winter survival, and territorial behaviour did not determine breeding density as previously supposed. We postulate differences with other studies may reflect variations in scale and predation pressure.