Predation, predator control and grouse populations: a review

Abstract

Predation by mammalian and avian predators is an important cause of mortality in grouse species during all life stages and has been linked to impaired reproductive performance. Some grouse species are important game birds, but many populations are red-listed at the national level. In consequence, predator control is often conducted as a grouse conservation measure, but remains a contentious issue, also because evidence of its effectiveness is lacking. Here, we review the evidence on predation as a limiting factor for grouse populations and perform a quantitative assessment of the effectiveness of predator control to benefit grouse population parameters. We found support that grouse populations appear to be typically limited by their predators. Predator control was associated with an overall positive effect size on grouse population parameters (i.e. mean of 1.43 times the reference value, 95% CI of 1.22–1.68). We found positive effect sizes for most population parameters (reproductive success; adult abundance and survival), but not all (brood size, nest success). Our results suggest that predator control is likely to achieve short-term conservation benefits for grouse if well-designed and rigorously conducted. We suspect, however, that the majority of control programmes conducted for conservation do not meet this standard.