Increased nest predation near protected capercaillie leks: a caveat against small reserves

Abstract

Protecting animal aggregation sites is intuitively an efficient conservation approach, particularly for threatened species in fragmented landscapes. However, the appropriate scale of protection depends on accompanying threats, such as predator attraction to the same aggregation sites, to which the target species may need to respond by moving to alternative habitat patches. We performed experiments using artificial ground nests around protected capercaillie leks in commercially managed forest landscape in Estonia. We considered two scales: the landscape up to 3 km from the lek centre, and among 10–30-ha forest compartments, which differed in predator abundance. We found that nest predation significantly declined with distance from the lek. Nests were depredated by multiple mammalian and avian predator species and total predator abundance explained most of the between-forest variation in predation rate. Our results indicate that, in this hemiboreal area, (i) ground nest predation is largely determined by landscape-scale distribution of predators and (ii) predators can aggregate at capercaillie leks. The implication is that lek-centred habitat protection used for the capercaillie and other grouse may be ineffective unless the peripheral habitat quality and predator abundance are specifically addressed. More generally, predation pressure can be a serious problem in small set-asides within hostile landscapes for threatened ground-nesting birds.