Capercaillie breeding success in relation to forest habitat and predator abundance

摘要: Summary 1 The capercaillie Tetrao urogallus is widely valued as a game bird and an indicator of forest ecosystem quality. In Scotland, its numbers have declined since the 1970s, due primarily to poor breeding success. We investigated whether differences in success among forests are related predator abundance or aspects structure, with view identifying beneficial management practices. 2 Capercaillie was estimated 7–14 areas Scotland each year during 1991–2001. Forest habitat, including ground vegetation, indices were assessed 14 1995. 3 Capercaillie increased increasing bilberry Vaccinium myrtillus cover, but did not improve further above 15–20% cover. 4 The main predators carrion crow Corvus corone, fox Vulpes vulpes raptors. Indices their confounded such that respective effects on could readily be distinguished. However, negatively principal component score represented combined crows, foxes and, lesser extent, raptors. 5 A trial one showed bred better when most crows some killed than they not. 6 An index pine marten neither other nor success. 7 Synthesis applications. Capercaillie reared more young fewer predators. Management should aim for at least legal control foxes.