Observations on breeding and dispersal by Capercaillie in Strathspey

Abstract

Capercaillie in Scotland have undergone a considerable decline in numbers and range contraction since the 1970s. The latest national survey in 2015/16 concluded that they remain at a critically low level of around 1,000 birds, with previous studies highlighting low breeding success as the proximate cause of decline. This study used radio-tagged females to assess the likely causes of poor breeding. Of the 12 possible breeding attempts followed, clutches were found for nine, six of which hatched, but only two (17%) successfully fledged young, giving an overall rate of 0.25 chicks reared per potential breeding attempt. Low productivity occurred due to 60% of first-year females not nesting and low chick survival, estimated at 8%. Over the same years, surveys in four local forests found 0.49 chicks per female (210 females found of which 24% were found with wellgrown broods). Dispersal distances of six juvenile females ranged from 3.5 to 16.3 km highlighting the importance of conservation action across neighbouring forests at a landscape scale.