Altitudinal and habitat selection of capercaillie Tetrao urogallus: an assessment of change after ten years in the Scanuppia reserve (Central Alps, Northern Italy)

Capercaillie (Tetrao urogallus L.), a territorial galliform, favours intermediate canopy cover forest, formed by old and open stands and with a high presence of ericaceous species (in particular Vaccinium myrtillus L.). Although Capercaillie is not thought to be at risk, it has undergone a decline over much of its range. This study was undertaken in the Scanuppia reserve (546 ha) in the Trento Province in spruce (Picea abies (L.) Karsten) dominated forest with some areas of silver-fir (Abies alba Miller), larch (Larix decidua Miller), beech (Fagus sylvatica L.), and mixed stands, as well as open areas of pasture. The aim of this study was to determine change in summer Capercaillie habitat between 2001 and 2011. A systematic sampling design was used in which 10-m radius circular plots were sampled along contour lines between ca. 1500 and 1800 m asl in which stand structural and vegetation characteristics were quantified and the presence/absence of Capercaillie was determined by droppings. Whilst the overall population count appeared to remain unchanged, the 2011 results showed that there had been an upward altitudinal shift in distribution whereas the 2001 results emphasised the effects of habitat variables at a lower altitude. The selection of habitat towards the upper limit of forests may be linked to increased summer temperatures, to anthropogenic disturbance or to a combination of both. This study underlines the need for further research to disentangle potential factors explaining the observed changes in Capercaillie habitat selection in relation to management.