The May diet of Capercaillie (Tetrao urogallus) in an extensively logged area of NW Russia

Abstract

The May crop contents of Capercaillie (Tetrao urogallus) from a highly disturbed (logged) area of NW Russia are documented for the first time. Plants of the tree-shrub layer and bog plants of the field layer together formed the main part of the diets of both cocks (75% of fresh weight) and hens (58%). Fragments of pine (Pinus sylvestris) and bil-berry (Vaccinium myrtillus) were more abundant in crops of cocks, whereas hens con-sumed more young herbaceous shoots and track-side plants. Hens also garnered spruce seeds (Picea spp.) from tracks. Track-side food items formed up to a third of the diet of hens. These included shoots of clover (Trifolium spp.) and especially flower buds of coltsfoot (Tussilago farfara). Complete elimination of some forest tracks, as a manage-ment technique for Capercaillie, could result in a loss of food sources important to hens in most of their Eastern-European range. The closure of tracks from people and vehicles, and their conversion to habitat where spring-blooming plants for hens abundantly grow, seems a more viable conservation option. Even in a highly disturbed area, plants of the na-tive taiga biotopes composed almost all the diet of cocks (ca. 97%). Compared to the cocks, the feeding strategy of hens was more opportunistic; hence, their spring diet may be less vulnerable to logging perturbations.