Vegetative structure, concealment, and success at nests of two races of spruce grouse

Abstract

Vegetative structure, concealment, and success were compared at nests of two races of spruce grouse: Canachites canadensis canace (N = 37) in New Brunswick (1976–1980) and C. c. franklinii (N = 67) in Alberta (1970–1975). Nests of both races were similar in design and were often located near the bole of trees or near the perimeter of tree or shrub clumps. Female spruce grouse, particularly in New Brunswick, nest in an array of stand types, densities, and ages. Hens may use certain structural cues when choosing areas to nest since canopy closure, density and percent ground cover, and density of trees at nest sites were different from what was generally available. Concealment and success at nests of canace were significantly greater than at franklinii nests. We attribute these differences partially to the absence of a uniform dense layer of dwarf shrub ground vegetation in Alberta. Nests of adults of both races were better concealed than nests of yearlings and well-concealed nests usually were successful.