Attributes / relations provided by
♦ ¹del Hoyo, J., Elliott, A., Sargatal, J., Christie, D.A. & de Juana, E. (eds.). Handbook of the Birds of the World Alive. Lynx Edicions, Barcelona.
♦ ²Starling-Westerberg, A. N. N. E. (2001). The habitat use and diet of black grouse Tetrao tetrix in the Pennine hills of northern England. Bird Study, 48(1), 76-89.