Bird species inhabiting the moorlands include red grouse, black grouse, ptarmigan, and the capercaillie. Bird species are represented by capercaillie, black grouse, hazel grouse, spotted nutcracker and cuckoos. Bird species are represented by capercaillie, black grouse, hazel grouse, spotted nutcracker, and cuckoos. They have also produced hybrids with peafowl, chachalacas, capercaillie, grouse, quail, curassows, pheasants and guans. The forest is home to the endangered capercaillie and endemic Scottish crossbill. Pheasant and capercaillie are protected game species that may not be hunted. Around 1920, the capercaillie population in the Harz died out. Male and female western capercaillie can easily be differentiated by their size and colouration. For example, the mixed mountain forest is the natural habitat of the capercaillie ("Tetrao urogallus"). Western capercaillie are diurnal game, i.e., their activity is limited to the daylight hours. The word "capercaillie" is a corruption of the Scottish Gaelic "capall-coille" () "wood-horse". Manus is best known as a member of Celtic supergroup Capercaillie. An attempt to return the capercaillie ("Auerhuhn") however did not succeed. Additionally, western capercaillie have two appendixes which grow very long in winter.