A male capercaillie.
capercaillie definition by Webster's New World
Origin: ; from Gaelic capull (; from Classical Latin caballus, horse) plush coille, forest, hence literally , horse of the woods
capercaillie definition by American Heritage Dictionary
Origin: Scottish Gaelic capull coille : capull, horse (from Middle Irish capall, from Old Irish, ultimately from Latin caballus, of Celtic origin) + coille, genitive of coille, forest (from Old Irish caill).