Up on Strines Moor the other day (Derbyshire) we were surrounded by Red Grouse. But every so often there would be one which looked exactly like a Red Grouse but was black in colour except for a reddish neck and head. I've looked on the net and in books but cannot find any mention of Red Grouse going black in the Winter. Do reds go black or was it a female/juv Black Grouse?