He now rapidly sheds the old feathers of the last winter's plumage which remained throughout the summer upon his breast and abdomen, and replaces them with the exceedingly handsome narrow cross-barred red or brown or blackish feathers of the coming winter plumage. There is no second moult or replacement of these feathers of the breast and abdomen in the cock. Once in the year is enough for this special area, and the feathers that "carry through" are wholly of the winter plumage. They are often broadly tipped with white. The chin feathers which survived with those of the breast and abdomen are now also replaced by new ones. It is noticeable that in the Ptarmigan it is also the white feathering of the chin and of the breast and belly, as well as of the wings and tail, which is changed once only in the year, exactly as with the winter plumage of the Grouse. It suggests that these two plumages are analogous in each species.
The plumage changes in the Ptarmigan are, strange to say, quite different to the chancres in the Grouse. The Ptarmigan has three distinct moults and plumages in the year. The Red Grouse has but two.
In August, as has been said, the cock Red Grouse has begun to put on his winter plumage. The feathers of the breast and abdomen are full of sheaths and sheath-scurf, the growth of these feathers being very rapid and often scarcely noticeable. On the rump, back, and to a less extent on the shoulders, new rich red-brown feathers finely marked with black lines are showing here and there. Primaries, secondaries, tail feathers, and coverts are now replaced by new and blackish feathers with perfect and unbroken outlines. Even a few new rich copper-coloured feathers are appearing as isolated touches of bright colour amongst the faded broad-barred autumn feathers of the upper breast. The feet and legs are bare, save where new white feather tips are just appearing through the skin, and the claws of all the healthy birds are being shed (Pl. xiii., Figs. 3, 4, 5, 6).
In September the chin and throat of the cock Grouse are a mixture of many pale autumn feathers much worn and faded, and a few new September. copper-red ones. Most of the frayed "autumn plumage" feathers are now falling out. The breast and abdomen, wings and tails, are clothed with altogether new feathers, while the head and neck, back, shoulders, rump, and coverts of the tail are in a transition state, the "autumn" feathers frayed and bleached at the tips, contrasting with the new rich chestnut and darker brownish winter feathers with their fine black transverse markings.
