Mr Millais also, in speaking of the cock Grouse, makes use of the expression autumn plumage which, he says, appears late in June; and he adds that the autumn plumage, together with the "spring feathers" (or what Mr Ogilvie-Grant considers the first beginning of the autumn plumage on the Grouse's neck), remain till the main moult in August and September.
Mr Millais also makes the following statement, which appears to be based on a misinterpretation. He says: "as a matter of fact the male Grouse sheds in September and August a plumage which is a mixture of its winter, spring, and eclipse feathers."[1]
These so-called "spring" and "eclipse" feathers are no doubt, as Mr Ogilvie-Grant holds, the commencement of the plumage which is completed gradually during the summer months, and which he has described as the autumn plumage. It is naturally a little misleading to find the autumn plumage beginning to appear in early summer, but so long as the term is understood to mean the paler, more buff-coloured plumage with bolder bars of black, which begins to appear first on the neck of the cock at the end of May or early in June, and is eventually cast for the winter plumage in October, there need be no real misunderstanding.
That feathers of the previous winter plumage should be mentioned in speaking of the moult of this autumn plumage is also quite intelligible, since the old winter plumage of the breast and abdomen is being quickly shed and replaced by a similar new winter plumage at the time when the autumn plumage on the rest of the body is being cast. There are in addition very frequently a few feathers of the copper-red plumage on the chin really belonging to and remaining over from the previous winter plumage.
Instead of going into further details, however, with regard to the two moults and plumages of the cock Grouse, it will be simpler at this point to take its plumage changes in detail, successively month by month, explaining as nearly as possible what can be gathered from the examination of a series of skins such as has been brought together by the Committee, including as it does a great number of specimens in all stages of disease as well as in health.
These illustrate every month of the year and most of the local variations to be found in England, Scotland, and Ireland; and there are a sufficient number of sick as well as healthy birds to show the very great influence that disease has in altering the individual capacity for feather growth. Unless this effect, which results as a rule in the Red Grouse from excessive parasitism, is
- ↑ In lit., "British Birds," for April 1910, vol. iii. p. 352. London: Witherly & Co.
