shedding the grey ends of the feathers, leaving the blacker parts exposed. This method is common among birds, but the Red Grouse has been credited with changing in situ the colour and pattern of the flank feathers. Now, with still less reason as it seems, the cock bird has been credited by Mr Millais with achieving his summer or breeding plumage "for the most part by repigmentation and pattern change of most of the winter feathers below the neck."[1]
This view cannot be upheld physiologically, and there is much to support the contention that the feathers which are believed to effect this change of pattern without moult are actually new growing feathers. This can readily be shown by the demonstration of their unshed sheaths. The misleading birds are again in this case the cocks which have been too sick to shed the previous "autumn plumage," and so are still struggling, with increasing success as the food improves, to produce a "winter plumage," which they should, and would in health, have achieved in October.
That the cock bird should moult the feathers of the legs and feet between March 30th and June 17th is no longer difficult to understand when the prevalence of Strongylosis is fully grasped. No bird is safe from the nematode infestment, and we are led to think that the majority of cock birds are so badly infested that they are forced to defer the autumn moult which should precede that of the previous winter. It is therefore obvious that between March and June there will be every stage of good or bad leg and foot-feathering between the newly acquired thick, white winter stocking of the sick cock, and the naked featherless clean moulted leg and foot of the really healthy male bird in June. In July, again, the healthy cock bird will be found beginning to produce white feather tips over the legs and feet.
In July the general appearance of the healthy cock is much lighter in colour-tone, and much more broken and mottled in pattern-character than July. that of the same bird in the winter. The claws are in many cases now ready to be shed, and the primaries, secondaries, and tail feathers are in moult. Some six or eight new clean-grown primaries are often to be found in July, and the long tail coverts are broad-barred buff and black.
In August the cock Grouse has, of course, the appearance of full summer August. or autumn plumage, but it requires very little examination to see that he has already begun to put on feathers of the winter plumage.
- ↑ "Natural History of British Game Birds," p. 40.
