CHAPTER III
the changes in plumage in the red grouse in health and in disease
By Edward A. Wilson
Part I. — Plumage Changes of the Cock Grouse
When a large number of skins of the cock Grouse are arranged together, side by side, according to the month in which the birds were killed, it will be found that, even taking into account the differences of well-marked local variations in plumage, the series can readily be divided into two very distinct sets.
There is first a very marked uniformity in the plumage of the cock birds killed from the middle of November to the end of June; and Seasonal
changes of
plumage. likewise amongst those killed from the end of June to the middle changes of of November.
These two periods, November to June and June to November, mark the two seasonal changes of plumage in the cock Grouse.
The first is a plumage worn throughout the winter, as well as during the courting and breeding season of the spring.
The second is a plumage worn throughout the late summer and early autumn.[1]
It is necessary to lay stress upon this general broad division of the cock Grouse's plumage, and if a large number of skins can be arranged as suggested the time at which the Grouse has definitely changed from the one plumage to the other cannot possibly be overlooked. The birds obtained at the end of May are definitely in the darker and redder winter plumage, and those procured at the end of June are definitely in the paler and more buff-coloured summer plumage; those killed at the beginning of October are still partly in the paler summer plumage, and by the end of November all are in the darker winter plumage.
- ↑ Reprinted from the Proceedings of the Zoological Society of London, 1910.
