coloration. In this “summer protective” plumage the birds of both 
sexes are as difficult to see against the green, brown, and gray of the 
open tundra, as they were in winter plumage against the white 
landscape. 
All these remarkable changes in appearance are the result of 
nwlt<;. by which feathers of one color fall out and new ones of a dif¬ 
ferent color grow in. In the autumn exactly the same process leads 
from the brown and mottled coloration of both old birds and young- 
of-the-year to the pure white of winter dress. But while in the spring 
molt the feathers of the head, neck, and back are the first to be re¬ 
placed, in the fall these are the last tracts affected; so that by the 
middle of October birds are to be seen with dark feathers still pre¬ 
dominating in the head and back. This, of course, gives much the 
same effect as at an early stage of the spring molt. 
The female ptarmigan selects the site for her nest during the 
third week of May, and by the second week of June full sets of eggs 
have been laid. The nest is a slight depression in the moss on the 
open ground; usually the summit of a hummock is selected, as being 
a drier situation during the period of early summer rains. A scanty 
lining of dry grasses in the nest keeps the eggs from actual contact 
with the saturated moss of the foundation. 
The full set of eggs numbers from eleven to thirteen. They are 
very deeply and closely spotted and blotched with chestnut-brown, 
the effect being to render them difficult to distinguish from their sur¬ 
roundings, even when lying in plain view but a few feet from the 
observer. The female bird does all of the sitting, and when ap¬ 
proached on the nest does not take flight until almost trodden upon. 
She then exhibits the greatest solicitude, tumbling about within a 
few yards of the intruder in the most distressing manner. The male 
bird sometimes appears, but keeps discreetly at a much greater dis¬ 
tance. 
After the eggs are hatched, the precocious youngsters are ac¬ 
companied by both parents. They then have the faculty, so like that 
of young c[uails and grouse, of concealing themselves at a moment’s 
notice, while the parents attempt to call the intruder’s attention else¬ 
where. The young are at first clothed with down, of yellow and 
brown shades; but before they are half-grown this is entirely replaced 
by loose-textured feathers, and even before half-grown they are able 
to fly as readily as the adults. 
In summer, the willow ptarmigan’s bill of fare includes many 
sorts of insects, as well as green herbs. In the fall the abundant 
66 
