Of all the various members of this group none is more interesting in many particulars than the Ptarmigan (Lagopus), of which some fifteen species and subspecies are recognized. They are circumpolar in distribution, and while as at present understood are most numerously represented in North America, it is probable that when thoroughly studied, it will be found that the Old World is nearly, if not quite, as rich in recognizable forms. Their most prominent peculiarity is the striking seasonal change of plumage which they undergo, these changes being not only more marked than in any other member of this group, but are perhaps the most pronounced enjoyed by any birds. With one exception, all the species have three or even four, more or less complete changes of plumage, that in winter being chiefly, or entirely, pure white, while at other seasons it is varied with brown, buff, gray, and black. As they live mainly in the high, Arctic lands or on rugged, snow-covered mountains, these changes admirably adapt them to their surroundings and afford a means of protection from their numerous enemies. To show how strikingly different they are at the various seasons, the following rather full description is given of a male Rock Ptarmigan (Lagopus rupestris): In winter, as stated above, the plumage is pure white, with the exception of the outer tail-feathers and lores, which are black. In summer the ground color is grayish brown, “coarsely vermiculated with black, the vermiculations having a tendency to form irregular zigzag bars; the scapulars and interscapulars are largely black centrally, producing large blotches or irregular spots; the outermost wing-coverts, quills, and secondaries white; lores black; rest of head mixed dusky and white; chest, upper breast, and sides regularly barred with blackish and light umber-brown, while the remainder of the lower parts are white.” This gives place in fall to a pale brownish ground-color of the upper parts, variously freckled and spotted, while the wings are much as in the summer condition, and the chest, upper breast, sides, and flanks are much like the upper parts, but are without black spots. The female enjoys a similar change, but is bright ochraceous in summer, irregularly spotted and barred above with black, and is more distantly barred below. These changes are so pronounced, and follow each other with such quick succession, that they have been supposed to lend support to the theory that it was possible to have a change of plumage without moult, but this has been so thoroughly exploded of late that it is not necessary to further refer to it. Mr. J. G. Millais, who has enjoyed exceptional opportunities of observing the change of plumage in the common European Ptarmigan (L. Mutus), has given, in his entertaining “Game Birds and Shooting Sketches,” a very full account of the changes for an entire year, but lack of space forbids our quoting it. Although it is nearly impossible to distinguish many of the Ptarmigan in winter plumage, which has led to the denial of their specific rank by certain writers, the other plumages afford a reasonably satisfactory basis for delimiting them.
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