As a general thing, the severity of our winters does not seem much to affect the birds that stay with us. I have found chickadees and some of the smaller sparrows apparently frozen to death, but the extravasation of blood usual in such cases leaves us in doubt whether some accident may not have first disabled the bird; and if dead birds are more often found in winter than in summer, it may be only that the body keeps longer, and, from the absence of grass and leaves, and the white covering of the ground, is more readily seen. At all events, such specimens are not usually emaciated, and sometimes they are in remarkably good case, which, considering the rapid circulation and the corresponding waste of the body, shows that the cold had not affected their activity and their power of obtaining food.
The truth is, that birds are remarkably well guarded against cold by their quick circulation, their dense covering of down and feathers, and the ease with which they can protect their extremities. The chickadee is never so lively as in clear, cold weather;—not that he is absolutely insensible to cold; for on those days, rare in this neighborhood, when the mercury falls to fifteen degrees or more below zero, the chickadee shows by his behavior that he, too, feels it to be an exceptional state of things. Of such a morning I have seen a small flock of them collected on the sunny side of a thick hemlock, rather silent and quiet, with ruffled plumage, like balls of gray fur, waiting, with an occasional chirp, for the sun's rays to begin to warm them up, and meanwhile not depressed, but only a little sobered in their deportment, and ready, if the cold continued, to get used to that too.
The matter of food-supply during the winter for the smaller birds is more easily understood than in the case of the crow. The seeds of grasses and the taller summer flowers, and of the birches, alders, and maples, furnish supplies that are not interfered with by cold or snow; also the buds of various trees and shrubs,—for the buds do not first come into existence in the spring, as our city friends suppose, but are to be found all winter. Nor is insect-life suspended at this season to the extent that a careless observer might suppose. A sunny, sheltered nook, at any time during the winter, will show you a variety of two-winged flies, and several species of spiders, often in considerable abundance, and as brisk as ever. And the numbers of eggs, and larvae, and of the lurking tenants of crevices in tree-bark and dead wood, may be guessed by the incessant and assuredly not aimless activity of the chickadees and gold-crests and their associates.
This winter activity of the birds ought to be taken into account by those who accuse them of mischief-doing in summer. In winter, at least, no mischief can be done; there is no fruit to steal; and even sap-sucking, if such a practice at any time be not altogether fabulous, certainly cannot be carried on now. Nothing can be destroyed now except the farmer's enemies, or at best neutrals. Yet the birds keep at work all the time.
The only bird that occurs to me as a proved sufferer from famine in the winter is the quail. This is the most limited in its range of all our birds. Not only does it not migrate, (or only exceptionally,) but it does not even wander much,—the same covey keeping all the year, and even year after year, to the same feeding-ground. Nor does it ever seek its food upon trees, like the partridge, but solely upon the ground.
The quail is our nearest representative of the common barn-yard fowl. This it resembles in many respects, and among others, in its habit of going a-foot, except when the covey crosses from one feeding or roosting ground to another, or when the cock-bird mounts upon a rail-fence or stone-wall to sound his call in the spring. This persistence exposes the quail to hardship when the ground is covered with snow, and the fruit of the skunk-cabbage and all the berries and grain are inaccessible. He takes refuge at such times in the smilax-thickets, whose dense, matted covering leaves an open feeding-ground below. But a snowy winter always tells upon their numbers in any neighborhood. Whole coveys are said to have been found dead, frozen stiff, under the bush where they had huddled together for warmth; and even before this extremity, their hardships lay them open to their enemies, and the fox and the weasel, and the farmer's boy with his box-trap, destroy them by wholesale. The deep snows of 1856 and 1857 have nearly exterminated them hereabouts; and I was told at Vergennes, in Vermont, that there were quails there many years ago, but that they had now entirely disappeared.
The appearance and disappearance of species within our experience teach us that Nature's lists are not filled once for all, but that the changes which geology shows in past ages continue into the present. Sometimes we can trace the immediate cause, or rather occasion, as in the case of the quail's congeners, the pinnated grouse, and the wild turkey, both of them inhabitants of all parts of the State in the early times. The pinnated grouse has been seen near Boston within the present century, but is now exterminated, I believe, except in Martha's Vineyard. The wild turkey was to be found not long since in Berkshire, but probably it has become extinct there too. Sometimes, for no reason that we can see, certain species forsake their old abodes, as the purple martin, which within the last quarter-century has receded some twenty miles from the seaboard,—or appear where they were before unknown, as the cliff swallow, which was first seen in the neighborhood of the Rocky Mountains, but within about the same space of time has become as common hereabouts as any of the genus. In examples so conspicuous the movement is obvious enough; but in the case of rarer species, for instance, the olive-sided flycatcher, who can tell whether, when first observed, it was new to naturalists merely, or to this part of the country, or to the earth generally? The distinction sometimes made in such cases between accidental influences and the regular course of nature is a superficial one. The regular course of nature is in itself a series of accidental influences; that is, the particular occasion is subservient to a general law with which it does not seem at first sight to have any connection. A severe winter may be sufficient to kill the quails, just as the ancient morass was sufficient to drown the mastodon. But the question is, why these causes began to operate just at these times. We may as well stop with the evident fact, that the unresting circulation is forever going on in the universe.
But if the quail, who is here very near his northern limits, has a hard time of it in the winter, and is threatened with such "removal" as we treat the Indians to, his relative, the partridge, our other gallinaceous or hen-like bird, is of a tougher fibre, as you see when you come upon his star-like tracks across the path, eight or nine inches apart, and struck sharp and deep in the snow, or closer together among the bushes, where he stretched up for barberries or buds, and ending on either side with a series of fine parallel cuts, where the sharp-pointed quills struck the snow as he rose,—a picture of vigor and success. He knows how to take care of himself, and to find both food and shelter in the evergreens, when the snow lies fresh upon the ground. There, in some sunny glade among the pines, he will ensconce himself in the thickest branches, and whir off as you come near, sailing down the opening with his body balancing from side to side.
The partridge is altogether a wilder and more solitary bird than the quail, and does not frequent cultivated fields, nor make his nest in the orchard, as the quail does, but prefers the shelf of some rocky ledge under the shadow of the pines in remote woods. He is one of the few birds found in the forest; for it is a mistake to suppose that birds abound in the forest, or avoid the neighborhood of man. On the contrary, you may pass days and weeks in our northern woods without seeing more than half a dozen species, of which the partridge is pretty sure to be one. All birds increase in numbers about settlements,—even the crow, though he is a forest bird too. Hence, no doubt, has arisen the notion that the crow (supposed to be of the same species with the European) made his appearance in this country first on the Atlantic coast, and gradually spread westward, passing through the State of New York about the time of the Revolution. I was told some years since by a resident of Chicago, that the quails had increased eight-fold in that vicinity since he came there. The fact is, that the bird population, like the human, in the absence of counteracting causes, will continue to expand in precise ratio to the supply of food. The partridge goes farther north than the quail, and is found throughout the United States. With us he affects high and rocky ground, but northward he keeps at a lower level. At the White Mountains, the regions of this species and of the Canada grouse or spruce partridge are as well defined in height as those of the maples and the "black growth." Still farther north I have observed that our partridge frequents the lowest marshy ground, thus equalizing his climate in every latitude.
There are few of our land-birds that flock together in summer, and few that are solitary in winter,—none that I recollect, except birds of prey. And not only do birds of the same kind associate, but certain species are almost always found together. Thus, the chickadee, the golden-crested wren, the white-breasted nuthatch, and, less constantly, the brown creeper and the downy woodpecker, form a little winter clique, of which you do not often see one of the members without one or more of the others. No sound in nature more cheery and refreshing than the alternating calls of a little troop of this kind echoing through the glades of the woods on a still, sunny day in winter: the vivacious chatter of the chickadee, the slender, contented pipe of the gold-crest, and the emphatic, business-like hank of the nuthatch, as they drift leisurely along from tree to tree. The winter seems to be the season of holiday enjoyment to the chickadee, and he is never so evidently and conspicuously contented as in very cold weather. In summer he withdraws to the thickets, and becomes less noisy and active. His plumage becomes dull, and his brisk note changes to a fine, delicate pee-peh-wy, or oftenest a mere whisper. They are so much less noticeable at this season that one might suppose they had followed their gold-crest companions to the North, as some of them doubtless do, but their nests are not uncommon with us. Fearless as the chickadee is in winter,—so fearless, that, if you stand still, he will alight upon your head or shoulder,—in summer he becomes cautious about his nest, and will desert it, if much watched. They build here, generally, in a partly decayed white-birch or apple-tree, excavating a hole eighteen inches or two feet deep,—the chips being carefully carried off a short distance, so as not to betray the workman,—and lining the bottom of it with a felting of soft materials, generally rabbits' fur, of which I have taken from one hole as much as could be conveniently grasped with the hand.