Besides the species that we regularly count upon in winter, there are more or less irregular visitors at this season, some of them summer birds also,--as the purple finch, cedar-bird, gold-finch, robin, the flicker, or pigeon woodpecker, and the yellow-bellied and hairy woodpeckers. Others, again, linger on from the autumn, and sometimes through the winter,--as the snow-bird, song-sparrow, tree-sparrow. Still others are seen only in winter,--as the brown and shore larks, the crossbills, redpolls, snow-buntings, pine grosbeak, and some of the hawks and owls; and of these some are merely accidental,--as the pine grosbeak, which in 1836 appeared here in great numbers in October, and remained until May. This beautiful and gentle bird (a sweet songster too) is doubtless a permanent resident within the United States, for I have seen them at the White Mountains in August. What impels them to these occasional wanderings it is difficult to guess; it is obviously not mere stress of weather; for in 1836, as I have remarked, they came early in autumn and continued resident until late in the spring; and their food, being mainly the buds of resinous trees, must have been as easy to get elsewhere as here. Their coming, like the crow's staying, is a mystery to us. I have spoken only of the land-birds; but the position of our city, so embraced by the sea, affords unusual opportunities for observing the sea-birds also. All winter long, from the most crowded thoroughfares of the city, any one, who has leisure enough to raise his eyes over the level of the roofs to the tranquil air above, may see the gulls passing to and fro between the harbor and the flats at the mouth of Charles River. The gulls, and particularly that cosmopolite, the herring gull, are met with in this neighborhood throughout the year, though in summer most of them go farther north to breed. On a still, sunny day in winter, you may see them high in the air over the river, calmly soaring in wide circles, a hundred perhaps at a time, or pluming themselves leisurely on the edge of a hole in the ice. When the wind is violent from the west, they come in over the city from the bay outside, strong-winged and undaunted, breasting the gale, now high, now low, but always working to windward, until they reach the shelter of the inland waters. In the spring they come in greater numbers, and other species arrive: the great saddle-back, from the similarity of coloring almost to be mistaken for the white-headed eagle, as he sits among the broken ice at the edge of the channel; and the beautiful little Bonaparte's gull.