When you drive through ag land during the winter, you can see flocks of birds rising, falling, and drifting over the landscape as if they were clouds of corn husks tumbling in the wind. These are species that come south from the tundra and stick with their predilection for tree-less spaces by combing through the post-harvest cuttings of corn, grain, and hay fields. Even in snowy winters the wind scrapes down to the bare earth or near it and makes foraging possible.
The most common of these birds in my own experience are the snow buntings. In their breeding plumage this species is quite white, as its name suggests, with black primaries and a black center to their tails. By the time they get down to our latitude in the fall, they have molted into a plumage that is buffier, but retains more white than any other sparrow-like bird.
In 2007 the Christmas Bird Count suggested a sharp population decline of 64 percent over the previous 40 years. But subsequent research, reported through Partners in Flight, a worldwide bird survey, showed that snow bunting numbers had declined 38 percent between 1970 and 2014. Not insignificant, but their population is estimated at 29 million and they are species of “least concern” from a conservation perspective. Researchers’ first guess as to the cause was, of course, climate change, which is manifest most clearly at the high northern latitudes.
But again, further research suggested that the species may have been coming down off a mid-century population peak caused by forest clearance in its Canadian winter range through the first half of the 20th century. As the forest has grown up again, the birds’ foraging grounds have contracted.
The Lapland longspur shares the tundra nesting grounds with the snow bunting, but winters slightly further south. Curiously, the distribution map at allaboutbirds.com shows them as passing through New Hampshire in migration, but remaining through the winter in Vermont and in coastal Maine. They are even more abundant than snow buntings, but you are less likely to seem them locally.
While the breeding males have distinctive black and brown markings, these are lost in the fall and the winter birds are among the least distinctive of the sparrow-like species. Field marks include a dark line that arcs back from the eye, down and then forward and a rusty patch on the wings. It is their proclivity for being out in the middle of a cut-over field in the worst winter weather that will most readily distinguish them from ordinary sparrows.
The horned lark is not confined to tundra like the previous two species, but is also found throughout the center of the continent as a breeder with a range extending eastward into southern Vermont. It is seen in New Hampshire only as a winter bird, where it will join the buntings in the winter fields.
It is a true lark and not a finch like the bunting and longspur, but it is about the same size as a sparrow, but slimmer and longer. Whereas finches tend to hop, larks have a scurrying walk. The eastern birds are uniformly brownish above, but they have a black band across the chest, a black mask through the eyes and a thin black band across the head that culminates in small horns (which can be raised or lowered.). The females’ plumage is a faded version of the males’.
Like the snow bunting, the numbers of the lark are determined by the amount of open country available. While for the bunting this applies to its wintering grounds for the lark it means its breeding grounds. Consequently, as the forest has replaced agricultural land uses in the East through the second half of the 20th century, horned lark distribution has become patchy and its abundance has declined.
The tundra bird that you are least likely to see is the American pipit. Most of its breeding range overlaps that of the bunting and longspur, but it also breeds in alpine tundra, including the highest peaks of the White Mountains here in New Hampshire. This drab, brown-streaked bird looks like a sparrow with a thin beak that walks instead of hopping. It migrates to the southern United States for the winter, merely passing through the northern windblown fields.