With the arrival of the winter solstice, bird life on Martha’s Vineyard has settled into a fairly stable winter pattern. Vagrants are always possible, but in general, relatively little migration is occurring now, and winter residents have largely found and settled into patches of their preferred habitat. Prominent among our winter residents is one of my favorite songbirds: the white-throated sparrow. Never known to breed here, this species is a conspicuous winter resident of thickets, woodland edges, and settled areas across the Island.
On the large side for a sparrow, distinctly bigger than the very common song sparrow, this species shows the streaked, brownish upper parts typical of its close relatives. The flanks are grayish and indistinctly streaked. The most notable feature is the head pattern: a white-striped crown, with the contrast between brown and white varying from strong to more muted, depending on the individual. The eponymous white throat is obvious: While some other sparrows show contrast between a white throat and a darker breast, this feature is truly striking in this species. One handy field mark is distinct yellow coloration of the lores (the space in front of the eyes and above the beak).
You might assume that more muted individuals of this species are female, but in fact the sexes of white-throated sparrow are not generally separable in the field. Unusually for North American songbirds, white-throated sparrows appear in two distinct color variants, or morphs: so-called “white-striped” and “tan-striped” forms. The former has crisp markings on the head, with strong contrast between clean white and dark brown stripes. In tan-striped birds, the markings are more muted and the contrast is reduced. Oddly, these forms also differ in general behavior, with (for example) white-striped males more strongly territorial than tan-striped individuals, and tan-striped birds typically providing more parental care of young than white-striped birds. Even more strangely, individuals of each form are said to mate preferentially with members of the other form.
White-throated sparrows are easy to detect and identify by their vocalizations. Their usual call note, often given by birds hidden deep within thickets, is a loud, metallic “chink.” They also give a thin “tsee” note, especially in flight. And the song of the species is loud and memorable: a high, whistled “Sam Peabody, Peabody, Peabody.” Like the males, females of this species sometimes sing, with female white-striped birds reportedly singing more than tan-striped females.
This songbird breeds at higher elevations in the northern Appalachians, across most of Canada, and in the northernmost portions of the Midwest and New England. It winters on the West Coast and in most of the eastern United States, occurring at least occasionally as a migrant across most of the rest of the country.
Massachusetts Audubon’s breeding bird atlas project showed a sharp decline in Massachusetts breeding numbers between the 1970s and 2010, including the virtual extirpation of a scattered but not insignificant breeding population in the southeast coastal plain of the state. Meanwhile, though, Vineyard Christmas Bird Count (CBC) numbers of white-throated sparrows have steadily increased across the years, from the tens to low hundreds in the 1960s to well up into the hundreds, sometimes approaching 1,000 individuals, in recent years.
Fall migrants begin to arrive here in the second half of September and can turn up virtually anywhere there is low, dense vegetation. While this is a very common spring migrant in most of mainland Massachusetts, spring white-throated sparrow migration on the Island seems to consist mainly of the gradual departure of our wintering birds, with few transients typically evident. Most years, the species is gone from the Island by the middle of May.
The white-throated sparrow is among our wintering songbirds showing a marked preference for greenbriar thickets. The dense, spined stems of greenbriar create a perfect refuge for small birds, protecting against mammalian and probably larger avian predators. An added attraction are the bluish berries of greenbriar. These are said to be edible and reasonably palatable, though sources almost invariably assert that the nutritional content of greenbriar berries is limited due the thinness of the meat that covers the large seed. But these same sources also generally state that greenbriar berries are an important food source for many kinds of wintering birds, so perhaps the birds know something that humans don’t.
The white-throated sparrow is also a common winter resident in densely settled areas, happy to exploit fruit- or seed-bearing ornamentals and even happier to visit feeding stations. This does not always work out well for the sparrows. I’ve found no scientific information to support my impression, but white-throated sparrows seem to me to be especially vulnerable to window strikes. We don’t have many such events at our house, but over the years, an extraordinarily high percentage of the birds that have hit our windows have belonged to this species.
So if you feed birds, keep an eye out for this attractive species. But please place feeding stations safely away from windows, and close to sheltering thickets where sparrows and finches can dive for shelter when necessary.
