Most of the U.S. and Canada is graced by the cheerful presence of the Dark-eyed Junco at least part of the year, and a big swath counts this handsomely suited sparrow as a year-round resident.
Though the species exhibits some striking plumage variation across multiple distinct populations in North America, the Dark-eyed Junco is overall a very easy songbird to identify. It’s also among our most conspicuous, easily seen and heard on a walk in the woods or the park (depending on the season) and around the backyard feeder, where in its winter range it may show up for lunch in blizzard or frigid conditions.
Indeed, the junco’s high-profile residence during winter in nearly all of the Lower 48 states – when, of course, many other passerines have fled the scene – explains its widely used nickname: “snowbird.”
Appearance and identification
Dark-eyed Juncos are members of that very well-stocked sparrow family, and have the size and shape of a typical sparrow: big-headed, short-billed, plump-bodied, short-winged, and fairly long-tailed. The bird is on the order of 5 or 6 inches in length with a wingspan of 8 or 9 inches or so; it generally weighs between half an ounce and an ounce.
Many brownish, speckled sparrows look confusingly alike, but the juncos – the Yellow-eyed Junco is the only other North American kind, barely reaching north of the Mexico border – stand out boldly from the rest of the clan, at least in adult plumage.
That plumage, though, varies significantly across the six or so Dark-eyed Junco populations: the Oregon, the Slate-colored, the Pink-sided, the White-winged, the Red-backed, and the Gray-headed. (The taxonomy – that is, the scientific classification – of Dark-eyed Juncos is still sort of unsettled business; these populations were formerly considered separate junco species, and each includes multiple subspecies. It’s all a bit too complicated to do justice here!)
All of these “snowbird” varieties have dark heads, eye masks (“lores”), flanks, and upper wingfeathers contrasting with white underparts, but the hues and patterns differ between the races, with several western ones being the most colorful.
The Oregon Junco has a strikingly dark head and neck–soot-colored in females, black in males–and a reddish-brown back and flanks. Slate-colored Juncos have brownish or grayish heads and upper bodies; the “hood” is less distinct from the back and flanks. The same goes for the White-winged Junco, which is blueish-gray. The Pink-sided Junco has (surprise, surprise) pink-tinted flanks; its hood is blueish-gray. Gray-headed and Red-backed Juncos are quite similar-looking to one another, with a gray head and flanks and a flashy orange-red upper back.
Probably the signal feature of all these Dark-eyed Junco varieties is the upper tail plumage, defined by dark middle feathers and white outer feathers. When the junco flies, it fans its tail, flashing white stripes at the edges – a conspicuous and surefire identifying feature of the species.
Location and habitat
The Dark-eyed Junco covers most of North America in a vast distribution stretching from the Alaskan and Canadian subarctic to north-central Mexico. Much of that, however, is seasonal range: In the north, the junco is mostly a summertime breeder – more than half the total population of Dark-eyed Juncos nests in the boreal forest – with wintering populations covering large portions of the eastern, central and far southwestern U.S.
In most of the American West and Northwest, in the northern Upper Midwest, in New England, and south along the Appalachian Mountains, the Dark-eyed Junco is a permanent, year-round inhabitant, though depending on the location this may reflect summer and winter populations of different varieties.
Dark-eyed Junco southbound migration peaks in October, while the spring journey north takes place in March and April.
In terms of habitat, the Dark-eyed Junco mainly nests in coniferous forests, though in some areas it may also do so in mixed and deciduous woods; it prefers more open stands with a heavy understory. During migration and during the winter, this sparrow roams over a broader spread of landscapes, including brushy fields, roadside thickets, and urban and suburban yards.
In winter, Dark-eyed Juncos travel in large flocks, making them all the more conspicuous as they forage along the ground and the underbrush. A dominance hierarchy maintains order in these seasonal congregations.
Sometimes juncos travel in mixed winter flocks with other songbirds, including close relatives such as White-crowned and American Tree sparrows. They may also hang around with winter gangs of Black-capped Chickadees: attractive to other songbirds because of their loud-and-clear alarm calls and announcements of discovered food.
What do they eat?
Seeds and invertebrates are by far the most important foods for the Dark-eyed Junco. In winter, seeds of grasses and herbs constitute up to 75 percent of the junco’s diet; during the nesting season, it incorporates more insects and spiders onto the menu. The Boreal Birds Initiative suggests that, on an annual basis, seeds account for about three-fourths of snowbird fare and arthropods compose the rest; berries are a much less important supplementary food source.
Dark-eyed Juncos typically search out food by hopping along the ground or flitting low through the underwood, easily navigating tangles and briars with their agile flight.
Dark-eyed Junco communication and call song
Dark-eyed Juncos let out short, sharp chirps and buzzes while foraging and flying; when flushed, they may issue a rapid-fire twitter. A dominant junco often makes a kew call when displacing or chasing a lower-ranked flock-mate.
The typical song of the male Dark-eyed Junco is a piercing, evenly pitched trill similar to that of a Chipping Sparrow. Males and females also sing more quietly with warbling trills, particularly in spring.
You can listen to examples of the Dark-eyed Junco song here.
Nesting and mating
Male Dark-eyed Juncos court females by hopping about, flashing wings and tailfeathers, wiping their bills, and brandishing moss, grass, or other potential nesting material. Females seem especially attracted to males showing more white in their fanned tails. The males sing from a prominent perch to mark their territory and will aggressively chase rivals who intrude upon it.
While mated pairs of Dark-eyed Juncos hold territories and raise young together, romance is on the fluid side of things: Both males and females may also mate on the side with birds from neighboring territories.
Dark-eyed Juncos are primarily ground-nesting birds: The female makes it in a shallow depression or hole on a slope or bank or sequestered amid exposed tree roots, draping vegetation, or under logs or rocks. Rarely the junco nests in low-hanging branches or on window ledges. The female often begins the cup-shaped nest with coarse grasses, pine needles, and other leaves, then lines it inside with softer material, including moss, feathers, and animal fur.
Eggs and young
A typical Dark-eyed Junco clutch is three to six eggs, and there may be more than one brood per year. After an incubation of 12 or so days, hatchlings remain in the nest nine to 13 days, fed by both parents.
References
- Boreal Songbird Initiative. Guide to Boreal Birds: Dark-eyed Junco.
- Cornell Lab of Ornithology. All About Birds: Dark-eyed Junco.
- National Audubon Society. Guide to North American Birds: Dark-eyed Junco.
- Sibley, David Allen. 2000. The Sibley Guide to Birds. Alfred A. Knopf.
