Junco hyemalis
dark-eyed junco

Dark-eyed juncos (Junco hyemalis) breed from Alaska and central Yukon to Labrador and Newfoundland, south to central coastal California, in the mountains to eastern California, central Arizona, and western Texas, southern Alberta, northern and east-central Minnesota, central Michigan, southern New England, and in the Appalachian Mountains to northern Georgia and northwestern South Carolina; also in the Black Hills. This species winters from central and south coastal Alaska, coastal British Columbia and across southern Canada south to Mexico, the Gulf Coast and northern Florida. It is found only in the Nearctic region of the world. (United States Department of Agriculture, 1991)

The habitat of J. hyemalis occurs from sea level to timberline in a variety of woodland areas that have openings with dense herbaceous ground cover. These areas include coniferous and deciduous forests, forest edges, woodland clearings, stream borders, open woodlands, brushy cover bordering mountain meadows, and old barns. This species avoids deep forest interiors in favor of woodland edges and openings. In winter they prefer weedy fields, but also inhabit open woodlands, hedgerows, suburbs, and farmyards. They are found from sea level to 3500 meters. (Nolan et al., 2002; United States Department of Agriculture, 1991)

All J. hyemalis are small and slender with an overall length of 5 to 6.5 inches (12.5 to 16.5 cm). This species has dark gray plumage on its head, breast and upper parts which are a contrast to their striking white, outer tail and white belly. Sexes are colored or patterned differently with female and immature J. hyemalis somewhat browner than the adult male; juveniles also have streaked breasts. Males are usually around 5% larger than females. Members of this species have a pink bill and dark eyes. A typical weight for J. hyemalis is 0.67 oz (19 g) and an average wingspan is 9.25 inches (23.5 cm). (Barrowclough, 1983; Reader's Digest Association, 1991; Sibley, 2000; Sullivan, 1999)

The average lifespan of J. hyemalis is approximately 3 to 11 years. The oldest known wild dark-eyed junco lived at least 11 years 1 month. Most commonly, predation by other species (hawks, squirrels, weasels, etc.) limits their lifespan. (Nolan et al., 2002; The Norman Bird Sanctuary, 2000)

Dark-eyed juncos usually hop or walk as they move along the ground and can travel up to 30 cm in one hop. Exceptions are running in short spurts when chasing a rival or to capture moving food. This species is social during autumn and winter months and consorts in flocks. Winter flocks tend to be small, typically 15 to 25 individuals. Flocks form in the morning, 20 to 30 minutes before sunrise and disperse in the evening, 45 minutes before sunset to roost for the night. Daylight hours are spent either perching or foraging for food and allocation of time between these two activities varies with season and the stage of reproductive cycles. On average, individuals forage for 4.5 hours a day in the summer and 6 hours a day in the winter to meet higher energy demands. It is not uncommon for these flocks to associate with those of American tree sparrows (Spizella arborea).

Dark-eyed juncos tend to winter in the same area year after year. The flock stays in an area roughly 10 to 12 acres in size, but not all members of the flock are together all of the time. There is a social hierarchy within the winter flocks. Males tend to be dominant over females and adults are dominant over the younger birds. Because males are dominant over females in winter flocks, females have less access to food. Therefore, they do not fair well in flocks composed of many males. Females tend to winter farther south away from the males. Males need to risk harsh winters farther north in order to be closer to their breeding grounds. Females do not need to compete for territories in the spring and can take their time returning. Older males almost always return to their old, established territories. The younger males winter the farthest north and must work hard to claim a breeding spot. Dominant birds have an advantage when feeding and claiming territories and will face another bird and raise and fan their tails, revealing the white outer tail feathers. They may also rush at or peck at subordinate birds in order to chase them away. Aggressive behavior occurs mainly in winter flocks and increases with increasing flock size.

Most dark-eyed junco populations are migratory. However, some populations, particularly several montane subspecies, are sedentary or partially migratory. (Bent and et al, 1968; McPeek, 1994; Sibley, 2000; Stokes Nature Company, 2002; Sullivan, 1999)

Home Range

Winter flocks have a home range of 10 to 12 acres. (Sullivan, 1999; United States Department of Agriculture, 2002)

Dark-eyed juncos (Junco hyemalis) possess considerable variation in song. The most common song is a simple, musical trill, all in one pitch, or a series of rapid notes which may be too rapid to discern. Only male dark-eyed juncos sing. To proclaim occupancy of a territory, two or three trills on different pitches may be joined to form a single warbling song. A simple explosive call is used as an alarm, while a smacking sequence is used to scold. This species uses a combination of twanging, buzzing, and smacking notes when fighting.

Junco hyemalis also uses territorial and courtship displays to communicate (see Mating Systems and Behavior). (Bent and et al, 1968; Sullivan, 1999)

Dark-eyed juncos forage on the ground, picking up a wide variety of seeds and some insects. In the non-breeding season, they prefer to feed on insects, non-insect arthropods, and seeds. During the breeding season, they eat mostly insects. They are commonly seen at bird feeders during migration and in the winter months, however, even then they prefer to feed on the ground rather than pick seeds from an elevated feeder. One method of foraging practiced by this species is "riding" a grass stem. This is accomplished by flying up onto a tall grass stem, riding the stem down to the ground as it bends under the bird's weight, and then plucking the seeds from the seed head as it sits on the ground. When a thin layer of snow lies on the ground, dark-eyed juncos scratch away a roughly circular hole, 3 or 4 inches in diameter, to get at the grain underneath. In the summer, half of the diet consists of insects. Caterpillars, beetles, and ants are the most common items in their diet. There is also a long list of mostly weed plants whose seeds J. hyemalis is known to eat. The most common are ragweed, bristlegrass, dropseed grass, crabgrass, pigweed, and goosefoot. Juncos are morphologically generalized enough to handle both seeds and insects as part of their diet. (Bent and et al, 1968; Dunning, 2001; McPeek, 1994; Sullivan, 1999; United States Department of Agriculture, 1991)

Because it inhabits open areas, Junco hyemalis is subject to attack by many different birds, including sharp-shinned hawks, shrikes and owls. They are also frequently killed by feral and domestic cats. Red squirrels (Tamiasciurus hudsonicus), weasels (genus Mustela), chipmunks (genus Tamias), American martens (Martes americana) and other mammals as small as jumping mice take eggs and young from nests.

In response to predators, adults flee to nearby shelter. Parents give "chips" excitedly and fly around nest areas when predators are present and sometimes even dive at predators attempting to prey on nestlings or eggs. (Bent and et al, 1968; Sullivan, 1999; United States Department of Agriculture, 2002)

Dark-eyed juncos, like many other bird species, are an integral part of forested ecosystems and play an important role in maintaining the health and productivity of the forests and woodlands. Members of this species aid in the dispersal of seeds and help to control insect populations. They are occasionally parasitized by brown-headed cowbirds (Molothrus ater). Antibodies of the St. Louis strain of encephalitis have been reported in dark-eyed juncos and there are 26 other genera of parasites that have been reported to use this species as a host. (Bent and et al, 1968; Nolan et al., 2002)

There are no known adverse affects of dark-eyed juncos on humans.

Junco hyemalis has little, if any, economic importance for humans. This species is an excellent subject for photography and art and provides an enjoyable pastime for many bird watchers. Due to the fact that they are commonly found at bird feeders during migration and winter months, they may play a small part in the sale and production of bird seed, bird feeders and binoculars. Juncos also eat insects that humans may consider pests. (Bent and et al, 1968)

Dark-eyed juncos are protected under the US Migratory Bird Treaty Act. They are quite abundant within their geographic range.

There are several distinctive races or groups of races of Junco hyemalis that were formerly considered to be separate species. However, because they interbreed freely where their ranges overlap, they are now treated as a single species. The common names of these former species are still used to refer to these identifiable forms of J. hyemalis. Included in this group are the "Dark-eyed" Junco, the "Slate-colored" Junco, the "White-winged" Junco, Oregon Junco, and the "Gray-headed" Junco. These sub-species were considered separate species until the 1970's when their rank was lowered from species to sub-species. (Barrowclough, 1983; Sibley, 2000)