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.

Biogeographic Regions: nearctic (Native )

occurs (regularly, as a native taxon) in multiple nations

Canada

Origin: Native

Regularity: Regularly occurring

Currently: Present

Confidence: Confident

Type of Residency: Year-round

United States

Origin: Native

Regularity: Regularly occurring

Currently: Present

Confidence: Confident

Type of Residency: Year-round

Global Range: (>2,500,000 square km (greater than 1,000,000 square miles)) Breeding range extends from Alaska eastward across central Canada to Labrador and Newfoundland, south to northern Baja California, Arizona, western Texas, southern Saskatchewan, southern Manitoba, Great Lakes region, and southern New England, and in the Appalachian Mountains to northern Georgia (Nolan et al. 2002). Winter range extends from southern Canada south through the United States to Florida, southern Texas, and northern Mexico.

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).

Average mass: 19 g.

Range length: 12.5 to 16.5 cm.

Average wingspan: 23.5 cm.

Average basal metabolic rate: 46 cm^3 oxygen/hour.

Other Physical Features: endothermic ; bilateral symmetry ; polymorphic

Sexual Dimorphism: male larger; sexes colored or patterned differently

Average mass: 18 g.

Average basal metabolic rate: 0.2959 W.

Length: 16 cm

Weight: 2 grams

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.

Range elevation: 0 to 3500 m.

Habitat Regions: temperate ; polar ; terrestrial

Terrestrial Biomes: forest

Other Habitat Features: urban ; suburban ; agricultural ; riparian

Comments: Habitats include various sorts of coniferous, mixed, and deciduous forest; forest edge; forest clearings; bogs; open woodland; brushy areas adjacent to forest; and burned-over lands. In migration and winter the species occurs in a wide range of openly wooded and brushy and grassy habitats (AOU 1998). Nests are in scrapes on the ground and usually are concealed by logs, rocks, tree roots, leaves, or ground vegetation.

Non-Migrant: No. All populations of this species make significant seasonal migrations.

Locally Migrant: Yes. At least some populations of this species make local extended movements (generally less than 200 km) at particular times of the year (e.g., to breeding or wintering grounds, to hibernation sites).

Locally Migrant: Yes. At least some populations of this species make annual migrations of over 200 km.

Generally this species is a long-distance migrant, but migrations are more localized in some areas of the West, and the Appalachian population is largely sedentary.

South-bound migration from the northern breeding range occurs primarily September-November. Migration to northern breeding areas occurs mainly March-May.

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.

Animal Foods: insects; terrestrial non-insect arthropods

Plant Foods: seeds, grains, and nuts

Primary Diet: omnivore

Comments: Diet includes seeds throughout the year, insects during the breeding season, and waste grain in fall and winter.

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.

Ecosystem Impact: disperses seeds

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.

Known Predators:

• sharp-shinned hawks (Accipiter striatus)
• chipmunks (Tamias)
• red squirrels (Tamiasciurus hudsonicus)
• shrikes (Lanius)
• weasels (Mustela)
• American martens (Martes americana)
• owls (Strigiformes)
• feral cats (Felis silvestris)
• domestic cats (Felis silvestris)

Note: For many non-migratory species, occurrences are roughly equivalent to populations.

Estimated Number of Occurrences: > 300

Comments: This species is represented by a very large number of occurrences (subpopulations).

>1,000,000 individuals

Comments: Total adult population size is unknown but certainly exceeds 1,000,000. Rich et al. (2004) estimated population size at 260,000,000.

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).

Communication Channels: visual ; acoustic

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.

Range lifespan

Status: wild: 11.1 (high) years.

Typical lifespan

Status: wild: 3 to 11 years.

Dark-eyed juncos are monogamous. Males usually arrive on breeding grounds in the spring, well in advance of the start of nesting, and pairs are formed by mid-April. Males claim territories by singing from the top of the tallest trees in a 2 to 3 acre area. When a female enters his territory, the male pursues her aggressively. He spreads his tail and struts around the female, uttering "chips" and songs. The male may alternate dropping his tail to the ground with lifting it at a 45 degree angle. Once a pair is formed, males follow their mates and are seldom more than 50 feet away. The only exception is when the male proclaims his occupancy of a territory from a high perch.

Mating System: monogamous

The breeding season for dark-eyed juncos begins in April. Females build the nest over a period of 1 to 9 days, but the male often helps by bringing nest material. Nests are commonly built on the ground near the edge of openings in wooded areas or in a slight depression. They are usually well concealed under weeds, grasses, fallen logs, tree roots, or other overhead shelter. Nests are occasionally built up to 8 feet above ground in a shrub or tree. The nest cup is often lined with fine grasses, mosses or mammal hair and is used for two or three broods in one season.

The female lays 3 to 6 white or pale green eggs spotted with brown. The eggs are usually ovate and slightly glossy. Average egg size is about 0.8 inches (19 mm). The incubation period lasts 12 to 13 days; incubation is usually done by the females. Chicks leave the nest 9 to 13 days after hatching. After leaving the nest, the young remain at least partially dependent on their parents for about 3 weeks. Most dark-eyed juncos begin breeding at at 1 year.

Breeding interval: May breed 2 to 3 times during the spring and early summer each year

Breeding season: Dark-eyed juncos begin breeding in April

Range eggs per season: 3 to 6.

Average eggs per season: 4.

Average time to hatching: 12 to 13 days.

Range fledging age: 9 to 13 days.

Range time to independence: 9 to 21 days.

Average age at sexual or reproductive maturity (female): 1 years.

Average age at sexual or reproductive maturity (male): 1 years.

Key Reproductive Features: seasonal breeding ; gonochoric/gonochoristic/dioecious (sexes separate); fertilization

Average time to hatching: 11 days.

Average eggs per season: 4.

The female parent incubates the eggs and broods the chicks after they hatch. Both parents defend the nest from predators, remove fecal sacs from the nest and feed the chicks regurgitated or partly digested food along with an occasional tender caterpillar. Chicks are altricial and begin to open their eggs at the end of the second day. Their feathers begin to show around the seventh day. Rapid tarsal development enables nestlings to run from the nest if threatened before they can fly. Youngsters leave the nest 9 to 13 days after hatching. After leaving the nest, the young remain at least partially dependent on their parents for food for about 3 weeks. Occasionally, young will attempt to solicit parental care and crouch in a begging posture even after they are adequately developed for independence. Parents become aggressive in these cases and chase the fledgling a short distance without feeding it.

Parental Investment: no parental involvement; altricial ; pre-fertilization (Provisioning, Protecting: Female); pre-hatching/birth (Protecting: Female); pre-weaning/fledging (Provisioning: Male, Female, Protecting: Male, Female); pre-independence (Provisioning: Male, Female)

In most areas, nesting occurs from April to as late as August, but earlier nesting may occur in southern lowland areas and fledging may sometime extend into September. Clutch size usually is 3-5. Incubation lasts about 11-12 days. Both parents feed nestling and newly fledged young.

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

US Migratory Bird Act: protected

US Federal List: no special status

CITES: no special status

State of Michigan List: no special status

IUCN Red List of Threatened Species: least concern

Canada

Rounded National Status Rank: N5B,N5N : N5B: Secure - Breeding, N5N: Secure - Nonbreeding

United States

Rounded National Status Rank: N5 - Secure

Rounded Global Status Rank: G5 - Secure

Reasons: Large range in North America; very large population size; many occurrences; apparently slowly declining.

Global Short Term Trend: Relatively stable to decline of 30%

Comments: BBS data suggest that the species has declined slowly over the past 10 years or three generations.

Global Long Term Trend: Decline of 30-50%

Comments: Long-term decline over the past 200 years is unknown. Breeding Bird Survey (BBS) data for 19662007 indicate a signidicant survey-wide decline of 1.3% per year; this amounts to a 42% decline over this time period. BBS abundance (average number of bird per route) declined from roughly 8-9 in the 1960s and 1970s to around 6 in 2000-2007. Overall, based on BBS data, the species appears to have undergone a slow but steady decline in abundance over the past several decades.

Comments: No major threats have been identified. Causes of the slow, apparently ongoing decline are not known.

Global Protection: Very many (>40) occurrences appropriately protected and managed

Comments: Many occurrences are in protected areas.

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.

Positive Impacts: controls pest population

Comments: The several recognizable groups or subspecies of dark-eyed juncos formerly were recognized as distinct species. Further genetic studies are likely to alter current views on the relationships of these groups and other junco species.

The groups of this complex that have been treated as species by many authors include: hyemalis (Slate-colored Junco); oreganus (Oregon Junco); aikeni (White-winged Junco); caniceps (Gray-headed Junco); and insularis (Guadalupe Junco) (AOU 1998); insularis is an isolated population closest to oreganus (AOU 1983); mearnsi form (Pink-sided Junco) may represent a distinct group from oreganus, and dorsalis form (Red-backed Junco) may represent a distinct group from caniceps (AOU 1998), and both formerly were treated as separate species.