Dark-eyed juncos are small gray and white songbirds that are common across much of North America. They are known for their distinctive white outer tail feathers that flash as they flit about. Juncos are one of the most abundant and familiar birds across large parts of the continent.
But while juncos can be found year-round across much of their breeding range in Canada and the western United States, the majority of those that nest in the colder northern regions and at higher elevations migrate south for the winter. Their annual migrations take many of these birds hundreds or even thousands of miles between their summer and winter homes.
Breeding Range
Dark-eyed juncos breed across Canada and Alaska, south throughout the western mountains and east throughout the Appalachians. Their breeding range extends as far south as southern California, Arizona, New Mexico and Georgia in higher elevation mountain forests.
They are found in coniferous or mixed forests, favoring areas with dense undergrowth. Juncos require these forest habitats for breeding and are most abundant where there is ample low cover.
Throughout their breeding range, juncos are rarely found far from conifers. They rely on the cover and seeds of these evergreen trees and shrubs during the breeding season.
Western Mountains
From Alaska through the western provinces south along the mountain ranges into Mexico, dark-eyed juncos nest among the conifers of mountain forests. This includes the coastal ranges along the Pacific, the Rockies, the Sierra Nevada and the Cascades.
Eastern Forests
In eastern North America, dark-eyed juncos breed across Canada into the Adirondacks, Appalachians and higher elevations of the southeastern mountains. Their breeding habitats here are boreal forests, mixed deciduous-coniferous forests and eastern hemlock stands.
Breeding Elevations
Throughout their range, most breeding dark-eyed juncos are found at elevations above 3,000 feet. Some exceptions include breeding juncos in coastal southeast Alaska, in the northern Appalachians and those that nest farther north at lower elevations. But in general, they favor higher elevations in summer.
Winter Range
While many juncos that breed at higher latitudes and elevations in the west migrate south and east for winter, others that nest farther south appear to be resident year-round. Wintering dark-eyed juncos can be found throughout much of the contiguous United States and south through Mexico.
Western Winter Range
In the west, wintering dark-eyed juncos are found along the Pacific Coast from southern Alaska through California. They also inhabit areas of the southwest U.S. and scattered montane forests farther inland that provide sufficient conifers for cover and food.
Eastern Winter Range
East of the Rockies, dark-eyed juncos winter throughout the southern half of the U.S. from the Great Plains through the entire eastern seaboard. Their winter range extends south throughout Mexico and the Caribbean to Panama.
Wintering Elevations
Unlike on their breeding grounds, wintering juncos can be found from sea level up to elevations around 8,000 feet where conditions allow. Along the Pacific Coast and farther south they mainly winter at lower coastal elevations. Throughout the interior west and east they winter in both lowland areas and foothill forests.
Migration Routes and Wintering Grounds
The majority of dark-eyed juncos that nest in Canada and across Alaska, south along the continental divide, migrate south and east to reach their wintering grounds. While not all migrate the entire distance between the breeding and wintering ranges, most undertake seasonal movements covering hundreds of miles.
Western Juncos
Juncos that nest in western mountain ranges move down in elevation and south along the coast or farther inland to winter. Those from inland and northern areas migrate down through the western interior to winter in the southwest U.S. and highlands of Mexico.
Eastern Juncos
Eastern breeders migrate south along the Appalachians and interior eastern states, often statewide, to reach their southern wintering areas. Those nesting farthest north may traverse the entirety of the eastern U.S. and into Mexico and beyond.
Southern Canada and Northern U.S.
Dark-eyed juncos that nest across southern Canada and the northern U.S. also migrate south for winter, but not quite as far. Their migrations take them south through the interior U.S., often on a broad front across the Great Plains and Mississippi River valley. These birds winter throughout the southern U.S. from California to the Carolinas.
Migration Timing
Fall migration begins in August and September, but peaks in October and early November as birds move south ahead of winter weather. Northward return migration occurs March through May as birds move back to breeding areas. Males tend to arrive on breeding grounds first and depart last in fall.
Winter Habitats
While coniferous forests provide ideal breeding habitat for dark-eyed juncos, they utilize a wider variety of habitats in winter. Winter habitats provide sufficient cover for foraging and night roosting along with reliable food sources.
Forests
Many juncos winter in both conifer and hardwood forests, from northeastern pine barrens to southeastern mixed pine-oak woods to the oak-juniper woodlands of Texas. Forest habitats provide cover, roost sites, and access to seeds and insects.
Woodland Edges
Woodland and forest edges, such as those along fields, provide cover and access to open areas with seeds. These transition zones, often with shrubs and small trees, are heavily used by wintering juncos.
Pine Plantations
Pine plantations are also inhabited by wintering dark-eyed juncos, which use the young conifers for cover and feed on waste seed. Stands of planted pines have allowed juncos to expand their winter range farther southeast where naturally occurring conifer forests are absent.
Residential Areas
Many juncos frequent backyards, parks and other residential green spaces in winter. They use shrubs and trees for cover and take advantage of feeders for supplemental food.
Threats and Conservation
Dark-eyed juncos remain widespread and common throughout their range. Partners in Flight estimates a global breeding population of 270 million. While thriving as a whole, juncos do face some local threats on their breeding and wintering grounds.
Breeding Ground Threats
On their breeding grounds, loss of coniferous forests to logging and fire negatively impact juncos. Fragmentation also reduces quality of remaining habitat. Climate change may shift conifer zones upslope, reducing available habitat.
Wintering Ground Threats
In winter, conversion of woodlands and shrublands to agriculture and development eliminates habitat. Insecticide use also reduces food resources. Reliance on supplemental feeding makes juncos vulnerable if feeders are not maintained.
Conservation Efforts
Maintaining connected tracts of conifer forest across the breeding range and shrubland habitats on wintering grounds conserves junco populations. Providing cover and supplemental food, especially in winter, benefits these migratory songbirds.
Conclusion
Dark-eyed juncos undertake annual migrations spanning hundreds or thousands of miles between their breeding areas across Canada and Alaska and wintering grounds throughout the U.S. and Mexico. The majority leave coniferous mountain forests in fall, traveling south and east along the coasts and through the interior to reach wintering habitats. Here they occupy forests, woodlands and residential areas that provide cover and access to seeds. Maintaining connected forests and woodlands throughout their migratory range will benefit junco populations into the future.