Author: Ann Bonnell
Date: January 2012
Sometimes called "Snowbirds," Darkeyed Juncos are slightly larger than House Finches, with white feathers at the outside edges of their tails. They always show up at your yards and feeders with the first snowfall of the season. The word junco comes from the scientific name for the genus coming from the Latin "a rush." This remains a mystery as juncos are not normally associated with reeds or rushes, only occasionally found in bogs. It may be from Junco - Medieval Latin for the Reed Bunting which this genus resembles. Linnaeus gave them their scientific name Junco hyemalis. He was a Swedish scientist and noticed they showed up only in winter, the Latin hiemalis meaning of or belonging to winter.
At one time the juncos were separate species, however in 1973 most of them were lumped into Dark-eyed Juncos. The old species are now called subspecies, forms, races or types depending upon the author. Currently under Dark-eyed Junco are Slatecolored Junco, Oregon Junco, Pink-sided Junco, Gray-headed Junco, White-winged Junco, and the Red-backed Junco. The Yellow-eyed Junco is a separate species. The juncos that were lumped into Dark-eyed Junco can often be identified separately; however because of cross-breeding some identifications can be difficult. Those we can't put in a definite slot we call "form." Juveniles in mid-summer are a challenge as they look like streaky sparrows. The adult juncos we see have pale, pinkish-white conical shaped bills and they are not streaked. Currently juncos belong to the Sparrow Family. At one time they were included in the Finch Family.
Juncos nest in relatively open coniferous forests or mixed woods with patches of open ground and brush from 8,000' to 10,000' elevation. The nest is often tucked up against a log, tree, and shrub or in a crevice. The nest is made of grass, plant fibers, moss, rootlets, bark, and twigs lined with finer materials such as hair. The female builds the nest. The male will sing his one pitch, soft trill from the top of a nearby tree. During courtship a pair may hop about with wings drooped and tail held forward showing their white, outer tail feathers. She lays 3-5 whitish eggs speckled with brown. Incubation is
about 12 days and hatching to fledging is about another 12 days. The legs of the immatures develop rapidly to aid in running from the nest if a predator shows up. Brown-headed Cowbirds sometimes lay eggs in junco nests. I observed an adult junco feeding a juvenile cowbird in the campground at Kenosha Pass. The junco was about ½ the size of the hungry cowbird. The eye color of Dark-eyed Juncos changes from gray or gray-brown to red-brown as they mature from juveniles to adults. In Colorado our breeding form of Dark-eyed Junco is the Gray-headed Junco. They live year-round in Colorado and are the only juncos we see in summertime. In fall as the weather gets colder and snows start our breeding Gray-headed Juncos move down in elevation and some may even leave the area
heading farther south. The other juncos: Grayheaded from farther north, Oregon from areas north and west of us, White-winged from the Dakotas, Slate-colored and Pink-sided from farther north show up along the Front Range. In winter they hang out in small flocks sometimes mixed with chickadees, Bushtits, nuthatches and other species. This gives them a better warning system from predators.
The juncos like to feed on the ground hopping and scratching to find seeds, nuts, some fruits and many different types of insects. Their diet in summer is mostly insects. They feed the nestlings only insects, sometimes regurgitated when the nestlings are very young. In winter their diet is mostly seeds. At your feeder they prefer the small seeds they can crack open such as white millet. They will feed on the ground or at an elevated tray.
Their predators would be hawk, accipiters, egg or nestling eating mammals and snakes. At one time humans shot them for food. John James Audubon commented in his classic Birds of America: Dark-eyed Junco ("... flesh is extremely delicate and juicy"). In 1918 legislation enacted as part of the Migratory Bird Act stopped the hunting of migratory non-game birds except for scientific purposes.
In cold weather juncos, sparrows and finches use thermoregulation while foraging on the ground for food. They will drop down and cover their legs and feet with their breast feathers, pausing in their search for food to warm up. In winter a favorite place to look for juncos is on sunny, bare, south facing slopes.
Some identifying marks to look for in differentiating the adult forms of Dark-eyed Juncos we would normally see in Colorado are: Gray-headed Junco – Dark eyes and area around the eyes, pink bill, pale gray overall, white belly, not distinctly defined, neat, rufous back; Oregon Junco – Only junco with jet black hood contrasting with brown back – the female is paler; Slate-colored Junco – Slate gray with pink bill and white belly; Pink-sided Junco – Slightly larger than Oregon Junco, with pale, bluish gray hood, dark around eyes and rich orange-buff sides; Whitewinged Junco – Larger than Slate-colored, dark around eyes, pale gray throat, distinct, white wingbars and more white feathers at tail edges than other juncos. The Red-backed Junco form from New Mexico is not found in Colorado. The Yellow-eyed Junco is a separate species found in Arizona and Mexico.
How long do juncos live? There are several records of recaptures after 8 ½ years. Young juncos have been recorded returning after migration to nest within 50 yards of the nest location they fledged.
Mila et al. (2007) conclude the entire Darkeyed Junco species has undergone a rapid post-Pleistocene radiation from the south, diversifying in the past 10,000 years into the various forms we see today.
Information for this article was collected from many sources. Perhaps the Snowbirds will visit you this winter.
Copyright © 2013 Ann Bonnell