Dark-eyed Junco - Slate-colored race #4
by J McCombie
Title
Dark-eyed Junco - Slate-colored race #4
Artist
J McCombie
Medium
Photograph - Untouched
Description
Dark-eyed Juncos are neat, even flashy little sparrows that flit about forest floors of the western mountains and Canada, then flood the rest of North America for winter. Theyre easy to recognize by their crisp (though extremely variable) markings and the bright white tail feathers they habitually flash in flight. One of the most abundant forest birds of North America, youll see juncos on woodland walks as well as in flocks at your feeders or on the ground beneath them. They are commonly called the snowbird (The Snow Bird) because of its sudden appearance around winter bird feeding stations.
Juncos vary across the country (see Regional Differences), but in general theyre dark gray or brown birds brightened up by a pink bill and white outer tail feathers that periodically flash open, particularly in flight. Dark-eyed Juncos are birds of the ground. They hop around the bases of trees and shrubs in forests or venture out onto lawns looking for fallen seeds. Youll often hear their high chip notes, given almost absent-mindedly while foraging, or intensifying as they take short, low flights through cover. Dark-eyed Juncos breed in coniferous or mixed-coniferous forests across Canada, the western U.S., and in the Appalachians. During winter youll find them in open woodlands, fields, parks, roadsides, and backyards.
Juncos are the "snowbirds" of the middle latitudes. Over most of the eastern United States, they appear as winter sets in and then retreat northward each spring. Some juncos in the Appalachian Mountains remain there all year round, breeding at the higher elevations. These residents have shorter wings than the migrants that join them each winter. Longer wings are better suited to flying long distances, a pattern commonly noted among other studies of migratory vs. resident species. The Dark-eyed Junco is one of the most common birds in North America and can be found across the continent, from Alaska to Mexico, from California to New York. A recent estimate set the juncos total population at approximately 630 million individuals. The oldest recorded Dark-eyed Junco was 11 years 4 months old.
When is a Junco a Junco? Scientists continue to change the names of birds. Why is it that birds of the same species may look very different in various regions, but have the same name? For instance, Dark-eyed Juncos in the Pacific Northwest may have a reddish back and a dark hood (Oregon race), while Dark-eyed Juncos in the northeast are generally a slate-gray color, without a hood (slate-colored race). Who decides where the lines are drawn between species? Why can birds that look very similar, like Black-capped Chickadees and Carolina Chickadees, be distinct species, while others that look obviously different, like Dark-eyed Juncos from the Oregon and slate-colored races, be the same species?
A history of name changes: Committees of 8-10 highly experienced ornithologists and taxonomists make official changes in species names. For North American birds, the Committee on Classification and Nomenclature of the American Ornithologists Union (AOU) maintains the official checklist. AOU checklists are updated every few years as new information on bird biology leads the committee members to either divide one species into two or more species (splitting), or to group species together under one name (lumping). Changes are often made based on new information regarding the genetics of the birds, how birds communicate (song-types), or the frequency of hybridization. Some groups of birds have been split and lumped several times. For instance, Dark-eyed Juncos had been split into as many as 7 different species before being lumped together under one name. Members of the titmouse family have been split from 3 species to 5 species since 1983 (see the history of name changes in titmice (see the history of junco and titmouse name changes below).
The dark-eyed junco was described by Linnaeus in his 1758 Systema naturae as Fringilla hyemalis. The description consisted merely of the laconic remark "F[ringilla] nigra, ventre albo. ("A black 'finch' with white belly"), a reference to a source, and a statement that it came from "America". Linnaeus' source was Mark Catesby who described the slate-colored junco before binomial nomenclature as his "snow-bird", moineau de neige or passer nivalis ("snow sparrow"). Still, at least the slate-colored junco is unmistakable enough to make it readily recognizable even from Linnaeus' minimal description. Its modern scientific name means "winter junco", from Latin hyemalis "of the winter".
It was first thought that there were five different species. Today, all have been re-classified as one species, the Dark-eyed Junco. This bird varies geographically. The eastern "Slate-colored" race is uniform dark gray or brownish gray depending on whether it is male or female. The western "Oregon" race has black (male) or gray (female) hood and brown back. The western "Pink-sided" race has a gray head and pinkish sides. The "Gray-headed" race of the southern Rockies and Southwest is light gray with a reddish-brown back. The "White-winged" race of north-central states has white on the tail and usually white wing bars.
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March 27th, 2016
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