Original description: Junco dorsalis Henry 1858
Taxonomic history in AOU/AOS Check-list
AOU 1 (1886): Red-backed Junco, Junco cinereus dorsalis
AOU 2 (1895): Red-backed Junco, Junco phaeonotus dorsalis
AOU 3 (1910): Red-backed Junco, Junco phaeonotus dorsalis
AOU 4 (1931): Red-backed Junco, Junco phaeonotus dorsalis
AOU 5 (1957): Gray-headed Junco, Junco caniceps dorsalis
AOU 6 (1983): Dark-eyed Junco, Junco hyemalis [caniceps group]
AOU 7 (1998): Dark-eyed Junco, Junco hyemalis [caniceps group]
IUCN Conservation Status: Of least concern
“An ecologically successful generalist,” this and most other races of the Dark-eyed Junco appear to be resilient in the face of most conservation challenges. The Red-backed Junco, as a ground-nesting resident of relatively dry ponderosa pine forest, may be more immediately susceptible to the negative effects of forest fire than some other populations, but even so it is unlikely to be severely affected on any but the most local of scales.
Behavior: Less unnervingly bold than the Yellow-eyed Junco, the Red-backed Junco is nevertheless fairly trusting and tame, always aware of human intrusion but fleeing only when approached carelessly or otherwise startled.
Red-backed Juncos feed on the ground among leaves and fallen pine needles, hopping and scratching for seeds and insects. They also ascend into trees to eat buds and insects.
Social at all seasons, these and other juncos are nonetheless fractious within flocks, charging one another on the ground and punctuating disputes with aggressive dew-dew-dew calls. In mixed winter flocks in Arizona, birds of this subspecies tend to dominate individuals of other, smaller races.
Like other members of the genus, Red-backed Juncos are rarely seen in long-sustained flight. When flushing into cover, they flash the white outer tail feathers on take-off and on landing, presumably increasing their chances of startling a potential predator into hesitation. The flushing call is a very distinctive series of rapid sharp notes, diminishing in length.
Males sing their territorial songs from perches in trees, usually on bare branches beneath the canopy.
Voice: The calls of the Red-backed Junco include ticking notes and high, slender lisps, similar or identical to the corresponding vocalizations of other Dark-eyed Junco subspecies. The most frequently heard calls from perched birds include a loud descending tu, with an abrupt attack and lingering decay; and a “square,” dry tek sometimes repeated three or four times; and a medium-length, rather low-pitched, slightly buzzy dsee. Startled birds take flight with a panicked series of tinkling tsit-tsit-tsit notes.
While the calls are unexceptional, this subspecies’ song is unlike that of more northern races of the Dark-eyed Junco, in its length and complexity sometimes even recalling the trilling and warbling performance of the Yellow-eyed Junco. The song is usually composed of two phrases, one a slow series of musical whistles, slurred up or down, and the other a faster trill; either phrase can begin the song. Some birds instead sing two canary-like trills, one slower and lower-pitched than the other, the cheerful tone and rapid transition between phrases bringing to mind a truncated goldfinch song.
Detailed description and measurements drawn from standard reference works
Adult: Tail feathers blackish. Outermost, rectrix 6, entirely white or nearly entirely white on both webs. Rectrix 5 mixed black and white on both webs in most birds, entirely white in some; rarely entirely black on outer web. Rectrix 4 entirely black or mixed black and white on outer web, mixed black and white on inner web. Upper tail coverts and rump gray. Back bright cinnamon rust. Scapulars gray in most individuals, but bright buffy or, less frequently, cinnamon rust in some. Primaries and secondaries dusky with pale gray edges. Tertials dusky gray with pale gray edges in most individuals, but outer webs broadly buffy to cinnamon rust in about a quarter of individuals. Greater and median coverts gray, the innermost with dusky shaft streaks; rarely with small buffy tips, and the greater coverts with cinnamon rust outer webs in about a quarter of individuals. Nape unstreaked pale gray.
Under tail coverts pale gray. Vent and center of belly whitish, shading into unmarked pale gray flanks and lower breast. Flank may show very slight faint buffy wash, especially towards rear. Upper breast and, especially, throat whitish gray. No lateral throat stripe; whitish gray of throat extends onto jaw stripe area and shades into pale gray of nape and ear coverts.
Crown same pale gray as nape and ear coverts, rarely with reddish rusty streaks and spots. Lores and area of supercilium from eye to bill satiny black; black continues narrowly above and below eye, just reaching back of eye, and narrowly across base of upper and lower mandibles.
Eye dark brown. Tarsus flesh-colored to grayish pink, toes darker brownish gray. Bill long, heavy, and sharply pointed. Lower mandible dull flesh-colored, slightly paler than tarsus, with tip dull flesh-colored to grayish. Upper mandible dull flesh-colored on edges, blackish elsewhere, occasionally with small whitish spot at base of bill at forehead.
Juvenile: Tail feathers blackish, averaging less white on outer three pairs than in adult. Upper tail coverts and rump dull pale gray with scattered fine blackish streaks. Back rusty brown with blackish streaking. Scapulars gray-brown to dull rust with blackish streaking. Primaries and secondaries dusky with pale gray edges. Tertials brown gray with broad buffy to brown edges on outer webs. Greater and median coverts grayish brown, the innermost with dusky shaft streaks; often with small buffy tips, and the greater coverts often brighter brown. Nape pale dull gray with blackish streaks.
Underparts pale gray with vague buffy wash on flanks and lower breast, dusky streaking heaviest across breast. Upper breast and throat paler whitish gray with dark streaking usually sparser. Lateral throat stripe narrow and poorly defined or absent. Whitish gray of throat extends onto jaw stripe area and shades into pale gray of nape and ear coverts, which are vaguely streaked dusky.
Crown same pale gray as nape and ear coverts, with dusky streaks. Lores and area of supercilium from eye to bill dull black; black continues diffusely above and below eye, just reaching back of eye, and across base of upper and lower mandibles.
Eye dark brown. Tarsus flesh-colored to grayish pink, toes darker brownish gray. Bill long, heavy, and sharply pointed. Lower mandible dull grayish pink, slightly paler than tarsus, with tip dull pink to gray. Upper mandible dull grayish pink on edges, blackish elsewhere, occasionally with small pinkish or whitish spot at base of bill at forehead.
Length 139-164 mm (5.5-6.5 inches)
Wing chord 76-87 mm (3.0-3.4 inches)
Tail 68-77 mm (2.7-3.0 inches)
Mass 22 g