Original description: Passerella schistacea Baird 1858
Taxonomic history in AOU/AOS Check-list
AOU 1 (1886): Slate-colored Sparrow, Passerella iliaca schistacea?
AOU 2 (1895): Slate-colored Sparrow, Passerella iliaca schistacea?
AOU 3 (1910): Slate-colored Fox Sparrow, Passerella iliaca schistacea
AOU 4 (1931): Slate-colored Fox Sparrow, Passerella iliaca schistacea; Inyo Fox Sparrow, Passerella iliaca canescens
AOU 5 (1957): Fox Sparrow, Passerella iliaca schistacea, Passerella iliaca olivacea, Passerella iliaca swarthi, Passerella iliaca canescens
AOU 6 (1983): Fox Sparrow, Passerella iliaca
AOU 7 (1998): Fox Sparrow, Passerella iliaca [schistacea group, Slate-colored Fox-Sparrow]
IUCN Conservation Status: Of least concern
The most significant threat to Slate-colored Fox Sparrows is the degradation of riparian shrub habitats across the species’ range. Agricultural conversion and urbanization can damage or destroy the lush, dense vegetation required by fox sparrows; these deleterious processes are more widespread in wintering areas and along migration routes than in the higher-elevation breeding localities, though uncontrolled livestock grazing threatens breeding populations both by altering the vegetation structure of riparian habitats and directly destroying nests.
Habitat: Wintering birds prefer damp habitats, frequenting thickets along forested creeks and streams. They are not common feeder visitors for the most part, though occasional birds may settle in at even urban feeding stations for the winter.
Breeders also prefer damp, dense cover, including “impenetrable riparian thickets” of alder, birch, willow, and brambles; they also breed in in dwarf alpine conifers in British Columbia and Alberta.
Behavior:In its feeding behavior, the Slate-colored Fox Sparrow recalls a Spotted or Green-tailed Towhee, kicking and scratching vigorously in or within easy reach of dark cover. This is a shy sparrow, spending most of its time on the ground or in low vegetation along small streams, and retreating quickly when disturbed. Like other large sparrows, Slate-colored Fox Sparrows feed on the ground using noisy “double-scratching,” kicking backwards through the duff with both feet simultaneously. They also take seeds and insects from low plants. Fox sparrows are not especially social, though half a dozen or more can be found in winter sharing a single stretch of wet thicket.
Fox sparrows are relatively powerful fliers, at least over short distances, when they fly low over the ground and disappear quickly into the brush. The wing beats of fleeing birds are strong and fast, and the broad tail is not pumped, as in the Song Sparrows, but twitched from side to side.
Migrants sing from low to medium-height perches in thickets and fairly open forest. Territorial males sing from perches near the top of tall vegetation, usually concealed within foliage and branches.
Voice: Disturbed in their thickety fastness, birds often give a square, harsh, anxious-sounding tchak, louder and lower-pitched than the tek note of a Lincoln Sparrow or junco and lower-pitched and less metallic than tchink of the Thick-billed Fox Sparrow. A prolonged, faintly trilled seeb note, with slow attack and decay, is given from a perch or in flight.
The loud, melodious song of the Slate-colored Fox Sparrow is given both in migration and on the breeding grounds; it can be heard, too, on bright, warm winter days when most other birds are silent. After an introduction of two or three short, well-separated notes, the two or three phrases can be thought of as comprising triplet groups with the emphasis on the second note. Some notes are buzzy, others more sweetly slurred. Individuals may sing several different song types, switching regularly from one to the other.
Detailed description and measurements drawn from standard reference works
Adult Passerella schistacea schistacea: Tail feathers and upper tail coverts bright brown. Rump, back, scapulars, and nape unstreaked medium gray. Primaries brown with paler brown edges; secondaries and tertials rusty brown with paler edges. Greater and median coverts rusty brown with dull whitish tips very indistinct or entirely absent.
Under tail coverts gray brown with conspicuous pale buffy tips and edges. Vent, belly, breast, and throat white with blackish spots and chevrons, heaviest on upper breast, where they form an extensive ill-defined smudge. Flanks with discrete blackish spots and streaks. Throat white with heavy blackish flecking; separated from speckled white jaw stripe by short, poorly defined lateral throat stripe. Ear coverts medium gray, faintly streaked whitish and faintly outlined by blackish whisker below and blackish eye line above.
Crown medium gray with variable rusty brown tinge. Very fine white eye ring, broken behind by faint blackish eye line. Lore and irregularly shaped spot above lore whitish gray.
Tarsus and toes dull pink. Rather small, thick-based, sharp-pointed bill yellow below and on edges of upper mandible; remainder of upper mandible dark gray.
Juvenile Passerella schistacea schistacea: Gray upperparts more noticeably brown-tinged. Greater and median coverts with indistinct pale rusty tips.
Underparts dull white, dark markings less clearly wedge-shaped.
Length 153-182 mm (6.0-7.2 inches)
Wing chord 77-87 mm (3.0-3.4 inches)
Tail 73-88 mm (2.9-3.5 inches)
Mass 31 g