Original description: Junco hyemalis cismontanus Dwight 1918
Taxonomic history in AOU/AOS Check-list
AOU 4 (1931):Slate-colored Junco, Junco hyemalis hyemalis or Junco hyemalis connectens
AOU 5 (1957): Slate-colored Junco, Junco hyemalis cismontanus
AOU 6 (1983): Dark-eyed Junco, Junco hyemalis [Slate-colored group]
AOU 7 (1998): Dark-eyed Junco, Junco hyemalis [Slate-colored group]
IUCN Conservation Status: Of least concern
Cassiar Juncos are described as common to very common in their British Columbia breeding range.
Behavior:Like Oregon and other juncos, Cassiar Juncos are fairly tame as they feed on open ground near thickets and brush, tolerating close approach by quiet human watchers and flushing only when startled. They eagerly visit bird feeders for seeds and suet, offering opportunities for extended observation and photography.
Voice:Cassiar Juncos are indistinguishable in their vocalizations from either the Oregon or the Slate-colored Junco.
Detailed description and measurements drawn from standard reference works
Adult female: Central tail feathers slaty with faintly paler edges. Outermost pair of tail feathers, rectrix 6, completely or nearly completely white on both webs; rectrix 5 mostly white, rectrix 4 mostly or entirely slaty. Upper tail coverts and rump plain medium to rather pale slaty gray. Back variable, from dull tan to dull buffy gray. Primaries and secondaries slaty with narrow paler gray edges. Tertials broadly edged dull tan to dull buffy. Greater and median coverts gray, rarely with white tips forming jagged wing bars. Nape plain medium slaty gray, in nearly all bordering the browner back along a definite straight line.
Under tail coverts, vent, center of belly, and center of lower breast white. Flanks and sides of lower breast buffy gray or mixed gray and buffy, the gray predominating on the breast sides, brown on the flanks. Upper breast and throat plain medium slaty gray, often with faint brownish wash; hood often meets lower breast and breast sides in a neat, straight line.
Crown, ear coverts, supercilium, and lore concolorous plain medium slate gray, sometimes with brownish or buffy wash; when present, that wash may continue as broad lines onto the sides of the nape.
Tarsus light brown or brownish pink, toes slightly darker. Conical bill with or without small dusky tip.
Females in their first winter are browner throughout, the colors less definitely set off and more smoothly blended; except in small minority showing clear hood with convex lower edge and neat boundary between nape and back, probably indistinguishable from Slate-colored Juncos of the same age.
Adult male: Central tail feathers slaty with faintly paler edges. Outermost two pairs of tail feathers, rectrices 6 and 5, completely or nearly completely white on both webs; rectrix 4 usually mostly slaty. Upper tail coverts and rump plain medium slaty gray. Back plain medium slaty gray, usually with brownish or yellowish wash. Primaries and secondaries slaty with narrow paler gray edges. Tertials gray with narrow paler gray or pale buffy edges. Greater and median coverts gray, rarely with white tips forming jagged wing bars. Nape plain slaty gray, in nearly all bordering the paler gray or browner back along a definite straight line.