Original description: Embernagra rufivirgata Lawrence 1851
Taxonomic history in AOU/AOS Check-list
AOU 1 (1886): Texas Sparrow, Embernagra rufivirgata
AOU 2 (1895): Texas Sparrow, Embernagra rufivirgata
AOU 3 (1910): Texas Sparrow, Arremonops rufivirgatus
AOU 4 (1931): Texas Sparrow, Arremonops rufivirgatus rufivirgatus
AOU 5 (1957): Olive Sparrow, Arremonops rufivirgata rufivirgata
AOU 6 (1983): Olive Sparrow, Arremonops rufivirgatus [superciliosus group, rufivirgatus group]
AOU 7 (1998): Olive Sparrow, Arremonops rufivirgatus [superciliosus group, rufivirgatus group]
IUCN Conservation Status: Of least concern
Behavior: Markedly shy, Olive Sparrows are far more often heard than seen, spending their entire lives in dark thickets impenetrable by humans and other potential predators. Almost all foraging takes place on the ground, where birds turn aside leaves with their bills and engage in active double-scratching, kicking both feet back simultaneously in the search for insects and small seeds.
Even singing birds perch out of sight on low branches and twigs, concealed by dense foliage; song perches are typically six to 15 feet above the ground, but occasionally as high as 30 feet.
Olive Sparrows fly only infrequently, preferring to move on the ground in cover. When they do fly, they are rarely seen more than a foot or two above the ground, and usually land just a few feet from where they began. The flight is weak and fluttering, with occasional twitches of the long, dull greenish tail.
Voice: The calls of the Olive Sparrow include dry, nervous tit-tt-tit notes and a long, rather towhee-like bzee. The monotonous song, soon familiar to even the most casual observer in areas where this species is common, is a series of faintly downslurred tdip notes, gradually accelerating into a slow, loose tremolo; some songs are vaguely cardinal-like in their sweet tone, while others are dryer and more staccato in articulation.
Detailed description and measurements drawn from standard reference works
Adult Arremonops rufivirgatus rufivirgatus: Tail feathers greenish olive. Upper tail coverts, rump, back, and scapulars dull olive. Primaries and secondaries greenish brown, the primaries with narrow pale whitish to faintly yellowish edges on outer web. Tertials greenish brown. Greater and median coverts greenish brown, greener on outer webs; lesser coverts brown at base, broadly edged and tipped greenish brown. Marginal coverts of under wing yellow. Nape grayish olive, grayest at center.
Under tail coverts and vent dull buffy whitish. Center of belly white; flanks and breast pale buffy. Throat whitish, sometimes with very fine, short dark lateral throat stripe. Area of jaw stripe whitish or buffy white.
Crown with dull gray median stripe, dull chestnut or brown lateral stripes. Ear coverts dull gray, bordered above by narrow brown eye line, which breaks narrow whitish eye ring before and behind eye. Lore buffy whitish.
Tarsus and toes dull pink. Bill dull brown above, dull yellowish or pinkish at base of lower mandible.
Juvenile Arremonops rufivirgatus rufivirgatus: Tail feathers brown with buffy olive edges. Upper tail coverts, rump, back, and scapulars grayish olive; back with brown or gray-brown spots and streaks. Primaries and secondaries brown, the primaries with buffy or yellowish edges on outer web. Tertials buffy brown. Greater and median coverts buffy brown with dull rust or olive-brown tips, forming ragged, sometimes obscure wing bars. Marginal coverts of under wing dull buffy. Nape grayish olive.
Under tail coverts deep buffy, vent and belly buffy olive. Flanks and breast tinged dull brown, with sparse darker brown spots or streaks. Throat pale olive buff.
Crown olive gray with variable short, fine brown spots and streaks. Ear coverts grayish olive, lore darker brownish or grayish.
Tarsus and toes light brownish pink. Bill brown above, yellowish at base of lower mandible.
Length 140-152 mm (5.5-6.0 inches)
Wing 59-67 mm (2.3-2.6 inches)
Tail 57-70 mm (2.2-2.8 inches)
W:T 1.02
Mass 21-23 g
