Original description: Spizella wortheni Ridgway 1884
Taxonomic history in AOU/AOS Check-list
AOU 1 (1886): Worthen’s Sparrow, Spizella wortheni
AOU 2 (1895): Worthen’s Sparrow, Spizella wortheni
AOU 3 (1910): Worthen’s Sparrow, Spizella wortheni
AOU 4 (1931): Worthen’s Sparrow, Spizella wortheni
AOU 5 (1957): Worthen’s Sparrow, Spizella wortheni wortheni
AOU 6 (1983): Worthen’s Sparrow, Spizella wortheni
AOU 7 (1998): Worthen’s Sparrow, Spizella wortheni
IUCN Conservation Status: Endangered
Behavior: This is a tame species, reacting to human disturbance as would a Chipping or Field Sparrow.
Worthen Sparrows flock in both the breeding and the non-breeding seasons. Though the largest recently recorded flocks have been observed in the non-breeding season , one careful study found no statistically significant seasonal differences in flock size. Mixed flocks are frequent, and sixteen additional species were found in association with Worthen Sparrows, including Black-throated, Lark, Vesper, Clay-colored, Chipping, and Field Sparrows and Lark Buntings.
Worthen Sparrows spend most of their foraging time on the ground, but also seek food in the foliage of low bushes. They have also been observed taking insects from the air.
Males sing from fences, posts, low bushes, and even the ground.
Voice: The clearest distinction between the Field Sparrow and the Worthen Sparrow is not visual but vocal. The song of the Worthen Sparrow
“consists of a thin, introductory seep … followed by 10 [to 17] chip notes that sound flat and harsh….”
Some males in Zacatecas, presumably browni, were found to slur the introductory note upward, others down.
The dryness of the concluding notes—more a rattle than a trill—recalls many Chipping Sparrow songs; some observers hear a similarity to juncos. The trill follows directly on the introductory seep without transition; it can be higher or lower in pitch than the introduction, and is delivered in a steady, even rhythm, without the “bouncing ball” acceleration typical of the Field Sparrow’s song.
The call is “a high, thin, fairly dry tssip or tsip, at times repeated rapidly.”
Detailed description and measurements drawn from standard reference works
Adult Spizella wortheni wortheni: Tail feathers dark blackish brown with pale gray edges. Upper tail coverts brownish gray with indistinct darker shaft streaks; rump brownish gray. Back and scapulars pale cold brown with narrow blackish streaks. Primaries and secondaries dusky brown with paler buffy brown edges. Tertials dusky with pale buffy or grayish edges. Greater coverts dusky with paler buffy grayish edges and very indistinct buffy tips, forming faint hint of a wing bar in fresh plumage; median coverts dusky with dull whitish or buffy spot at tip of outer web, forming single incomplete wing bar. Marginal coverts of under wing white. Nape gray with indistinct narrow dusky streaks.
Under tail coverts and vent white. Belly dull whitish gray; flanks and breast washed pale buffy or buffy grayish. Throat white, separated from diffuse grayish jaw stripe by very faint darker gray lateral throat stripe. Ear coverts grayish brown.
Crown brown with narrow, indistinct dusky streaking; crown averages buffier in female, more cinnamon in male. Forehead, and in some birds front of crown, gray. Grayish brown ear coverts fade into slightly paler jaw stripe; very faintly, or not at all, bordered above by short, very narrow rusty line behind eye. Lore gray. Fine white eye ring.
Tarsus and toes dark brownish black in winter or pinkish in breeding season. Small, sharp-pointed bill pink.
Juvenile Spizella wortheni wortheni: Tail feathers dark blackish brown with pale gray edges. Upper tail coverts brownish gray with indistinct darker shaft streaks; rump brownish gray. Back and scapulars pale cold brown with narrow blackish streaks. Primaries and secondaries dusky brown with paler buffy brown edges. Tertials dusky with pale buffy or grayish edges. Greater coverts dusky with paler buffy grayish edges and indistinct buffy tips, forming hint of a wing bar in fresh plumage; median coverts dusky with dull whitish or buffy spot at tip of outer web, forming single incomplete wing bar. Nape gray with indistinct narrow dusky streaks.
Under tail coverts, vent, and belly dull whitish gray; flanks and breast washed pale buffy or buffy grayish. Throat white, separated from diffuse grayish jaw stripe by very faint darker gray lateral throat stripe. Ear coverts grayish brown.
Crown dull grayish brown with narrow dusky streaking. Forehead, and in some birds front of crown, gray. Brownish ear coverts fade into slightly grayer jaw stripe; bordered above by short, narrow buffy line behind eye. Lore grayish brown. Fine pale buffy eye ring.
Length 129-139 mm (5.1-5.5 inches)
Wing 64-73 mm (2.5-2.9 inches)
Tail 56-65 mm (2.2-2.6 inches)
W:T 1.13
Mass 10-15 g
