Original description: Xenospiza baileyi Bangs 1931
Taxonomic history in AOU/AOSCheck-list
AOU 6 (1983): Sierra Madre Sparrow, Xenospiza baileyi
AOU 7 (1998): Sierra Madre Sparrow, Xenospiza baileyi
IUCN Conservation Status: Endangered
Habitat: Sierra Madre Sparrows occur at elevations from about 7500 to 10,000 feet. Bailey and Conover collected their 1931 specimen “in the dried grass of a little marsh”; it has been suggested that the birds had moved into the marsh because the grass in nearby drier habitats was too short. The habitat currently occupied by this species is bunchgrass meadows surrounded by scattered pine forest; the dominant grasses include Festuca, Muhlenbergia, and Stipa. The sparrows are not found in forest or on heavily grazed grasslands, though they do feed at times in grain fields. Nests are placed close to the ground in bunchgrass clumps, a situation that apparently provides protection from predators and from strong winds.
Behavior: The notoriously secretive nature of this sparrow over much of the year has left many of its habits unknown. Sierra Madre Sparrows forage for seeds and invertebrates on or near the ground at the base of tall clumps of grass or, sometimes, on the edges of grain fields; startled, they may flush, or run mouse-like along the ground beneath the vegetation. Sierra Madre Sparrows are said to be not especially social, most often seen as single individuals or pairs, but the scarcity of suitable habitat necessarily makes their territories small.
Voice: Males sing from conspicuous perches, including rocks, tall grass stems, and even telephone wires; they are also known to sing in flight. The song is a loud series of sharp chips, slurs, and buzzes, their sequence variable. One type, comprising an introduction of repeated chips, a higher-pitched buzzy trill, and a short slurred warble, is reminiscent of a Song Sparrow; other songs intersperse the three note types in a way that sounds almost conversational. The trill given by some birds resembles the conclusion of a Savannah Sparrow’s song. A bright, slightly nasal, upslurred chewip, recalling the contact calls of some Empidonax flycatchers, appears to be distinctive.
Detailed description and measurements drawn from standard reference works
Adult: Tail feathers dark brown with gray-brown edges. Upper tail coverts with large whitish edges and tips. Back deep rust, the feathers with broad black shaft streaks and, especially in fresh plumage, conspicuous scalloping created by buff-white edges and tips; scapulars rufous. Primaries dark brown with gray edges. Secondaries unusually broad, dark brown with rufous edges. Tertials black with broad brown edging. Greater coverts edged rusty, with large black teardrops and, in fresh plumage, narrow white tips forming a very thin wing bar. Median coverts blackish with rufous edges and very narrow white tips. Nape pale brown-gray with fine black streaking. Underparts whitish with subtle buffy wash on breast band, flanks, and under tail coverts. Crisp black streaking on breast and flanks, often coalescing into a central breast spot. Throat bordered by strong, slightly wedge-shaped black lateral throat stripe. Long jaw stripe white. Blackish crown with gray median crown stripe. Long, broad supercilium gray, whiter above the lore. Lore, well-defined eye line, and whisker black; ear coverts grayish. Bill dusky blue-gray at base, darker towards tip. Tarsi and toes dull brownish pink. Plumage patterns less contrasting in worn plumage.
Juvenile: Duller and less neatly and regularly marked below than the adult. Strongly scalloped above, the back feathers with broad black shaft streaks and olive-brown to buff edgings. Nape somewhat grayer. Tertials edged with deep yellowish brown. Underparts warm buff throughout in fresh birds, soon fading to cream; most richly colored on flanks and under tail coverts. Breast markings dark brown. Supercilium deep buff, yellowish in front of eye. Crown striping diffuse. Bill dull gray, lower mandible with paler base.
Length 140-152 mm (5.5-6 inches)
Wing Chord 60-64 mm (2.4-2.5 inches)
Tail 52-56 mm (2.0-2.2 inches)
W:T 1.14
Mass 17-18 g
