Rusty-crowned Ground-Sparrow

The rusty-crowned ground sparrow is 15 to 18 cm (5.9 to 7.1 in) long and weighs 35 to 41 g (1.2 to 1.4 oz). The sexes have the same plumage. Adults have a dusky black forecrown and a rufous crown; the rufous continues around behind the dusky black ear coverts and then forward under them. They have white lores and a broken white eye-ring. Their upperparts, wings, and tail are brown. Their underparts are mostly white with a black spot in the center of the breast, brown flanks, and rufescent undertail coverts. Juveniles have a rich dusky brown head and upperparts with darker streaks on the latter. Their throat and underparts are dirty pale lemon with dusky brown streaks and their undertail coverts are pale cinnamon. Subspecies M. k. grisior is cinnamon rufous or tawny on the head where the nominate is rufous. Their upperparts, wings, tail, and flanks are deep grayish olive and their undertail coverts are cinnamon or cinnamon buff. M. k. rubricata has a brighter rufous crown and paler brown upperparts than the nominate. Both sexes of all subspecies have a dark brown iris, a black or blackish bill, and brownish or pinkish legs and feet.

The rusty-crowned ground sparrow is found in western Mexico's Sierra Madre Occidental, Sierra Madre del Sur, and Cordillera Neovolcanica. Subspecies M. k. grisior is the northernmost. It is found in extreme southeastern Sonora and northern Sinaloa. The nominate is found from central Sinaloa south to Colima. M. k. rubricata is found from Guanajuato and Michoacán east to Puebla and western Oaxaca. The species inhabits a variety of arid to semi-humid landscapes in the upper tropical and subtropical zones including thorn forest, dry brushy woodlands, arid scrublands, and secondary forest. Sources differ on its elevational range. A twentieth century publication states it is from sea level to 1,500 m (4,900 ft). Two more recent sources state it as sea level to 2,000 m (6,600 ft).

The rusty-crowned ground sparrow's diet has not been studied but is assumed to include seeds and arthropods. It forages on the ground and in low vegetation, traveling by hopping. It usually is seen singly or in pairs.