About Baeolophus wollweberi (Bonaparte, 1850)
Bridled titmouse (Baeolophus wollweberi, originally described by Bonaparte in 1850) measures approximately 10 cm (3.9 in) in length and weighs about 10 g (0.35 oz). It is a small bird with a prominent crest, and males and females share identical plumage patterns. For the nominate subspecies B. w. wollweberi, adults have a black crown and crest with a large deep gray central patch. They have a black line running through the eye, which continues as an arc behind the ear coverts against an otherwise all-white face. The sides of the neck are white, while the chin and throat are black, connecting just to the base of the black facial arc. Upperparts, wings, and tail are deep olive gray, with a thin black line separating the hindneck from the upper back; the olive gray color shifts to a more olive tone towards the rear of the body. The breast is pale olive gray, fading to pale olive buffy on the belly and undertail coverts. Nominate adults have dark brown irises, black bills, and bluish gray legs and feet. Juveniles differ from adults by having a grayish throat and a paler iris. Four subspecies are recognized, with distinct plumage differences from the nominate: B. w. vandevenderi has a grayish green rump, a broad smoke gray wash across the breast and flanks, and a whiter belly than the nominate; B. w. phillipsi has a greenish yellow rump, a paler breast with less gray than B. w. vandevenderi, and a yellow wash on the belly; B. w. caliginosus is darker overall, has more olive-toned upperparts than the nominate, and wider black facial stripes than the nominate. This species has a disjunct distribution, with the southernmost subspecies B. w. caliginosus having a range that is not connected to the ranges of the other three subspecies. Each subspecies has a specific geographic range: B. w. vandevenderi is found in the mountains of central Arizona north of the Gila River, extending south and southeast along the Mogollon Rim into southwestern New Mexico; B. w. phillipsi inhabits the mountains of southeastern Arizona south of the Gila River, ranging south into western Chihuahua and southern Sonora in northern Mexico; B. w. wollweberi occurs across western Mexico from Sinaloa and western Durango south to Jalisco and Michoacán, across central Mexico from Colima and southern Jalisco east to Puebla and western Veracruz, and across eastern Mexico from central Nuevo León and western Tamaulipas south to west-central Veracruz; B. w. caliginosus is restricted to the Sierra Madre del Sur of southwestern Mexico, in the states of Guerrero and Oaxaca. The species has also been recorded as a vagrant in southwestern Arizona. In the United States, the bridled titmouse primarily lives in oak and oak-pine-juniper woodlands, and also occurs in riparian woods. In Mexico, it inhabits oak and pine-oak woodlands, and also uses oak savanna habitat in the southern part of its Mexican range. Its overall elevational range is generally 1,200 to 2,700 m (3,900 to 8,900 ft); in southeastern Arizona it typically occurs between 1,600 to 2,200 m (5,200 to 7,200 ft), and in southern Mexico it can be found as low as 300 m (1,000 ft).
