The genus Parus includes numerous species and has a widespread Holarctic distribution. Parids are the subjects of many ethological and ecological studies, so knowledge of the Mexican Chickadee facilitates comparative studies. Few natural history data, however, are available for the Mexican Chickadee, and more information is needed on all aspects of its biology.
The distribution of the Mexican Chickadee in the U.S. is restricted to the higher elevations of two mountain ranges (one in Arizona, the other in New Mexico), although the species is broadly distributed in the mountains of Mexico. An insectivore, it prefers montane coniferous forests, except in the southern part of its range in Mexico where it also occurs in oak-pine. It often flocks in the nonbreeding season with other bark and foliage gleaners such as titmice, nuthatches, kinglets, warblers, and vireos. Like other parids, it nests in tree cavities, but will also use nest boxes. Much of its breeding biology remains to be studied.
This chickadee shows interesting differences in its vocalizations and behavior from other North American gray-backed chickadees. Further studies might elucidate reasons for these differences, and additional genetic analysis would help to clarify its phylogenetic relationships to other chickadees.
The small number of breeding birds in the U.S. leads to concern about its long-term persistence here, given the genetic vulnerability of small isolated populations.