Mountain Chickadees reach the extreme southeast corner of their range in the Davis and Guadalupe mountains of Trans-Pecos Texas. These “mountain islands” are topped by vegetation which covered a much wider area at the end of the last ice age 15,0000 years ago (Gehlbach 1981).
Mountain Chickadee is a close relative of the better-known and studied Black-capped Chickadee (P. atricapillus) and these two species share many elements of their life histories. The primary differences are range and habitat. Mountain Chickadee can be distinguished visually from Black-capped and all other North American chickadees by the white line through the side of its black cap (McCallum et al. 1999).
DISTRIBUTION. During the 1987-1992 field work for the TBBA project, atlasers found confirmed breeding evidence for Mountain Chickadee in the Davis and Guadalupe mountains of Trans-Pecos Texas where Lockwood and Freeman (2004) describe this species as residents at the higher elevations.
Outside Texas this species is resident from northern British Columbia south through the Rockies, Cascades, and Sierras to southern Arizona and southern New Mexico as well as in the higher mountains in southern California and northern Baja California, Mexico (McCallum et al. 1999).
SEASONAL OCCURRENCE. Some Mountain Chickadees move to lower elevations within the Davis and Guadalupe mountains in winter and even to desert scrub around the Guadalupes (Lockwood and Freeman 2004). The species probably breeds in this state from late April to late July (Oberholser 1974). Atlasers in Colorado where many Mountain Chickadees breed, found confirmed evidence from May 2 to August 24 (Kingery 1998). Almost all breeding evidence in Arizona was obtained between May 15 and August 1 (Sitko 2005).
BREEDING HABITAT. In Texas Mountain Chickadee breeds from about 2000 to 2500 m (7000-8500 ft) in healthy coniferous forests (Oberholser 1974). In Colorado where nesting habitats have been quantified, about 75% of breeding was in conifers, 20% among deciduous trees and 5% in shrublands (Kingery 1998). In Arizona 66% or confirmed breeding evidence was found in ponderosa pine habitats, often mixed with Gambel’s oak, Douglas fir or aspen and 25% were in pinyon-juniper (Sitko 2005).
Mountain Chickadees excavate cavities in the soft wood of dead stubs or uses a natural cavity or nest box and lines them with hair felted together. The female usually lays 6-7 white eggs (see Harrison  for photo of markings). The median incubation period is 14 days and young birds usually leave the nest 18-21 days after hatching. Pairs may raise 2 broods per season (Harrison 1979, McCallum et al. 1999).
STATUS. Oberholser (1974) describes Mountain Chickadee as a fairly common resident in the Guadalupe Mountains and irregular in the Davis Mountains.
The North American Breeding Bird Survey does not sample this chickadee in Texas, but data from 459 routes across its range provides a statistically significant trend of -0.8% population change per year for the period 1966-2004 (Sauer et al. 2005). This relatively minor trend suggests Mountain Chickadee should continue to be residents, at least in the Guadalupe Mountains, for the foreseeable future.
Text by Robert C. Tweit
Gehlbach, F. R. 1981. Mountain islands and desert seas. Texas A&M University Press, College Station..
Harrison, H. H. 1979. A field guide to western birds’ nests. Houghton Mifflin, Boston, MA.
Kingery, H. E. 1998. Mountain Chickadee (Poecile gambeli). In Colorado breeding bird atlas, pp. 350-351 (H. E. Kingery, ed.). Colorado Bird Atlas Partnership, Denver.
Lockwood, M. W. and B. Freeman. 2004. The TOS handbook of Texas birds. Texas A&M University Press, College Station.
McCallum, D. A., R. Grundel and D. L. Dahlsten. 1999. Mountain Chickadee (Poecile gambeli). In The birds of North America, No. 453 (A. Poole and F. Gill, eds.). The Birds of North America, Inc., Philadelphia, PA.
Oberholser, H. C. 1974. The bird life of Texas. University of Texas Press, Austin.
Sauer, J. R., J. E. Hines, and J. Fallon. 2005. The North American Breeding Bird Survey, results and analysis 1966-2004. Version 2005.1. USGS Patuxent Wildlife Research Center, Laurel MD (Web site, http://www.mbr-pwrc.usgs.gov/bbs).
Sitko, S.. 2005. Mountain Chickadee (Poecile gambeli). In Arizona breeding bird atlas.p p. 382-383 (T. E. Corman and C. Wise-Gervais, eds.),.University of New Mexico Press, Albuquerque.