Chestnut-backed Chickadee Poecile rufescens Scientific name definitions

Found in humid coastal and interior forests from southeastern Alaska to southern California, this chickadee has expanded its geographic range during the past 5 decades by colonizing forest habitats in the central Sierra Nevada and suburban areas in eastern San Francisco Bay. Although plausible explanations have been proposed, the exact reasons for this geographic expansion remain unknown.

The Chestnut-backed Chickadee is apparently most closely related to other “brown-headed chickadees” such as the Boreal Chickadee (Poecile hudsonicus) and possibly the Grey-headed Chickadee (P. cinctus). Like its closest relatives (Mexican [P. sclateri] and Boreal Chickadees), this species lacks a whistled song; unlike them, it uses the Gargle call rarely. This reduction of repertoire diversity may be somewhat balanced by a particularly robust Chick-a-dee call complex.

Chestnut-backed Chickadees exhibit interesting patterns of foraging behavior by focusing on insects that live on Douglas fir (Pseudotsuga menziesii), and other conifer trees in the humid coastal regions and portions of the interior forest of the Pacific Northwest. They also make considerable use of insects and arthropod foods from broad-leaved trees. Like most chickadees and titmice, Chestnut-backed Chickadees nest in tree cavities and readily colonize available nest boxes. During winter, they forage in mixed-species flocks with other chickadees, primarily Black-capped (P. atricapillus) and Mountain (P. gambeli) chickadees, as well as other small birds such as kinglets (Regulus spp.) and nut-hatches (Sitta spp.).

Key studies of this species have been in Washington State on breeding habits and foraging ecology (Sturman Sturman 1968a Sturman, W. A. (1968). Description and analysis of breeding habitats of the chickadees Parus atricapillus and P. rufescens. Ecology 49:418–431. Close , Sturman 1968b Sturman, W. A. (1968). The foraging ecology of Parus atricapillus and P. rufescens in the breeding season, with comparisons with other species of Parus. Condor 70:309–322. Close ), and in California on foraging and habitat use (Brennan et al. Brennan et al. 1999b Brennan, L. A., M. L. Morrison and D. L. Dahlsten (1999). Winter flocking by Chestnut-backed and Mountain Chickadees in the western Sierra Nevada. Northwestern Naturalist 80:84–89. Close , Brennan et al. 1999a Brennan, L. A., M. L. Morrison and D. L. Dahlsten (1999). Influence of vegetation on occupation of nest boxes by Chestnut-backed and Mountain Chickadees. Northwestern Naturalist 80:90–98. Close ), foraging and nestling diet (Kleintjes and Dahlsten 1994 Kleintjes, P. K. and D. L. Dahlsten (1994). Foraging behavior and nestling diet of Chestnut-backed Chickadees in Monterey Pine. Condor 96:647–653. Close ), and ecological interactions (Root 1964 Root, R. B. (1964). Ecological interactions of the Chestnut-backed Chickadee following a range extension. Condor 66:229–238. Close ). Grinnell (Grinnell 1904b Grinnell, J. (1904). The origin and distribution of the Chestnut-backed Chickadee. Auk 21:364–378. Close ) used this chickadee in his classic paper about how species evolve in relation to a narrow range of environmental conditions.