The Juniper Titmouse is an uncommon resident in dry oak–juniper (Quercus–Juniperus) and pinyon–juniper (Pinus–Juniperus) woodlands in the southwestern United States and extreme northern Mexico. Until fairly recently, the Juniper Titmouse and the Oak Titmouse were regarded as a single species in the genus Parus, the Plain Titmouse (Parus inornatus). A comprehensive analysis of geographic variation in the species complex ( Cicero 1996 ), along with genetic evidence of relationships within the family ( Sheldon et al. 1992 , Slikas et al. 1996 ), led to their reclassification as sibling species in the genus Baeolophus ( American Ornithologists' Union 1997 ). Although very similar in appearance, the two species are distinguished by a suite of morphologic, colorimetric, genetic, vocal, and ecologic traits ( Cicero 1996 ).
Unlike the Oak Titmouse, the Juniper Titmouse is a surprisingly poorly known species, and there is little published information on foraging ecology, territoriality, juvenile dispersal, breeding biology, and demography. The species appears to be largely sedentary, with pairs defending territories year-round. Unlike many other parid species, but similar to the Oak Titmouse, the Juniper Titmouse generally does not form winter flocks. It nests in natural and woodpecker-excavated cavities and clutches typically contain 6–7 unmarked eggs.
The diet includes both invertebrates and seeds, and the species is known to cache food. The Juniper Titmouse is highly vocal, and individuals are most commonly recognized by their raspy calls which males and females utter throughout the year. Males may sing occasionally during the nonbreeding season, with singing intensity increasing toward spring. Vocalizations are directed primarily toward intraspecific defense of territories.