Bushtit Psaltriparus minimus Scientific name definitions

The only New World representative of the family of long-tailed tits (Aegithalidae), the Bushtit is a very small, drab-gray bird with a long tail and a social nature. Throughout its range, which is primarily limited to the western parts of North America and the highlands of Central America, it is a common resident year-round, and often observed in flocks of 3 to more than 40 conspecifics or in mixed-species flocks. It prefers oak (Quercus spp.)-pine (Pinus spp.) forests in the mountains and shrub vegetation in the coastal region of its range and forages by gleaning insects from foliage, often upside down in the manner of chickadees (Poecile spp.).

Appearance is variable, with some individuals possessing black ear coverts. For many years, the black-eared and the plain-eared forms of the Bushtit were separated into 2 distinct species (Psaltriparus melanotis and P. minimus, respectively). However, it is now clear that the amount of black in the face is a polymorphism, the frequency of which varies geographically. In general, it occurs commonly in the extreme southern populations, is absent in the north, and is more common in males than in females (Raitt 1967 Raitt, R. J. (1967). Relationships between black-eared and plain-eared forms of Bushtits (Psaltriparus). Auk 84:503-528. Close ).

One of the first birds ever described as having “helpers at the nest” (Guatemala; Skutch 1935 Skutch, A. F. (1935). Helpers at the nest. Auk 52:257-273. Close ), the Bushtit varies considerably in this behavior, geographically and from year to year. In coastal areas of California, nest supernumeraries, individuals above and beyond the primary breeding pair, are rare (Addicott 1938 Addicott, A. B. (1938). Behavior of the Bush-tit in the breeding season. Condor 40:49-63. Close , Ervin 1974 Ervin, S. (1974). Flock integrity, pair maintenance, and the occurrence of supernumerary birds in the Bushtit Psaltriparus minimus. Phd Thesis, Univ. of California at Santa Barbara, Santa Barbara, CA. Close ). However, in the Chiricahua Mountains of southeastern Arizona, an average of 37% of nests have supernumeraries (Sloane Sloane 1992 Sloane, S. A. (1992). Supernumeraries at Bushtit (Psaltriparus minimus) nests: incidence, origins, and proximate causes. Phd Thesis, Univ. of Michigan, Ann Arbor. Close , Sloane 1996 Sloane, S. A. (1996). Incidence and origins of supernumeraries at Bushtit (Psaltriparus minimus) nests. Auk 113:757-770. Close ). These extra individuals can be male or female, juvenile or adult. The majority are adult males that either are unmated or have lost a nest. Some of these individuals may be contributing genetically to the nest, making Bushtits potentially polygynous, polyandrous, or polygynandrous in most years (Sloane Sloane 1992 Sloane, S. A. (1992). Supernumeraries at Bushtit (Psaltriparus minimus) nests: incidence, origins, and proximate causes. Phd Thesis, Univ. of Michigan, Ann Arbor. Close , Sloane 1996 Sloane, S. A. (1996). Incidence and origins of supernumeraries at Bushtit (Psaltriparus minimus) nests. Auk 113:757-770. Close ; but see Bruce et al. 1996 Bruce, J. P., J. S. Quinn, S. A. Sloane and B. N. White. (1996). DNA fingerprinting reveals monogamy in the Bushtit: a cooperatively breeding species. Auk 113:511-516. Close ). The key to this unusual social system may lie in Bushtit physiology and the behavioral mechanisms, such as huddling and the building of heavily insulated nests, that they use to cope with cold (Sloane Sloane 1992 Sloane, S. A. (1992). Supernumeraries at Bushtit (Psaltriparus minimus) nests: incidence, origins, and proximate causes. Phd Thesis, Univ. of Michigan, Ann Arbor. Close , Sloane 1996 Sloane, S. A. (1996). Incidence and origins of supernumeraries at Bushtit (Psaltriparus minimus) nests. Auk 113:757-770. Close ).