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The Spotted Towhee is a widespread and locally familiar bird of thickets and other scrubby or seral habitats in three major physiographic regions of the West: the northern Great Plains, middle elevations of mountains and intermountain plateaus, and Pacific coastal lowlands and offshore islands. Northern interior populations are migratory, and individuals at high elevations tend to leave their breeding habitats in winter, although it is not known whether they move to valleys locally or undertake longer-distance movements.
From 1827 to 1858, three widely separated populations of this species in Mexico, Saskatchewan, and California were named and ranked as different species of Pipilo . The current systematic view of this species was established largely by Swarth (1913), Grinnell and Swarth (1926), and Sibley (1950). Geographic variation in plumage and morphology is best known in some Mexican populations. In a classic study of avian introgressive hybridization in the “red-eyed towhees” of southern Mexico, Sibley and his colleagues analyzed complex patterns of variation within and among populations that spanned the extremes of massive hybridization with a close relative (Collared Towhee [Pipilo ocai]) and of sympatric coexistence with no evidence of interbreeding. Likewise, across the northern Great Plains from Manitoba to Nebraska and extreme northwest Kansas, Spotted Towhees interbreed with Eastern Towhees (P. erythrophthalmus) along several east-west river valleys; this plains contact is simpler and more limited than those in Mexico with the Collared Towhee. Because of this evidence of hybridization in Mexico and the Great Plains, the question of species limits among red-eyed towhees has been a matter of some uncertainty and debate. Most recently, a single species concept that encompassed the “rufous-sided towhees” across the continent was replaced by a two-species view that had prevailed during much of the early twentieth century (Am. Ornithol. Union 1995).
Spotted Towhees are monogamous and territorial, with parental care roles typical of those in other emberizines. Like its eastern cousin, this towhee forages mainly on the ground and uses a 2-footed scratching maneuver to seek food under loose ground debris. Song structure in the species varies geographically from mostly simple trills in birds along the Pacific Coast to a short introductory phrase followed by a trill in mountain and plains birds from Canada to Mexico. Males in all populations studied have a small repertoire of songs that include both fast and slow trill types.
Most of the quantitative information on the Spotted Towhee comes from only a handful of studies that focused on a tiny sample of populations and population groups along the Pacific Coast and in Mexico. Most of what we now know in detail about geographic variation, distribution, and ecology in towhees south of the U.S.-Mexico border was established by Sibley (1950, 1954), Sibley and West (1958), and Sibley and Sibley (1964). In their study of a marked population in Mexico, Murray and Hardy (1981) also contributed important information on ecology, behavior, and interrelations with brush-finches (Atlapetes sp.). The core of our current knowledge on the breeding biology of this species is derived from studies by Baumann (1959) and Davis (1960), and on foraging and vocal behaviors from investigations by Davis (1958), Borror (1975), Roberts (1969), and Kroodsma (1971) in California and Oregon. The bulk of information on this towhee is in a scattered literature that often covers subjects on the species in an incidental or anecdotal fashion, or as part of a regional or faunal focus.