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 ( Swarth 1913 ), Grinnell and Swarth ( Grinnell and Swarth 1926a ), and Sibley ( Sibley 1950 ), and more recently by DaCosta et al. (2009). 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, the 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 20th century ( American Ornithologists' 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 two-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 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 ( Sibley 1950 , Sibley 1954 ), Sibley and West ( Sibley and West 1958 ), and Sibley and Sibley ( Sibley and Sibley 1964 ). In their study of a marked population in Mexico, Murray and Hardy ( 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 a 3-year demographic study in Oregon (see Bartos Smith 2008), as well as older studies by Baumann ( Baumann 1959 ) and Davis ( Davis 1960b ). Information on foraging and vocal behaviors comes from investigations by Davis ( Davis 1958a ), Borror ( Borror 1975 ), Roberts ( Roberts 1969 ), and Kroodsma ( Kroodsma 1971 ) in California and Oregon. Much work remains to be done on many aspects of Spotted Towhee biology, particularly in populations in the interior west and southwest.