Introduction

The California Towhee is a large, plainly marked ground-sparrow showing no sexual color dimorphism. Demonstrating wide geographic and ecological breadth, this sedentary inhabitant of low vegetation forages mostly on the ground and occurs widely from semiarid upland to moist riparian habitats. It is a permanent resident from southern Oregon south throughout most of the Upper and Lower Sonoran zones of California to the tropical tip of Baja California. One of the commonest and best known of California birds, it is tolerant of rural development and urbanization.

Until recently, the California Towhee was treated conspecifically under the name Pipilo fuscus (Brown Towhee) with the allopatric Canyon Towhee (Pipilo fuscus), the latter occurring east of the Colorado River into tropical mainland Mexico. Similarities between southern races of P. crissalis and P. fuscus that were used in the rationale for combining the 2 species may be at least partially the result of parallel evolution in arid regions rather than a reflection of recent common ancestry.

The California Towhee is a characteristic bird of chaparral and underbrush in oak woodland, generally occurring in wetter habitats than the Canyon Towhee, which is largely a desert-scrub and semidesert grass-land species. The California Towhee occupies rugged, remote back-country habitats like the Canyon Towhee but also commonly occurs in shrubby vegetation of densely populated urban and suburban areas, habitats shunned by the Canyon Towhee. The Inyo California Towhee (Pipilo c. eremophilus), with an endemic population of probably fewer than 200 individuals, occurs in riparian habitat of the arid Argus Mountains of central-eastern California. It has been classified as Threatened and critical habitat has been designated by the U.S. Fish and Wildlife Service (1987).

In several ways, the California Towhee also resembles the closely related Abert’s Towhee (P. aberti): in appearance, in its relatively nonmelodious songs, and in its use of metropolitan area habitat. California Towhee is geographically and ecologically much more widely distributed than Abert’s Towhee, which occurs in more mesic southwestern riparian habitats. These towhees and the closely related White-throated Towhee (P. albicollis) of Mexico, collectively known as “brown towhees,” provide a much-studied model for avian speciation; see Systematics, below. This was pointed out by Davis (1951), and more recently, studies have added new evidence to the century-old conflict regarding the relationship of California Towhee to Canyon Towhee and other species of Pipilo (see Zink 1988, Zink and Dittmann 1991, Dodge et al. 1995).

Few studies have focused on the California Towhee, but, because the species is so widely distributed, it has been included incidentally in a large number of studies. Most published studies have been conducted in the vicinity of Berkeley, Carmel Valley, and Los Angeles, California. The most extensive work, touching on most known aspects of the species, is found in Davis’ (1951) thorough monograph. Vocalizations have been studied most intensively by Quaintance (1938, 1941) and Marshall (1964), who also provided comparative information for brown towhees (Marshall 1960, 1964). Childs (1968f) reported breeding and other life-history information from one of the few studies using banded individuals. The only known food analysis was during the early 1900s (Beal 1910), referenced by Davis (1951).