The spotted and eastern towhees (formerly combined as the rufous-sided towhee) have a narrow hybrid zone in the central Great Plains. In general, a female spotted differs less from a male than in the eastern. Length 7.5".
Male: plumage like eastern towhee’s, except for white tips on median, greater coverts forming 2 white wing bars, variable white spotting on back and scapulars, lack of rectangular white patch at primary bases. Female: similar to male spotted, but with a slate-gray hood (variable by ssp.). Juvenile: like juvenile eastern, but lacks white primary patch.
Nine subspecies show weak to moderate variation. “Interior” birds have extensive white spotting above, prominent white tail corners; “Pacific” birds dark overall with white back spotting, reduced tail corners (variable). Oregonus is darkest; white increases southward to megalonyx. Within the “Interior” group, arcticus shows the most white spotting and most extensive white corners to the tail; other subspecies have less white, but are similar to one another. Females’ head color varies as well.
Distinguished from the eastern by white spotting on back, white wing bars, lack of patch at bases of primaries, and call. Hybrids occur in the Great Plains and winter to the south; often combine characteristics of both parents.
Song and calls also show great geographical variation. Call: a descending and raspy mewing in montanus; an upslurred, questioning queee in arcticus and coastal subspecies. All subspecies also give a high, thin lisping szeeueet that drops in middle (poss. flight note), like the eastern’s call, and various chips when agitated. Song: “interior” group gives introductory notes, then a trill. “Pacific” birds sing a simple trill of variable speed.
Status and Distribution
Common. Some populations are largely resident; others are migratory. The most migratory subspecies is arcticus. Resident south to Guatemala. Subspecies are oregonus (Oregon to British Columbia), falcifer (coastal northwest California), megalonyx (coastal central to southern California), clementae (certain Channel Islands); arcticus (Great Plains), montanus (Rocky Mountains), falcinellus (south-central California to Oregon), curtatus (primarily in Sierra Nevada), and gaigei (resident in mountains of southeastern New Mexico and western Texas). Migration: fall primarily September–October; spring March–early May; earlier in Pacific states than interior. Vagrant: subspecies arcticus is casual to East.
Stable in most areas. Clementae extirpated from San Clemente Island, one of California’s Channel Islands, due to overgrazing by introduced goats; persists on Santa Catalina and Santa Rosa Islands. Another island subspecies from Guadalupe Island, off Baja California, is extinct.
—From the National Geographic book Complete Birds of North America, 2006