About the Curve-Billed Thrasher
The curve-billed thrasher—the common thrasher of the rich, cactus-laden Sonoran Desert—can be very conspicuous, sitting up on saguaro or cholla cactuses, making its presence known by its loud 2- or 3-note call, whit-wheet. It often builds its nest within a cholla cactus. Its foraging behavior is similar to other desert thrashers, probing for critters in leaf litter or in holes in the ground, and it sometimes feeds on berries or cactuses fruit. Polytypic. Length 11".
Sexes similar. A largish, pale brown thrasher with uniform brown upperparts and round, somewhat blurry spots on the underparts. Wings have noticeable whitish wing bars, particularly in eastern birds. Tail has pale tips, the extent of which depends on subspecies. Bill is relatively long, black, and distinctly decurved. Eye is distinctly orange-yellow. Juvenile: recently fledged birds have less distinct spotting than do adults, and their bills are significantly shorter and less decurved.
Subspecies oberholseri (southeastern Arizona to south Texas) has clearer spotting below, more distinct white wing bars, and more extensive white tips to the tail feathers. Western birds, palmeri, have less distinct breast spots and less conspicuous white tips to the tail feathers. Calls between the subspecies are slightly different.
Adults distinctive; note different habitat and calls compared with the Bendire’s thrasher. Juvenile curve-billed easily confused with the Bendire’s (especially worn adult Bendire’s and juvenile curve-billed, which may overlap during late spring and early summer in southern Arizona). Very similar bill length and decurviture, but juvenile curve-billed typically shows some pale flesh at the gape on the shortish bill. The Bendire’s usually retains at least some fine dark streaking on the underparts, which is lacking on juvenile curve-billed.
Call: very distinctive loud whit-wheet or whit-wheet-whit. Song: long and elaborate, consisting of low trills and warbles, seldom repeating phrases. Quite different from Bendire’s, but possibly confused with songs of the crissal or the Le Conte’s thrasher.
Status and Distribution
Common resident in desert habitats, particularly those rich in cholla and other cactuses. Particularly common in suburban neighborhoods that retain natural desert vegetation. Also found in mesquite-dominated desert washes. Vagrant: extralimital records mostly pertaining to palmeri from California, Nevada, Idaho, and various states in the Midwest.
Although common, the species is experiencing habitat loss through urban development and increased agriculture in southern Arizona and southern Texas.
—From the National Geographic book Complete Birds of North America, 2006