The curve-billed thrasher (Toxostoma curvirostre) is a medium-sized mimid native to most of Mexico and to the deserts of southwestern United States. It is a non-migratory species, and throughout most of its range it is the most common desert thrasher. Several subspecies have been classified since 1827, though there is no consensus on the number. Allopatric speciation is believed to have played a major role in the variations of the curve-billed. It is grey-brown overall with a slightly curved bill, and is similar in appearance to the related Bendire's thrasher. It generally resides in desert regions of the United States and Mexico, but can inhabit areas predominately populated by humans. The demeanor of the curve-billed has been described as "shy and rather wild", but it allows humans to view it closely. It is very aggressive in driving out potential threats, whether competitors for food or predators of its chicks. The curve-billed thrasher sometimes mimics several other species, though not to the extent of other mimids. It has a variety of distinctive songs, and this extensive repertoire of melodies has led it to be known as cuicacoche (songbird) in Mexico. Taxonomy and systematics The species was first described as Toxostoma curvirostre by William John Swainson in 1827. Since then, six subspecies have been recognized, and have been divided into two branches. Genetic research has indicated that the curve-billed thrasher is the sister species of a clade consisting of the ocellated thrasher, brown thrasher, long-billed thrasher, and Cozumel thrasher. This contrasts with an earlier suggestion that curve-billed and ocellated thrashers are closest relatives. Subspecies Eastern: T. c. oberholseri (Law, 1928) Brownsville thrasher. Generally ranges from SE Texas to NE Mexico (E Coahuila, Nuevo León and Tamaulipas). T. c. curvirostre (Swainson, 1827) Ranges from Central to South-Central Mexico (towards Puebla, Oaxaca, and Veracruz). T. c. celsum (R. T. Moore, 1941) plateau thrasher. Range spans from SE Colorado, SW Kansas, extreme NW Oklahoma to S/SE Arizona, S New Mexico and W Texas to Northern Mexico (E Chihuahua to Guanajuato and Jalisco). Western: T. c. insularum (van Rossem, 1930) San Esteban thrasher. Located in the Islands of San Esteban and Tiburón off the coast of Sonora in the Gulf of California. T. c. maculatum (Nelson, 1900) spotted thrasher. Found in NW Mexico (S Sonora, N Sinaloa, SW Chihuahua). T. c. occidentale (Ridgway, 1882) Mazatlan thrasher. Located in Western Mexico (from Sinaloa and Nayarit to Jalisco).