Curve-billed Thrasher (Toxostoma curvirostre) [XC256401]
by Richard E. Webster from Portal, Arizona, United States (song)
Curve-billed Thrasher (Toxostoma curvirostre) [XC555494]
by Carlos Gonzalez from Tucson, Pima County, Arizona, United States (song)
Subspecies
Perhaps most closely related to, and forming a superspecies with, Ocellated Thrasher (Toxostoma ocellatum). Both are similarly close to the Brown Thrasher (Toxostoma rufum) superspecies. Subspecies form two groups, eastern "nominate group" (also including celsum and oberholseri) and smaller and less distinctly marked taxa in western "palmeri group" (also including maculatum, occidentale and insularum). The groups intergrade somewhat in south-western USA (Arizona). Recent genetic studies suggest that the two groups may represent separate species. Several subspecies (e.g. insulararum, celsum) are poorly differentiated and perhaps not distinguishable.
The following 7 subspecies are recognised:
palmeri (Coues, 1872) - South-western USA (south-western and central Arizona) south to north-western Mexico (south to central Sonora).
insularum van Rossem, 1930 - Tiburón I and San Estebán I, in Gulf of California off central Sonora coast (north-western Mexico).
occidentale (Ridgway, 1882) - West-central Mexico (Sinaloa south to Jalisco).
curvirostre (Swainson, 1827) - Central and south-central Mexico (south to Puebla and Oaxaca).
celsum Moore, RT, 1941 - Southern USA (south-eastern Colorado, south-western Kansas and extreme north-western Oklahoma south to south-eastern Arizona, New Mexico and western Texas) and north-central Mexico (south to Zacatecas).
oberholseri Law, 1928 - Southern Texas south to north-eastern Mexico (south to south-central Tamaulipas).
BirdLife International Species Factsheet