thrasher, any of numerous New World birds with downcurved bills, noted for noisy foraging on the ground in dense thickets and for loud varied songs. The 17 species, of the family Mimidae (order Passeriformes), range from the Canadian northwest to central Mexico and east to New England and the Caribbean. Best known is the brown thrasher (Toxostoma rufum) of North America east of the Rockies—a 30-centimetre (12-inch) red-brown bird with streaked underparts. In the arid southwestern United States and in Mexico are long-tailed drab forms, such as the California thrasher (T. redivivum), with sicklelike bills.