The sage thrasher, Oreoscoptes montanus (family Mimidae), a streaked, migratory, thrush-like bird that breeds on the sagebrush plains of western North America.
Origin
Mid 19th century.
Definition of mountain mockingbird in US English:
mountain mockingbird
noun
US
The sage thrasher, Oreoscoptes montanus (family Mimidae), a streaked, migratory, thrush-like bird that breeds on the sagebrush plains of western North America.