The wings and long tail are mostly dusky brown, with patches of white that show conspicuously in flight.

The throat, belly, and vent area are white and the breast and flanks buff to dull brown.

M. l. platensis is found only on Isla de la Plata, about 30 km (19 mi) off the coast of Manabi.

[3] The long-tailed mockingbird inhabits coastal desert scrub, arid woodland, and hedgerows and tree groves in agricultural areas.

[3] The long-tailed mockingbird nests from late December to July in southwestern Ecuador, where its breeding phenology has been most studied.

Its nest is a rough cup constructed of thorny twigs and lined with finer plant material and hair.

The long-tailed mockingbird's song is "a fairly slow-paced series of variable rich whistled notes, churrs, rattles, squawks, and other noises, often with phrases repeated.

[1] The two mainland coastal subspecies are common but their distribution is patchy due to discontinuous habitat.