Vocal and plumage variation in the Bewick’s wren is extensive, but all adults have a very long tail, tipped in white and flicked side to side. Eastern populations have disappeared from much of former range and are in continuing decline; conversely western populations are stable or increasing and/or expanding. Polytypic. Length 5.1".

Long, mobile tail with attenuated body shape and active demeanor impart a lean look. Adult: one molt a year; sexes similar. Plumage variable, but all subspecies gray-brown to rufous-brown above, gray-white below, with long, pale supercilium. White-tipped tail has black bands. Juvenile: plumage subtly paler than adult’s.

Complex, extensive. Variation in darkness of upperparts generally follows Gloger’s Rule, with paler populations in the arid Southwest and intermontane West vs. darker