it is 15 to 18 cm in length with the long, pointed tail feathers accounting for much of this. the bill is short and pointed and the wings are short and rounded. the plumage varies among the four subspecies. the nominate subspecies "l. a. aegithaloides" of central chile is mainly brown with paler underparts, rufous markings on the wings and crown and a white stripe above the eye. the head and upper breast are streaked while the back is plain. "l. a. berlepschi" occurs high in the andes in the northern part of the species' range and is larger and more buff-coloured than the other forms. "l. a. grisescens" is found in the arid lowlands of north chile and south peru. it is rather greyish in colour with little streaking on the breast. in most of argentina and south chile, "l. a. pallida" occurs. it is pale and greyish with only a small area of rufous in the wing.