Description wikipedia

The plain-mantled tit-spinetail (Leptasthenura aegithaloides) is a small passerine bird of South America in the Furnariinae subfamily of the ovenbird family Furnariidae. It is found in Argentina, Bolivia, Chile, and Peru. The plain-mantled tit-spinetail is 15 to 17 cm (5.9 to 6.7 in) long and weighs 7.5 to 11 g (0.26 to 0.39 oz). It is a small, slender, long-tailed furnariid with a short bill. The sexes have the same plumage. Adults of the nominate subspecies L. a. aegithaloides have a white supercilium on an otherwise dark brownish, whitish streaked, face. Their crown is dark brown with wide golden-tawny streaks, their hindneck dark brown with grayish-white streaks, and their back, rump, and uppertail coverts dull brownish. Their upperwing coverts are dull brownish with rufous edges and their flight feathers dull fuscous with dark rufous bases. Also, their tail feathers are dark fuscous brown with paler edges; the tail is graduated and appears forked due to the central feathers having reduced inner webs. Their throat is whitish with some dark feather edges that increase onto the upper breast. The rest of their breast is dull grayish brown and the rest of their underparts are slightly paler. Their iris is brown, their maxilla blackish to dark gray-brown, their mandible dark horn to greenish gray, and their legs and feet gray to blackish. Juveniles have indistinct crown and throat markings, a lightly spotted back, and rounded tail feathers. Subspecies L. a. grisescens is overall paler than the nominate, with wider and paler stripes on the crown, a grayer back and buffier rump, paler edges on the wing coverts, and grayer underparts. L. a. berlepschi is larger and bulkier than the nominate. It has a paler cinnamon crown whose streaks greatly contrast, pale buff streaks on the neck, cinnamon rather than rufous on the wing coverts and flight feathers, pale buff outer tail feathers, and entirely buffy underparts. L. a. pallida has the longest tail of all subspecies. Its crown and neck are similar to those of berlepschi. Its upperparts are mostly pale gray with a pale buffy rump. It is pale cinnamon on the wing coverts and flight feathers, and its belly is pale gray with sometimes a buff wash on the belly and flanks.