Rusty-fronted Canastero
Asthenes ottonis
The rusty-fronted canastero is 18 to 19 cm (7.1 to 7.5 in) long and weighs about 13 g (0.46 oz). The sexes have the same plumage. Adults have a grayish buff supercilium and arc below the eye, a small dark line in front of the eye, and a dark brownish patch behind the eye on an otherwise dull brownish face with pale streaks. Their forehead ("front") is rufous with faint pale streaks. Their crown, back, and rump are rich brown and their uppertail coverts chestnut-rufous. Their wings are mostly rufous-chestnut with dark fuscous tips on the flight feathers. Voice: The rusty-fronted canastero's song is "3 high-pitched ascending notes followed by a rapidly descending series, 'bsee-bzéé-bzee-di-di-di-di-d-d-d' ". Its call has been described as "high-pitched 'veer' and nasal 'djeeh' ".
ID text from Wikipedia, CC BY-SA 4.0
White-chinned Thistletail
Asthenes fuliginosa
The white-chinned thistletail is 18 to 20 cm (7.1 to 7.9 in) long and weighs 14 to 20 g (0.49 to 0.71 oz). It is the largest thistletail. The sexes have the same plumage. Adults of the nominate subspecies A. f. fuliginosa have a faint grayish-tawny supercilium and a whitish eyering on an otherwise blackish to dark brown face. Their crown, back, rump, and tail are dark reddish brown. Their wings are a brighter reddish brown. Their tail is long and deeply forked with few barbs at the feather ends that give a ragged appearance. Their chin is whitish. Voice: One of the white-chinned thistletail's songs is "a high-pitched, weak, slightly accelerating and ascending trill". Others are a "descending series of somewhat higher-pitched notes that accelerates into trill, and a slightly ascending series of tripled notes, 'tididit, tididit, tididit' ". Its calls include "a high-pitched, sharp, penetrating 'pyeek' or 'kick' " and "chink".
ID text from Wikipedia, CC BY-SA 4.0

Where you might meet both
Learn this pair in the BeakBrain App
Photo and call practice. Coming soon to iPhone and Android.
Play today's Daily BirdPhotos and recordings are credited to their authors under the licence shown. Full profiles: Rusty-fronted Canastero and White-chinned Thistletail.