Scale-crested Pygmy Tyrant
Lophotriccus pileatus
The scale-crested pygmy tyrant is 8 to 10 cm (3.1 to 3.9 in) long and weighs about 7 to 8 g (0.25 to 0.28 oz). It has long crown feathers that form the eponymous crest and that it sometimes erects and fans. Females have a smaller crest than males but the sexes otherwise have the same plumage. Adults of the nominate subspecies L. p. pileatus have a black crest with rufous edges on the feathers. They have whitish lores on an otherwise brownish face. Their back, rump, and uppertail coverts are olive. Voice: The scale-crested pygmy tyrant's main vocalization is a very loud trill that differs somewhat geographically. It has been written as "tr-tr-tr-tr-tr-tr-tr-tr" and "trrrrrreét", "dzzeeer-dzeer-dzeer", and "cre'e'e'e'e, k'e'e'e'e". It also makes "a series of sharp "preek" notes, sometimes widely spaced".
ID text from Wikipedia, CC BY-SA 4.0
Yellow-crowned Tyrannulet
Tyrannulus elatus
The yellow-crowned tyrannulet is 10 to 11 cm (3.9 to 4.3 in) long and weighs 6.5 to 8 g (0.23 to 0.28 oz). Adult males have a slate-gray to dark brown or blackish crown with a bright yellow to orange-yellow stripe along its middle. Their nape and back are bright olive-green. They have a grayish supercilium, a thin dark line through the eye, and a pale gray lower face. Their wings are dusky with two white to yellowish white bars. Their tail is dusky olive. Their throat is pale gray and their underparts pale to medium yellow with an olive wash on the breast. Voice: The yellow-crowned tyrannulet's song is a "2-noted, clear, plaintive 'wih-weér' (or 'free beer'), 2nd note higher, shorter, and stressed". It apparently differs little across the species' range.
ID text from Wikipedia, CC BY-SA 4.0
Where you might meet both
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