Torrent Tyrannulet
Serpophaga cinerea
The torrent tyrannulet is 9.5 to 12 cm (3.7 to 4.7 in) long; eight individuals weighed an average of 8.3 g (0.29 oz). Adults of the nominate subspecies have a mostly black head with a partially hidden white patch in the center of the crown. Their back, rump, and uppertail coverts are gray. Their wings are mostly black with gray or grayish white edges on the coverts. Their tail is black and sometimes has indistinct grayish white tips on the feathers. Their chin and throat are grayish white. The center of their breast and their belly are white and their undertail coverts slightly grayish. Voice: The torrent tyrannulet's dawn song in Costa Rica is a slow series of chip notes separated by as much as 10 seconds. Pairs also vocalize "in unison a short refrain made up of a sharp chip, rapidly repeated". Its song in the Andes has been described as "a high, thin seek!
ID text from Wikipedia, CC BY-SA 4.0
Yellow Tyrannulet
Capsiempis flaveola
The yellow tyrannulet is 10 to 11.5 cm (3.9 to 4.5 in) long and weighs about 8 grams (0.28 oz). The sexes have the same plumage. Adults of the nominate subspecies C. f. flaveola have a dark yellowish olive crown with a somewhat bushy crest. They have a bright yellow supercilium, a bright yellow partial eye ring, and a dark line through the eye on an otherwise yellowish face. Their upperparts are dark yellowish olive. Voice: The yellow tyrannulet is very vocal; its songs vary across its wide range and often include duets. In Costa Rica it sings a "sputtering series of wheep or wee-deep notes". In Ecuador the song is described as "a pleasant and rollicking series of notes that often seem to lack much pattern, usually starting slowly but then quickly speeding up".
ID text from Wikipedia, CC BY-SA 4.0
Where you might meet both
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Play today's Daily BirdPhotos and recordings are credited to their authors under the licence shown. Full profiles: Torrent Tyrannulet and Yellow Tyrannulet.