Andean Swift
Aeronautes andecolus
The Andean swift is about 14 cm (5.5 in) long. It has sharply pointed wings and a long deeply forked tail. The sexes are alike. Adults of the nominate subspecies have mostly black upperparts with a white collar and band on the rump. Their face and underparts are mostly white to off-white with mottled buff on the flanks and vent. Subspecies A. a. parvulus is smaller than the nominate and the borders between black and white areas are very sharply defined. A. a. peruvianus is also smaller than the nominate. Voice: The Andean swift's most common vocalization is "a buzzy, grating 'tzee-tz-tz-trrr...tzee-tz-tz-tzee...'." It also makes "a series of single notes 'tzree..tzree..tzree...'."
ID text from Wikipedia, CC BY-SA 4.0
White-throated Swift
Aeronautes saxatalis
The white-throated swift is medium-sized bird that is primarily black and white. Its back and wings are blackish-brown or black, and its breast, belly, chin, and throat are white. In newly molted adults, the dark feathers may have a slight greenish sheen, though this is rarely observable in the field. Sexes cannot be distinguished by plumage. Juvenile (first basic) plumage is similar to adult (definitive basic) plumage, but with the feathers on juveniles' heads and necks appearing duller and paler. Voice: White-throated swifts make vocalizations while in the air that are described as "staccato chattering", and may also make a sharp one- or two-note call or a shrill drawn-out "scree" call. In the morning and evening, "twittering" sounds may be made at their roost sites. Additionally, juveniles may make begging sounds that are higher-pitched versions of the adult's shrill scree call.
ID text from Wikipedia, CC BY-SA 4.0
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