Band-rumped Swift
Chaetura spinicaudus
The band-rumped swift is 10.5 to 12.6 cm (4.1 to 5.0 in) long and weighs 13.8 to 18.5 g (0.49 to 0.65 oz). It has a protruding head, a short square tail, and wings that bulge in the middle and somewhat hook at the end. The sexes are alike. Adults of the nominate subspecies have black-brown upperparts with a white band on the rump. Their underparts are dark with a slightly paler throat. Juveniles have white tips on some wing feathers. Subspecies C. s. aetherodroma is smaller than the nominate; its rump patch is grayer and its throat paler. Voice: The nominate subspecies of band-rumped swift "gives a diagnostic bisyllabic 'pseee-trr' or more burry 'prrrree-trtr'" and sometimes also "several repeated notes 'tsee-tsee-tsee'". The vocalizations of subspecies C. s. aetherodroma are not well known.
ID text from Wikipedia, CC BY-SA 4.0
Costa Rican Swift
Chaetura fumosa
The Costa Rican swift is about 11 cm (4.3 in) long. The sexes are alike. Their head is dusky. Their upperparts are mostly sooty black with a blue gloss and a pale grayish rump and dull black uppertail coverts. Their throat and breast are pale grayish. Voice: The Costa Rican swift makes "high-pitched calls such as single 'weet', 'tsew' or 'tsee' notes" and usually combines them with "longer twittering series such as 'titititititititi' or 'titititrrrr'."
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: Band-rumped Swift and Costa Rican Swift.