Masked Flowerpiercer
Diglossa cyanea
The masked flowerpiercer grows to a length of about 15 cm (6 in). The adult male is deep ultramarine blue with a dark mask. The beak is large, black, and upturned, with a characteristic hook on the tip of the upper mandible. The iris is bright red. The female is similar in appearance but altogether duller. The juvenile has a reddish-brown iris. At the northern end of its range, the song is a series of reedlike notes terminating in a twitter, while at the southern end, it is a jangling series of high-pitched notes ending with several lengthy "tseee" notes.
ID text from Wikipedia, CC BY-SA 4.0

White-sided Flowerpiercer
Diglossa albilatera
A fairly small flowerpiercer - slightly larger than a black-capped chickadee and slightly smaller than a great tit. Length is 12.2-13.2cm, mass is typically 9.84-10.2g. The male is a blackish-slate colour overall with the exception of white "sides" (pectoral tufts and underwing linings). On a perched bird these white markings are not always noticeable but when the bird flicks its wings as it frequently does the white flash is obvious. Females are olive-brown above and buffy-brown below, with the same white sides.
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: Masked Flowerpiercer and White-sided Flowerpiercer.