Black Flowerpiercer
Diglossa humeralis
Adult black flowerpiercers are 13–14 cm in length. They are uniformly black (slightly glossy black with subtle blue gloss in males). They have brown eyes and a black bill with a grey base. Females are a duller black with no blue gloss and their wings and tail are brownish. Juvenile birds are also duller. Voice: A rapid series of squeaky trills and twitters even faster than the glossy flowerpiercer (Diglossa lafresnayii). The black flowerpiercer sounds almost like the cinereous conebill (Conirostrum cinereum).
ID text from Wikipedia, CC BY-SA 4.0

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

Where you might meet both
Learn this pair in the BeakBrain App
Photo and call practice. Coming soon to iPhone and Android.
Play today's Daily BirdPhotos and recordings are credited to their authors under the licence shown. Full profiles: Black Flowerpiercer and Masked Flowerpiercer.