Masked Flowerpiercer is a large, predominantly dark blue flowerpiercer of the genus Diglossa (sometimes classified as Diglossopis) with a long and slender hooked bill. This species also has a distinctive black "mask" that gives it its English name, and differentiates it from other similar blue flowerpiercers (see Similar Species). The scientific name Diglossa cyanea describes some of its physical features. The genus name comes from the Greek word diglossos, which means "double-tongued" (referring to its specialized nectar-feeding tongue), and the specific epithet comes from the Latin word cyaneus, which means "dark blue" (Jobling 2010).
Bluish Flowerpiercer (Diglossa caereulescens) is mostly blue with black lores, although it is much duller and more grayish blue compared to Masked Flowerpiercer (Schulenberg et al. 2007). The reddish irides of Bluish Flowerpiercer are also much duller than those of Masked Flowerpiercer, and it does not have the same mask coloration around its face. It is regularly found in the same mixed-species flocks as the Masked Flowerpiercer, but is less numerous (Ridgely and Greenfield 2001). The song of Bluish Flowerpiercer also is similar, though the song of Masked Flowerpiercer generally is more melodic and complex (Schulenberg et al. 2007).
Indigo Flowerpiercer (Diglossa indigotica) is a similar ultramarine blue bird with dark-colored flight and tail feathers, though it is much smaller in size than Masked Flowerpiercer, and has thin black eyering and lores, rather than a larger black "mask" (Hilty and Brown 1986).
Deep-blue Flowerpiercer (Diglossa glauca) also has ultramarine blue plumage much like Masked Flowerpiercer, but has bright yellow irides rather than red, lacks the distinctive black "mask" of Masked Flowerpiercer, and has a less melodic and complex song (Schulenberg et al. 2007).
The following description refers to the nominate subspecies, Diglossa cyanea cyanea; for the other subspecies, see Geographic Variation.
Adult: Masked Flowerpiercer is known for its distinctive black "mask" covering the forecrown, lores, chin, and ear coverts (Restall et al. 2007). The bill is upturned and hooked (Hilty 2003). The body plumage is mostly dark blue, while the wing (coverts, remiges, tertials) and tail are black with dark blue edges (Hilty 2011). Adult females are similar in appearance to males but generally duller in plumage, with paler blue plumage above and slightly grayer plumage below (Restall et al. 2007). The species is dichromatic when quantified using a model of avian vision (Burns and Shultz 2012). Thus, birds probably can easily distinguish between males and females, but for humans, these differences are more subtle.
Juveniles are a dull grayish blue (Restall et al. 2007).
Tanagers that have been studied have either a Complex Basic Strategy or Complex Alternative Strategy (Ryder and Wolfe 2009). However, most tanagers only molt once a year (Isler and Isler 1987), and this prebasic molt likely occurs after the breeding season (Isler and Isler 1987, Ryder and Wolfe 2009). Although a juvenile plumage is described for Masked Flowerpiercer (Restall et al. 2007), more specific information on molt and its timing is not available for this species.
Iris: bright red; brown in juveniles (Restall et al 2007)
Bill: black ;base of mandible pale in juveniles (Restall et al. 2007).
Tarsi and toes: black ; brown in juveniles (Restall et al 2007)
Total length: 13.5–15 cm
Mass: male, mean 17.4 g (range 14.9–19.6 g, n = 51); female, mean 16.7 g (range 15.4–19, n = 23) (Echeverry-Galvis et al. 2006).