Diglossa humeralis, commonly known as the Black Flowerpiercer, is a medium-sized flowerpiercer belonging to Thraupidae, the tanager family. Both sexes are between 13-14 cm long, and are difficult to differentiate from afar because they are so similar. Being part of the flowerpiercers, they posses a sharp hooked bill to aid in their food consumption. They also resemble the Glossy ¬¬Flowerpiercer (Diglossa lafresnayii), which inhabit some of the same areas of South America as the Black flowerpiercer, so distinguishing the two species can be a challenge (Hilty and Brown 1986).
The Black Flowerpiercer is close in appearance to Diglossa lafresnayii, the Glossy Flowerpiercer. The two flowerpiercers belong to the same genus and occupy the same geographic region of the Andes, thus living in sympatry. Both species share the all black coloring and hooked bills, so distinguishing the two in the field is a bit of a challenge. If comparing the different species up close there are some differences. Black Flowerpiercers have a slightly shorter bill than Glossy Flowerpiercers, and a faint gray rump. As their name implies, the Glossy Flowerpiercer has shiny black feathers, while the Black Flowerpiercers appear to be a bit duller (Hilty 2003).
Adult: The black flowerpiercer is one of the simplest tanagers when it comes to color and markings. They are distinguishable by their all black feathers that have a faint blue gloss to them, and a small triangular blue-gray shoulder patch (Hilty 2003). Black flowerpiercers display sexual dimorphism, so the sexes have their own defining traits. Females do not display glossiness to their feathers; they are on the duller side and have no blue hints like the males do. Females are also not completely black, but instead will have gray-brown colored wings and tail (Restall et al. 2007).
Juvenile: Unlike the adults, the young Black Flowerpiercers are not black. Immatures start off as a grayish-brown with a dusky streaked back. The belly is paler overall while the streaks are darker and more prominent (Hilty 2003).
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). Many species have been found to breed in subadult plumage (Isler and Isler 1987). Although a juvenile molt is described for Diglossa humeralis (Hilty 2003), more specific information on molt and timing is not found available for this species.
Bill: Black, with basal portion of lower mandible is pale gray in color (Hilty 2011)
Iris: Reddish-brown (Hilty 2011)
Legs: Dark Gray (Hilty 2011)
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