Black-capped Tanager

The black-capped tanager is approximately 13 centimetres (5 in) long, and weighs between 18 and 20 grams. The bird's iris is dark brown, while the beak and legs are black. The male of the species has a black crown, with the black extending to the lores, forehead, and upper nape. Its upper-parts are a shining silvery bluish-grey, which extends to the upper tail coverts, and contrasts sharply with the black crown. The upperwing-coverts are a duller bluish-grey, with an edging of duller blue, whereas the primary coverts are black, with a dull blue edge paler than that of the wing coverts. The tertial feathers are also black with a blue outer edge. The throat, the sides of the neck, the sides of the head till the eye, and the chest are a shining aquamarine-green or opalescent green. The feathers are lanceolate, or spear-shaped. Their black bases are thus visible, giving this area of the bird a streaked or scaly appearance, which is especially visible on the chest. The rest of the underparts are a dull and uniform greyish-blue, with the exception of the undertail-coverts: these feathers have dark centers and broad, white edges. The female, in contrast, has a dusky crown, the feathers of which are edged in green, giving it a slightly scaly appearance. It is also generally duller than the male. The upperparts are a uniform shining green, while the tail is a duller green or olive-green. The primary coverts are dusky, with a green outer edge, while the greater coverts are dusky on the inner half and dull green on the outer half, and the lesser coverts and median upperwing-coverts are greenish, with a dull base, and the lesser and median upperwing-coverts mainly greenish with dusky bases. The wing coverts generally appear green. The flight feathers are dusky, with a bluish-green edging, while the tertial feathers are similar to the greater coverts, being dull green on the outer half. The underside of the female is similar to but duller than the male, with the throat, neck, and chest being green with a scaled appearance similar to the male created by dark bases to the feathers. The rest of the underside is grey, while the sides are olivaceous yellow-green, and the undertail coverts being similar to those of the male. Juvenile, immature, and subadult males are intermediate in appearance between the adult males and females. Juvenile males resemble the female, but have a pale blue edge to their primary feathers. Immature individuals of both sexes are duller counterparts of the female adults. Subadult males resemble the females but have adult male feathers mixed in with their other plumage, including a mixed green and black crown, and mixed green and silvery-grey feathering on the back and mantle. The black-capped tanager resembles the silver-backed tanager (Stilpnia viridicollis), which replaces it at the southern edge of its range. Females of the two species are especially alike, but those of the silver-backed tanager have a coppery, rather than a green, throat. The beryl-spangled tanager (Tangara nigroviridis) is also similar, but lacks the dark crown and is uniformly opalescent over its head; it also has a more strongly spangled underside. In contrast to other members of its genus, the black-capped tanager sings frequently. It shows no preference for singing at specific times of the day. It usually sings from a high and occasionally exposed position. The songs are up to ten seconds long, low-pitched, and have a mechanical, ringing quality, described as "t'kling-t'kling-t'kling". The call is often repeated within a few minutes. Other calls include a high-pitched and nasal "zheet", and a high-pitched "tsit".