Variable antshrike

The variable antshrike (Thamnophilus caerulescens) is a species of bird in subfamily Thamnophilinae of family Thamnophilidae, the "typical antbirds". It is found in Argentina, Bolivia, Brazil, Paraguay, Peru, and Uruguay.

The variable antshrike, as its common name suggests, is arguably the species of antbird with the most variable plumage. It is 14 to 16 cm (5.5 to 6.3 in) long and weighs 15 to 24 g (0.53 to 0.85 oz). Members of genus Thamnophilus are largish members of the antbird family; all have stout bills with a hook like those of true shrikes. This species exhibits significant sexual dimorphism as well as the differences among subspecies. Adult males of the nominate subspecies T. c. caerulescens have a black crown and nape and a gray face. Their upperparts are dark gray with some black on the lower back and a white patch between the scapulars. Their outer scapulars are black with white edges, their wing coverts black with white spots, and their flight feathers blackish brown with pale brown and white edges. Their tail is brownish black with white tips on the feathers. Their underparts are gray with a somewhat lighter belly, and often have faint scalloping. Adult females have an olive-brown crown. Their upperparts are mostly olive-brown with a tinge of clay color and yellow-brown edges on the uppertail coverts. They have little or no white between the scapulars. Their wing coverts are very dark brown with white edges on their tips and their flight feathers are dark brown with clay edges. Their tail feathers are dark brown with small white tips. Their throat and upper breast are ochraceous-gray and the rest of their underparts cinnamon-tawny with an olive tinge on the lower breast and sides. Subadults resemble adult females but are more buffy.

The other subspecies of the variable antshrike differ from the nominate and each other thus:

T. c. melanchrous: Males are mostly black with some gray mixed on the rump, belly, and crissum, white edges on their primaries, and small white spots on their tail feathers. Females have an olive-gray forehead and nape and a black crown, very small spots on their wing coverts, and cinnamon-tawny belly and crissum.

T. c. aspersiventer: Both sexes are similar to melanchrous. In addition males have black and white scallops on their belly and crissum and larger white spots on their tail. Females have a dark olive-gray crown with blackish spots.

T. c. dinellii: Males' underparts vary from mostly cinnamon to cinnamon only on the crissum with a blackish throat and breast. Females have ochraceous gray crown and upperparts, yellow-brown flight feathers, light gray throat and upper breast with a faint yellow tinge, and pale cinnamon belly and crissum.

T. c. paraguayensis: Both sexes are paler than the nominate. Males have white or buff-tinged white belly and crissum. Females have an olive-gray crown, olive-gray wing coverts with white tips and in some areas blackish spots, and white underparts with variable intensity of a yellowish brown tinge.

T. c. gilvigaster: Males have clay-colored edges to their flight feathers, gray throat, breast, and upper belly, and gray lower belly and crissum with a cinnamon-tawny wash. Females are yellowish gray from their throat to upper belly and cinnamon-tawny lower belly and crissum.

T. c. ochraceiventer: Males have a clay tinge to their upperparts and flight feathers, a gray throat, and grayish ochraceous underparts. Females have a black crown with some olive-gray on the forehead.

T. c. cearensis: Males are similar to the nominate but with a lighter black crown and upperparts. Females have a rufous crown, ochraceous olive-brown wing coverts, a clay tinge on their tail, and a pale ochraceous throat.