Red-billed Tyrannulet

The red-billed tyrannulet (Zimmerius cinereicapilla) is a species of bird in the family Tyrannidae, the tyrant flycatchers. It is found in Bolivia, Ecuador, and Peru. == Taxonomy and systematics == The red-billed tyrannulet was originally described as Phyllomyias cinereicapilla. During much of the twentieth century the red-billed tyrannulet and several other tyrannulets were placed in genus Tyranniscus but a study published in 1977 erected the present genus Zimmerius for them. Early in the twentieth century some taxonomists treated it as a subspecies of the slender-footed tyrannulet (Z. gracilipes) but it has been widely accepted as a species since the 1990s. The two are now known to not be closely related, and the red-billed and Mishana tyrannulet (Z. vaillarejoi) appear to be sister species. The red-billed tyrannulet is monotypic. == Description == The red-billed tyrannulet is 11.5 to 12 cm (4.5 to 4.7 in) long; four males weighed 11.3 to 13.8 g (0.40 to 0.49 oz) and two females 10.7 and 11.2 g (0.38 and 0.40 oz). The sexes have the same plumage. Adults have a pale gray or dusky olive crown. Their face, back, and rump are olive green. Their wing's lesser coverts are dusky with olive green tips and…