Guianan Tyrannulet

The Guianan tyrannulet (Zimmerius acer) is a species of bird in the family Tyrannidae, the tyrant flycatchers. It is found in Brazil, French Guiana, Guyana, Suriname, and Venezuela. == Taxonomy and systematics == The Guianan tyrannulet was originally described as Tyranniscus acer. Through much of the twentieth century it and several other tyrannulets were kept in genus Tyranniscus but a study published in 1977 erected the present genus Zimmerius for them. Also in much of the twentieth century the Guianan tyrannulet was treated as a subspecies of the slender-footed tyrannulet (then T. gracilipes, now Z. gracilipes) until a study published in 2008 returned it to full species status. The Guianan tyrannulet is monotypic. == Description == The Guianan tyrannulet is 9 to 12 cm (3.5 to 4.7 in) long and weighs 5.7 to 11 g (0.20 to 0.39 oz). The sexes have the same plumage. Adults have a gray forehead and crown. They have a thin whitish supercilium that starts at their lores and a dark stripe through the eye on an otherwise almost pure white face. Their back and rump are dull olive. Their wings are dusky with thin yellow edges on the coverts and inner parts of the…