Mistletoe Tyrannulet

The mistletoe tyrannulet (Zimmerius parvus) a very small passerine bird in the family Tyrannidae, the tyrant flycatchers. It is found from Guatemala and Belize to Colombia. == Taxonomy and systematics == The mistletoe tyrannulet was originally described in 1862 by the American amateur ornithologist George Newbold Lawrence under the binomial name Tyranniscus parvus. During much of the twentieth century it and several other tyrannulets were placed in genus Tyranniscus but a study published in 1977 erected the present genus Zimmerius for them. It was formerly treated as a subspecies of what was then the paltry tyrannulet (Zimmerius vilissimus sensu lato). Based on a molecular phylogenetic study published in 2013 taxonomic systems began recognizing them as separate species in 2016. The mistletoe tyrannulet is monotypic. == Description == The mistletoe tyrannulet is about 9.5 to 10 cm (3.7 to 3.9 in) long and weighs about 8.5 to 10 g (0.30 to 0.35 oz). The sexes have the same plumage. Adults have a grayish crown and a short but wide whitish supercilium. Their upperparts are olive green. Their wings and tail are mostly olive green with yellow edges on the wing coverts, flight feathers, and tail feathers. Their underparts are mostly off-white…