About Zimmerius vilissimus parvus (Lawrence, 1862)
The Guatemalan tyrannulet, Zimmerius vilissimus parvus, measures 10 to 12 cm (3.9 to 4.7 in) in length. Males and females have identical plumage. Adult individuals have a grayish crown and a short whitish supercilium. Their upperparts are olive green, while 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, with faint darker streaks on the breast, and sometimes a pale yellow wash on the belly and undertail coverts. Both sexes have a light brown or brownish black iris, a short brownish black bill, and long brownish black legs and feet. Immature birds have dark irises and more green coloring in their crown than adults. This subspecies is distributed from the southern Mexican state of Chiapas east across Guatemala into southern Belize, and south through Guatemala into El Salvador. It lives in the interior and edges of evergreen forest, as well as more open forest, plantations, and fields with scattered trees and shrubs. It particularly favors areas that contain mistletoes from the family Loranthaceae. Its elevation range spans from 500 to 2,500 m (1,600 to 8,200 ft).
