The Plain Antvireo, Dysithamnus mentalis, is a passerine bird species in the antbird family. It is a resident breeder in tropical Central and South America from southern Mexico south to northern Argentina, and on Trinidad and Tobago.
The Plain Antvireo is typically 11.4 cm long, and weighs 13.5 g. The adult male has a slate grey head and upperparts, blackish cheeks, three narrow white wing bars, pale grey underparts and a white belly. The female has olive brown upperparts, a rufous crown, yellowish-buff underparts and weakly buff-barred rufous wings. Immature males are much like the adult male, but have brown edgings to the flight feathers, an olive rump and yellowish underparts.
If the nest is approached, an incubating bird will drop to the ground and flutter weakly to distract the potential predator. It then shows a white (male) or buff (female) shoulder stripe which is not normally visible.
There are a number of subspecies of this antvireo, so the appearance is very variable throughout its range. It has a musical buu-bu-bu-bu-u-u-u song, and calls include a weak naaa and a questioning bu-u-u-u-u?
This is a common and confiding bird of primary and second growth forest. The Plain Antvireo feeds like a vireo on small insects and other arthropods taken from twigs and foliage in the lower branches of trees. It is usually found in pairs or small groups like adults with last years' young or birds congregating at a special food source. Mated pairs are quite territorial against conspecifics however, and defend a patch of habitat of about 7,000 square metres, but sometimes only half that big.
The female lays two cinnamon-marked white eggs in a small deep cup nest in the lateral fork of a sapling. The eggs are incubated by both parents for 15 days to hatching, with a further 9 days to fledging.
Due to its large range, this species is not considered threatened by the IUCN. It appears to be tolerant of some degree of habitat disturbance and/or human activity.