Fork-tailed Flycatcher is a distinctive inhabitant of grassland and open terrain from southern Mexico south to Argentina. Fork-tailed Flycatcher is mostly black and gray above with white underparts, and, as the name implies, has an extremely long forked tail. This flycatcher, which is a member of the kingbird genus Tyrannus, often perches prominently on the top of fence posts or shrubs; from such conspicuous perches, the flycatcher sallies after insects or hover-gleans to feed on fruit. The southernmost populations are migratory while populations in southern Mexico are resident. During migration Fork-tailed Flycatchers are very gregarious and may roost in flocks of up to 10,000 individuals.