Polioptilidae

Polioptilidae, the gnatcatchers and gnatwrens, is a family of small passerine birds comprising 20 species in three genera: Ramphocaenus with two species, Microbates with two species, and Polioptila with 16 species. The family is found in North and South America, except for the far south and the high Andean regions, and most species are year-round residents though the blue-grey gnatcatcher migrates seasonally between the United States and Canada and more southern regions. Gnatcatchers are soft bluish grey birds with a typical insectivores long sharp bill, many with distinctive black head patterns, especially in males, and long, regularly cocked, black and white tails, moving restlessly through foliage in search of insects; the related gnatwrens are browner and more thickset, with proportionally shorter tails and longer bills, and live in more concealed forest undergrowth.