There are about 15 species of birds in the Polioptilidae family, which includes gnatcatchers and gnatwrens. They are found from Canada through North, Central, and South America.

These small birds have slender bodies, long tails, and thin, pointed bills. Many species are bluish-gray or gray. They live in a variety of habitats, including forests, woodlands, scrubland, and deserts. They feed mainly on insects and other small invertebrates.

 BLUE-GRAY GNATCATCHER

The Blue-gray Gnatcatcher (Polioptila caerulea) is about 3.9–4.3 inches (9.9–10.9 cm) long. It has pale blue-gray feathers on its upperparts and grayish-white feathers on its underparts. Its long tail is mostly black with white edges, and it has a white ring around its eyes. It lives throughout much of the United States and southern Canada during the breeding season and is found in the southern United States, Mexico, and parts of Central America during the winter. It is also found in New Hampshire during the breeding season.

 BLACK-TAILED GNATCATCHER

The Black-tailed Gnatcatcher (Polioptila melanura) is about 4.3–5.1 inches (10.9–13.0 cm) long. It is gray overall, with a black tail marked with white flashes and a thin white ring around its eyes. It lives year-round in desert scrub in the southwestern United States and northern Mexico. It feeds on small insects and often searches for food among shrubs and thorny plants.

 CALIFORNIA GNATCATCHER

The California Gnatcatcher (Polioptila californica) is a small, nonmigratory bird found in coastal and inland scrub habitats of California and Baja California, Mexico. The federally threatened Coastal California Gnatcatcher (Polioptila californica californica) is a subspecies found in coastal southern California and northwestern Baja California, Mexico. It is about 4.3 inches (11.0 cm) long and has dark blue-gray upperparts, grayish-white underparts, a mostly black tail, and a white ring around its eyes. It lives primarily in coastal sage scrub. The Coastal California Gnatcatcher has been listed as threatened under the U.S. Endangered Species Act since 1993.

BLACK-CAPPED GNATCATCHER

The Black-capped Gnatcatcher (Polioptila nigriceps) is about 3.9–4.7 inches (9.9–11.9 cm) long. It is a small, gray bird that lives mainly in dry forests and scrub in northwestern Mexico. It also occurs regularly in southeastern Arizona and occasionally in southwestern New Mexico. Breeding males have a black cap.