Their range extends north from Mexico's Baja California to coastal southern California, where they remain year-round depending on a variety of scrub habitats.
The California Gnatcatcher is a small, slender, gray, non-migratory songbird having a long, black tail with white tips and fine white edging. They are about 10.8 cm (4.25 inches) long. It has a long, thin black tail with narrow white tips and edges on the underside of the tail feathers.
Male in breeding plumage has a black cap, otherwise has a black line over the eye. Males are mostly gray with darker upperparts. After the breeding season, males obtain a plumage color like the females.
The female looks similar to the male, but she has a blue-grey crown instead of the black crown of the male. Females have more of a brown tone on the back, flanks and belly.