Adults are gray-black birds speckled with white on the upperparts. They have a black crown and chestnut back of the neck. The eye is ruby red and the bill is black. The legs are dusky pink (or wine-colored). Immatures are similar but with less distinct white markings and amber or hazel eyes that turn red at 3 months of age.
Forages by walking through marsh to seize prey from marsh vegetation, on the ground, or in shallow water. Males call repeatedly from several spots in the territory, particularly before the female has laid eggs. Northern populations migrate.
Nests in wet meadows, shallow freshwater marshes, and the shallower or drier (“upland”) portions of saltmarshes. Winters in shallow coastal and interior marshes that do not freeze. Migrants may show up in similar habitats and sometimes in rice fields.
Ornithologists recognize five subspecies of Black Rail. Eastern North America, the Caribbean, and Central America are home to the jamaicensis subspecies, which is partly migratory. It has a grayish crown and chestnut nape. In California and adjacent Baja California and Arizona, the nonmigratory subspecies coturniculus nests. Compared to jamaicensis, it has a shorter, finer bill, a rich brownish crown, and chestnut upper back as well as nape. Outside of North America, the subspecies tuerosi inhabits marshes around Lake Junín, Peru. It is darker overall, with more prominent white barring than the more northerly subspecies. On the coast of Peru, the paler subspecies murivagans has pale rusty or even pinkish undertail coverts and very strong white barring above, almost appearing like white bands. The southernmost subspecies, salinasi, is the largest on average. It inhabits central Chile and adjacent Argentina. It is also strongly marked with white above and has an extensive rich rufous patch on the nape and upper back.