Black Rails are sparrow-sized (length 12-15 cm) dark marsh birds with laterally compressed bodies that allow them to maneuver through dense marsh vegetation. They are blackish-gray in color, except for a chestnut patch on the back of the neck and white spotting on the back, wings and tail. Adults have bright red eyes. Males and females are very similar in coloration and size, except that females have a lighter-colored throat.
Black Rails prefer moving on foot, hidden in dense vegetation, to flying. As a result, they are rarely seen. They will, however, make their presence known with their distinctive ki-ki-krr call or an aggressive, presumably territorial, growl. Black Rails build well concealed nests on the ground, often under dense vegetation, and usually lay between 5-8 eggs per clutch. Chicks are precocial, meaning they are relatively mature and mobile from the moment of hatching. Very little is known about Black Rail behavior or interactions with other species.