The river martins form a distinctive subfamily Pseudochelidoninae within the swallow and martin bird family Hirundinidae. The two species are the African river martin "Pseudochelidon eurystomina", found in the Congo and Gabon, and the white-eyed river martin "Pseudochelidon sirintarae", known only from one site in Thailand. These are medium-sized, largely black swallows that have a light buoyant flight and feed on insects caught in the air. They appear to be more terrestrial than other swallows, frequently walking rather than perching, and the white-eyed may be crepuscular. The African species excavates nest holes in sandy ridges in rivers, while the breeding locations and habits of the Asian bird are unknown.