When discovered, it was not initially recognised as a swallow, and its structural differences from most of its relatives, including its stout bill and robust legs and feet, have led to its current placement in a separate subfamily shared only with the Asian white-eyed river martin.

The African river martin is a large swallow, mainly black with a blue-green gloss to the head and a greener tint to the back and wings.

The African river martin is migratory, wintering in coastal savanna in southern Gabon and the Republic of the Congo.

Breeding also occurs in these coastal areas, but it is unknown whether the migrants are raising a second brood or if there is a separate resident population.

However, due to a lack of detailed information about its breeding range and population numbers, this species is classed as Data Deficient by the International Union for Conservation of Nature (IUCN).

[3][4] The only other member of the subfamily is the white-eyed river martin Pseudochelidon sirintarae, known only from one site in Thailand and possibly extinct.

These two species possess a number of features which distinguish them from other swallows and martins, including their robust legs and feet, stout bills, large syrinxes (vocal organs) and different bronchial structure.

[3] Genetic studies confirmed that the two river martins form a distinct clade from the typical swallows in the subfamily Hirundininae.

Following a suggestion by the Thai bird's discoverer, Kitti Thonglongya,[12] Richard Brooke proposed in 1972 that the white-eyed river martin was sufficiently different from the African species to be placed in a separate genus Eurochelidon,[13] leaving the African river martin in a monotypic genus.

The black square tail is 4.8 cm (1.9 in) long,[3] and the soft feather shafts project beyond the barbed section.

[17] The African river martin has brown legs with a 1.5 cm (0.59 in) long tarsus, red eyes, pink eye-rings, and a broad orange-red bill.

It has a jingling song given in the aerial breeding display, and a number of contact calls, kee-r-r, chee-chee and similar short, unmusical sounds.

The swamp forests contain trees such as Symphonia globulifera, raffia palms and Mitragyna species, and the riverbanks are often lined with arrowroot.

[1] The African river martin has flight displays in which pairs or small groups chase each other while making jingling calls.

Wintering birds use elevated perches much more readily, landing on treetops, wires and roofs, and feed in flight over rivers and forests, often far from water.

The flocks feed on insects including flies, small beetles and bugs,[3] but mainly on winged ants.

[1] In January 2010, 250 martins were seen at a new location in Bakoumba, and single birds were observed in hirundine flocks near Moanda, at Mounana, and at Lekoni.

[26] Despite sightings of large flocks and a population which may exceed 100,000,[3] the species is classed by the IUCN as Data Deficient due to the lack of detailed information on its range and numbers.