The African River Martin (Pseudochelidon eurystomina) is a passerine bird of the swallow family Hirundinidae. It is one of two members of the river martin subfamily Pseudochelidoninae, which possess distinctive features which mark them out from other swallows and martins. It breeds along the Congo River and its tributary, the Ubangi and is fairly common within its restricted range, despite being caught in large numbers by the local population for food. It is migratory, wintering in coastal savannah in southern Gabon. It has recently been discovered to also breed in that area.
When the African River Martin was first discovered in the 19th century, it was not thought to be a member of the swallow and martin family; Hartlaub placed it with the rollers, and later authors either placed it in its own family, or with the woodswallows. Study of the anatomy of the species by Lowe (1938) revealed that the species was closest to the swallows and martins, but sufficiently distinct to be placed in a separate subfamily Pseudochelidoninae.
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 distinctive features which mark them out from other swallows and martins, including their robust legs and feet, and stout bill.
The extent of their differences from other swallows and the wide geographical separation of these two martins suggest that they are relict populations of a group of species that diverged from the main swallow lineage early in its evolution.
The genus name Pseudochelidon (Hartlaub, 1861) comes from the Ancient Greek prefix ?????/pseudo "false" and ???????/chelid˘n, "swallow".
The African and Asian Pseudochelidon species differ markedly in the size of their bills and eyes, suggesting that they have different feeding ecologies, with White-eyed River Martin probably being able to take much larger prey. The Thai species also has a swollen, hard gape (fleshy interior of the bill) unlike the soft, more fleshy, and much less prominent gape of African River Martin, and is sometimes placed in a separate monotypic genus Eurochelidon.
Distribution and habitat
Congo River near Maluku
The African River Martin breeds along the Congo River and its tributary, the Ubangi in the Democratic Republic of the Congo. Its breeding habitat is forested rivers with islands with sandy shores for breeding. It is non-migratory, wintering in coastal savannah in southern Gabon, where it has recently been discovered to also breed in beach ridges in coastal savanna.
The adult African River Martin is large, at 14 cm long. It is mainly black with a silky blue-green gloss, distinctly green on the back. It has a red eye and pink eye ing, and a broad orange red bill. The tail is square. The sexes are similar, but juveniles are dull sooty brown.
This species gives a short chee chee or similar call, and flocks call together, cheer-cheer-cheer. This martin is very vocal on migration, giving harsh gull-like calls.
The habitat requirement of this species is forested rivers with sandbanks for breeding. The breeding season is December to April when the river is low. This species breeds in large colonies of up to 800 birds, each pair excavating a 1-2 m long tunnel in the sandbars. The pocket at the end of the tunnel has a few twigs and leaves to serve as a nest, onto which two to four unspotted white eggs are laid.
On the breeding grounds it rarely perches, but will walk on the ground; however, wintering birds regularly perch on treetops, wires and roofs. The African River Martin feeds in flocks over river and forest, often far from water on insects, mainly taking winged ants. The flight is strong and fast, interspersed with glides. It has chasing flight displays, and also displays on the ground, but the function of these displays is uncertain.
The total population size of the African River Martin is unknown; in the late 1980s, it appeared to be common, if local, and large numbers were seen on migration in Gabon However, it is particularly poorly known in the Democratic Republic of the Congo (DRC) and it is not known if there is any relationship between the birds breeding in the DRC and those breeding in coastal areas of Gabon and Congo. In the 1950s, the species was caught and eaten in large quantities in the DRC by the local population, and this practice could be on the increase. Breeding colonies in river sandbars are liable to flooding. Due to the lack of detailed information, the species is classed as Data Deficient.