page_title: River martin
section_title: Behaviour
hierarchical_section_title: River martin / Behaviour
caption_attribution_description: fr:Congo (fleuve) river at fr:Maluku (Congo); fr:jacinthe d'eau on the bank
context_page_description: 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.
  When the African river martin was first discovered in the 19th century, Gustav Hartlaub thought it was a roller, and later authors either placed it in its own family, or with the woodswallows. Study of the anatomy revealed that the species was closest to the swallows and martins, but that it possessed a number of distinctive features, such as its robust legs and feet and stout bill. These indicated that it should be placed in a separate subfamily.
context_section_description: Breeding behaviour is known only for the African river martin. It nests in large colonies of up to 800 birds from December to April, when the river levels are low. Each pair excavates a 1–2 m (39–79 in) long tunnel in the exposed sandbanks. 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. It has chasing flight displays and will walk on the ground; it also displays on the ground, but the function of this is uncertain. It rarely perches during the breeding season. Although it has been assumed that the breeding habits of the white-eyed species resemble those of the African species, distinctive differences in foot and toe morphology suggest that it might not use a burrow for nesting.
  The African river martin feeds in flocks over river and forest, often far from water. It eats insects, mainly taking winged ants. The flight is strong and fast, interspersed with glides. Wintering birds regularly perch on treetops, wires and roofs. The white-eyed river martin feeds on insects, including beetles, which are caught on the wing. Given its size and unusual mouth structure, it may take larger insects than other swallows. This species is described as graceful and buoyant in flight, and, like its African relative, appears reluctant to use perches. This behaviour, together with its unusual toe-shape and the fact that mud was found on the toes of one of the first specimens, suggests that this species may be relatively terrestrial. In winter, it roosts with barn swallows in reedbeds. Pamela C. Rasmussen suggested that, given its unusually large eyes, the species might be nocturnal or crepuscular, a factor that could make it highly cryptic and thus partly explain how such a distinctive species remained undetected for so long. Although the fact that the first specimens were supposedly collected roosting at night in reed-beds might be a contraindication, it is possible that the birds might not actually have been caught at the roost; or they might be crepuscular, feeding at dawn and dusk; or they might be capable of both diurnal and nocturnal behaviour, depending on the season or local circumstances.
caption: The Congo River is a major breeding area of the African river martin
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