Behaviour This species is a intra-African migrant^{1, 2, 4}, undertaking post-breeding¹ seasonal movements in relation to water level changes (departing when an area becomes flooded² and arriving when bare rocks are exposed by drought⁴). It breeds during the dry season^{1, 2} in small, loose colonies of up to 26 pairs^{1, 4}, and often with many attendant non-breeders⁴. The species is strongly gregarious even when not breeding^{1, 2} and is commonly found in groups of 2-10², sometimes gathering in flocks of more than 100 individuals prior to migration⁴. It is mainly crepuscular, foraging on the wing at dawn and dusk¹. Habitat This species shows a preference for exposed emergent rocks in large rivers and streams^{1, 3}, sometimes also frequenting mud and sandbars by lagoons², dams and ponds on migration⁴. When rivers flood it may move to coastal areas, or other inland waters¹. Diet This species is insectivorous, its diet consisting chiefly of flies (including tsetse flies Glossina), ants, beetles¹, moths, grasshoppers, leaf cicadas and termite alates⁴. Breeding site Eggs are laid directly into shallow depressions, cracks, and on the flat tops of bare rocks^{1, 2} surrounded by deep and sometimes fast-flowing water³, or on rock ledges and under overhangings⁴. Most nests are found within a metre or two of the water level⁷.

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This species is threatened by dam construction^{4, 5, 7} as it is vulnerable to the fluctuating water levels of dammed rivers, and the loss of suitable habitat through the creation of lakes^{1, 4, 5, 6, 7}. Destruction of the species' riverine rocky habitat has occurred in southern Africa through extensive siltation of the southeastern lowveld rivers⁷. Utilisation Nestlings and eggs may be gathered for human use from breeding areas along the Zambezi River⁶.