The African darter (Anhinga rufa), sometimes called the snakebird, is a water bird of sub-Saharan Africa and Iraq. This species builds a stick nest in a tree and lays 3–6 eggs. It often nests with herons, egrets and cormorants.It often swims with only the neck above water, hence the common name snakebird. This, too, is a habit shared with the other anhingas.
Unlike many other waterbirds the feathers of the African darter do not contain any oil and are therefore not waterproof. Because of this, the bird is less positively buoyant and its diving capabilities are enhanced. After diving for fish, the feathers can become waterlogged. In order to be able to fly and maintain heat insulation, it needs to dry its feathers. Thus the African darter is often seen sitting along the waterside spreading its wings and drying its feathers in the wind and the sun along with cormorants which may share its habitat.
Source : Wikipedia