The Hamerkop (Scopus umbretta) is a medium-sized wading bird and the sole member of the family Scopidae. The shape of its head with a curved bill and crest at the back is reminiscent of a hammer, hence its name.

The Hamerkop occurs in Africa south of the Sahara, Madagascar and coastal southwest Arabia in all wetland habitats, including irrigated land such as rice paddies, as well as in savannas and forests.

The Hamerkop's behavior is unlike other birds. One unusual feature is that up to ten birds join in "ceremonies" in which they run circles around each other, all calling loudly, raising their crests, fluttering their wings. Another is "false mounting", in which one bird stands on top of another and appears to mount it, but they may not be mates and do not copulate.

The strangest aspect of Hamerkop behavior is the huge nest, sometimes more than 1.5 m across, comprising perhaps 10,000 sticks and strong enough to support a man's weight. The birds decorate the outside with any bright-coloured objects they can find. When possible, they build the nest in the fork of a tree, often over water, but if necessary they build on a bank, a cliff, a human-built wall or dam, or on the ground. These birds are compulsive nest builders, constructing 3 to 5 nests per year whether they are breeding or not.

There are many legends about the Hamerkop. It is known in some cultures as the lightning bird, and the Kalahari Bushmen believe or believed that being hit by lightning resulted from trying to rob a Hamerkop's nest. They also believe that the inimical god Khauna would not like anyone to kill a Hamerkop. According to an old Malagasy belief, anyone who destroys its nest will get leprosy, and a Malagasy poem calls it an "evil bird".