The hamerkop (Scopus umbretta), also known as hammerkop, hammerkopf, hammerhead, hammerhead stork, umbrette, umber bird, tufted umber, or anvilhead, has a head with a long bill and crest at the back which is reminiscent of a hammer, hence its name. It ranges from Africa, Madagascar to Arabia, in wetlands of a wide variety, including estuaries, lakesides, fish ponds, riverbanks and rocky coasts in Tanzania. The hamerkop has, for unknown reasons, partially webbed feet. The strangest aspect of hamerkop behaviour is the huge nest, sometimes more than 1.5 metres (4 ft 11 in) 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.