The hammerkop, also known as the hammerhead, hammerhead stork, anvilhead, umber bird or tufted umber is a wading bird that lives in wetlands in southwest Arabia, Madagascar and Africa south of the Sahara.

Hammerkops build enormous nests that can be 5 feet across and are made up of thousands of sticks. The nests are dome-shaped, plastered with mud and decorated with brightly colored objects, bones, or pieces of cloth. The hammerkop's nest contains several chambers.

Hammerkop; photo by Joachim HuberNests are usually built in tree forks, but can be built on cliffs, banks, on the ground or on the walls of dams or canals made by humans.

Hammerkops build nests compulsively, even when it is not breeding season. A pair of nests may build many nests each year.

Other birds, as well as bees, will sometimes take over hammerkop nests that have been abandoned.

Part of a hammerkop nest, photo by Jerry FriedmanThe female lays between 3 and 7 eggs. Both parents incubate the eggs and care for the young.

African legends say that many birds work together to build the hammerkop's nest.

Some cultures say that the hammerkop is a sign of good luck, while others believe that it is an evil omen.

The hammerkop has brown feathers. Its back has some iridescent purple.

It eats insects, snails, worms, frogs and fish.