There’s no mistaking the hamerkop or its distinctive nest. But the bird’s unusual appearance is easily rivalled by its out-of-the-ordinary behaviour. By Albert and Marietjie Froneman

The hamerkop is an African endemic and the only member of the family Scopidae (one extinct species is known from the fossil record). They are a familiar sight near open shallow water and are widespread across South Africa. Hamerkops are always associated with fresh-water wetlands and rivers.

When feeding, they shuffle and stamp their feet in shallow water to disturb insects, worms, fish, tadpoles and frogs. Using their formidable beak, they swiftly grab prey forced out in this way. The hamerkop’s large bill is well adapted to grabbing slippery aquatic prey. Food is usually swallowed whole. These birds are very agile and have been seen to snatch surfacing tadpoles or fish in flight over the water.

The hamerkop earns its name from the hammer-shaped head. Photo by Albert Froneman

Why is it called a hamerkop?

This wading bird is named after the shape of its head. The crest on the back of its head and curved bill resemble a hammer. The rest of the bird is fairly non-descript brown with slightly darker tail feathers, and thin, black legs. Females look similar to males but are slightly smaller.

Disguised as raptors

In flight, the hamerkop’s wings appear broad and the neck is not pulled back but only slightly curved. Being almost buzzard sized, they are often mistaken for a raptor by birdwatchers – and even by small birds. Their broad winged profile in flight and soaring behaviour are the culprits. Together these make them look just like one of those confusing, difficult-to-identify medium-sized, brown raptors.

Ritualised displays

Hamerkops are not territorial and can aggregate in large groups of up to 20 individuals. Social interactions are usually very noisy, and they often utter their characteristic squeaky, whistling cries. They have a wide range of ritualised displays, including one called false mounting. This involves one or more birds standing on the back of the other(s). When three or four birds are involved, ‘stacking’ would be a more appropriate and descriptive term.

An interesting aspect of hamerkop behaviour is their ritualised displays. One such display involves one or more birds standing on the back of the other(s).  Photo by Marietjie Froneman

Compulsive nest builders

Although the hamerkop breeds throughout the year, the breeding season shows a slight bias towards the dry season. They are solitary, monogamous nesters and they are compulsive nest builders. They may build 3-5 nests per year whether they breed or not.

They construct their gigantic nests in trees or on cliffs close to water, using a variety of materials. These vary from sticks and grass to bits of rubbish, leather, old bones and even strips of cloth. Interestingly, the nest is often adorned with unusual articles that range from old clothes and pieces of newspaper to pot fragments, plastic and even tinfoil. They seem to have an affinity for materials in the colour blue.

A hamerkop nest can measure up to 2m in diameter and is a collection of sticks, grass and various scavenged items. Photo by Marietjie Froneman

Home sweet home

The huge nest structure has an entrance hole angled upwards, just big enough for an adult hamerkop to pass though. To enter, the bird has to fly upwards towards the nest with enough speed to close its wings and enter through the entrance like a projectile. Nest structures can measure up to 2m in diameter and 1-2m tall. They usually take up to two months to construct and can weigh up to 50kg. The same nest is often used year after year.

The nest chamber of about 80cm in diameter is mud-lined. Three to nine white eggs are laid but they quickly become mud stained. Incubation is around 30 days and chicks fledge after about 50 days. Young are often left alone for long periods of time when the parents forage. Breeding success is about 30% with the main cause of losses interference by other animals.

The hamerkop in culture

In many African societies the hamerkop is regarded with superstitious awe and ill omen, featuring prominently in folklore. This may be as a result of the the bird’s strange habit of collecting discarded items to decorate the top of their nests. However, in Nigeria, the hamerkop is hunted for traditional medicine. Currently, the bird is classified as least concern by the IUCN Red List of Threatened Species, but deterioration in wetland water quality could pose a risk.

This summer, as you’re travelling around your favourite park, keep an eye open for the hamerkop around water bodies. Don’t forget to look out for their huge and kooky nests.