Hamerkop

About the hamerkop

The hamerkop is a medium-sized water bird with brown plumage, found across mainland Africa, Madagascar, and coastal southwest Arabia. Its name comes from the Afrikaans word for "hammerhead," a reference to the shape of its head, which combines a long bill with a crest at the back to create a hammer-like silhouette. It is the only living species in its genus, Scopus, and its family, Scopidae, and one extinct relative, Scopus xenopus, is known only from Pliocene-era fossil bones found in South Africa. For a long time the hamerkop was grouped with the storks and their relatives, but it is now considered closer to pelicans and the shoebill.

The hamerkop stands about 56 cm (22 in) tall and weighs around 470 g (17 oz), with a smaller West African subspecies, S. u. minor, that is also darker in color. Its plumage is drab brown with a purple iridescent sheen on the back, and its tail carries faint darker barring. Males and females look alike, and young birds resemble adults. The bill is long — 80 to 85 mm (3.1–3.3 in) — slightly hooked, thin, and compressed, especially on the lower half; it starts out brown in young birds and turns black by fledging. The legs are proportionately short and black, feathered only up to the upper tibia, and the feet are partially webbed for reasons that aren't well understood, with a comb-like middle toe similar to a heron's.

In flight, the hamerkop stretches its neck forward like a stork or ibis, but coils it back like a heron when flapping, and it soars less often than storks or the shoebill. On the ground its walk is jerky and rapid, with the head and neck moving back and forth with each step, and it sometimes holds its wings out while running for extra stability.

Behavior and diet

The hamerkop is active mainly during the day, often resting at midday when the heat is highest, and can be crepuscular around dusk, though it is not nocturnal. Alone, it is mostly silent apart from a shrill "nyip" or "kek" flight call, but in pairs or groups it becomes vocal, using cackles, nasal rattles, and a distinctive social "yip-purr" call made with the neck extended, sometimes accompanied by wing flapping, when three to twenty birds gather. Groups also engage in "false mounting," where one bird stands on another without copulating — a behavior seen between mates and non-mates alike, including between members of the same sex — and in mutual preening, where one bird presents its face or the back of its head to another.

As a feeder, the hamerkop is a generalist, though amphibians and fish make up the largest part of its diet, along with shrimp, insects, and rodents; the balance shifts by location, with clawed frogs and tadpoles important in East and Southern Africa and small fish dominating in Mali. It typically hunts by walking through shallow water, locating prey by sight in clear water or by probing its open bill into mud when the water is murky, and it will shuffle a foot along the bottom or flare its wings to flush hidden prey. It also hunts on the wing, flying low with legs dangling before dipping down to snatch prey and swallow it in flight, a technique recorded catching prey in 27 of 33 attempts in one session. It has also been seen foraging alongside grazing cattle and buffalo, fishing off the backs of hippopotamuses, and following bands of banded mongooses to catch frogs the mongooses flush out.

The hamerkop is best known for its enormous nest, sometimes more than 1.5 m (nearly 5 ft) across and strong enough to bear a person's weight. Pairs build a stick-and-mud platform, then walls and a domed roof, with a mud-plastered entrance leading through a tunnel up to 60 cm (24 in) long to an internal nesting chamber — an unusual design for a wading bird. Nests take 10 to 14 weeks to build and may require around 8,000 sticks or bunches of grass, and pairs are compulsive builders, constructing three to five nests a year whether breeding or not. Clutches hold three to seven eggs, both parents incubate, and incubation takes around 30 days from the first egg to hatching. Chicks first leave the nest 44 to 50 days after hatching but keep using it for roosting until about two months old.

Range and habitat

The hamerkop occurs in Africa south of the Sahara, in Madagascar, and along coastal southwest Arabia. It requires shallow water for foraging and turns up in nearly every kind of wetland habitat: rivers, streams, seasonal pools, estuaries, reservoirs, marshes, mangroves, irrigated land such as rice paddies, savannas, and forests. In Tanzania it has recently begun feeding on rocky shores as well, and in Arabia it favors rocky wadis with running water and trees. Most hamerkops are sedentary within a paired territory, though some populations move into suitable habitat only during the wet season. The species tolerates people well and readily feeds and breeds in villages and other human-altered landscapes.

Conservation status

The hamerkop is listed as Least Concern on the IUCN Red List, in a 2016 assessment by BirdLife International. It is not globally threatened and is locally abundant across mainland Africa and Madagascar.

Folklore has helped it. In several cultures, disturbing a hamerkop or its nest is believed to bring lightning strikes, leprosy or other misfortune, a belief that has given the bird informal protection over time.