The hamerkop (Scopus umbretta), also called the umbrette, is a medium-sized water bird with brown plumage. It is found in mainland Africa, Madagascar and Arabia, living in a wide variety of wetlands, including estuaries, lakesides, fish ponds, riverbanks, and rocky coasts. The shape of its head, with its long bill and crest at the back, gives this species its name, hamerkop being the Afrikaans word for hammerhead. Long considered to sit with the Ciconiiformes, the species and its family is now placed with the Pelecaniformes, its closest relatives thought to be the pelicans and the shoebill. It is the only living species in the genus Scopus and the family Scopidae. The hamerkop is a sedentary bird that often shows local movements. Usually hunting in shallow water, either by sight or touch, it feeds mostly on fish and amphibians; however, the species is adaptable and will take any prey it can. The species is renowned for its enormous nests, several of which it builds during the breeding season. Unusually for a wading bird, the species constructs its nest with an internal nesting chamber where the eggs are laid. Both parents incubate the eggs and raise the chicks. The species is not globally threatened and is locally abundant in mainland Africa and Madagascar. The International Union for Conservation of Nature (IUCN) has assessed it as being of least concern.
Taxonomy and systematics The hamerkop was first described by the French zoologist Mathurin Jacques Brisson in 1760 in his landmark Ornithologia, which was published two years after the tenth edition of Carl Linnaeus' Systema Naturae. The species was subsequently described and illustrated by French polymath Comte de Buffon. When the German naturalist Johann Friedrich Gmelin revised and expanded Linnaeus's Systema Naturae in 1788 he included the hamerkop and cited the earlier authors. He placed the species in the genus Scopus that had been introduced by Brisson and coined the binomial name Scopus umbretta. Brisson's names for bird genera were widely adopted by the ornithological community despite the fact that he did not use Linnaeus' binomial system. The International Commission on Zoological Nomenclature ruled in 1911 that Brisson's genera were available under the International Code of Zoological Nomenclature, so Brisson is considered to be the genus authority for the hamerkop. The generic name, Scopus, is derived from the Ancient Greek skia for "shadow". The specific name umbretta is modified from the Latin for "umber" or "dark brown". The hamerkop is sufficiently distinct to be placed in its own family, although the relationships of this species to other families has been a longstanding mystery. The hamerkop was usually included in the Ciconiiformes, but is now thought to be closer to the Pelecaniformes. Recent studies have found that its closest relatives are the pelicans and shoebill. Although the hamerkop is the only living member of its family, one extinct species is known from the fossil record. Scopus xenopus was described by ornithologist Storrs Olson in 1984 based on two bones found in Pliocene deposits from South Africa. Scopus xenopus was slightly larger than the hamerkop and Olson speculated based on the shape of the tarsus that the species may have been more aquatic. The hammerkop fossil record also includes fossil tracks from 90-130 thousand years ago. The hamerkop is also known as the hammerkop, hammerkopf, hammerhead, hammerhead stork, umbrette, umber bird, tufted umber, or anvilhead.
Subspecies Two subspecies are recognized—the widespread nominate race S. u. umbretta and the smaller of West African S. u. minor, described by George Latimer Bates in 1931. Two other subspecies have been proposed. S. u. bannermani of south-west Kenya is usually lumped with the nominate race. Birds in Madagascar have been suggested to be distinct, in which case they would be placed in the subspecies S. u. tenuirostris. That proposed subspecies was described by Austin L. Rand in 1936. It has also been suggested that birds near the Kavango River in Namibia may be distinct, but no formal description has been made.
Description
The hamerkop is a medium-sized waterbird, standing 56 cm (22 in) high and weighing 470 g (17 oz), although the subspecies S. u. minor is smaller. Its plumage is a drab brown with purple iridescence on the back; S. u. minor is darker. The tail is faintly barred with darker brown. The sexes are alike and fledglings resemble adults. The bill is long, 80 to 85 mm (3.1–3.3 in), and slightly hooked at the end. It resembles the bill of a shoebill, and is quite compressed and thin, particularly at the lower half of the mandible. The bill is brown in young birds, but becomes black by the time a bird fledges.
The neck and legs are proportionately shorter than those of similar looking Pelecaniformes. The bare parts of the legs are black and the legs are feathered only to the upper part of the tibia. The hamerkop has, for unknown reasons, partially webbed feet. The middle toe is comb-like (pectinated) like a heron's. Its tail is short and its wings are big, wide, and round-tipped; it soars well, although it does so less than the shoebill or storks. When it does so, it stretches its neck forward like a stork or ibis, but when it flaps, it coils its neck back something like a heron. Its gait when walking is jerky and rapid, with its head and neck moving back and forth with each step. It may hold its wings out when running for extra stability.
Distribution and habitat The hamerkop occurs in Africa south of the Sahara, Madagascar, and coastal south-west Arabia. It requires shallow water in which to forage, and is found in all wetland habitats, including rivers, streams, seasonal pools, estuaries, reservoirs, marshes, mangroves, irrigated land such as rice paddies, savannahs, and forests. In Tanzania, it has also recently begun to feed on rocky shores. In Arabia, it is found in rocky wadis with running water and trees. Most are sedentary within their territories, which are held by pairs, but some migrate into suitable habitat during the wet season only. The species is very tolerant of humans and readily feeds and breeds in villages and other human-created habitats.
Behaviour and ecology The hamerkop is mostly active during the day, often resting at noon during the heat of the day. They can be somewhat crepuscular, being active around dusk, but are not nocturnal as has sometimes been reported.
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