19-3-2015 JURONG, SINGAPORE - SHOEBILL (Balaeniceps rex)

The shoebill (Balaeniceps rex), also known as the whalebill, whale-headed stork, and shoe-billed stork is a large long-legged wading bird. It derives its name from its enormous shoe-shaped bill. It has a somewhat stork-like overall form and has previously been classified with the storks in the order Ciconiiformes based on this morphology. However, genetic evidence places it with pelicans and herons in the Pelecaniformes. The adult is mainly grey while the juveniles are more brown. It lives in tropical East Africa in large swamps from South Sudan to Zambia.

Molecular studies have found the hamerkop to be the closest relative of the shoebill.

The shoebill may have been known to Ancient Egyptians but was not classified until the 19th century, after skins and eventually live specimens were brought to Europe. John Gould very briefly described it in 1850 from the skin of a specimen collected on the upper White Nile by the English traveller Mansfield Parkyns. Gould provided a more detailed description in the following year. He placed the species in its own genus Balaeniceps and coined the binomial name Balaeniceps rex. The genus name comes from the Latin words balaena "whale", and caput "head", abbreviated to -ceps in compound words. Alternative common names are whalebill, shoe-billed stork and whale-headed stork.

The shoebill is distributed in freshwater swamps of central tropical Africa, from southern Sudan and South Sudan through parts of eastern Congo, Rwanda, Uganda, western Tanzania and northern Zambia. The species is most numerous in the West Nile sub-region and South Sudan (especially the Sudd, a main stronghold for the species); it is also significant in wetlands of Uganda and western Tanzania. More isolated records have been reported of shoebills in Kenya, the Central African Republic, northern Cameroon, south-western Ethiopia, Malawi. Vagrant strays to the Okavango Basin, Botswana and the upper Congo River have also been sighted. The distribution of this species seems to largely coincide with that of papyrus and lungfish. They are often found in areas of flood plain interspersed with undisturbed papyrus and reedbeds. When shoebill storks are in an area with deep water, a bed of floating vegetation is a requirement. They are also found where there is poorly oxygenated water. This causes the fish living in the water to surface for air more often, increasing the likelihood a shoebill stork will successfully capture it. The shoebill is non-migratory with limited seasonal movements due to habitat changes, food availability and disturbance by humans.

Petroglyphs from Oued Djerat, eastern Algeria, show that the shoebill occurred during the Early Holocene much more to the north, in the wetlands that covered the present-day Sahara Desert at that time.

The shoebill occurs in extensive, dense freshwater marshes. Almost all wetlands that attract the species have undisturbed Cyperus papyrus and reed beds of Phragmites and Typha. Although their distribution largely seems to correspond with the distribution of papyrus in central Africa, the species seems to avoid pure papyrus swamps and is often attracted to areas with mixed vegetation. More rarely, the species has been seen foraging in rice fields and flooded plantations.

The shoebill is noted for its slow movements and tendency to stay still for long periods, resulting in descriptions of the species as "statue-like". They are quite sensitive to human disturbance and may abandon their nests if flushed by humans. However, while foraging, if dense vegetation stands between it and humans, this wader can be fairly tame. The shoebill is attracted to poorly oxygenated waters such as swamps, marshes, and bogs where fish frequently surface to breathe. They also seem to exhibit migratory behaviors based upon differences in the surface water level. Immature shoebills abandon nesting sites which increased in the surface water level whereas adult shoebills abandon nesting sites which decreased in surface water level. It is suggested that both adult and immature shoebills prefer nesting sites with similar surface water levels. Exceptionally for a bird this large, the shoebill often stands and perches on floating vegetation, making them appear somewhat like a giant jacana, although the similarly sized and occasionally sympatric Goliath heron (Ardea goliath) is also known to stand on aquatic vegetation. Shoebills, being solitary, forage at 20 m (66 ft) or more from one another even where relatively densely populated. This species stalks its prey patiently, in a slow and lurking fashion. While hunting, the shoebill strides very slowly and is frequently motionless. Unlike some other large waders, this species hunts entirely using vision and is not known to engage in tactile hunting. When prey is spotted, it launches a quick violent strike. However, depending on the size of the prey, handling time after the strike can exceed 10 minutes. Around 60% of strikes yield prey. Frequently water and vegetation is snatched up during the strike and is spilled out from the edges of the mandibles. The activity of hippopotamus may inadvertently benefit the shoebill, as submerged hippos occasionally force fish to the surface.