Shoebill

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 where fish frequently surface to breathe. 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 typically feed in muddy waters and, 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. Shoebills are largely piscivorous but are assured predators of a considerable range of wetland vertebrates. Preferred prey species have reportedly included marbled lungfish (Protopterus aethiopicus) and Senegal bichir (Polypterus senegalus) and various Tilapia species and catfish, the latter mainly in the genus Clarias. Other prey eaten by this species has included frogs, water snakes, Nile monitors (Varanus niloticus) and baby crocodiles. More rarely, turtles, snails, rodents and small waterfowl have reportedly been eaten. There is a single unconfirmed report of shoebills feeding on lechwe (Kobus leche) calves. Given its sharp-edged beak, huge bill and wide gape, the shoebill can hunt large prey, often targeting prey bigger than is taken by other large wading birds. Fish eaten by this species are commonly in the range of 15 to 50 cm (5.9 to 19.7 in) long and weigh around 500 g (1.1 lb), though lungfish of as much as 1 m (3.3 ft) have been attacked. Snakes preyed upon are commonly from 50 to 60 cm (20 to 24 in) long. In the Bangweulu Swamps of Zambia, the main prey items fed to young by the parents were the catfish Clarias gariepinus (syn. C. mossambicus) and water snakes. In Uganda, lungfish and catfish were mainly fed to the young. The big beak is sometimes used to dig into pond-bottom mud to extract lungfish from their aestivation burrows.

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 population is estimated at between 5,000 and 8,000 individuals, the majority of which live in swamps in South Sudan, Uganda, eastern Democratic Republic of the Congo, and Zambia. There is also a viable population in the Malagarasi wetlands in Tanzania. BirdLife International has classified it as Vulnerable with the main threats being habitat destruction, disturbance and hunting. The bird is listed under Appendix II of the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES).