The shoebill (Balaeniceps rex), also called the whale-headed stork, whalebill, and shoe-billed stork, is a large wading bird with long legs. It is named for its large, shoe-shaped bill. The bird has a body shape similar to storks and was once grouped with storks in the order Ciconiiformes. However, scientific studies show it is related to pelicans and herons in the order Pelecaniformes. Adult shoebills are mostly gray, while young birds are brown. They live in tropical East Africa, in large swamps from South Sudan to Zambia.
Taxonomy
The shoebill may have been known to Ancient Egyptians, but Europeans did not classify it until the 19th century, after dried skins and later live birds were brought to Europe. In 1850, John Gould briefly described the shoebill based on a skin collected from the upper White Nile by English traveler Mansfield Parkyns. The following year, Gould gave a more detailed description and placed the species in its own genus, Balaeniceps. He named it Balaeniceps rex, combining Latin words for "whale" and "head." Other names for the shoebill include whalebill, shoe-billed stork, and whale-headed stork.
Traditionally, the shoebill was grouped with storks (Ciconiiformes). This classification remained in the Sibley-Ahlquist taxonomy, which placed many unrelated birds into the same group. In 1957, Patricia Cottam suggested the shoebill might be related to pelicans based on bone evidence. In 1995, Konstantin Mikhailov studied the structure of shoebill eggshells under a microscope and found they closely resembled those of other pelicans, which also have a thick layer of material covering their shells. In 2003, scientists again suggested the shoebill might be closely related to pelicans (based on anatomy) or herons (based on biochemical tests). A 2008 DNA study confirmed the shoebill belongs to the Pelecaniformes group.
So far, two ancient relatives of the shoebill have been discovered: Goliathia from the Early Oligocene in Egypt and Paludiavis from the Late Miocene in Pakistan and Tunisia. A mysterious African fossil bird called Eremopezus has been noted to share some features with the shoebill and the secretary bird.
Description
The shoebill is a tall bird, typically measuring between 110 to 140 cm (43 to 55 in) in height, with some birds reaching up to 152 cm (60 in). From tail to beak, the bird’s length ranges from 100 to 140 cm (39 to 55 in), and its wingspan measures 230 to 260 cm (7 ft 7 in to 8 ft 6 in). The shoebill weighs between 4 to 7 kg (8.8 to 15.4 lb), with males usually weighing about 5.6 kg (12 lb) and females about 4.9 kg (11 lb). The most distinctive feature of the shoebill is its large, round bill, which is pinkish with irregular grey markings. The top part of the upper beak (called the culmen) measures 18.8 to 24 cm (7.4 to 9.4 in), making it the third-longest bill among living birds, after pelicans and large storks. The bill is also very wide, sometimes matching the size of pelican bills. The upper beak has a strong ridge and ends in a sharp point. The bird’s legs are dark and long, with the lower leg (tarsus) measuring 21.7 to 25.5 cm (8.5 to 10.0 in). The shoebill’s feet are unusually large, with the middle toe reaching 16.8 to 18.5 cm (6.6 to 7.3 in) in length. This helps the bird stand on water plants while hunting. The shoebill’s neck is shorter and thicker compared to other long-legged wading birds like herons and cranes. Its wings are broad, with a wing chord length of 58.8 to 78 cm (23.1 to 30.7 in), and are well-suited for soaring.
Adult shoebills have blue-grey feathers with darker, slaty-grey flight feathers. The chest area has longer feathers with dark centers. Juvenile birds have similar colors but are darker and have a brownish tint. When newly hatched, shoebill chicks have small, silvery-grey bills that grow larger by 23 days and become fully developed by 43 days.
Shoebills are usually quiet but make loud, clattering noises with their bills during nesting. They also produce a sound similar to a cow’s moo and high-pitched whines. Both young birds and adults use bill-clattering to communicate during nesting. When begging for food, young shoebills make sounds that resemble human hiccups. In one instance, an adult shoebill was heard making rough croaks to show aggression toward a nearby marabou stork (Leptoptilos crumeniferus).
The shoebill flies with its wings held flat and its neck folded, similar to pelicans and storks in the genus Leptoptilos. It flaps its wings about 150 times per minute, one of the slowest rates among birds, except for larger storks. The bird alternates between flapping and gliding in cycles lasting about 7 seconds. Its gliding distance is between that of large storks and the Andean condor (Vultur gryphus). When startled, shoebills typically fly only 100 to 500 meters (330 to 1,640 ft). Long-distance flights are rare, and most travel stays within 20 meters (66 ft) of their nesting or feeding areas.
Distribution and habitat
The shoebill lives in freshwater swamps of central tropical Africa, including southern Sudan, South Sudan, eastern Congo, Rwanda, Uganda, western Tanzania, and northern Zambia. The largest populations are found in the West Nile region and South Sudan, especially in the Sudd, which is a key area for the species. Shoebills are also common in wetlands of Uganda and western Tanzania. Occasionally, they have been seen in Kenya, the Central African Republic, northern Cameroon, south-western Ethiopia, and Malawi. Some shoebills have been spotted in the Okavango Basin in Botswana and the upper Congo River. Shoebills usually live in areas with papyrus plants and lungfish. They often stay in floodplain areas covered with undisturbed papyrus and reedbeds. When shoebill storks are in deep water, floating vegetation is needed for them to hunt. They also live in water with low oxygen levels, which causes fish to surface for air more often, making it easier for shoebills to catch them. Shoebills do not migrate, but they may move short distances due to changes in their habitat, food supply, or human activity.
Ancient carvings in eastern Algeria show that shoebills lived much farther north during the Early Holocene, when wetlands covered the Sahara Desert.
Shoebills are found in large, dense freshwater marshes. Most wetlands that support shoebills have undisturbed Cyperus papyrus and reed beds made of Phragmites and Typha plants. Although shoebills are often found where papyrus grows in central Africa, they avoid areas with only papyrus and prefer places with mixed vegetation. Rarely, shoebills have been seen hunting in rice fields and flooded plantations.
Behaviour and ecology
Shoebills are known for moving slowly and staying still for long periods, which makes them appear "statue-like." They are very sensitive to humans and may leave their nests if disturbed. However, when dense vegetation separates them from humans, they may stay calm. Shoebills often live in areas with poor water quality, such as swamps, marshes, and bogs, where fish come to the surface to breathe. They may also move based on changes in water levels. Young shoebills leave nests when water levels rise, while adults leave when water levels drop. Both young and adult shoebills prefer nesting areas with similar water levels.
Unlike most large birds, shoebills often stand on floating plants, resembling giant jacanas. The similarly sized Goliath heron also stands on aquatic plants. Shoebills are solitary and forage at least 20 meters apart, even in areas with many birds. They hunt patiently, moving slowly and waiting. They rely on sight, not touch, to find prey. When they spot prey, they strike quickly, but handling large prey can take over 10 minutes. About 60% of their strikes result in catching prey. Water and plants are often caught during strikes and spilled from their beaks. Hippopotamuses may help shoebills by forcing fish to the surface when they swim underwater.
Shoebills are solitary during breeding. Their nests are spaced less than 3 per square kilometer, unlike other birds that nest in groups. A breeding pair defends a territory of 2 to 4 square kilometers from other shoebills. In northern and southern parts of their range, nesting begins after rains stop. In central areas, they nest near the end of the wet season so eggs hatch at the start of the next wet season. Both parents build nests on floating platforms, clearing an area about 3 meters wide. The platform is partially submerged and can be up to 3 meters deep. The nest itself is 1 to 1.7 meters wide and made of aquatic plants. One to three white eggs are laid, each about 80 to 90 mm tall and 56 to 61 mm wide, weighing around 164 grams. Incubation lasts about 30 days. Both parents care for the nestlings, with females possibly being more attentive. During hot weather, they cool eggs by swallowing water and pouring it onto the nest. Parents feed nestlings by regurgitating food directly into their bills. Shoebills rarely raise more than one chick, though they may hatch more. Younger chicks often die or act as backups if the oldest chick is weak. Chicks fledge around 105 days and can fly well by 112 days. They may be fed for a month or more after fledging. Shoebills take three years to reach sexual maturity.
Shoebills are hard to observe while nesting, so cameras are used to study them from a distance. Their early breeding helps because chicks are cared for longer.
Shoebills mainly eat fish but also hunt other wetland animals. Common prey includes marbled lungfish, African lungfish, Senegal bichir, tilapia, and catfish. They also eat frogs, watersnakes, Nile monitors, and baby crocodiles. Occasionally, they eat small turtles, snails, rodents, waterfowl, and carrion.
Shoebills have a large, sharp beak and wide mouth, allowing them to hunt large prey. In Zambia’s Bangweulu Swamps, they often eat fish 15 to 50 cm long. Parents feed young catfish and watersnakes up to 50 to 60 cm long. In Uganda, young are fed lungfish and catfish. In Tanzania, larger lungfish and catfish, up to 60 to 80 cm, are eaten. The largest fish caught was 99 cm long. Large prey is often cut into pieces and swallowed in parts. The time to catch and swallow prey ranges from 2 to 30 minutes, depending on size. However, large prey is sometimes stolen by African fish eagles.
Relationship to humans
This bird is one of the five most popular birds in Africa among birdwatchers. It is calm around people and does not act aggressively. Scientists observed a bird on its nest from a distance of about 2 meters (6 feet 7 inches). Shoebills are often found in zoos, but they rarely breed in captivity. However, they have successfully bred at Pairi Daiza in Belgium and at Tampa's Lowry Park Zoo in Florida.
Starting in 2014, the shoebill became a topic of internet memes, partly because of its unusual appearance and its habit of standing still for long periods. For example, a video shows a shoebill standing in the rain while looking directly at the camera. These memes later appeared on TikTok, helping to introduce this lesser-known bird to more people. The shoebill also inspired the design of the Loftwing birds in the 2011 video game The Legend of Zelda: Skyward Sword.
Status and conservation
The population is estimated to be between 5,000 and 8,000, with most of them living in swamps in South Sudan, Uganda, eastern Democratic Republic of the Congo, and Zambia. A group that can survive also lives in the Malagarasi wetlands in Tanzania. BirdLife International has classified this bird as Vulnerable because the main threats include 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. Habitat destruction and degradation, hunting, disturbance, and illegal capture are all causing the species to decline. Farming and creating pastures for cattle have led to major habitat loss. People living near shoebill habitats sometimes take their eggs and young for food and trade. Frequent fires in southern Sudan and fires set intentionally to help grazing also harm their habitat. In some swamps in Sudan, water is being drained to build a canal to manage nearby waterways, which causes more habitat loss.