Overview

Brief Summary

Biology

A predominantly solitary species, in which adults come together only to breed. The breeding season is ill-defined, but some evidence suggests that it coincides with the onset of the dry season (5), to prevent flooding of the nests (2). One to three eggs are laid in large flat nests built amid swamp grasses (5), and incubated for approximately 30 days (7). Young can stand only after two and a half months, and are able to hunt after three and a half, but remain dependent on their parents for food until somewhat older (2). It takes three to four years for young to become sexually mature (5) and individuals have been known to live 36 years in captivity (9). The shoebill usually feeds at night (7), hunting chiefly by ambush, standing motionless waiting for prey, then attacking with remarkable speed and power (5). Prey is grasped from the water in the bird's sharp, hooked beak, which grips, crushes and pierces in one instant. African lungfish are common prey, alongside a variety of smaller and larger fish, amphibians, water-snakes, lizards, turtles, rats, young waterfowl and even young crocodiles (5).
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Description

The unmistakable, prehistoric-looking shoebill is one of the most impressive birds to be found in Africa. A mysterious inhabitant of impenetrable marshes, this tall wading bird possesses a bluish-grey plumage, long black legs, broad wings and muscular neck, but is undeniably dominated by its fantastically unique 'shoe-like' bill, from which its common name derives. This imposing greenish-brown bill is huge and powerful at a remarkable 23 cm long and 10 cm broad, ending in a ferociously sharp nail-like hook (5). The eyes are a pale yellow and at the back of the head exists a small hood of feathers (2). Primitive in appearance, the bird has baffled taxonomists over its affinities, showing similarities to storks, pelicans, hamerkop and herons in some respects, yet remaining different in others. Indeed, the shoebill's defiantly unusual appearance indicates how much it has evolved to occupy a highly individual niche, and one which happens to tie it to some of the most inaccessible habitat in the world (5).
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Comprehensive Description

Description

Large grey, stork-like waterbird with a fantastically unique bill.

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The Shoebill stork's most prominent feature is an enormous bill, which ends in a sharp curved hook and is said to resemble a wooden shoe. Shoebills stand 110 to 140 cm (43 to 55 in.); males are taller than females and have longer bills. Their stilt-like black legs end in feet characterized by extremely long toes.

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Distribution

Range Description

Balaeniceps rex is widely but very locally distributed in large swamps from South Sudan to Zambia. Approximate national estimates proposed by T. Dodman in litt. (2002) to Wetlands International (2002) are: South Sudan: c. 5,000 (50-80% of the total population [Briggs 2007]), Uganda: 100-150, (but possibly over 200 [Briggs 2007]), western Tanzania: 100-500 (this figure also proposed by Dinesen and Baker 2006), Zambia: <500 (though a later estimate of 1,760 with 1,296 in the Bangweulu Swamps alone is provided by Roxburgh and Buchanan 2010), Democratic Republic of Congo DRC: <1,000, Central African Republic (irregular), Rwanda: <50 and Ethiopia: <50. In 1997, the population was estimated to be 12,000-15,000 individuals (Rose and Scott 1997), but a more recent review makes a conservative estimate of 5,000-8,000 individuals (T. Dodman in litt. 2002 to Wetlands International 2002). This figure may prove too low, depending on research into the South Sudan populations (T. Dodman in litt. 2002 to Wetlands International 2002). An estimate of 3,830 birds was given for the Sudd (including areas of Zeraf Reserve) by Fay et al. (2007). A total population of less than 10,000 individuals is supported by a literature review in which the extent of certain wetland habitats was found to have been significantly overestimated by previous studies. Surveys in September-October 2005 support the suggestion that there are a few hundred individuals in the Malagarasi region of Tanzania (Briggs 2007). There is little doubt that the species is declining in Tanzania, Zambia and Rwanda, with declines perhaps in Uganda as well, and the species may be more threatened than available information suggests (L. Dinesen in litt. 2007).

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Range

Dense swamps of central Africa.

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Geographic Range

Shoebill or whale-headed storks are endemic to Africa and inhabit the east-central part of the continent. The main populations are found in southern Sudan (mainly in the White Nile Sudd), the wetlands of northern Uganda and western Tanzania and the Bangweulu swamp of northeastern Zambia. Smaller populations occupy eastern Zaire and Rwanda. This bird's range usually coincides with that of papyrus and lungfish.

Biogeographic Regions: ethiopian (Native )

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Central Africa: Albertine Rift Valley and surroundings from Sudan to Zambia.

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Range

Broken distribution in tropical east Africa from Sudan and western Ethiopia to Zambia (6) (7).
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Physical Description

Morphology

Physical Description

Large, somewhat frightful looking birds, shoebill storks stand 110 to 140 cm tall. Males are larger than females and have longer bills. The plumage is slaty blue-grey overall with a darker grey head. The primaries are black-tipped and secondaries have a greenish tint. The underparts are a lighter shade of grey. Adult breeding plumage does not differ from non-breeding plumage. On the back of the head is a small tuft of feathers that can erect in a crest. A newly hatched shoebill stork is covered in silvery-grey silky down and juveniles are a slightly darker shade of grey than adults. The bill is the most prominent feature of shoebill storks and resembles a wooden shoe. It is an enormous structure ending in a sharp, curved hook. The color of the bill is yellowish with blotchy dark spots. The mandibles have sharp edges that aid in capturing and eating prey. The eyes are large and yellowish or grayish-white in color. The legs are long and blackish. The toes are extremely long and completely divided with no webbing between them.

Range length: 110 to 140 cm.

Other Physical Features: endothermic ; homoiothermic; bilateral symmetry

Sexual Dimorphism: sexes alike

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Size

120 cm

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Ecology

Habitat

Habitat and Ecology

Habitat and Ecology
Behaviour This species is mostly sedentary, although it may make some movements in order to find optimal feeding habitat as water levels vary (del Hoyo et al. 1992). In South Sudan there are regular seasonal movements between feeding and breeding zones (Guillet 1978). It is very solitary. Even within the pair, male and female will often feed at opposite ends of their territory (del Hoyo et al. 1992). Loose aggregations may occasionally occur where receding water levels and large numbers of fish become concentrated in a small area (Hancock, Kushlan and Kahl 1992). It breeds solitarily, usually maintaining a density of fewer than three nests per km2 (Hancock, Kushlan and Kahl 1992). The breeding season is long. Eggs are laid at the end of the rains, as waters start to recede, and chicks fledge towards the end of the dry season (Hancock, Kushlan and Kahl 1992). Habitat Breeding It both breeds and forages in seasonally flooded marshes (Renson 1998) where vegetation is dominated by a mixture of Papyrus Cyperus papyrus, reeds (eg Phragmites), cattails (Typha species) and grasses, particularly Miscanthidium (Hancock, Kushlan and Kahl 1992). It is often found in areas with abundant floating vegetation, often Papyrus (Baker 1996). It also uses permanent non-papyrus swamps in areas such as the Malagarasi (Tanzania) (Dinesen and Baker 2006) and Lake Victoria (Uganda) (L. Dinesen in litt. 2007). Non-breeding It usually forages in shallow water (del Hoyo et al. 1992) where it makes use of clear channels among the vegetation that have been created by the movements of large mammals (del Hoyo et al. 1992). It tends to avoid areas where the vegetation is too dense to be penetrated easily, or is taller than the bird's back (Hancock, Kushlan and Kahl 1992). It is reported to prefer water that is poorly oxygenated, where fish are forced to surface to breathe, and are thus more easily caught (Guillet 1987), and it is for this reason that it is thought not to frequent swamps that are characterised by Papyrus alone (Guillet 1987). In South Sudan it has been known to forage on rice fields and other flooded plantations (Hancock, Kushlan and Kahl 1992). Diet When feeding, it shows a preference for lungfish Protopterus aethiopicus, but takes a variety of fish species including Senegal Bichir Polypterus senegalus, catfish (Clarias spp.) and tilapia (Tilapia spp.) (Guillet 1979, del Hoyo et al. 1992). It also preys on aquatic animals such as amphibians, young crocodiles and watersnakes (Briggs 2007, Hancock, Kushlan and Kahl 1992), and may even take rodents and young waterfowl (Hancock, Kushlan and Kahl 1992). Diet seems to vary geographically: lungfish and catfish appear to be the main prey species in Uganda, while catfish and watersnakes were found to constitute the preferred diet in Zambia (Hancock, Kushlan and Kahl 1992). Breeding site The nest is grassy construction, up to three metres wide, on a mound of floating vegetation or a small island (Briggs 2007), and often among dense stands of Papyrus (Hancock, Kushlan and Kahl 1992). The maximum clutch-size is three, although usually only one nestling will survive. The species can live for around 50 years, takes three to four years to reach reproductive maturity and is monogamous.


Systems
  • Freshwater
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Shoebill storks inhabit freshwater swamps and extensive, dense marshes. 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.

Habitat Regions: tropical ; saltwater or marine

Wetlands: marsh ; swamp

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Large swamps

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Shoebill storks are inhabitants of freshwater swamps and extensive dense marshes throughout east-central Africa. Especially large populations of Shoebills are found in the Sudd of southern Sudan, northernUganda, western Tanzania and Zambia’s Bangweulu swamp.

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Found in extensive papyrus grass and reed swamps and seasonally flooded marshes with floating vegetation, preferring those formed by papyrus (6) (8).
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Dispersal

Movements and dispersal

Mostly sedentary, with some movements (to find optimal feeding habitat)

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Trophic Strategy

Food Habits

Shoebill storks spend most of their time foraging in aquatic environments. The main part of their carnivorous diet consists of lungfish (Protopterus), bichirs (Polypterus), catfish, tilapia (Tilapia) and watersnakes. On occasion, they will also consume frogs, monitor lizards, turtles, young crocodiles, mollusks and carrion. The most suitable area for catching prey is one with shallow water and tall vegetation to camouflage the bird as it stalks prey. If the water is deep, a firm, floating platform of vegetation must be present in order to hunt.

The two mechanisms by which shoebill storks hunt are "stand and wait" and "wade and walk slowly." When a prey item is spotted, shoebill storks will begin the "collapse". The head and neck quickly stretch forward into the water causing the bird to over-balance and collapse forwards and downwards. After a collapse, a shoebill stork cannot immediately perform a second collapse. It must regain its balance and start from the standing position again. Along with the prey, a mouthful of vegetation is also collected. In order to expel the vegetation, shoebill storks sway their heads from side to side while keeping hold of the prey. Before swallowing, the prey is usually decapitated.

Animal Foods: amphibians; reptiles; fish; carrion ; mollusks

Primary Diet: carnivore (Eats terrestrial vertebrates, Piscivore )

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Associations

Ecosystem Roles

Shoebill storks are important predators in the swamps and marshes where they live.

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Predation

There are few predators of adult shoebill storks. Young and eggs may be taken by nest predators, but shoebill storks aggressively defend their young and build nests in areas inaccessible to many predators.

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Predator: prey includes lungfish, catfish, tilapia and water snakes.

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Life History and Behavior

Behavior

Communication and Perception

Shoebill storks are usually silent, but will often participate in bill-clattering, a behavior characteristic of true storks. Adults will often do this when greeting each other at the nest, but young shoebills also perform the bill-clatter. Adults will also make a whining or "mooing" noise and young will make a hiccupping noise especially when begging for food.

The principal senses used during hunting are vision and hearing. In order to facilitate binocular vision, shoebill storks hold their heads and bills vertically downward against the breast.

Communication Channels: visual ; acoustic

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Behaviour

Solitary

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Important wetland predators, Shoebill storks feed primarily on fishes such as lungfish, catfish, tilapia and water snakes. These stealthy hunters stand still or walk slowly through the water, then “collapse” forward and downward to snatch prey from just beneath the surface.

Shoebills form monogamous pairs and aggressively defend their breeding territories. Each pair constructs a large ground nest from grasses and other vegetation located on a small island or mass of floating vegetation. Although two eggs are laid, a pair is typically able to rear only a single chick each year.

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Life Expectancy

Lifespan/Longevity

Shoebill storks live to almost 36 years in the wild.

Range lifespan

Status: wild:
35.7 (high) years.

Average lifespan

Sex: male

Status: captivity:
35.7 years.

Average lifespan

Status: captivity:
36.0 years.

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Lifespan, longevity, and ageing

Maximum longevity: 35.7 years (captivity) Observations: One captive animal lived to be 35.7 years of age (Flower 1938).
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Reproduction

Shoebill storks form monogamous pairs for breeding.

Mating System: monogamous

Shoebill storks are solitary breeders and have territories measuring approximately 3 square kilometers. In the breeding season, these birds are very territorial and will defend the nest against any predators or competitors. Breeding time varies depending on location, but usually coincides with the start of the dry season.  The reproductive cycle from nest building to fledging spans a period of 6 to 7 months. An area with a 3 meter diameter is trampled and cleared for the nest. The nest is located on either a small island or on a mass of floating vegetation. Nesting material, such as grass, is weaved on the ground, forming a large structure of about 1 meter in diameter. One to three, normally two, flaky whitish eggs are laid. However, by the end of the breeding cycle usually only one chick remains due to predation or food availability. The incubation period is about 30 days. After hatching, adult shoebill storks must feed the chicks regurgitated food at least 1 to 3 times per day and up to 5 to 6 times per day as the chick grows older. Parents hold out food to the chicks, which must feed themselves.

Breeding interval: Shoebill storks breed once yearly.

Range eggs per season: 1 to 3.

Average time to hatching: 30 days.

Average fledging age: 95 days.

Average time to independence: 125 days.

Key Reproductive Features: seasonal breeding ; gonochoric/gonochoristic/dioecious (sexes separate)

Shoebill storks are monogamous breeders and both parents participate in every aspect of nest building, incubation, and chick rearing. Egg-watering is a behavior that has been recorded on many occasions and that is also observed in true storks. In order to keep the eggs cool, the adult shoebill will get a mouthful of water and pour it over the nest. It will also get mouthfuls of wet grass to place around the eggs and will roll and turn over the eggs with its feet or bill. The dousing behavior and also shading will continue after the eggs hatch until the feathers of the chicks are fully developed.

The development of shoebill storks is a slow process compared to most other birds. Feathers do not fully develop until about 60 days and the birds fledge at 95 days. However, the young cannot fly until about 105 to 112 days. Parents continue to feed the young for about one month after fledging. After this point, young shoebill storks are totally independent of their parents.

Parental Investment: altricial ; pre-fertilization (Provisioning, Protecting: Female); pre-hatching/birth (Provisioning: Female, Protecting: Male, Female); pre-weaning/fledging (Provisioning: Male, Female, Protecting: Male); pre-independence (Provisioning: Male, Female, Protecting: Male, Female)

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Evolution and Systematics

Functional Adaptations

Functional adaptation

Probing mud for prey: shoebill stork
 

The beak of the shoebill stork efficiently probes and scoops mud to search for prey thanks to its hooked, shoe-like shape.

       
  "The shoebill stork or whalebird lives in the papyrus swamps of the Upper White Nile and East Africa. Its main food is lungfish, for which it probes in the mud with its grotesque hooked bill, which may be up to 20 cm long. The bill is also used as a scoop to catch frogs and other small vertebrates." (Foy and Oxford Scientific Films 1982:151)
  Learn more about this functional adaptation.
  • Foy, Sally; Oxford Scientific Films. 1982. The Grand Design: Form and Colour in Animals. Lingfield, Surrey, U.K.: BLA Publishing Limited for J.M.Dent & Sons Ltd, Aldine House, London. 238 p.
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Conservation

Conservation Status

IUCN Red List Assessment


Red List Category
VU
Vulnerable

Red List Criteria
C2a(ii)

Version
3.1

Year Assessed
2012

Assessor/s
BirdLife International

Reviewer/s
Taylor, J. & Butchart, S.

Contributor/s
Baker, N., Brouwer, K., Dinesen, L., Dodman, T., Fishpool, L., Melamari, L., Morrison, K., Ndang'ang'a, P. & Roxburgh, L.

Justification
This rare and localised species is listed as Vulnerable because it is estimated to have a single small population within a broad Extent of Occurrence. The population is undergoing a continuing decline owing to hunting, nesting disturbance and the modification and burning of its habitat.

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There have been many estimates of shoebill stork populations, but the most accurate is 11,000-15,000 birds over the entire range. Since populations of shoebill storks are scattered and most are inaccessible to humans (or nearly so) for much of the year, it is hard to get a reliable number. The IUCN rates shoebill storks as "Lower risk - near threatened". They are also listed in Appendix II of CITES. They are protected by law in Sudan, the Central African Republic, Uganda, Rwanda, Zaire and Zambia, and included in Class A of the African Convention of Nature and Natural Resources. Local folklore also protects shoebill storks and native people are taught to respect and even fear these birds.

Shoebill storks are most threatened by habitat destruction. They have specific habitat needs for nesting and foraging and their swamps and marshes are being rapidly converted to agricultural land and cattle grazing. Fishermen disturb the shoebill's habitat, especially their feeding areas. Another cause for concern is the zoo trade. The demand for shoebill storks in zoos is very high. They sell for US $10,000-$20,000 making them the most expensive birds in the zoo trade. This encourages native people to capture and sell these birds to zoos, thus reducing wild populations. There have been few accounts of shoebill storks breeding in captivity. If they do breed, the young imprint on the zookeepers and will not go on to breed themselves when they reach adulthood.

US Migratory Bird Act: no special status

US Federal List: no special status

CITES: appendix ii

IUCN Red List of Threatened Species: vulnerable

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Vulnerable

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IUCN Red List Status: VULNERABLE

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Status

Classified as Vulnerable (VU) on the IUCN Red List 2006 (1), listed on Appendix II of CITES (3), and listed under Annex II of the African-Eurasian Migratory Waterbird Agreement (4).
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Population

Population
The total population has been estimated at 5,000-8,000 individuals (T. Dodman in litt. 2002), and a total population estimate of fewer than 10,000 individuals is supported by Dinesen and Baker (2006). The range of 5,000-8,000 individuals roughly equates to 3,300-5,300 mature individuals.

Population Trend
Decreasing
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There is little doubt that the species is declining in Tanzania, Zambia and Rwanda, with declines perhaps in Uganda as well, and the species may be more threatened than available information suggests (L. Dinesen in litt. 2007 in BirdLife International 2011).

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Threats

Major Threats
Over most of its range, it is threatened by habitat destruction and degradation, disturbance, hunting, and capture for the bird trade (Baker 1996, T. Dodman in litt. 2002) . Suitable habitat is being converted for cultivation and pasture, and cattle have been known to trample nests (Briggs 2007). The species is hunted for food and cultural reasons, for example it may be viewed as a bad omen, and it is captured for the zoo trade, which is a problem especially in Tanzania, where trading of the species is still legal (Briggs 2007). Interviews with people in the Bangweulu Swamps (Zambia) indicate that eggs and chicks are taken for consumption and sale, probably to zoos or collectors (Roxburgh et al. 2006). 5 chicks per month were estimated as taken for trade in one district in 2011, with only 2 individuals surviving the transit (D. Ngwenyama in litt. 2011). In 2007, an undisclosed number of specimens, illegally imported from Tanzania, were confiscated by the Danish authorities in Copenhagen (L. Dinesen in litt. 2007) and at least two birds were exported from Tanzania to a zoo in the USA (T. Dodman in litt. 2007). Small-scale trading poses a serious threat to small local populations rather than the global population (Briggs 2007), though recent reports suggest that levels of disturbance and trade are not sustainable in Zambia (T. Dodman in litt. 2011). In Zambia, fire and drought threaten habitat (especially in Bangweulu, where a decline is apparent) (T. Dodman in litt. 2002), there is some evidence for trapping and persecution (T. Dodman in litt. 2002), and nests are trampled by large herbivores feeding in the swamps (Renson 1998). Conflict in Rwanda and DRC has disrupted protected areas (e.g. Akagera National Park) that support the species (T. Dodman in litt. 2002); for example, the proliferation of firearms has greatly facilitated hunting of this species. In South Sudan, its stronghold, it has been said to be "very much endangered by destruction of papyrus swamps by cattle and fire" (Nikolaus 1987). Between 1952 and 1980 the area of the Sudd swamps of South Sudan increased (Howell et al. 1988) from 6,700 km2 to 19,200 km2. Whilst this habitat was earlier threatened by drainage due to plans for the Jonglei Canal, these plans are no longer supported, though canalisation and related schemes for the oil industry do pose a threat (T. Dodman in litt. 2008). The construction of several dams along the lower Nile will allow artificial manipulation of water levels in the Sudd (Briggs 2007). In the Malagarasi, large areas of Miombo woodland adjacent to swamps are being cleared for tobacco farming and agriculture, and the human population, which includes fishermen, farmers and semi-nomadic pastoralists, has increased very rapidly in recent decades (Dinesen and Baker 2006). In this region, dry-season burnings and cattle-grazing in the species's core area are severe and expanding, and the first rice paddies have appeared at the edge of the species's key swamps. Also in Malagarasi, a railway line has bisected swamps and rice paddies in some of its core areas (L. Dinesen in litt. 2007). Records of birds outside their core areas may be due to the displacement of birds by fires in dry years (Dinesen and Baker 2006).

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Widespread but rare, Shoebills are estimated to have a world population of 5,000 – 8,000. Their wetland habitats are being rapidly converted to agricultural land. In addition, these unusual birds demand such high prices in the zoo trade that native people are capturing and selling them to zoos around the world.

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Although widespread, the shoebill is considered uncommon, with a total world population estimated at 5,000-8,000 (10). The small population is declining due to habitat destruction and degradation, nest disturbance, increased hunting levels and capture for the bird trade. Fire and drought threaten habitat in Zambia, nests are trampled by large herbivores feeding in swamps, and there is some evidence for trapping and persecution. Conflict in Rwanda and the Democratic Republic of Congo has disrupted some protected areas (e.g. Akagera National Park) that support the species, and the proliferation of firearms has greatly facilitated hunting of this bird. Destruction of papyrus swamps by cattle and fire also endanger the shoebill in its stronghold, Sudan. The area of Sudd swamps of southern Sudan almost trebled between 1952 and 1980, but this habitat is now threatened by its potential further drainage to facilitate renewed prospective plans for the Jonglei Canal (6). The current status of shoebills in the Sudd is unclear.
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Management

Conservation Actions

Conservation Actions
Conservation Actions Underway
CITES Appendix II. A Single Species Conservation Action Plan is being developed in 2012, including a stakeholder workshop, with representatives of all range states. Steps are being taken in South Sudan to understand the population better and improve the status of protected areas. Several key shoebill sites are designated Ramsar sites in South Sudan, Uganda, Tanzania and Zambia.

Conservation Actions Proposed
Agreed conservation actions for the species will be developed in 2012 and provided in the Shoebill Single Species Action Plan. Identify key areas for monitoring and conduct regular surveys. Select important areas for protection. Reduce disturbance and establish buffer zones in protected areas (L. Dinesen in litt. 2007). Enforce legislation in protected areas (L. Dinesen in litt. 2007). Create community-based environmental awareness programmes focussed on generating shoebill-pride to discourage hunting. Encourage further development of ecotourism based around this species. Investigate the potential occurrence of seasonal movements (Briggs 2007). Monitor rates of habitat conversion across its range. Re-submit the proposal to upgrade the species to CITES Appendix I, and implement trade control. Determine the Sudd swamps population size and trend (T. Dodman in litt. 2002 to Wetlands International 2002), and refine the national and global population estimates. Assess the viability of the population in Gambella, Ethiopia, an area under high pressure from agricultural developments.

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Conservation

International trade in the shoebill is limited by the species' listing on Appendix II of the Convention on International Trade in Endangered Species (CITES) (3). However, trade does still occur, and this certainly poses an unwelcome pressure to already-dwindling populations. Plans are underway to upgrade the shoebill to Appendix I of CITES, which would render all trade illegal (11). This bird occurs in a number of reserves, although some of these are inadequately protected or have been given up after political unrest (8). The key site in Tanzania, the Moyowosi/Kigosi/Ugalla complex has a population of a few hundred individuals, and part of the area was designated as the country's first Ramsar Site in 2000 (12). The key site in Zambia, Bangweulu Swamps, is also a Ramsar Site (11). The Ramsar Convention on Wetlands is an international treaty for the conservation and sustainable utilization of wetlands, which aims to stem the progressive encroachment on and loss of wetlands, recognizing their fundamental ecological, economic, cultural, scientific, and recreational value (13). Uganda attaches economic value to the shoebill, which is an important asset for ecotourism in the country (11). A few injured birds are generally housed at the Kampala Zoo, some of which were confiscated from trappers and fisherman by the government (14). It has been suggested that a future priority for this bird might be to create community-based environmental awareness programmes focussed on generating national pride in the shoebill to discourage hunting (6). Indeed, recognition of the shoebill as one of the great African species can only serve to aid conservation efforts to save this unusual and cherished bird (5). It is also a priority to determine its current status in the extensive swamps and floodplains of southern Sudan, and to put an end to the live trade of this globally threatened species (11).
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Relevance to Humans and Ecosystems

Benefits

Economic Importance for Humans: Negative

There are no known adverse effects of shoebill storks on humans.

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Economic Importance for Humans: Positive

Shoebill storks are caught and sold for food. The native people also can receive large amounts of money from selling captured shoebill storks to zoos. They also bring in money through tourism because many people go to Africa on river excursions to look at wildlife.

Positive Impacts: food ; ecotourism

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Wikipedia

Shoebill

"B. rex" redirects here. For the dinosaur, see B-rex.

The shoebill (Balaeniceps rex) also known as whalehead or shoe-billed stork, is a very large stork-like bird. It derives its name from its massive shoe-shaped bill. Although it has a somewhat stork-like overall form and has previously been classified in the order Ciconiiformes, its true affiliations with other living birds is ambiguous. Some authorities now reclassify it with the Pelecaniformes. The adult is mainly grey while the juveniles are browner. It lives in tropical east Africa in large swamps from Sudan to Zambia.[2]

Taxonomy and systematics[edit]

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

The shoebill was only classified in the 19th century when some skins were brought to Europe. It was not until years later that live specimens reached the scientific community. However, the bird was known to both ancient Egyptians and Arabs. Traditionally allied with the storks (Ciconiiformes), it was retained there in the Sibley-Ahlquist taxonomy which lumped a massive number of unrelated taxa into their "Ciconiiformes". More recently, the shoebill has been considered to be closer to the pelicans (based on anatomical comparisons)[3] or the herons (based on biochemical evidence; Hagey et al., 2002).[4] A recent DNA study suggests they are part of the Pelecaniformes.[5]

The dispute has turned out to be mainly one of where to draw the boundary between Ciconiiformes and Pelecaniformes, or whether to draw it at all. Since cormorants and relatives are probably not actually Pelecaniformes, a solution adopted by some modern authors is to merge the "core" Pelecaniformes with the Ciconiiformes. The shoebill and the hammerkop (Scopus umbretta) are the "missing links" that connect pelicans and storks, and including the pelican lineage in the Ciconiiformes expresses this more adequately than other treatments do.

So far, two fossil relatives of the shoebill have been described: Goliathia from the early Oligocene of Egypt and Paludavis from the Early Miocene of the same country. It has been suggested that the enigmatic African fossil bird Eremopezus was a relative too, but the evidence for that is unconfirmed. All that is known of Eremopezus is that it was a very large, probably flightless bird with a flexible foot, allowing it to handle either vegetation or prey.

Description[edit]

The shoebill's conspicuous bill is its most well-known feature.

The shoebill is a tall bird, with a typical height range of 110 to 140 cm (43 to 55 in) and some specimens reaching as much as 152 cm (60 in). Length from tail to beak can range from 100 to 140 cm (39 to 55 in) and wingspan is 230 to 260 cm (7 ft 7 in to 8 ft 6 in). Weight has reportedly ranged from 4 to 7 kg (8.8 to 15.4 lb).[6][7] A male will weigh on average around 5.6 kg (12 lb) and is larger than a typical female of 4.9 kg (11 lb).[8] The signature feature of the species is its huge, bulbous bill, which is straw-coloured with erratic greyish markings. The exposed culmen (or the measurement along the top of the upper mandible) is 18.8 to 24 cm (7.4 to 9.4 in).[8] The sharp edges in the mandibles help the shoebill to decapitate their prey and also to discard any vegetation after prey has been caught. As in the pelicans, the upper mandible is strongly keeled, ending in a sharp nail. The dark coloured legs are fairly long, with a tarsus length of 21.7 to 25.5 cm (8.5 to 10.0 in). The shoebill's feet are exceptionally large, with the middle toe reaching 16.8 to 18.5 cm (6.6 to 7.3 in) in length, likely assisting the species in its ability to stand on aquatic vegetation while hunting. The neck is relatively shorter and thicker than other long-legged wading birds such as herons and cranes. The wings are broad, with a wing chord length of 58.8 to 78 cm (23.1 to 30.7 in), and well-adapted to soaring.

Flight pattern[edit]

Its wings are held flat while soaring and, as in the pelicans and the storks of the genus Leptoptilos, the shoebill flies with its neck retracted. Its flapping rate, at an estimated 150 flaps per minute, is one the slowest of any bird, with the exception of the larger stork species. The pattern is alternating flapping and gliding cycles of approximately seven seconds each, putting its gliding distance somewhere between the larger storks and the Andean condor (Vultur gryphus). When flushed, shoebills usually try to fly no more than 100 to 500 m (330 to 1,640 ft) from their prior location.[8] Long flights of the shoebill are rare, and only a few flights beyond its minimum foraging distance of 20 m (66 ft) have been captured.

The plumage of adult birds is blue-grey with darker slaty-grey flight feathers. The breast presents some elongated feathers, which have dark shafts. The juvenile has a similar plumage colour, but is a darker grey with a brown tinge.[2] When they are first born, shoebills have a more modestly-sized bill, which is initially silvery-grey. The bill becomes more noticeably large when the chicks are 23 days old and becomes well developed by 43 days.[8]

Identification[edit]

At close range, it can be easily identified by its unique features. In flight, if its unique bill cannot be seen, the shoebill's silhouette resembles that of a stork or condor, but its feathers are a distinctive medium blue-grey. Unusually also, its tail is the same colour as its wings. Under poor viewing conditions, its size and wingspan compared to other birds in its habitat can identify it. Its legs, roughly the length of storks, extend straight back far past its tail when in flight. The wing to tail size can't be used for identification; it is similar to several other birds.

A shoebill at a zoo, (video)

Distribution and habitat[edit]

The shoebill is distributed in freshwater swamps of central tropical Africa, from southern Sudan through parts of eastern Congo, Rwanda, Uganda and western Tanzania. The species is most numerous in the West Nile sub-region and adjacent areas of the south Sudan; 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. The shoebill is non-migratory with limited seasonal movements due to habitat changes, food availability and disturbance by humans.[8]

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.[8]

Behaviour and ecology[edit]

The shoebill is noted for its slow movements and tendency to remain still for long periods, resulting in repeated 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 birds, forage at a minimum distance of 20 m (66 ft) 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 are successful in yielding prey. Frequently water and vegetation is snatched up during the strike and is spilled out from the edges of the mandibles. Occasionally, the activity of hippopotamus may inadvertently benefit the shoebill, as the huge mammals occasionally force fish to the surface of the water while they are submerged.[8]

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) as well as 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 exists a single report of shoebills feeding on lechwe (Kobus leche) calves, although this would need confirmation. Given its sharp-edged beak, huge bill and wide gape, the shoebill can hunt large prey, often targeting prey bigger than 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 consisted of the catfish Clarias gariepinus (syn. C. mossambicus) and water snakes. In Uganda, lungfish and catfish were mainly fed to the young.[8]

Breeding[edit]

The solitary nature of shoebills extends to their breeding habits. Nests typically occur at less than three nests per square kilometre, unlike herons, cormorants, pelicans and storks which predominantly nest in colonies. The breeding pair of shoebills vigorously defends a territory of 2 to 4 km2 (0.77 to 1.54 sq mi) from conspecifics. In the extreme north and south of the species' range, nesting starts right after the rains end. In more central regions of the range, it may nest near end of wet season in order to hatch around the beginning of the following wet season. Both parents engage in building the nest on floating platform, after clearing out an area of approximately 3 m (9.8 ft) across. The large, flattish nesting platform is often partially submerged in water and can be as much as 3 m (9.8 ft) deep. The nest itself is about 1 to 1.7 m (3.3 to 5.6 ft) across. Both the nest and platform are made of aquatic vegetation. In Sudan, the nests apparently were able to support the weight of an adult man, although this was not the case in Zambia. From one to three white eggs are laid. These eggs measure 80 to 90 mm (3.1 to 3.5 in) high by 56 to 61 mm (2.2 to 2.4 in) and weigh around 164 g (5.8 oz). Incubation lasts for approximately 30 days. Both parents actively brood, shade, guard and feed the nestling, though the females are perhaps slightly more attentive. Food items are regurgitated whole from the gullet straight into the bill of the young. Shoebills rarely raise more than one chick, but will hatch more. The younger chicks are intended as back-ups in case the eldest dies or is weak. Fledging is reached at around 105 days and the young birds can fly well by 112 days. However, they are still fed for possibly a month or more after this. It will take the young shoebills three years before they become fully sexually mature.[8]

Voice[edit]

The shoebill is normally silent, but they perform bill-clattering displays at the nest.[2] When engaging in these displays, adult birds have also been noted to utter a cow-like moo as well as high-pitched whines. Both nestlings and adults engage in bill-clattering during the nesting season as a means of communication. When young are begging for food, they call out with a sound uncannily like human hiccups. In one case, a flying adult bird was heard uttering hoarse croaks, apparently as a sign of aggression at a nearby marabou stork (Leptoptilos crumeniferus).[8]

Status and conservation[edit]

The population is estimated at between 5,000 and 8,000 individuals, the majority of which live in swamps in Sudan, Uganda, eastern Democratic Republic of the Congo, and Zambia.[9] BirdLife International has classified it as Vulnerable with the main threats being habitat destruction, disturbance and hunting.

Relationship to humans[edit]

This species is considered to be one of the five most desirable birds in Africa by ornithologists.[10] There are Egyptian images depicting the shoebill, while the Arabs referred to the bird as abu markub, which means one with a shoe, a reference to the bird's distinctive bill.[citation needed]

References[edit]

  1. ^ BirdLife International (2012). "Balaeniceps rex". IUCN Red List of Threatened Species. Version 2013.2. International Union for Conservation of Nature. Retrieved 26 November 2013. 
  2. ^ a b c del Hoyo, J. Elliott, A. & Sargatal, J. (editors). (1992) Handbook of the Birds of the World. Volume 1: Ostrich to Ducks. Lynx Edicions. ISBN 84-87334-10-5
  3. ^ Mayr, Gerald (2003). "The phylogenetic affinities of the Shoebill (Balaeniceps rex)". Journal für Ornithologie. doi:10.1046/j.1439-0361.2003.03002.x. 
  4. ^ Hagey, J. R.; Schteingart, C. D.; Ton-Nu, H.-T. & Hofmann, A. F. (2002). "A novel primary bile acid in the Shoebill stork and herons and its phylogenetic significance". Journal of lipid research 43 (5): 685–90. PMID 11971938. 
  5. ^ Hackett, SJ; Kimball, RT; Reddy, S; Bowie, RC; Braun, EL; Braun, MJ; Chojnowski, JL; Cox, WA; Han, KL et al. (2008). "A phylogenomic study of birds reveals their evolutionary history". Science 320 (5884): 1763–8. doi:10.1126/science.1157704. PMID 18583609. 
  6. ^ Balaeniceps rex. Fsbio-hannover.de. Retrieved on 2012-08-21.
  7. ^ Stevenson, Terry and Fanshawe, John (2001). Field Guide to the Birds of East Africa: Kenya, Tanzania, Uganda, Rwanda, Burundi. Elsevier Science, ISBN 978-0856610790
  8. ^ a b c d e f g h i j Hancock & Kushan, Storks, Ibises and Spoonbills of the World. Princeton University Press (1992), ISBN 978-0-12-322730-0.
  9. ^ Williams, J.G; Arlott, N. A Gield Guide to the Birds of East Africa. Collins. ISBN 0-00-219179-2. 
  10. ^ Matthiessen, Peter (1991). African Silences. New York: Random House. p. 56. ISBN 0-679-40021-4. 
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