Shoebill
Scientific name: Balaeniceps rex
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.
Identification
120 cm. Large grey, stork-like waterbird with a fantastically unique bill. Unmistakable.
Distribution and population
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).
Population justification
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.
Trend justification
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).
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.
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).
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.
