Perhaps the most eagerly sought of all African birds, the shoebill is also one of the few that is likely to make an impression on those travellers who regard pursuing rare birds to be about as diverting as hanging about in windswept railway stations scribbling down train numbers. Three factors combine to give the shoebill its bizarre and somewhat prehistoric appearance. The fi rst is its enormous proportions: an adult might stand more than 150cm (5ft) tall and typically weighs around 6kg. The second is its unique uniform slate-grey coloration. Last but emphatically not least is its clog-shaped, hook-tipped bill – at 20cm long, and almost as wide, the largest among all living bird species. The bill is fi xed in a permanent Cheshire-cat smirk that contrives to look at once sinister and somewhat inane, and when agitated the bird loudly claps together its upper and lower bill, rather like outsized castanets.
The first known allusions to the shoebill came from early European explorers to the Sudan, who wrote of a camel-sized flying creature known by the local Arabs as Abu Markub – Father of the Shoe. These reports were dismissed as pure fancy by Western biologists until 1851, when Gould came across a bizarre specimen amongst an avian collection shot on the Upper White Nile. Describing it as ‘the most extraordinary bird I have seen’, Gould placed his discovery in a monotypic family and named it Balaeniceps Rex – King Whale-Head! Gould believed the strange bird to be most closely allied to pelicans, but it also shares some anatomic and behavioural characteristics with herons, and until recently it was widely held to be an evolutionary off shoot of the stork family. Recent DNA studies support Gould’s original theory, however, and the shoebill is now placed in a monotypic subfamily of Pelecanidae.
The life cycle of the shoebill is no less remarkable than its appearance. One of the few birds with an age span of up to 50 years, it is generally monogamous, with pairs coming together during the breeding season (April to June) to construct a grassy nest up to 3m wide on a mound of fl oating vegetation or a small island. Two eggs are laid, and the parents rotate incubation duties, in hot weather filling their bills with water to spray over the eggs to keep them cool. The chicks hatch after about a month, and will need to be fed by the parents for at least another two months until their beaks are fully developed. Usually only one nestling survives, probably as a result of sibling rivalry.
The shoebill is a true swamp specialist, but it avoids dense stands of papyrus and tall grass, which obstruct its take-off, preferring instead to forage from patches of low fl oating vegetation or along the edge of channels. It consumes up to half its weight in food daily, preying on whatever moderately sized aquatic creature might come its way, ranging from toads to baby crocodiles, though lungfish are especially favoured. Its method of hunting is exceptionally sedentary: the bird might stand semi-frozen for several hours before it lunges down with remarkable speed andand power, heavy wings stretched backward, to grab an item of prey in its large, inescapable bill. Although it is generally a solitary hunter, the shoebill has occasionally been observed hunting co-operatively in small flocks, which splash about flapping their wings to drive a school of fish into a confined area.
Although the shoebill is an elusive bird, this – as with the sitatunga antelope – is less a function of its inherent scarcity than of the inaccessibility of its swampy haunts. Nevertheless, BirdLife International has recently classified it as Vulnerable, and it is classed as CITES Appendix 2, which means that trade in shoebills, or their capture for any harmful activity, is forbidden by international law. Estimates of the global population vary wildly. In the 1970s, only 1,500 shoebills were thought to exist in the wild, but this estimate has subsequently been revised to 5,000–10,000 individuals concentrated in five countries – Sudan, Uganda, Tanzania, DRC and Zambia. Small breeding populations also survive in Rwanda and Ethiopia, and vagrants have been recorded in Malawi and Kenya.
The most important shoebill stronghold is the Sudd floodplain on the Sudanese Nile, where 6,400 individuals were counted during an aerial survey in 1979–82, a figure that dropped to 3,830 when a similar survey was undertaken in 2005. Another likely stronghold is western Tanzania’s rather inaccessible Moyowosi- Kigosi Swamp, whose population was thought to amount to a few hundred prior to a 1990 survey that estimated it to be greater than 2,000, though recent reports suggest a maximum of 500. Ironically, although Uganda is the easiest place to see the shoebill in the wild, the national population probably amounts to no more than 250 adult birds, half of which are concentrated in the Kyoga–Bisina–Opeta complex of wetlands. For tourists, however, the most reliable locations for shoebill sightings are Murchison Falls National Park, Toro-Semliki Wildlife Reserve and the Mabamba Swamp near Entebbe – none of which is thought to hold more than a dozen pairs. Visitors to Uganda who fail to locate a shoebill in the wild might take consolation from the Wildlife Orphanage in Entebbe, where a few orphaned individuals are kept in a large aviary.
The major threat to the survival of the shoebill is habitat destruction. The construction of several dams along the lower Nile means that the water levels of the Sudd are open to artificial manipulation. Elsewhere, swamp clearance and rice farming pose a localised threat to suitable wetland habitats. Lake Opeta, an important shoebill stronghold in eastern Uganda, has been earmarked as a source of irrigation for a new agricultural scheme. A lesser concern is that shoebills are hunted for food or illegal trade in parts of Uganda. In the Lake Kyoga region, local fishermen often kill shoebill for cultural reasons – they believe that seeing a shoebill before a fishing expedition is a bad omen. As is so often the case, tourism can play a major role in preserving the shoebill and its habitat, particularly in areas such as the Mabamba Swamp, where the local community has already seen financial benefits from ornithological visits.