The scientific name of this outlandish bird – Balaeniceps rex – translates as "King whale-head". Easy to spot, then? Hardly. So elusive is the shoebill that Western science didn't lay eyes on one until 1851. Today, it remains top of the global twitchers' wish list; only those prepared to brave the deepest swamps of central Africa need apply.
Strike lucky, however, and you'll see why John Gould described his first specimen as "the most extraordinary bird I have seen for many years".
What impressed the great Victorian naturalist was, of course, that preposterous beak. Imagine a size-10 clog on the face of an outsized heron and you'll get the picture. Some 23cm by 10cm, it is certainly as capacious as your average shoe. And what is more, it is a deadly weapon, with sharp slicing edges and a wicked hook that allow it to scoop, stab and crush all in one.
Its prey include fish (notably the African lungfish), snakes, water birds and even young crocodiles. In short, anything that fits the bill. And the hapless victims never know what hits them, as the shoebill is a master of ambush, lurking in the shallows and then lunging forward with a speed that belies its size.
Drag your eyes from that bill and you'll see a tall, grey and long-legged bird that resembles a stork or heron but is actually more closely related to pelicans. It is a solitary resident of freshwater swamps, especially papyrus stands, and often frequents narrow channels where fish concentrate. A breeding pair require at least two square kilometres.
Today, an estimated 5,000 to 10,000 shoebills are scattered in their swampy hideouts from southern Sudan to northern Zambia. Although never easy to find, certain key locations (including Uganda's Murchison Falls National Park and Zambia's Bangweulu Wetlands) now offer a decent chance.
* Expert Africa (020-8232 9777; expertafrica.com) offers a 12-day safari to Zambia that includes three nights at Shoebill Island Camp searching for shoebills and other wildlife of the Bangweulu Wetlands. It also includes four nights in Kasanka National Park and two nights spotting big game in South Luangwa. From £4,619 per person, based on two people sharing, including all accommodation, activities, transfers, international flights and meals. The best shoebill viewing period is from November to June.
Mike Unwin is the author of 100 Bizarre Animals, published by Bradt Travel Guides (£16.99). Readers of The Independent can buy the book for only £11.50 including UK p&p at www.bradt-guides.com. Enter coupon code "mudskipper" at the checkout.