Shoebill

The shoebill (Balaeniceps rex) also known as the whalebill, whale-headed stork or shoe-billed stork, is a very large long-legged wading bird. It derives its name from its enormous shoe-shaped bill. It has a somewhat stork-like overall form and has previously been classified with the storks in the order Ciconiiformes based on this morphology. However, genetic evidence places it with pelicans and herons in the Pelecaniformes. The adult is mainly grey while the juveniles are more brown. It lives in tropical east Africa in large swamps from South Sudan to Zambia.

The shoebill may have been known to Ancient Egyptians^[3] but was not classified until the 19th century, after skins and eventually live specimens were brought to Europe. John Gould very briefly described it in 1850 from the skin of a specimen collected on the upper White Nile by the English traveller Mansfield Parkyns. Gould provided a more detailed description in the following year. He placed the species in its own genus Balaeniceps and coined the binomial name Balaeniceps rex.^[4]^[5]^[6] The genus name comes from the Latin words balaena "whale", and caput "head", abbreviated to -ceps in compound words.^[7] Alternative common names are whalebill,^[8] shoe-billed stork and whale-headed stork.^[9]

Traditionally considered as 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". Based on osteological evidence, the suggestion of a pelecaniform affinity was made in 1957 by Patricia Cottam.^[10] Microscopic analysis of eggshell structure by Konstantin Mikhailov in 1995 found that the eggshells of shoebills closely resembled those of other Pelecaniformes in having a covering of thick microglobular material over the crystalline shells.^[11] In 2003, the shoebill was again suggested as closer to the pelicans (based on anatomical comparisons)^[12] or the herons (based on biochemical evidence).^[13] A 2008 DNA study reinforces their membership of the Pelecaniformes.^[14]

So far, two fossilized 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.