Leptoptilos Explained

Leptoptilos is a genus of very large tropical storks, commonly known as adjutants. The name means thin (lepto) feather (ptilos). Two species are resident breeders in southern Asia, and the marabou stork is found in Sub-Saharan Africa.

These are huge birds, typically 110–150 cm tall with a 210–250 cm wingspan. The three species each have a black upper body and wings, and white belly and undertail. The head and neck are bare like those of a vulture. The huge bill is long and thick. Juveniles are a duller, browner version of the adult.

Leptoptilos storks are gregarious colonial breeders in wetlands, building large stick nests in trees. They feed on frogs, insects, young birds, lizards and rodents. They are frequent scavengers, and the naked head and neck are adaptations to this, as are those of the vultures with which they often feed. A feathered head would become rapidly clotted with blood and other substances when a scavenging bird's head was inside a large corpse, and the bare head is easier to keep clean.

Most storks fly with neck outstretched, but the three Leptoptilos storks retract their necks in flight like a heron.

Taxonomy and species

The genus Leptoptilos was introduced in 1831 by the French naturalist René Lesson.^[1] The genus name combines the Ancient Greek leptos meaning "delicate" or "slender" with ptilon meaning "feather".^[2] The type species was subsequently designated as the greater adjutant by George Robert Gray.^{[3] [4]}

The genus contains three extant species.^[5]

Fossils

There is an ample fossil record of this genus. Many fossils members of the genus were much larger than living species, standing as tall as a man, with the earliest being Leptoptilos falconeri from the Pliocene of Afro-Eurasia. Giant Leptoptilos storks survived into the Late Pleistocene on the Southeast Asian islands of Java (L. titan) and Flores (L. robustus).^[6]

• †Leptoptilos falconeri (Early to Late Pliocene of south Asia and east Africa)
• †Leptoptilos indicus (Late Pliocene of Siwalik, India) – formerly Cryptociconia indica, may be the same as L. falconeri (Louchart et al. 2005)
• †Leptoptilos lüi (Middle Pleistocene of Jinniushan, Liaoning, China)
• †Leptoptilos patagonicus (Puerto Madryn Late Miocene of Valdés Peninsula, Argentina)
• †Leptoptilos pliocenicus (Early Pliocene of Odesa, Ukraine and Urugus, Ethiopia to Late Pliocene of Koro Toro, Chad and Olduvai, Tanzania) – includes L. cf. falconeri, may be the same as L. falconeri
• †Leptoptilos richae (Beglia Late Miocene of Bled ed Douarah, Tunisia, and Wadi Moghara, Egypt?)
• †Leptoptilos robustus (Pleistocene, Flores, Indonesia)^[7]
• †Leptoptilos titan (Notopuro Middle/Late Pleistocene of Watualang, Java, Indonesia)
• †Leptoptilos sp. (Ngorora Formation Late Miocene of Baringo District, Kenya: Louchart et al. 2005)

†Leptoptilos siwalicensis from the Siwalik deposits (Late Miocene? to Late Pliocene) may belong to this genus or to a closely related one (Louchart et al. 2005).

In culture

The adjutant bird features in the arms of Baron Sinha. In the satirical French puppet show Le Bébête Show, Valéry Giscard d'Estaing was, for a time, depicted as a Leptoptilos.

Notes and References

1. Book: Lesson, René . René Lesson . 1831 . Traité d'Ornithologie, ou Tableau Méthodique . 1 . French . Paris . F.G. Levrault . 583 (Livraison 8) . Published in 8 livraisons between 1830 and 1831. For the publication date see: Book: Dickinson . E.C. . Edward C. Dickinson . Overstreet . L.K. . Dowsett . R.J. . Bruce . M.D. . 2011 . Priority! The Dating of Scientific Names in Ornithology: a Directory to the literature and its reviewers . Northampton, UK . Aves Press . 978-0-9568611-1-5 . 119 .
2. Book: Jobling, James A. . 2010. The Helm Dictionary of Scientific Bird Names . Christopher Helm . London . 978-1-4081-2501-4 . 222 .
3. Book: Gray, George Robert . George Robert Gray . 1840 . A List of the Genera of Birds : with an Indication of the Typical Species of Each Genus . London . R. and J.E. Taylor . 67 .
4. Book: Mayr . Ernst . Ernst Mayr . Cottrell . G. William . 1979 . Check-List of Birds of the World . 1 . 2nd . Museum of Comparative Zoology . Cambridge, Massachusetts . 251 .
5. Web site: Gill . Frank . Frank Gill (ornithologist) . Donsker . David . Rasmussen . Pamela . Pamela Rasmussen . August 2022 . Storks, frigatebirds, boobies, darters, cormorants . IOC World Bird List Version 12.2 . International Ornithologists' Union . 16 November 2022 .
6. Meijer . Hanneke J. M. . Sutikna . Thomas . Wahyu Saptomo . E. . Tocheri . Matthew W. . More bones of Leptoptilos robustus from Flores reveal new insights into giant marabou stork paleobiology and biogeography . Royal Society Open Science . 2022 . 9 . 7 . 220435 . 10.1098/rsos.220435. 35845853 . 9277297 . 2022RSOS....920435M . 250459008 . free .
7. A new species of giant marabou stork (Aves: Ciconiiformes) from the Pleistocene of Liang Bua, Flores (Indonesia). Meijer HJ, Due RA . Zoological Journal of the Linnean Society. 2010. 160. 4 . 707–724. 10.1111/j.1096-3642.2010.00616.x. free.