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The shelducks, most species of which are found in the genus Tadorna (except for the Radjah shelduck, which is now found in its own monotypic genus Radjah), are a group of large birds in the tribe Tadornini of the Anatidae, the biological family that includes the ducks and most duck-like waterfowl such as the geese and swans.

Biology

Shelducks are a group of large, often semi-terrestrial waterfowl, traditionally seen as intermediate between geese and ducks,[2] but now known to be significantly more closely related to ducks than to geese or swans, forming a clade that is sister to all other ducks.[3] They are medium-sized (from 55–70 cm) Old World waterfowl. The sexes are slightly differently coloured in most species, and all have a characteristic upperwing pattern in flight, with the secondary remiges forming an iridescent green speculum, the primaries black, and the coverts (forewing) white. Their diet consists of small shore animals (winkles, crabs, etc.) as well as grasses and other plants.

They were originally known as “sheldrakes“, which remained the most common name until the late 19th century, with ‘sheld’ meaning variegated.[4] Other archaic names include bergander, burrow-duck, and vulpanser, the last meaning “fox goose”.[5] The word “sheldrake” is still sometimes used to refer to a male shelduck.[6]

Systematics

The genus Tadorna was introduced by the German zoologist Friedrich Boie in 1822.[7][8] The type species is the common shelduck.[8] The genus name comes from the French name Tadorne for the common shelduck.[9] It may originally derive from Celtic roots meaning “pied waterfowl”, essentially the same as the English “shelduck”.[10] A group of them is called a “dopping”, taken from the Harley Manuscript.[11]

Tadorna is very closely related to the genus Alopochen, which includes the Egyptian goose and its extinct relatives from the Madagascar region, and slightly less closely related to the genus Radjah, which includes the radjah shelduck.[3] While the classical shelducks form a group that is obviously monophyletic, the interrelationships of these, the aberrant common and especially Radjah sheducks, and the Egyptian goose were found to be poorly resolved by mtDNA cytochrome b sequence data;[12] this genus may thus be paraphyletic. A 2018 analysis clarified some of the interrelationships, but did not include all the species, notably not common shelduck,[3] and likewise a 2025 study which did not include Alopochen or Radjah.[13]

Fossil bones from Dorkovo (Bulgaria) described as Balcanas pliocaenica may actually belong to this genus. They have even been proposed to be referable to the common shelduck, but their Early Pliocene age makes this rather unlikely.[citation needed]


Table of species

The following table is based on the Avilist checklist.[14]

Genus Tadorna – F. Boie, 1822 – five species
Common name Scientific name and subspecies Range Size and ecology IUCN status and estimated population
Common shelduck


Male

{{{image2-alt}}}
Female

Tadorna tadorna
(Linnaeus, 1758) 		Europe, Asia, North Africa
Map of range 		Size:

Habitat:

Diet: 		 LC 


Crested shelduck

 Tadorna cristata
(Kuroda, 1917) 		Eastern Russia, northeast Asia
Map of range 		Size:

Habitat:

Diet: 		 CR 


Probably extinct

South African shelduck


Male

{{{image2-alt}}}
Female

Tadorna cana
(Gmelin, JF, 1789) 		Namibia, Botswana, South Africa Size:

Habitat:

Diet: 		 LC 


Ruddy shelduck


Male

{{{image2-alt}}}
Female

Tadorna ferruginea
(Pallas, 1764) 		Europe, Asia, North Africa
Map of range 		Size:

Habitat:

Diet: 		 LC 


Paradise shelduck


Male

{{{image2-alt}}}
Female

Tadorna variegata
(Gmelin, 1789) 		New Zealand
Map of range 		Size:

Habitat:

Diet: 		 LC 


Australian shelduck


Male

{{{image2-alt}}}
Female

Tadorna tadornoides
(Jardine & Selby, 1828) 		Australia, New Zealand
Map of range 		Size:

Habitat:

Diet: 		 LC 



References

  1. ^ “Anatidae”. aviansystematics.org. The Trust for Avian Systematics. Retrieved 2023-08-05.
  2. ^ Cramp, Stanley (1986). Handbook of the birds of Europe, the Middle East, and north Africa: the birds of the western Paleartic. Oxford London New York: Oxford university press. p. 445. ISBN 0-19-857358-8.
  3. ^ a b c Janet C. Buckner; Ryan Ellingson; David A. Gold; Terry L. Jones; David K. Jacobs (2018). “Mitogenomics supports an unexpected taxonomic relationship for the extinct diving duck Chendytes lawi and definitively places the extinct Labrador Duck”. Molecular Phylogenetics and Evolution. 122: 102–109. Bibcode:2018MolPE.122..102B. doi:10.1016/j.ympev.2017.12.008. PMID 29247849.
  4. ^ Lockwood, W. B. (1984). Oxford Book of British Bird Names. Oxford University Press. p. 138.
  5. ^ https://www.oed.com/dictionary/vulpanser_n Oxford English Dictionary
  6. ^ Simpson, J. A. (1989). Oxford English Dictionary. Oxford University Press.
  7. ^ Boie, Friedrich (1822). Tagebuch gehalten auf einer Reise durch Norwegen im Jahre 1817 (in German). Schleswig: Königl Taubstummen – Institut. pp. 140, 351.
  8. ^ a b Dickinson, E.C.; Remsen, J.V. Jr., eds. (2013). The Howard & Moore Complete Checklist of the Birds of the World. Vol. 1: Non-passerines (4th ed.). Eastbourne, UK: Aves Press. p. 13. ISBN 978-0-9568611-0-8.
  9. ^ Jobling, James A (2010). The Helm Dictionary of Scientific Bird Names. London: Christopher Helm. p. 377. ISBN 978-1-4081-2501-4.
  10. ^ Kear, Janet (2005). Ducks, Geese, and Swans. Oxford University Press. p. 420. ISBN 0-19-861008-4.
  11. ^ Lipton, James (1991). An Exaltation of Larks. Viking. ISBN 978-0-670-30044-0.
  12. ^ Sraml, M.; Christidis, L.; Easteal, S.; Horn, P. & Collet, C. (1996). Molecular Relationships Within Australasian Waterfowl (Anseriformes). Australian Journal of Zoology 44 (1): 47-58. doi:10.1071/ZO9960047 (HTML abstract)
  13. ^ a b Rawlence, N. J.; Lubbe, P.; Adams, A. L.; Shepherd, L. D.; Cole, T. L.; Knapp, M.; Llamas, B.; Wood, J. R.; Mitchell, K. J.; Tennyson, A. J. D. (2025). “Ancient DNA and morphometrics reveal a new species of extinct insular shelduck from Rēkohu Chatham Islands”. Zoological Journal of the Linnean Society. 204 (3) zlaf069. doi:10.1093/zoolinnean/zlaf069.
  14. ^ AviList Core Team (2025). “AviList: The Global Avian Checklist, v2025”. doi:10.2173/avilist.v2025. Retrieved 2026-04-15.