Sheathbill

Sheathbills
A Snowy Sheathbill (C. albus)
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Class: Aves
Order: Charadriiformes
Family: Chionidae
Bonaparte, 1832
Genus: Chionis
Forster, JR, 1788
Species

Chionis albus
Chionis minor

The sheathbills are a family of birds, Chionidae. Classified in the wader order Charadriiformes, the family contains one genus, Chionis, with only two species. They breed on subantarctic islands and the Antarctic Peninsula, and the Snowy Sheathbill migrates to the Falkland Islands and coastal southern South America in the southern winter; they are the only bird family endemic as breeders to the Antarctic region.[1] They are also the only Antarctic birds without webbed feet.

Contents

Description

They have white plumage including a thick layer of down, with only the face and leg colours distinguishing the two species. They look plump and dove-like, but are believed to be similar to the ancestors of the modern gulls and terns. There is a rudimentary spur on the "wrist" (carpal) joint, as in plovers. The skin around the eye is bare, as is the skin above the bill, which has carbuncular swellings. They derive their English name from the horny sheath which partially covers the upper mandible of their stout bills.[1]

Behaviour

They habitually walk on the ground, somewhat like rails. They fly only when alarmed or in migration, looking like pigeons.[1]

Food and feeding

The sheathbills are opportunistic feeders, consuming invertebrates, faeces, and carrion—including seal afterbirths and stillborn seal pups—between the tidelines. They will take chicks and eggs from cormorants or penguins.

Breeding

During the penguin breeding season, which is also the sheathbill breeding season, pairs of sheathbills in penguin colonies maintain territories covering a number of penguin nests. Two mated sheathbills often work together to harass adult penguins, nimbly avoiding their attempts to peck; they gain access to the eggs or chicks or steal the krill that the adult penguins regurgitate to feed their chicks. Near the few human settlements of the region, they boldly forage for offal. Because of this diet, they spend a good deal of time cleaning themselves.[1]

They lay 2 or 3 blotchy white eggs in crevices or rock cavities.[2] The nests are lined messily with seaweed, stones, feathers, guano, bones, and occasionally plastic trash; even dead chicks may not be removed. Incubation lasts 28 to 32 days, and the young fledge 50 to 60 days later.[1]

Taxonomy

Genetic studies of the order Charadriiformes show the sheathbills to be a sister group of the thicknees of the family Burhinidae. These two groups together are a sister group to Recurvostridae-Haematopodidae and Charadriidae.[3] Recent research on the Magellanic Plover (Pluvianellus socialis) of southern South America has indicated it too may be classified within the sheathbill family.[4][5][6]

The two species are the Snowy Sheathbill (Chionis albus) and the Black-faced Sheathbill (C. minor).

References

  1. ^ a b c d e Mead, Christopher J.; Richford, Andrew S. (2003). "Sheathbills". In Perrins, Christopher. The Firefly Encyclopedia of Birds. Firefly Books. pp. 256–257. ISBN 1-55297-777-3. 
  2. ^ Harrison, Colin J.O. (1991). Forshaw, Joseph. ed. Encyclopaedia of Animals: Birds. London: Merehurst Press. pp. 109. ISBN 1-85391-186-0. 
  3. ^ Christidis and Boles, p. 128
  4. ^ Christidis and Boles, p. 132
  5. ^ Paton, Tara A. & Baker, Allan J. (2006): Sequences from 14 mitochondrial genes provide a well-supported phylogeny of the Charadriiform birds congruent with the nuclear RAG-1 tree. Mol. Phylogenet. Evol. 39(3): 657–667. doi:10.1016/j.ympev.2006.01.011 (HTML abstract)
  6. ^ Paton, T.A.; Baker, A.J.; Groth, J.G. & Barrowclough, G.F. (2003): RAG-1 sequences resolve phylogenetic relationships within charadriiform birds. Mol. Phylogenet. Evol. 29: 268-278. doi:10.1016/S1055-7903(03)00098-8 (HTML abstract)

External links


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Look at other dictionaries:

  • Sheathbill — Sheath bill , n. (Zo[ o]l.) Either one of two species of birds composing the genus {Chionis}, and family {Chionid[ae]}, native of the islands of the Antarctic seas. [1913 Webster] Note: They are related to the gulls and the plovers, but more… …   The Collaborative International Dictionary of English

  • sheathbill — [shēth′bil΄] n. any of a family (Chionidae) of white plumed antarctic shorebirds distinguished by a horny, saddlelike sheath at the base of the upper bill …   English World dictionary

  • sheathbill — /sheeth bil /, n. either of two white sea birds, Chionis alba or C. minor, of the colder parts of the Southern Hemisphere: so called from the horny sheath covering the base of the upper bill. [1775 85; SHEATH + BILL2] * * * ▪ bird Sy Montgomery… …   Universalium

  • sheathbill — makščiasnapiai statusas T sritis zoologija | vardynas atitikmenys: lot. Chionis angl. sheathbill vok. Scheidenschnabel, f rus. белая ржанка, f pranc. chionis, m ryšiai: platesnis terminas – makščiasnapiniai siauresnis terminas – baltasis… …   Paukščių pavadinimų žodynas

  • sheathbill — noun Date: circa 1781 either of two white shorebirds (Chionis alba and C. minor of the family Chionididae) of colder parts of the southern hemisphere that have a horny sheath over the base of the upper mandible and suggest the pigeons in general… …   New Collegiate Dictionary

  • sheathbill — noun /ˈʃiːɵ.bɪl/lang=en Either of two species of scavenging birds in the family Chionididae which breed only on the Antarctic Peninsula and subantarctic islands …   Wiktionary

  • sheathbill — noun a mainly white pigeon like bird of subantarctic islands, with a horny sheath around the base of the bill. [Genus Chionis.] …   English new terms dictionary

  • sheathbill — sheath•bill [[t]ˈʃiθˌbɪl[/t]] n. orn either of two white, pigeonlike shorebirds, Chionis alba or C. minor, of the Antarctic, having a horny sheath covering the base of the short bill • Etymology: 1775–85 …   From formal English to slang

  • sheathbill — /ˈʃiθbɪl/ (say sheethbil) noun either of two seabirds with white plumage, Chionis alba and C. minor, of the colder parts of the Southern Hemisphere, so called from the horny case which partly sheathes the bill. {sheath + bill2} …   Australian English dictionary

  • sheathbill — ˈ ̷ ̷ˌ ̷ ̷ noun : any of several white shorebirds constituting the family Chionididae that are confined to the colder parts of the southern hemisphere, have a saddle shaped horny sheath over the base of the upper mandible and a blunt carpal spur… …   Useful english dictionary

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