Tern

Taxobox
name = Terns

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image_width = 250px
image_caption =Greater Crested Tern
regnum = Animalia
phylum = Chordata
classis = Aves
ordo = Charadriiformes
subordo = Lari
familia = Sternidae
familia_authority = Bonaparte, 1838
subdivision_ranks = Genera
subdivision =
*"Anous"
*"Procelsterna"
*"Gygis"
*"Onychoprion"
*"Sternula"
*"Phaetusa"
*"Hydroprogne"
*"Gelochelidon"
*"Larosterna"
*"Chlidonias"
*"Thalasseus"
*"Sterna"

Terns are seabirds in the family Sternidae, previously considered a subfamily (Sterninae) of the gull family Laridae (van Tuinen "et al.", 2004). They form a lineage with the gulls and skimmers which in turn is related to skuas and auks. Terns have a worldwide distribution.

Most terns were formerly treated as belonging into one large genus "Sterna", with the other genera being small. However analysis of DNA sequences supports the splitting of "Sterna" into several smaller genera (see list, below) (del Hoyo "et al.", 1996; Bridge "et al". 2005; Collinson 2006).

Biology and habits

Many terns breeding in temperate zones are long-distance migrants, and the Arctic Tern probably sees more daylight than any other creature, since it migrates from its northern breeding grounds to Antarctic waters. One Arctic Tern, ringed as a chick (not yet able to fly) on the Farne Islands off the Northumberland coast in eastern Great Britain in summer 1982, reached Melbourne, Australia in October 1982, a sea journey of over 22,000 km (14,000 statute miles) in just three months from fledging—an average of over 240 km per day, and one of the longest journeys ever recorded for a bird.

They are in general medium to large birds, typically with grey or white plumage, often with black markings on the head. They have longish bills and webbed feet. They are lighter bodied and more streamlined than gulls, and look elegant in flight with long tails and long narrow wingscite book |editor=Forshaw, Joseph|author= Harrison, Colin J.O.|year=1991|title=Encyclopaedia of Animals: Birds|publisher= Merehurst Press|location=London|pages= 110-112|isbn= 1-85391-186-0] . Terns in the genus "Sterna" have deeply forked tails, those in "Chlidonias" and "Larosterna" shallowly forked tails, while the noddies (genera "Anous, Procelsterna, Gygis") have unusual 'notched wedge' shaped tails, the longest tail feathers being the middle-outer, not the central nor the outermost. Terns ranges in size from the Least Tern, at 42 g (1.5 oz) and 23 cm (9 inches), to the Caspian Tern, at 630 g (1.4 lbs) and 53 cm (21 inches). They make harsh, single-note calls.

Most terns ("Sterna" and the noddies) hunt fish by diving, often hovering first, but the marsh terns ("Chlidonias") pick insects of the surface of fresh water. Terns only glide infrequently; a few species, notably Sooty Tern, will soar high above the sea. Apart from bathing, they only rarely swim, despite having webbed feet.

Terns nest in large, densely packed colonies. Depending on the species and habitat, the nests may consist of unlined scrapes in the ground, or of flimsy collections of sticks on trees or floating vegetation. Terns are generally long-lived birds, with several species now known to live in excess of 25-30 years.

Classification and species list

A recent study (Thomas "et al.", 2004) of part of the cyt b gene sequence found a closer relationship between terns and the Thinocori, some species of aberrant waders. These results are in disagreement with other molecular and morphological studies (see Paton & Baker, 2006) and are best interpreted to prove an extraordinary amount of molecular convergent evolution between the terns and these waders, or as retention of an ancient genotype.

According the mtDNA studies and review by Bridge "et al" (2005), the genera and species of terns are as follows:

* Genera "Anous, Procelsterna, Gygis" - noddies. A tropical group, characterised by the notch-wedge shaped (not forked) tail; coastal and pelagic oceanic.
** Brown Noddy "Anous stolidus"
** Black Noddy "Anous minutus"
** Lesser Noddy "Anous tenuirostris"
** Blue Noddy "Procelsterna cerulea"
** Grey Noddy "Procelsterna albivitta"
** White Tern "Gygis alba"
** Little White Tern "Gygis microrhyncha"

* Genus "Onychoprion" - "brown-backed" terns
** Grey-backed Tern "Onychoprion lunata"
** Bridled Tern "Onychoprion anaethetus"
** Sooty Tern "Onychoprion fuscata"
** Aleutian Tern "Onychoprion aleutica"

* Genus "Sternula" - little white terns
** Fairy Tern "Sternula nereis"
** Damara Tern "Sternula balaenarum"
** Little Tern "Sternula albifrons"
** Saunders's Tern "Sternula saundersi" (formerly considered a subspecies of Little Tern)
** Least Tern "Sternula antillarum" (formerly considered a subspecies of Little Tern)
** Yellow-billed Tern "Sternula superciliaris"
** Peruvian Tern "Sternula lorata"

* Genus "Phaetusa" - Large-billed Tern
** Large-billed Tern " Phaetusa simplex"

* Genus "Hydroprogne" - Caspian Tern
** Caspian Tern "Hydroprogne caspia"

* Genus "Gelochelidon" - Gull-billed Tern
** Gull-billed Tern "Gelochelidon nilotica"

* Genus "Larosterna - Inca Tern
** Inca Tern "Larosterna inca"

* Genus "Chlidonias" - marsh terns
** Black Tern "Chlidonias niger"
** White-winged Tern or White-winged Black Tern "Chlidonias leucopterus"
** Whiskered Tern "Chlidonias hybridus"
** Black-fronted Tern "Chlidonias albostriatus" (ex-"Sterna albostriata")

* Genus "Thalasseus" - crested terns
** Lesser Crested Tern "Thalasseus bengalensis"
** Royal Tern "Thalasseus maximus"
** Greater Crested Tern or Swift Tern, "Thalasseus bergii"
** Chinese Crested Tern "Thalasseus bernsteini"
** Elegant Tern "Thalasseus elegans"
** Sandwich Tern "Thalasseus sandvicensis"

* Genus "Sterna" - large white terns
** Forster's Tern "Sterna forsteri"
** Trudeau's Tern "Sterna trudeaui"
** Common Tern "Sterna hirundo"
** Roseate Tern "Sterna dougallii"
** White-fronted Tern "Sterna striata"
** Black-naped Tern "Sterna sumatrana"
** South American Tern "Sterna hirundinacea"
** Antarctic Tern "Sterna vittata"
** Kerguelen Tern "Sterna virgata"
** Arctic Tern "Sterna paradisaea"
** River Tern "Sterna aurantia"
** Black-bellied Tern "Sterna acuticauda" (possibly "Chlidonias")
** White-cheeked Tern "Sterna repressa" (possibly "Chlidonias")

Gallery

References

* Bridge, E. S.; Jones, A. W. & Baker, A. J. (2005): A phylogenetic framework for the terns (Sternini) inferred from mtDNA sequences: implications for taxonomy and plumage evolution. "Molecular Phylogenetics and Evolution" 35: 459–469. [http://www2.hawaii.edu/~khayes/Journal_Club/summer2006/Bridge_et_al_2005_MPE.pdf PDF fulltext]

* Collinson, M. (2006). Splitting headaches? Recent taxonomic changes affecting the British and Western Palaearctic lists. "British Birds" 99 (6): 306-323.

* del Hoyo, J.; Elliott, A. & Sargatal, J. (editors) (1996): "Handbook of Birds of the World, Volume 3: Hoatzin to Auks". Lynx Edicions, Barcelona. ISBN 84-87334-22-9

* 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. "Molecular Phylogenetics and Evolution" 39(3): 657–667. DOI|10.1016/j.ympev.2006.01.011 (HTML abstract)

* Thomas, Gavin H.; Wills, Matthew A. & Székely, Tamás (2004a): Phylogeny of shorebirds, gulls, and alcids (Aves: Charadrii) from the cytochrome-"b" gene: parsimony, Bayesian inference, minimum evolution, and quartet puzzling. "Molecular Phylogenetics and Evolution" 30(3): 516-526. doi|10.1016/S1055-7903(03)00222-7 (HTML abstract)

* van Tuinen, Marcel; Waterhouse, David & Dyke, Gareth J. (2004): Avian molecular systematics on the rebound: a fresh look at modern shorebird phylogenetic relationships. "Journal of Avian Biology" 35(3): 191-194. [http://www.stanford.edu/group/hadlylab/images/Lab%20Members/Marcel/JAB2004.PDF_1.pdf PDF fulltext]

External links

* [http://ibc.hbw.com/ibc/phtml/familia.phtml?idFamilia=67 Tern videos] on the Internet Bird Collection
* [http://www.amiright.com/parody/60s/thebyrds19.shtml "Tern! Tern! Tern!"] Song parody