Birds Guide

Terns
Arctic Tern
Scientific classification
Kingdom: Animalia   Phylum: Chordata   Class: Aves   Order: Charadriiformes   Suborder: Lari   Family: Sternidae Bonaparte, 1838
Genera
Anous Procelsterna Gygis Onychoprion Sternula Phaetusa Hydroprogne Gelochelidon Larosterna Chlidonias Thalasseus Sterna z

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, but 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).

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 Britain in summer 1982, reached Melbourne, Australia in October 1982, a sea journey of over 22,000 km (14,000 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 wings. 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.

A flock of Royal Terns in flight in Florida, USA.

Common Tern by the River Thames

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 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)

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. 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. PDF fulltext

External links

• Tern videos on the Internet Bird Collection
• "Tern! Tern! Tern!" Song parody