Tern

Terns are seabirds in the family Sternidae. They were previously considered to be a subfamily (Sterninae) of the gull family Laridae. They are less closely related to the waders, auks and skimmers and are found worldwide.

Most terns belong to the large genus Sterna, with the other genera being small. Some authorities have split the genus Sterna into several smaller genera (see list, below).

Many terns breeding in temperate zones are known to migrate for long distances, 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 14,000 miles (22,000 km) 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 generally medium to large birds with grey or white plumage and often with black markings on the head. They have long bills and webbed feet. Lighter bodied and more streamlined than gulls, terns are elegant in flight with long tails and long narrow wings. Terns in the genus Sterna have deeply forked tails. Those in Chlidonias and Larosterna have shallowly forked tails. The noddies (genera Anous, Procelsterna, Gygis) have unusual ‘notched wedge’ shaped tails and the longest tail feathers being the middle-outer, not the central nor the outermost.

Most terns (Sterna and the noddies) dive for their meal of fish, often hovering first, however the marsh terns (Chlidonias) pick insects of the surface of fresh water. Terns do not glide often but a few species, notably Sooty Tern, will soar high above the sea. Apart from bathing, they rarely swim, even though they have webbed feet.

Terns are generally long-lived birds, with several species now known to live in excess of 25-30 years.

Classification & species list

• Genus Sterna
• Subgenus Gelochelidon
  • Gull-billed Tern, Sterna nilotica (Gelochelidon nilotica)
• Subgenus Hydroprogne – Caspian Tern.
  • Caspian Tern, Sterna caspia (Hydroprogne caspia)
• Subgenus Thalasseus – crested terns.
  • Royal Tern, Sterna maximus (Thalasseus maximus)
  • Greater Crested Tern or Swift Tern, Sterna bergii (Thalasseus bergii)
  • Chinese Crested Tern, Sterna bernsteini (Thalasseus bernsteini)
  • Elegant Tern, Sterna elegans (Thalasseus elegans)
  • Lesser Crested Tern Sterna bengalensis (Thalasseus bengalensis)
  • Sandwich Tern, Sterna sandvicensis (Thalasseus sandvicensis)
• Subgenus Sterna – typical white terns
  • River Tern Sterna aurantia
  • Roseate Tern, Sterna dougallii
  • White-fronted Tern, Sterna striata
  • Black-naped Tern, Sterna sumatrana
  • South American Tern, Sterna hirundinacea
  • Common Tern Sterna hirundo
  • Arctic Tern Sterna paradisaea
  • Antarctic Tern, Sterna vittata
  • Kerguelen Tern, Sterna virgata
  • Forster’s Tern, Sterna forsteri
  • Trudeau’s Tern, Sterna trudeaui
  • White-cheeked Tern Sterna repressa
  • Black-bellied Tern, Sterna acuticauda
  • Black-fronted Tern, Sterna albostriata
• Subgenus Sternula – little tern group.
  • Little Tern Sterna albifrons
  • Saunders’ Tern, Sterna saundersi (Often considered conspecific with Little Tern)
  • Least Tern Sterna antillarum (Often considered conspecific with Little Tern)
  • Yellow-billed Tern, Sterna superciliaris
  • Peruvian Tern, Sterna lorata
  • Fairy Tern, Sterna nereis
  • Damara Tern, Sterna balaenarum
• Subgenus Haliplana – “brown-backed” terns.
  • Aleutian Tern, Sterna aleutica
  • Grey-backed Tern, Sterna lunata
  • Bridled Tern, Sterna anaethetus
  • Sooty Tern, Sterna fuscata
• Chlidonias – marsh terns.
  • Whiskered Tern Chlidonias hybridus
  • White-winged Tern or White-winged Black Tern Chlidonias leucopterus
  • Black Tern Chlidonias niger
• Phaetusa – Large-billed Tern.
  • Large-billed Tern Phaetusa simplex
• Anous, Procelsterna, Gygis – noddies. A tropical group, characterized 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
• Larosterna – Inca Tern.
  • Inca Tern Larosterna inca

PHOTO CAPTION: Arctic Tern