Gull-billed tern
| Gull-billed tern | |
|---|---|
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Scientific classification 
| |
| Domain: | Eukaryota |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Aves |
| Order: | Charadriiformes |
| Family: | Laridae |
| Genus: | Gelochelidon |
| Species: | G. nilotica
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| Binomial name | |
| Gelochelidon nilotica (Gmelin, 1789)
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| Synonyms | |
|
Sterna nilotica | |
The gull-billed tern (Gelochelidon nilotica), formerly Sterna nilotica,[2] is a tern in the family Laridae. The genus name is from Ancient Greek gelao, "to laugh", and khelidon, "swallow". The specific niloticus is from Latin and means of the Nile.[3] The Australian gull-billed tern was previously considered a subspecies.
Description
This is a fairly large and powerful tern, similar in size and general appearance to a Sandwich tern, but the short thick gull-like bill, broad wings, long legs and robust body are distinctive. The summer adult has grey upperparts, white underparts, a black cap, strong black bill and black legs. The call is a characteristic ker-wik. It is 33–42 cm (13–17 in) in length and 76–91 cm (30–36 in) in wingspan.[4][5] Body mass ranges from 150–292 g (5.3–10.3 oz).[6]
In winter, the cap is lost, and there is a dark patch through the eye like a Forster's tern or a Mediterranean gull. Juvenile gull-billed terns have a fainter mask, but otherwise look much like winter adults.
Juvenile Sandwich terns have a short bill, and are frequently mistaken for gull-billed tern where the latter species is uncommon, such as North Sea coasts.
Subspecies
There are five listed subspecies of the gull-billed tern:[7]
- G. n. nilotica – (Gmelin, 1789): nominate, found in Europe, North Africa through the Middle East & south-central Asia to western China & Thailand
- G. n. affinis – (Horsfield, 1821): found in Transbaikalia to Manchuria, Japan, south and east China through southeast Asia to the Philippines, Borneo, Sulawesi & Sumatra
- G. n. aranea – (Wilson, 1814): found in eastern & southern United States, Greater Antilles
- G. n. vanrossemi – Bancroft, 1929: found from southern California to northwestern Mexico
- G. n. gronvoldi – Mathews, 1912: found from French Guiana to northeastern Argentina
Range
It breeds in warmer parts of the world in southern Europe, temperate and eastern Asia, both coasts of North America, eastern South America. This bird has a number of geographical races, differing mainly in size and minor plumage details.
All forms show a post-breeding dispersal, but the northern breeders are most migratory, wintering south to Africa, the Caribbean and northern South America, southern Asia and New Zealand.
The gull-billed tern is one of the species to which the Agreement on the Conservation of African-Eurasian Migratory Waterbirds (AEWA) applies.
Life history
This species breeds in colonies on lakes, marshes and coasts. It nests in a ground scrape and lays two to five eggs. While widely distributed in freshwater areas in Eurasia, it is associated almost solely with saltwater, coastal areas in North America.[4]
This is a somewhat atypical tern, in appearance like a Sterna tern, but with feeding habits more like the Chlidonias marsh terns, black tern and white-winged tern. It used to be grouped in the genus Sterna but is now placed on its own in the genus Gelochelidon.
The gull-billed tern does not normally plunge dive for fish like the other white terns, and has a broader diet than most other terns. It largely feeds on insects taken in flight, and also often hunts over wet fields and even in brushy areas, to take amphibians and small mammals.[4] It is also an opportunistic feeder, and has been observed to pick up and feed on dead dragonflies from the road.[8]
Gallery
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Juvenile/ 1st winter in Chilika, Odisha, India -
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in Krishna Wildlife Sanctuary, Andhra Pradesh, India -
van Rossem's gull-billed terns at the San Diego National Wildlife Refuge -
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References
- ^ BirdLife International (2015). "Gelochelidon nilotica". IUCN Red List of Threatened Species. 2015: e.T62026481A66570901. doi:10.2305/IUCN.UK.2015-4.RLTS.T62026481A66570901.en.
- ^ 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 (2): 459–469. doi:10.1016/j.ympev.2004.12.010. PMID 15804415.
- ^ Jobling, James A (2010). The Helm Dictionary of Scientific Bird Names. London: Christopher Helm. pp. 171, 272. ISBN 978-1-4081-2501-4.
- ^ a b c "Gull-billed Tern". All About Birds. Cornell Lab of Ornithology.
- ^ "Gull billed Tern (Gelochelidon nilotica)". Planet of Birds. 2011. Archived from the original on 2019-06-23. Retrieved 2011-10-20.
- ^ Dunning, John B. Jr., ed. (1992). CRC Handbook of Avian Body Masses. CRC Press. ISBN 978-0-8493-4258-5.
- ^ Gill, Frank; Donsker, David, eds. (2019). "Noddies, gulls, terns, auks". World Bird List Version 9.2. International Ornithologists' Union. Retrieved 23 June 2019.
- ^ Sivakumar, S. (2004). "Gull-billed Tern Gelochelidon nilotica (Gmelin, 1789) feeding on insect road kills" (PDF). Newsletter for Ornithologists. 1 (1–2): 18–19.
External links
- BirdLife species factsheet for Gelochelidon nilotica
- "Gelochelidon nilotica". Avibase.
- "Gull-billed tern media". Internet Bird Collection.
- Gull-billed tern photo gallery at VIREO (Drexel University)
- Interactive range map of Gelochelidon nilotica at IUCN Red List maps
- Audio recordings of Gull-billed tern on Xeno-canto.
- Gelochelidon nilotica in Field Guide: Birds of the World on Flickr
- Gull-billed tern media from ARKive
