The great crested tern (Thalasseus bergii) belongs to the family of gulls and terns, the Laridae.
The great crested tern species is distributed in the Persian Gulf, Arabian peninsula, Africa, Sri Lanka, India, southeast Asia and Australia. These tern species are colonial breeders. These terns are polytypic species.
Appearance, physical description and identification
The great crested tern (Thalasseus bergii) is a large tern, measuring 40 to 55 cm in length and weighing 320 to 400 grams. The wingspan is 100 to 130 cm.The breeding great crested terns have dark grayish back and upperparts. The forehead, hinderneck, nape, throat and the underparts are white. The crown is black and the glossy black crest is shaggy at its rear. In wintering birds, the upperparts are pale gray. The crown becomes white with spotted crest.
The bill is long, pointed and yellowish. The irises are dark brown. The legs are black. The juveniles have black, white and brown pattern on the upperparts and wings. Their call is a loud, raucous "kerrak" or a "korrkorrkorr" sound
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| 1.Birds of India - Image of Great crested tern - Thalasseus bergii by JJ Harrison |
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| 2.Indian birds - Picture of Great crested tern - Thalasseus bergii by C Watts |
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| 3.Birds of India - Photo of Great crested tern - Thalasseus bergii by David Cook |
Origin, geographical range and distribution
The great crested tern species are distributed on the coastline of Africa, Madagascar, Arabian Peninsula, Persian Gulf, islands of the western Indian Ocean, Pakistan, India, Sri Lanka, Bangladesh, southeast Asia and Australia.In India, these great crested terns are distributed in the coastline of Maharashtra, Goa, Karnataka, Lakshadweep Islands, Tamil Nadu, Odisha and West Bengal. Vagrant great crested terns were observed in USA, North Korea, New Zealand and Jordan.
The Important Bird and Biodiversity Areas (IBA) of these great crested terns in Australia are, Seagull Island, Michaelmas Cay, Bountiful Islands, Lowendal Islands and Pearce, Urquhart and Hervey Islands.
The IBA of these these great crested tern species in China are, Beiji Islands, Yushan Islands, Jiushan Islands Nature Reserve and Taizhou Islands. The IBA in India is Baliapannium Islands (Lakshadweep).
The IBA of the great crested terns in South Africa are, Robben Island, Berg River Estuary, False Bay Nature Reserve, Dassen Island, Dyer Island Nature Reserve and West Coast National Park and Saldanha Bay islands.
Ecosystem and habitat
These great crested tern species do not normally occur in forest. They normally occur in altitudes from 0 to 100 meters. The artificial ecosystems and habitats of these species include, salt production facilities, wastewater treatment ponds and coastal aquaculture farms.The natural ecosystems and habitats of these great tern species include, rocky offshore islands, coral reefs, shorelines, estuaries, shallow seas with submerged macroalgae, open seas, tidal flats and sandy beaches.
Diet and feeding behavior
The diet of this great crested tern consists mainly of pelagic fish. Fish, prawns, crabs, squids, crustaceans, baby turtles and insects are their primary food.The great terns feed mainly by plunge diving to depth of about one meter. The terns also follow fishing vessels and feed on discards from commercial fishing.
Reproduction and breeding habits
The breeding season of these great crested tern species is during April to June in the Indian Ocean region. The laying season is during May and June in Sudan and South Africa. The breeding season is in October in Kenya and is in August in Somalia.The great crested tern nesting sites are usually located in sandy beaches, coral reefs, mudflats and salt pans. The nest is a shallow scrape on sand, rock or coral. Sometimes they nest on the roof of buildings.
These great crested tern species are monogamous and colonial breeders. The nesting territory is protected by the pair. The courtship display includes head raising and bowing and offering of fish by male to the female.
The typical clutch of great crested tern contains one or two pale buff colored eggs with dark blotching. Both parents take part in incubating eggs and caring for the chicks.
The chicks hatch out after 25 days of incubation. The chicks are precocial and begin to wander from the nest after two days. They fledge by 40 days and are dependent on the parents for nearly four months.
Migration and movement patterns
These great crested tern species are non-migrant, resident birds. They disperse locally after breeding. Some populations have been observed to move over longer distances.Post breeding, the juveniles may disperse and establish in new locations within the range. Within their range they may make local movements for feeding and breeding.
Great crested tern - Quick Facts
- Scientific name: Thalasseus bergii
- Species author: (Lichtenstein, 1823)
- Synonyms/Protonym: Sterna Bergii M. H. C. Lichtenstein, 1823
- Family: Laridae › Charadriiformes › Aves › Chordata › Animalia
- Vernacular names: English: Great crested tern, Chinese: 大凤头燕鸥, French: Sterne huppée, German: Eilseeschwalbe, Spanish: Charrán piquigualdo, Russian: Крачка Берга, Japanese: オオアジサシ, Indonesian: Daralaut Jambul
- Other names: Large Crested Tern, Swift Tern, rested Tern
- Distribution: Persian Gulf, Arabian peninsula, Africa, Madagascar, Sri Lanka, India, southeast Asia, China, Australia
- Diet and feeding habits: fish, squid, crabs, insects, baby turtles, aquatic invertebrates
- IUCN status listing: Least Concern (LC)
Conservation and survival
The global population size of the great crested tern (Thalasseus bergii) is estimated to number 150,000 to 1,100,000 individual birds. The overall population trend of the species is considered to be stable.In most of its range, this tern species is reported to be common. The generation length is 10.5 years. Its distribution size is about 142,000,000 sq.km.
Habitat alteration and destruction, climate change, severe weather, hunting and egg collection are the main threats that are endangering the survival of these great tern species.
IUCN and CITES status
The great crested tern (Thalasseus bergii) does not approached the thresholds for being Vulnerable either under the range size criterion, or under the population trend criterion, or under the population size criterion.The IUCN (International Union for Conservation of Nature) has categorized and evaluated the tern species and has listed it as of "Least Concern".
The CITES (Convention on International Trade in Endangered Species of Wild Fauna and Flora) status is ‘Not Evaluated’ for great crested tern (Thalasseus bergii).
| Taxonomy and scientific classification of Thalasseus bergii | |
|---|---|
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Aves |
| Order: | Charadriiformes |
| Family: | Laridae |
| Subfamily: | - |
| Genus: | Thalasseus |
| Species: | T. bergii |
| Binomial name: | Thalasseus bergii |
| IUCN status listing: |
 Least Concern |
The five recognized subspecies of the great crested tern (Thalasseus bergii) are: T. b. bergii (M. H. C. Lichtenstein, 1823), T. b. thalassinus (Stresemann, 1914), T. b. velox (Cretzschmar, 1827), T. b. gwendolenae (Mathews, 1912) and T. b. cristatus (Stephens, 1826).
1.Photo source: https://en.wikipedia.org/wiki/File:Crested_Tern_Tasmania.jpg (cropped)
Photo author: JJ Harrison | License: CC BY-SA 3.0
2.Photo source: https://www.flickr.com/photos/watts_photos/28492937976/ (cropped)
Photo author: C Watts | License: CC BY 2.0 as on 1/23/18
3.Photo source: https://www.flickr.com/photos/kookr/3040113557/ (cropped)
Photo author: David Cook | License: CC BY-NC 2.0 as on 1/23/18
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