Biology
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Little is known about the biology of the Chinese crested tern. The stomachs of adult specimens were found to contain fish (6) and breeding is thought to occur from May to July, although no definite breeding sites have ever been found (2).
Conservation
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The Mazu Dao islands were declared as the National Matzu Nature Reserve for Terns in 2000, offering some protection to the birds there (4) (6). The most recent sighting in China was from Huanghe Sanjiaozhou Nature Reserve in Shandong in 1991 and several other protected areas exist along the Chinese coast where the species may occur (4). This bird is nationally protected in China and Thailand, and the area where it was once recorded in Thailand is protected as the Laem Talumphuk Non-Hunting Area (4) (6). Further studies are certainly needed to better understand this species, its range, what sort of breeding success it is having, the exact threats it faces and its protection needs (7). One suggested measure, that has been successful elsewhere, is to give local people a vested interest in seeing the birds remain alive, perhaps by allowing or encouraging fishermen to take birdwatchers to see the rare seabirds, rather than collecting their eggs (7). Thus, special boat trips have now been made available from Matsu Island to the National Matsu Nature Reserve for Terns during the months of June and July for NT$350 (approx. US$11). Landing on the nesting island is not permitted and viewing is from the boat at a safe distance, so that the terns are not disturbed, but this revenue may help protect the bird by making it more valuable alive than dead (5).
Description
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Previously thought to be possibly extinct, the Chinese crested tern was rediscovered in 2000 with a population of just four adult pairs and four chicks (4). This largish, slender bird has a diagnostic black-tipped yellow bill, sometimes with a tiny white spot at the extreme tip (5). Breeding adults have a white head and black crested cap (5). Underparts are white and upper parts are a pale pearl-grey, with blackish outer primary flight feathers (4) (5). The tail is white and deeply forked, and the legs and feet are black. The non-breeding adult is similar, except that the crown is mottled black and white, merging into the black nape. Juveniles are a mottled brown colour on upper parts, with a paler inner part of the wing lining and two dark bars on the inner wing (5).
Habitat
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Although poorly understood, available records indicate that this bird roosts in coastal areas and is otherwise pelagic (4).
Range
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The Chinese crested tern is poorly understood. The bird has been recorded in the past on the eastern coast of China, in Hebei, Shandong, Fujian and Guangdong, and outside the breeding season on Halmahera (Indonesia), in Sarawak (Malaysia) and in Taiwan, Thailand and the Philippines. The only recent records are from China in Hebei in 1978 and Shandong in 1991, with a possible record from peninsular Thailand in 1980. The only known current population was found on the Mazu Dao islands off the east coast of mainland China (but under the administration of Taipei) in 2000. The current total numbers are unknown but are thought to be very small given the rarity of recent records (4).
Status
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Classified as Critically Endangered (CR) on the IUCN Red List 2007 (1) and listed under Appendix I of the Convention on the Conservation of Migratory Species (CMS) (3).
Threats
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The specific threats facing this exceptionally rare bird have not yet been identified, but a range of environmental issues are known to affect other species within its range and are therefore highly plausible threats to this species (4). Offshore islets, which appear to be the key nesting areas of this bird, are thought to be relatively safe from human disturbance. However, other coastal wetlands in this species' presumed breeding range in eastern China have been affected by large-scale development projects (4) (6). Seabirds are also hunted and exploited for food in China. Indeed, the main threat to the newly discovered population on the Mazu Dao islands is from fishermen from mainland China, who visit the nesting islets to collect seashells and bird eggs. Other potential threats include the introduction of rats and cats to currently predator-free offshore islands, oil pollution and contamination of estuarine areas by industrial and agricultural pollutants, and human disturbance (6).
Chinese crested tern
provided by wikipedia EN
The Chinese crested tern (Thalasseus bernsteini) is a tern in the family Laridae. It is the county bird of Lienchiang County, Fuchien.
Description
It is closely related to the Sandwich tern, T. sandvicensis, and the lesser crested tern, T. bengalensis. It is most similar to the former, differing only in the bill pattern, which is the reverse of the Sandwich tern's, being yellow with a black tip. From the lesser crested tern, which it overlaps in wintering distribution, it can be told by the white rump and paler grey mantle, as well as the black tip to the bill, which seen from up close also has a white point. The larger greater crested tern is also similar, differing in its stouter, all-yellow bill and darker grey mantle and rump, as well as in size.
Distribution and conservation
It is a critically endangered species, and previously thought extinct. Only four pairs were rediscovered in 2000 nesting in a greater crested tern colony on an islet in the Matsu Islands (a territory governed by Taiwan), just off the coast of Fujian Province, China, and wintering south to the Philippines. In the past, it had a wider distribution of the Chinese east coast north to Shandong Province. The decline is thought to be due to past hunting and egg collection for food. This colony may have been protected due to the islands' disputed status (administered by the Taiwanese government but claimed by mainland China), and the military sensitivity of the area, which has restricted access. The islet has now been declared a wildlife sanctuary. It is possible that other small colonies may yet be found off the Chinese and Taiwanese coasts; migrant birds have been seen near the mouth of the Pachang River in southern Taiwan. The total population is speculated to be less than 50 birds.
In 2007 it was estimated that the Chinese crested tern would be extinct in five years if authorities would not protect it. BirdLife International of Cambridge, England, stated that a survey of Chinese experts found that the number of crested terns fell to 50 birds, half the population of 2004. A Chinese survey team led by Chen Shuihua stated that the bird was "on the verge of extinction."[2]
It is currently threatened by illegal egg collection, typhoons, and disturbance of nesting colonies by fishermen. There is also a threat of hybridization with the greater crested tern. [3]
In 2016, for the first time, Chinese crested terns were found breeding in South Korea. Setting up a new colony in such a faraway area would prove a boon for the species.[4]
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
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^ BirdLife International (2018). "Thalasseus bernsteini". IUCN Red List of Threatened Species. 2018: e.T22694585A131118818. doi:10.2305/IUCN.UK.2018-2.RLTS.T22694585A131118818.en. Retrieved 20 November 2021.
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^ Chinese seabird on verge of extinction
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^ Yang, J.; Chen, G.; Yuan, L.; Huang, Q.; Fan, Z.; Lu, Y.; Lui, Y.; Chen, S. (2018). "Genetic evidence of hybridization of the world's most endangered tern, the Chinese Crested Tern Thalasseus bernsteini". Ibis. 160 (4): 900–906. doi:10.1111/ibi.12616. S2CID 90714317.
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^ International, BirdLife. "A tern for the better | BirdLife". www.birdlife.org. Retrieved 2017-06-24.
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Chinese crested tern: Brief Summary
provided by wikipedia EN
The Chinese crested tern (Thalasseus bernsteini) is a tern in the family Laridae. It is the county bird of Lienchiang County, Fuchien.
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