Greater Crested Tern

Greater Crested Tern ©Kenneth Lam Common name: Greater Crested Tern Scientific name: Thalasseus bergii Local names:Крачка Берга (Russian), 大凤头燕鸥 (Simplified Chinese), 大鳳頭燕鷗 (traditional Chinese), 큰제비갈매기 (Korean), オオアジサシ(Japanese), Dara laut jambul besar (Indonesian), Camar Besar Berjambul (Malayu), Nhàn mào (Vietnamese), นกนางนวลแกลบหงอนใหญ่ (Thai). Also known as Swift Tern in Africa, and Crested Tern in Australia Conservation status: IUCN - Least Concern The Greater Crested Tern is a large-sized tern species distributed in tropical and subtropical Old World, usually nesting in dense colonies in coastal islands.  There are four subspecies recognized: Thalasseus bergii bergii, Thalasseus bergii thalassinus, Thalasseus bergii velox, Thalasseus bergii cristatus, with T.b. cristatus found within the EAA Flyway.     Identification Identification: Size: 43–53 cm; wingspan 100–130 cm. Body: Grey upper parts and white under parts. It has a distinctive white forehead, glossy black cap with a long crest, crest recedes in the non-breeding season Beak:  Yellow Juvenile: Juveniles appear like non-breeding adults, with crown feathers brownish with pale spots, underparts and upper wings are barred and ashy brown. Distribution range Thalasseus bergii cristatus: Northern-most breeding range in Ryukyu Islands and southeastern China up to the Yangtze Estuary, all-year-round to the Philippines, Southeast Asia, the Sunda Islands, Wallacea, New Guinea, Australia, and the tropical Pacific Ocean (to southeastern Polynesia). Non-breeding movement is understudied. Satellite tracking showed those breeding in SE China winter in coastal Indo-China, Thailand, Myanmar and northern Philippines. Birds breeding at Paracel (Xisha) Islands in the South China Sea winter in central Philippines and Borneo. Non-breeding birds in Wallacea were mostly tracked to visit northern Australia where they may breed, with one tracked to Palau. Habitat Breeding habitat Nests on offshore islands, low-lying sandy, rocky or coral islets, usually unsheltered bare surface. The bird forages in shallow waters in estuaries, lagoons and barrier reefs, along beaches, and also in the open sea. They may take rest on buoys or sandbars. Breeding habitat of Greater Crested Tern in Zhejiang, China © Simba Chan Dense nesting colony of Greater Crested Tern in Zhejiang, China © Simba Chan Non-breeding habitat Greater Crested Tern wanders and disperses after the breeding season. They use sandy islands, coastal sandy or tidal flats. Greater Crested Tern resting on buoy ©Kenneth Lam Behavior Greater Crested Tern nest in dense breeding colonies, also highly vocal during breeding season. Colony size is depending on food abundance and habitat area. Largest colony can be up to 15,000 pairs. Although the bird nest in dense colony, but each pair establish small area of territory and they would peck any intruder bird in the territory. The male bird would perform courtship dance for female, with nuptial gifts, usually fish. Population estimate Global estimated population: The global population is estimated to number c.150,000-1,100,000. while regional population estimates in EAA Flyway are 100,000-1,000,000 according to the 1st Conservation Status Review. However, the estimation seemed to lump several populations together. From present knowledge the Greater Crested Tern breeding along the coasts of Zhejiang, Fujian, Taiwan and Guangdong are likely belonged to one population that migrates to Indo-china, Thailand, Myanmar and the northern Philippines. This population is probably around 30,000 birds with an increasing trend. Main threats Human disturbance, e.g. recreational and tourism activities in coastal areas close to breeding colonies Egg collection Habitat loss (Note: A regular migratory stop-over site for this species and many other terns and shorebirds, the tidal flat of Pamawaran, Bulacan in Manila Bay, the Philippines, is currently under threats from reclamation for airport expansion. Hundreds of Greater Crested Terns, including up to 10 individuals color-banded from Zhejiang and Taiwan, have been recorded at these sites since 2021.) GCT color-banded in Zhejiang, China sighed at Manila Bay, the Philippines on 28 October 2022 © Irene Dy Other threats: Pollution Plastic pollution Over-fishing Natural threats: Adverse weather conditions, e.g. typhoons, heavy rains, strong winds and waves Natural predators (e.g. gulls, Peregrine Falcon, snakes, rats) Conservation Work Satellite tracking study of Greater Crested Terns in collaboration with Indonesia shed light to conservation of Criticallty Endangered Chinese Crested Tern wintering ground Greater Crested Terns provide socia protection to the critically endangered Chinese Crested Terns in both breeding and wintering grounds. Studying both or either one species could provide useful information for the conservation of both crested terns. HKBWS in collaboration with partners in Indonesia conducts satellite-tracking studies of the Greater Crested Terns in Wallacea region of Indonesia since 2018. Previously we assumed the Greater Crested Terns in this area could have a northern breeding origin, through the tracking study we could find out migration routes and stopover sites of Greater Crested Tern and potentially to the Chinese Crested Terns too. The results brought us unexpected findings that birds in Wallacea region migrated south to the Gulf of Carpenteria of northern Australia for breeding and one bird migrated to Palau. These birds stayed in the areas where are the known tern breeding sites. Non-adults did not migrate to these breeding areas but wandered around Banda Sea, Timor Sea and Arafura Sea. Migration route and hotspots are now being identified with this study as site and habitat management could now be considered to apply in the important sites. This finding can also help promoting seabird conservation collaboration between Indonesia, Australia and other neighouring countries. Mr. Yu Yat Tung, Research Manager of HKBWS released a Greater Crested Tern fitted with a satellite transmitter in the wintering island of Indonesia © HKBWS Greater Crested Tern fitted with satellite transmitter in Indonesia © Simba Chan Learn more: https://www.hkbws.org.hk/cms/en/hkbws/cct2019   Tubbataha Reefs Natural Park  holds the largest breeding colony of Greater Crested Terns in the Philippines with at least 14,000 individuals as of the last survey.  They breed in the two islets of Tubbataha.  These breeding grounds are off limits to tourists to prevent stress and disturbance especially during the breeding months of March to July. Marine park rangers conduct monthly estimates of adults and a more comprehensive quarterly inventory which includes eggs, pulli, and juveniles. The Philippine Red List of Threatened Fauna classifies the  Greater Crested Terns as Vulnerable. Tubbataha Reefs Natural Park ©Godfrey Jacosalem Tubbataha Reefs Natural Park ©Kymry Delijero   Fun Fact Although Greater Crested Tern is among one of the biggest terns, it is a very nerous breeder. They tend to form very big and dense nesting colonies thus easy to be found during breeding season. Because the critically endangered Chinese Crested Terns nest in the same colony amid Greater Crested Terns in Zhejiang, Fujian and Taiwan, attracting Greater Crested Tern to breed in desired protected site supported restoring the population of Chinese Crester Tern. Hybridization is reported but the threat is much lower than commonly believed as they have a very strong sense of species identify. Hybrid birds (which may be the result of wrong imprinting) are very difficult to find a mate (pers. obs.). Chinese Crested Tern is a close relative to Greater Crested Tern, so close that the type specimen of Chinese Crested Tern collected near Halmahera, Indinesia in 1861 was long regarded as a Greater Crested Tern (corrected since 1975), and a specimen of Chinese Crested Tern collected near Chemulpo (now Incheon), Korea in 1917 was also misidentified as a Greater Crested Tern (corrected since 2016). References  IUCN Red List: https://www.iucnredlist.org/species/22694571/132561035 Birds of the World: https://birdsoftheworld.org/bow/species/grcter1/cur/introduction Gochang Big Bird Race 2023 brought birdwatchers to contribute bird data to the UNESCO World Heritage Site Special achievement award to the Chinese Crested Tern team Webinar on Chinese Crested Tern in the Yellow Sea and Seabird Conservation in China Chinese Crested Tern banded in Republic of Korea sighted in China Chinese Crested Tern Restoration of the Critically Endangered Chinese Crested Tern using social attraction technique A Conservation Success in Minjiang River Estuary A tern for the better Critically Endangered Chinese Crested Terns appear on a deserted island in South Korea The First Ever Banded Chinese Crested Tern Chick has Fledged

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