Justification of Red List Category
This poorly known species qualifies as Critically Endangered because it is estimated to have a tiny population, which is in decline owing to egg-collection, disturbance and the loss of coastal wetlands.
The number of breeding adults varies each year, ranging from 12 in 2012 to at least 43 in 2014. Given this the total number of mature individuals is likely to number fewer than 50, and perhaps most likely 30-49 (S. Chan in litt. 2013).
Repeat surveys at the two known breeding sites since 2003 have shown an overall decrease in the number of breeding pairs.
The species is poorly-known, recorded breeding recently at only three sites on the eastern coast of China (Matsu Islands of Fujian, Jiushan Islands, Wuzhishan Islands of Zhejiangand Islands) and one site in South Jeolla Province, South Korea. Outside the breeding season, the species has been recorded in Indonesia, Sarawak, Malaysia, China, Thailand and the Philippines (BirdLife International 2001). In June-July 1937, a total of 21 specimens were collected on islets off the coast of Shandong, where it was presumably breeding, indicating that it was locally not uncommon in the past; however, surveys conducted in June-July 2006 suggest that the regional breeding population has been extirpated from the coast of southern Shandong (Chen Shuihua et al. 2009, Liu et al. 2009). Until the rediscovery of the breeding sites on Matsu and Jiushan Islands, the only records were from China, in Hebei in 1978 and Shandong in 1991, with a possible record from peninsular Thailand in 1980.
In summer 2000 four adults and four chicks were found amongst a tern colony in the Matsu Archipelago off the east coast of mainland China (but administered by Taiwan). Breeding again took place in 2003, and in 2006 5-7 birds, including a pair of adults and a juvenile, were present (Candido 2006), with a total of 20, including three chicks, reported in 2008 (Hansbro in litt. 2008). In 2010 there were 15 adults and three nestlings at Matsu; there were six adults in 2011 and only four adults (with no successful breeding) in 2012 (S. Chan in litt. 2013). In 2015 the species again bred successfully on the Matsu Islands (Hurrell 2015).
A small group of Chinese Crested Tern was also found breeding at Jiushan off the Zhejiang coast in 2004 (Chen et al. 2005), but none bred there in 2005 or 2006; four pairs were recorded in 2007 but all eggs were collected by local people (Chen et al. 2009). Two pairs mixed in about 2000 Greater Crested Terns which were considered to be a former breeding group at Jiushan were found breeding at the Zhoushan Wuzhishan Archipelago nature reserve in Zhejiang in 2008 (Chen et al. 2010), with a maximum of 14 adults and six nestlings there in 2013 (Chen et al. 2013).
Surveys of the coasts of Shandong and Zhejiang in 2003-2007 suggested that the breeding colonies on the Matsu and Jiushan Islands were the only ones still extant (Chen et al. 2009). One to 11 birds (thought to be birds from the Matsu colony) are present from April to September at the Min Jiang estuary, Fujian. Since 2008, a small number of putative hybrid S. bernsteini x S. bergii have also been recorded and photographed at Min Jiang estuary (Chen Lin and He Fenqi 2011), with two recorded at the Matsu Archipelago in June 2011 (Wang Jianhua and He Fenqi in press). The species's movements and wintering grounds remain poorly understood, but heightened awareness in Taiwan (China) has resulted in several records of 1-2 birds using the Pachang River outside the breeding season since 1998 (P. Kennerley in litt. 2003), and more recently in 2004 at Chongming Dongtan National Nature Reserve, Shanghai (Kejia et al. 2004), and the Xisha Archipelago, indicating that it may winter around islands in the South China Sea. An individual was recorded off the coast of Seram Island, north Seram, Indonesia in December 2010 (C. Robson in litt. 2010, Robson 2011). The species was again recorded at this location in November-December 2014, indicating that it may winter in eastern Indonesia (C. Robson in litt. 2015, S. Chan in litt. 2015).
The discovery in 2016 of two pairs breeding in a colony of Black-tailed Gulls (Larus crassirostris) on an uninhabited island off the southeast tip of the Republic of Korea (Muan-gun, South Jeolla Province) represents the first breeding record outside of coastal China (Yang Liu in litt. 2016). There is also a very northern record from Tangu, Tianjin, in September 2008 (per Yang Liu in litt. 2012).
Records indicate that it is exclusively coastal and pelagic in distribution. In China (including Taiwan), it has been found on offshore islets (breeding) and tidal mudflats. Breeding season mid-May to early September. Typically nests within large colonies of Great Crested Tern T. bergii (Chen et al. 2011) but recently two pairs discovered nesting in a Black-tailed Gull colony in coastal South Korea (Yang Lui in litt. 2016).
Many coastal wetlands within its presumed breeding range in eastern China are affected by large-scale development projects and, in China, seabird eggs are exploited for food. The apparent extirpation of the population that formerly bred along the coast of southern Shandong is thought to be linked to the colonisation and development of its breeding islands since the 1950s (Liu et al. 2009). Breeding failures in 1999, 2001, 2002, 2003 and 2005 at the Matsu Islands tern colonies, and in 2007 in the Jiushan Islands, Zheijang Province may have been attributed to fishermen landing to collect shellfish and tern eggs (Candido 2006, Anon. 2007a, Chen et al. 2009) and this is probably by far the most serious immediate threat to the species. A study that monitored 45 nesting attempts by the species between 2004 and 2013 found that egg harvest accounted for 44% of nest failures (11 nests) whilst 48% (12 nests) were lost to typhoons (Chen et al. 2015). Many of the nest failures attributed to typhoons (58%) were re-nesting attempts after the first nesting attempt failed due to egg harvest, highlighting the synergistic effects that these two threats can have on the species (Chen et al. 2015). A typhoon hit Tiedun Dao during the 2015 breeding season but interventions to protect the colony (maintaining vegetation to act as a shelter and discouraging chicks from moving down to the shore) resulted in a casualty rate of less than 5% of all chicks on the colony (Hurrell 2015). Most of the failures occurred before 2008; since then measures have been put in place to protect colonies from illegal egg harvest. The going rate for one seabird egg in Zhejiang more than doubled between 2005 and 2007, encouraging more people to enter the egg-harvesting trade (Anon 2007a). An attempt to harvest eggs from a newly restored colony on Tiedun Dao in the Jiushan Islands was prevented during the 2014 breeding season (Anon. 2014).
Putative S. bernsteini x S. bergii hybrids have been recorded and photographed at Min Jiang estuary since 2008 at least, and at all three colonies along the China coast; thus hybridisation may also be a significant threat to the population (Chen Lin and He Fenqi 2011). Oil spills are another potentially serious threat: a partly-oiled pair were present at Min Jiang estuary in 2010 (P. Morris in litt. 2010). Lesser rice-field rats (Rattus losea) are possibly present on the Matsu, Jiushan, and Wuzhishan islands, and may depredate tern eggs on those islands (Anon. 2007b). King rat snakes (Elaphe carinata) have been trapped on nesting islands in the Jiushan and Wuzhishan islands, and are known to consume tern eggs and possibly chicks and adults as well (Chen S. in litt. 2016). Over-fishing and disturbance associated with fishing activities and tourism are additional potential threats (Chen et al. 2009, Chan et al. 2010). Disturbance from dynamite fishing and other fishing activities in the likely wintering areas in eastern Indonesia also pose a threat (C. Robson in litt. 2015). The potential threat from the impact of pollution from domestic sewage and industrial effluent on the species's food supply is no longer considered likely (I. C. T. Nisbet in litt. 2010).
Conservation Actions Underway
The Matsu colony and surrounding islands were declared a national nature reserve in 2000 and eight islets have been declared 'preserved areas', with no-one allowed to land during the breeding season (Shouhua and Dustin 2008). The Taiwanese Coast Guard patrols waters around the Matsu Islands and has recently begun seizing fishermen's nets if they are caught egg-collecting - this appears to be a major deterrent as there has been no recorded egg loss since (Anon. 2007b). Reclamation at Min Jiang estuary was halted in 2006 and the site is now a provincial-level reserve (F. Morning in litt. 2008). The estuary was recently identified as of international importance for the species (Bai et al. 2015). In Thailand, the species is nationally protected, and the locality where it was historically recorded is protected as the Laem Talumphuk Non-Hunting Area. A Special International Meeting of the Pacific Seabird Group was held in Lukang, Taiwan, in October 2007, at which the Chinese Crested Tern Working Group was formed and various conservation actions were discussed (Anon. 2007b).
Surveys for the breeding colonies of this critically endangered species were conducted along Fujian, Zhejiang, and Shandong coasts since 2003 (Liu et al. 2009, Chen et al. 2009, Fan et al. 2011). In Zhejiang Province, the Jiushan Archipelago is protected by the Zhejiang Jiushan Archipelago National Nature Reserve, and the Wuzhishan Archipelago is protected by the Zhejiang Wuzhishan Archipelago Provincial Nature Reserve. Since 2005, education and outreach for the public have been conducted in Zhejiang, and since 2008 the breeding colonies in Wuzhishan and Jiushan have been closely monitored and protected (Chen S. in litt. 2016)
An 18-month 'Critically Endangered Chinese Crested Tern' project ran from July 2008, aiming to locate undiscovered breeding colonies and feeding areas in Fujian Province, to conduct education and awareness work at schools and local communities around key sites in northern Fujian, and raise awareness of the need for strengthened law enforcement and other actions among stakeholders in Fujian and Zhejiang provinces (BirdLife International 2009). In April 2009, 20 participants attended the Cross-Strait Chinese Crested Tern Conservation Meeting in Fuzhou City, Fujian (Cheung 2010). Amongst the coordinated conservation actions, there were: i) synchronized surveys carried out twice a month from June to August 2009 in the Matsu Islands and Min Jiang estuary to confirm the total number of individuals off the coast of Fujian, ii) surveys for new breeding sites along the eastern coast of mainland China, iii) investigation of migration routes and iv) basic training for nature reserve staff and volunteers. A public seminar and photo exhibition were held in the public library of Fujian to raise awareness of the species and major threats. In October 2009, further awareness-raising activities were conducted in schools in coastal areas of Zhejiang and Fujian provinces (Cheung 2010). Environmental education work is on-going (Hong Kong Bird Watching Society in litt. 2011). Since 2007, six cross-strait or international symposia on the Chinese Crested Tern were held in Taiwan or on the China mainland (Gill 2010, Chen et al. 2013). A Species Action Plan was published in 2010 (Chan et al. 2010). A training workshop on Chinese Crested Terns was held in Zhejiang province, China in March 2013. The workshop focused on habitat restoration at breeding colonies (Anon. 2013).
In 2013, Tiedun Dao islet in the Jiushan Islands was restored as a seabird colony (BirdLife International 2013). Vegetation was cleared, 300 tern decoys were placed on the island and solar-powered playback systems were used to play contact calls of Great and Chinese Crested Terns. By late July, 19 adult Chinese Crested Terns and 2,600 Great Crested Terns were present, and by September at least one juvenile Chinese Crested Tern had successfully fledged. During the 2014 and 2015 breeding seasons two colony monitors were stationed on Tiedun Dao to monitor the species and deter illegal egg harvest. At least 13 chicks fledged in 2014 (Anon. 2014) and at least 16 chicks fledged successfully in 2015 (Hurrell 2015). In 2015, 31 Great Crested Tern chicks were fitted with field readable bands at Yaque Shan in the Wuzhisham Islands in order to learn more about their movements among colonies, migration routes, and wintering range (Hurrell 2015, Chen, S. in litt. 2016). It is hoped that banded Great Crested Terns will help us to learn more about the ecology of Chinese Crested Terns. A series of meetings and workshops were organised to discuss the tern restoration work and a successful education campaign was implemented (Chan 2014). Plans are in place for the BirdLife Asia Division to work with Burung Indonesia to raise awareness of the species at potential wintering sites (Hurrell 2015).
Conservation Actions Proposed
A CMS International Single Species Action Plan (Chan et al. 2010) recommended 13 actions: (1) conducting surveys at its former localities, both in the presumed breeding and non-breeding ranges, and at other potentially suitable breeding sites in China, (2) taking immediate conservation measures to safeguard any sites found, especially nesting colonies, (3) upgrading the level of protection afforded to Min Jiang Estuary, (4) monitoring the known breeding colonies, while taking care to avoid disturbance, (5) enforcing a ban on landing on the breeding islands, (6) stopping the exploitation of the species, ensuring that no eggs are taken - posting a warden at the Matsu Islands (however this may not currently be possible for political reasons), (7) surveying potential wintering areas and migration sites, including islands in the Seram Sea and Banda Sea (Robson 2011); recent records of the species during the winter found it in areas with high concentrations of Great Crested Terns Sterna bergii [C. Robson in litt. 2015] so these areas could be targeted in any future searches), (8) identifying threats in the wintering areas (S. Chan in litt. 2015), (9) lobbying to reduce the amount of pollution from industry; (10) strengthening the species's legal protection status; (11) conducting an education/awareness raising campaign to raise the profile of the species, including working in eastern Indonesia where the species is thought to winter (S. Chan in litt. 2015), (12) implementation of suggested actions by all range countries, (13) improving the knowledge of the species's breeding ecology, migration pathways, and genetic diversity, as well as detecting and removing other potential threats at the breeding colonies(Liu et al. 2009, Chen et al. 2009,2015); studies using colour-ringing and satellite telemetry have been initiated on Great Crested Terns nesting with Chinese Crested Terns along the China coast (S. Chan in litt. 2015, H. Yuan H. in litt. 2016, S. Chen in litt. 2016).
43 cm. Largish, slender, crested tern with black-tipped yellow bill. In flight, shows sharp contrast between pale grey upperwing and blackish outer primaries. Similar spp. Great Crested Tern S. bergii is larger, lacks prominent black tip to bill and has darker grey upperside.
Text account compilers
Pilgrim, J., Peet, N., Ashpole, J, Calvert, R., Taylor, J., Bird, J., Benstead, P., Crosby, M., Symes, A., Moreno, R., Lascelles, B.
Chen, S., He, F., Hsiao-Wei , Y., Le-Ning, C., Chan, S., Hansbro, P., Roby, D., Chung-Hang, H., Zhongyong, ., Yu, Y., Kennerley, P., Fu, V., Nisbet, I., Morning, F., Fawen, Q., Robson, C., Morris, P., Liao, S., Yang, L., Jin, Y., Liu, Y.
BirdLife International (2018) Species factsheet: Thalasseus bernsteini. Downloaded from http://www.birdlife.org on 19/11/2018. Recommended citation for factsheets for more than one species: BirdLife International (2018) IUCN Red List for birds. Downloaded from http://www.birdlife.org on 19/11/2018.