Little known Oriental bird: Discovery of a breeding colony of Chinese Crested Tern

by Chieh-Teh Liang, Shou-Hua Chang, and Woei-horng Fang, from OBC Bulletin 32, December 2000.

Prior to the recent observations detailed below, the Chinese Crested Tern was only known from a few old specimens and sight records. There are a few historical records from China including 21 collected off Shandong in 1937. More recent records from China are of three birds observed on sand flats at Beidaihe on 10 June 1978 and a further three, probably of this species were observed at the mouth of the Yellow River in Sept 1991.

Outside of the breeding season there are three specimen records from Fujian dating from 1913 and 1916 and two probable observations from Guangdong, one of which was after a typhoon.

Away from China there are specimen records as follows: two from the Philippines (1905 and undated), one from Halmahera, Indonesia (1861) and three each from Malaysia (Sarawak 1890, prior to 1891 and 1913) and Thailand (three winter-plumage males collected in 1923). The only recent sight record concerned 10-20 reported from Ko Libong Wildlife Sanctuary in Thailand in July 1980.

In June 2000 Liang Chieh-teh was fortunate to discover a Chinese Crested Tern Sterna bernsteini colony in the Matzu Archipelago. Here the authors give some background to this exciting discovery.

The Chinese Crested Tern is a critically endangered species. It was first described in 1863 and since its discovery only five group of birds have been recorded. The two most recent records concerned ten in Thailand in July 1980 and three in northern China in September 1991. Several authors consider this bird may already be extinct (1,2).

The Matzu Archipelago (25°56'-26°18'N, 119°51'-120°01'E) is a short distance east of the Fukien province of mainland China and due to its strategic importance was under military regulation and very difficult to visit for the general public. The fauna and flora of the area were largely unknown. In recent years the central government of China eased the military regulation of the area and more birdwatchers and naturalists began to visit the area.

A three year project to study bird ecology in the area, coordinated by Wild Bird Federation of Taiwan (formerly Chinese Wild Bird Federation) and financed by Agriculture Improvement Bureau of Lienchiang County began in April 1996 and improved our understanding of the bird fauna. The survey found that several uninhabited islets are very important breeding sites for terns with large colonies of Greater Crested Tern Sterna bergii, Bridled Tern, S. anaethetus and Roseate Tern S. dougallii. The results of the survey prompted the Lienchiang County Government to define the islets as a nature reserve and in January 2000, eight islets used by breeding terns were officially designated as 'National Matzu Nature Reserve for Terns' by Central Government Council of Agriculture.

In order to increase public awareness of conservation in the reserve, Lienchiang County Government supported a project of Wild Bird Federation of Taiwan to film the breeding terns. The project started in June 1999 and was carried out by Liang Chieh-teh. In mid-June 2000 while editing the film of a Greater Crested Tern colony videoed on 1 June, several pairs of strange terns were noted. After checking a reference book 3 these birds were identified as Chinese Crested Tern based on their smaller size and paler upperparts than Greater Crested Tern and black tips to their bills. The film was sent to Dr. Lucia Liu Severinghaus who helped to confirm the identification.

On 29 June Liang and Mr. Chang Shou-Hua, the Secretary General of Wild Bird Society of Matzu visited the colony for more fieldwork. They surveyed the area and found four breeding pairs of Chinese Crested Tern, with eight adults and four chicks. This is the highest count of the species ever.

In late July Liang took Dr. Severinghaus to the Terns' colony to confirm the identification in the field and a press conference was later held to announce the important find. On 26th August the authors again visited the terns' colony but only one Chinese Crested Tern in non-breeding plumage remained at the site along with 40+ Greater Crested Tern. This was the last sighting of this bird this year.

Currently the breeding site is in a National Nature Reserve under the protection of law and the Magistrate Liu of Liengchiang County Government is very supportive of the conservation of the site. The major threat now is fisherman from mainland China invading these islets to collect seashells or bird eggs. After disturbance by fisherman in 1999 a previous Bridled Tern breeding site had no birds in the following breeding season. Since the colony is very sensitive to disturbance, control of visiting tourists will also be a problem during next breeding season.

After the announcement of the rediscovery we received reports of two earlier sightings. One was from Chang Shou-Hua who took many photographs of the Matzu tern colony in previous years. Using a magnifying glass to examine early photographs he found some Chinese Crested Terns in a Greater Crested Tern colony. This finding suggests the Chinese Crested Tern may have been breeding at this site for some time. The other report was from Weng Jung-Hsiun, who took a picture of a single Chinese Crested Tern in a flock of Caspian Terns S.caspia at Putai, Chiayi County (23¥21'N, 120¥10'E) on 17 April 1998. Initially, this bird was thought to be an immature Greater Crested Tern but was later re-identified as the first and the only Chinese Crested Tern record from Taiwan.

We consulted several handbooks and fieldguides about this bird. According to our observations, the plates of this bird are not entirely accurate (1-7); there is a white point to the black tip of the bill. Only two books demonstrated this feature (1,4). The bill colour is more orange than Greater Crested Tern but all the plates illustrated it as yellow (as in Greater Crested Tern) except duPont (5).

Note: Under a different spelling system, Matzu may be spelled as Matsu and Liangchiang as Lian-jiang.

References

1. Robson, C. (2000) A field guide to the birds of south-east Asia. New Holland: UK.

2. Viney, C, Phillipps, K., and Lam, C.Y. (1996) Birds of Hong Kong and South China. Hong Kong.

3. del Hoyo, J., Elliot, A., and Sargata, J. eds (1996) Handbook of the Birds of the World, Vol 3, Hoatzin to Auks. Lynx Edicions, Barcelona: Spain.

4. Harrison, P. (1983) Seabirds, an identification guide. Houghton Mifflin, Boston, USA.

5. duPont, J.E. (1971) Philippine Birds. Delaware Museum of Natural History, Greenville: USA.

6. Lekagul, B., and Round, P.D. (1991) A Guide to the Birds of Thailand. Bangkok: Thailand.

7. Sonobe, K. and Usui S. eds (1993) A field guide to the water birds of Asia. Wild Bird Society of Japan. Tokyo: Japan.

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