Asia’s rarest seabird could be easier to spot in the future
Researchers celebrate breeding success in South Korea for the Chinese Crested Tern – a bird once thought extinct. Decoy model birds have helped bolster the new colony, and the species has been spotted in Japan for the first time.
Trying to spot a Chinese Crested Tern amongst a colony of similar-looking Greater Crested can be likened to playing a high-pressure game of ‘Where’s Wally?’, in which rather than simply completing a fun puzzle-book by spotting a man in a red-striped jumper, the fate of an entire species relies on your attentive eyes.
So when, about three years ago, we reported a momentous discovery in the conservation of Asia’s rarest seabird, the Chinese Crested Tern Thalasseus bernsteini, we were very excited by what it could mean. Korean researchers had spotted five adults and one chick amidst a colony of Black-tailed Gulls on an uninhabited rocky island (Chilsando), 7 km off the southwest coast of South Korea. This was extra special because Chinese Crested Tern was feared extinct until 2000 when breeding birds were rediscovered on the Matsu Islands of Chinese Taiwan, and hadn’t been seen on the eastern side of the Yellow Sea for almost 100 years. Yunkyoung Lee, Researcher from the National Institute of Ecology (South Korea), remembers the moment well:
“When I realised that we were looking at Chinese Crested Terns, I felt a thrill throughout my whole body”, she says. “Their slender appearance with black caps and white backs was eye-catching in the crowded colony of Black-tailed Gulls Larus crassirostris, which have white rounded heads and grey backs. However, in the field, we did not know immediately what they were. We had never seen this species before, let alone ever anticipated that they would lay eggs in Korea.”
Taking quick action, Lee and her team immediately ensured the Critically Endangered terns’ safety by restricting access to the area. At the time the species’ entire global population was thought to be less than 100 individual birds.
As well as the importance of the location, the fact the birds were nesting amongst gulls was special, because previously Chinese Crested Terns found nesting well on the west of the Yellow Sea since 2000 were amongst colonies of Greater Crested Terns Thalasseus bergii, the slightly larger, much more common cousins of the Chinese Crested. The Greater Crested aren’t found as far north as the Korean peninsula, and Chinese Crested’s range was further north historically, so it was assumed they’d adapted their range in order to find a way to breed in a colony.
You see it’s tough being naturally sociable when there’s no-one left to hang around with. The Chinese Crested Tern is a very gregarious species, relying on the presence of a large colony to feel comfortable enough to breed successfully. Late-breeders will even desert their nests if the colony starts to disperse, according to close observation by BirdLife’s Simba Chan, Senior Conservation Officer of BirdLife Asia Division and National Geographic Explorer, when he dedicated two breeding seasons in 2014 and 2015 carefully camped out (relying on shipment of food and water, and braving a typhoon) on the Jiushan Islands (off the coast of Zhejiang, southeast China [see map below]) in order to protect newly-found Chinese Crested Terns there (amongst Greater Crested) from disturbance. The 2016 discovery in South Korea also indicates that Chinese Crested Terns there are breeding earlier than normal in order to match the breeding times of the Black-tailed Gulls.
The key, therefore, to the conservation of Chinese Crested Terns is increasing nesting success by making the birds feel safe. This is achieved through preventing disturbance and by using social attraction techniques, such as using model decoy birds and call-playback systems to bolster the colony. Almost three years later, this kind of direct conservation effort is paying off in South Korea: this breeding season seven Chinese Crested Terns were monitored at the South Korean island, with at least one chick fledged.
