Researchers helping China's rarest seabird rebound from near-extinction
A collaborative project between researchers in Asia and Oregon has helped establish a new breeding colony for one of the world's most endangered seabirds – the Chinese crested tern, which has a global population estimated at no more than 50 birds.
Until this year, there were only two known breeding colonies for the critically endangered species (Thalasseus bernsteini) – both in island archipelagos close to the east coast of the People's Republic of China. Once thought to be extinct, there were no recorded sightings of Chinese crested terns from the 1930s until 2000, when a few birds were rediscovered on the Matsu Islands.
This summer an innovative tern colony restoration began, with assistance from students and faculty in the Department of Fisheries and Wildlife at Oregon State University. Dan Roby, a professor of wildlife ecology at OSU, had previously led efforts to relocate populations of Caspian terns from locations along the Columbia River in Oregon, where the birds were consuming significant quantities of juvenile salmon.
"The problem was different in Oregon than it is in China, but the goal was the same – to alter the habitat in a good location in hopes of creating a breeding colony," Roby said. "The methods also were similar and based on tern restoration techniques developed by Steve Kress of the National Audubon Society. You have to partially clear an island of vegetation, place decoys there, and attract birds using sound."
In early May of 2013, an international team did just that on a small island in the Jiushan Islands called Tiedun Dao. Chinese crested terns used to breed on the archipelago a decade ago, increasing the chances that restoration could be successful there, Roby said.
The project team included members from the Xiangshan Ocean and Fishery Bureau, the Jiushan Islands National Nature Reserve, the Zhejiang Museum of Natural History, and OSU's Department of Fisheries and Wildlife. The team members cleared brush off Tiedun Dao, place 300 tern decoys on the island, and used solar-powered playback systems to broadcast recorded vocalizations of both greater crested terns and Chinese crested terns.
"Greater crested terns are not endangered and when they establish colonies, it sometimes attracts the endangered Chinese crested tern," Roby pointed out. "We thought if we could get them in to colonize the island, their numbers would eventually grow and the Chinese crested terns might follow.
"We just didn't expect it to happen that quickly," Roby added.
The researchers thought it might take years – but by July, a handful of greater crested terns were spotted flying over the decoys. By the end of that month, 2,600 greater crested terns had been documented and hundreds of pairs had laid eggs and begun incubating them. To the surprise of the restoration team, 19 adult Chinese crested terns were spotted on the island and at least two pairs laid eggs.
It was the highest single count of the endangered seabird in one location since the species' rediscovery in 2000.
By late September – despite typhoons and a late start to the breeding season – more than 600 greater crested tern chicks, and at least one Chinese crested tern chick had successfully fledged.
Local officials say they are committed to the protection of the emerging colony.
"We will do our best to ensure good management of the Jiushan Islands National Nature Reserve and we also hope to receive more support for the conservation of the tern colony here in Xiangshan," said Yu Mingquan, deputy director of the provincial Xiangshan Ocean and Fishery Bureau.
The success of the colony on Tiedun Dao is a "landmark for contemporary conservation in the region," said Simba Chan, the senior Asia conservation officer for Birdlife. "No one dared imagine that the first year of such a challenging restoration project would be so successful."