Conservationists have reported an “alarming” decline in the population of the endangered black-faced spoonbill in Hong Kong, despite global numbers reaching a record high.

The Hong Kong Bird Watching Society on Wednesday also warned that the species’ numbers had become overly concentrated in Taiwan, where any changes in its habitat could further endanger its survival. The island is home to nearly two-thirds of the bird’s worldwide population.

Releasing its annual black-faced spoonbill census, the group said the global population reached 6,603 last winter, compared with 6,162 the previous year and 5,222 between December 2020 and January 2021. The latest figures follow a steady trend of growth since 1989.

Black-faced spoonbills foraging at the Mai Po nature reserve.

But there was a significant drop in their numbers in Hong Kong, from 369 last year to just 299 in January, marking the first time the figure had fallen below 300 in eight years. The group counted the birds in Deep Bay marshes.

Society director Yu Yat-tung said more time was needed to find out why the population had dwindled.

“It could be from human disturbance or it could be from a decrease in food sources,” he said. “But it’s never too early to start taking action, even if we are not entirely clear on the reasoning yet.”

Yu added the government should consider encouraging fishermen to return to the area or continue working there amid a decline in local freshwater fish farming, ensuring black-faced spoonbills had enough to eat, while also limiting other types of human traffic.

The group also said an exotic and highly invasive species of mangrove – the Sonneratia caseolaris – had been spreading in the mudflats, resulting in loss of habitat for the birds.

Latest figures show a drop in the local population of black-faced spoonbills.

In Taiwan, the black-faced spoonbill population continued to grow this year, reaching 4,228, a 10.6 per cent increase year on year. They accounted for 64 per cent of the global population.

“Although global numbers have risen, the threat remains for the species,” Yu said.

“So many of them are concentrated in Taiwan. If anything were to happen to the environment there, a majority of the global population would immediately fall into danger, so it’s important we continue to do our part here in Hong Kong.”

Population increases were also reported in mainland China, with the number of birds growing by 15.1 per cent to 1,307, and in South Korea, where there was a 45.9 per cent rise to 54 spoonbills.

Japan reported 610 black-faced spoonbills this year, marking a 10.7 per cent drop in its population. Local experts attributed the decline to a bird flu outbreak and loss of stopover sites, the group said.

Black-faced spoonbill are wading birds that spend the winter across eastern Asia and was nearly driven to extinction in the 1980s before international efforts steadily brought its numbers back up again.