Endangered black-faced spoonbill numbers dwindle again as wetland habitats in Hong Kong and Shenzhen degrade
Factors include continuous development and reclamation in Deep Bay area, decline in freshwater fish farming and rise in illegal traps
Degradation of wetland habitats in the ecologically sensitive Deep Bay area between Hong Kong and Shenzhen led to another decline in black-faced spoonbill numbers this wintering season, a conservation group said on Sunday.
Continuous development and reclamation works in the area and the decline of freshwater fish farming in both the northwestern New Territories and Shenzhen have shrunk the area of mudflats and fish ponds where the endangered migratory waterbirds roost and feed.
According to the 2018 International Black-faced Spoonbill Census, a total of 3,941 spoonbills were recorded between January 19 and 21, roughly similar to last year’s count.
Of this figure, 350 were recorded in Deep Bay, 25 birds – or 6.7 per cent – fewer than the 375 recorded last year, said the Hong Kong Bird Watching Society, one of the census’ participating organisations.
“In 2010 there were more than 460 black-faced spoonbills, but that number has continued to drop and drop to this year’s 350. That’s more than a hundred fewer birds,” research manager Yu Yat-tung said.
Yu identified the shrinking food supply of fish and shrimp as a result of constant habitat degradation and damage as a possible catalyst for the steady decline in numbers.
Reclamation works in Shenzhen and habitat destruction from unauthorised land-use changes and landfilling in the northwest New Territories were cited as factors in reducing the size of mudflats in Deep Bay over the years.
Sedimentation due the proximity to the Pearl River estuary as well as the rapid growth of mangroves have also shrunk natural feeding grounds for the waterbird.
The society said the figures indicated the birds were increasingly relying on artificial wetlands such as fish ponds, though the sustainability of these habitats was not as high as for natural ones such as mudflats. But fewer fish farms in the area also mean fewer artificial wetlands for them to feed in.
“The situation will change the foraging patterns of the black-faced spoonbill and affect the stability of their numbers,” Yu added. “Conservation of natural mudflats is urgent.”
Yu also pointed to a more recent phenomenon behind the decline: a rise in illegal animal traps around fish ponds suspected to be laid by fish farmers to drive the birds away.
At least six cases involving 15 illegal traps were reported to the group over the last two years. Birds have been found with their beaks snapped off by snares.
Yu appealed to fish farmers to use safer and legal methods to drive the birds away.
Mai Po Inner Deep Bay, off Yuen Long, is an internationally recognised and vital wetland site under the 1995 Ramsar Convention. It is a wintering site for a tenth of the world’s black-faced spoonbills.
From about October to March, spoonbills fly south from their breeding grounds in the Korean Peninsula to the warmer tropics. Deep Bay is located at the mid-point of this East Asian-Australasian Flyway.
About 1,800 spoonbills were recorded in the fish ponds and salt pans of Taiwan’s Chiayi and Tainan counties. In mainland China, primarily in the fish ponds in Fujian province, the number doubled to 270.