First observations in 20 years of Brent Geese Branta bernicla wintering on the Shandong coast, China

Abstract

The East Asian Brent Goose Branta bernicla nigricans population is currently estimated at 5,000–8,700 individuals (just c. 1% of all Brent Geese B. bernicla globally) and is designated by the Conservation of Arctic Flora and Fauna (CAFF) as a priority species for conservation on the East Asian-Australasian Flyway (EAAF). Wintering numbers are concentrated in Japan (where c. 2,500 individuals occur, with an increasing trend), but numbers currently in China (estimated at 5,000 two decades ago) are unknown, emphasising the need for an updated assessment of their abundance and distribution there. A Brent Goose caught in Japan was tracked for five months as it wintered on Sanggou Bay in Shandong Province, confirming this area as a wintering site occupied by the population. Coastal and offshore surveys of Sanggou Bay in January 2023 and 2024 found up to 319 Brent Geese in offshore waters (124 in 2023; 319 in 2024), foraging in aquaculture areas > 2 km from the coastline. As these numbers exceed 1% of the East Asian Brent Goose population (i.e. > 65 individuals), Sanggou Bay qualifies as a site of international importance for the species. The Brent Geese were seen feeding on algal growth within Sweet Kelp Saccharina japonica and oyster (Ostreidae) aquaculture infrastructure and were rarely disturbed by kelp and oyster farmers (who are active mainly in summer), so were subject to almost zero human disturbance. A literature review of Brent Goose distribution and abundance during 1912–2024 suggested that the population historically wintered in the coastal waters of Shandong and Jiangsu Provinces, with up to 10,000 individuals recorded (before 2002), but reports were of < 10 birds present during 2002–2012. Despite our observations, and those documented since 2012, we suspect that fewer Brent Geese winter in China now than two decades ago. We recommend that the Sanggou Bay offshore area be protected and a national survey undertaken, both of the geese and their food resources (e.g. subtidal eelgrass Zostera sp. areas in the Yellow and Bohai Seas) to confirm their distribution, with long-term monitoring put in place for sites where they occur. Restoration of natural seagrass habitats around Changdao Island, Shandong Province (where the Bohai Sea and Yellow Sea meet), which supported the largest numbers historically, is also needed to attract Brent Geese to winter there again.