However, although there are hundreds of records, pictures and poems from18th century up to now that this gull has appeared frequently in China, ornithologists who went to Li Shangyin's hometown and nearby areas to explore the clues of this bird have repeatedly returned empty-handed.
Until the winter of 187 1, a European explorer named Robert Swinhoe claimed to have seen this bird and its nest in the coastal area of Xiamen, and named it "Walking Gull". 13 years later, another French explorer claimed to have seen it twice near Lake Baikal in Russia. Unfortunately, for more than a century after that, the black-billed gull successfully escaped the eager search of ornithologists and explorers all over the world, and no one knew the habitat, habits and breeding laws of this bird.
Things finally turned around in the spring of 1988. Shi Zerong, who went to study waterfowl in the coastal swamp of Yancheng, Jiangsu, China, brought back specimens of black-billed gulls and their eggs and nests. His discovery is undoubtedly one of the most important achievements in the history of ornithology research in the 20th century. Following Shi Zerong's breakthrough, on May 22nd, 1989, Liang Yu, a worker in Shuangtaihekou Nature Reserve, Xinglongtai District, Panjin City, Liaoning Province, China, discovered two black-billed gull nests and four bird eggs. This news has caused great repercussions in the field of ornithology research. Soon, an investigation team composed of Chinese and foreign ornithologists entered Shuangtai Estuary Nature Reserve to confirm whether this is the breeding ground of the mysterious black-billed gull. The survey results show that there are about 1200 adult black-billed gulls and more than 3 10 black-billed gulls' nests in Shuangtai Estuary Nature Reserve, accounting for about 70% of the global estimated total. After centuries, the arduous journey to find the breeding ground of black-billed gulls has finally come to an end and the dream has finally come true.