I. Country of origin
Bird's nest is produced in Southeast Asia. There are three places of bird's nest in China: Yanyan in Huaiji County, Zhaoqing City, Guangdong Province, Yanzidong in Jianshui County, Honghe Prefecture, Yunnan Province, and Dazhou Island, Hainan Province (only two bird's nests were collected in 2002, and only 15 Jin Siyan was left in September 2006, which has been protecting the island for a long time). Due to its proximity to the Tropic of Cancer, the collection of bird's nest is seasonal and the output is scarce, with the total amount less than one tenth of the global output of bird's nest. A large number of people in Southeast Asia go to caves to collect bird's nest, which is not only extremely dangerous, but also plunders nature after they collect caves. On the cliffs of several small islands in Thailand, many rotten bamboo ladders lead to caves once rich in bird's nest. Now these caves are abandoned, and Yaner is gone. With the increasing calls for protecting nature, the Yanwu invented by China people came into being. The structure of these swallow houses is no different from that of ordinary houses, but raising swallows is not raising birds. Swallows are still wild and feed on their own. The house is only used to attract swallows to live together, so that swallows can nest in the house and collect a large number of bird's nests. The bird's nest in the swallow house with environmental awareness will not be picked until 18-24 days when the swallows hatch and fly in 45 days. Jin Siyan went back to the house and built a new nest, which was handed down from generation to generation. Environmental protection swallow is cleaner, smoother, whiter and more delicate than cave swallow in harsh environment.