Supply on demand The TRAFFIC report also pointed out that long-term studies by ecologists have discovered that over the last twenty years, in Thailand, Burma, and Sarawak in Malaysia (the greatest swiftlet nest producing area in the world), the number of two types of swiftlet nests has dropped by about 4O % due to excessive collection and theft.
野生動植物交易調查組織的報告也指出，生態學者長期追蹤調查發現，二十年來，泰國、緬甸與世界最大金絲燕產地﹘ ﹘馬來西亞沙越，由於過度採收與偷獵，有兩種金絲燕已經減少四十％左右。