Sales have increased year after year.

1. Swiftlet nests are vegetarian and are made from the mixed saliva of some swifts and swiftlets.

2. The sales of swiftlet nests have been increasing year after year, but there are very few real swiftlets on the market.

3. Cordyceps cannot be cultivated artificially, and the sales volume on the market may be hundreds of times greater than the output.