Knowledge: Bird nest as food?

Bird nest as delicacy? Seems odd, but for some Chinese, its delectable...swallow nest..made of birds saliva, which feeds on seaweeds...so the nest soup tastes fishy....

I had read somewhere, this nest hunting is endangering the bird population........

Now I saw the nest soup being sold in COSTCO...and was surprised...where do they gather the nest in so bulk to be sold in wholesale chain....

Below is a oriole nest...