This video clip shows how you can get a few thousands swiftlet during your bird call test if you know where to find them.
I took them about 6 months ago in Kelantan.
The test was conducted just after sun rise at about 6:30 am.
The key issue here is there are suitable land which those birds passed by day in and day out if you know how to find them.
Once you have located this type of location your risk in building a BH is minimum.
If I am given the responsibility to build one, I am sure I can get 1000 nests within 12 months.
Just keep searching for this type of location and you will be a successful swiftlet farmer.