Something that I saw and captured on my iPhone at Durian Tunggal.
This video clip shows a crowd of swiftlet that are harvesting those insect produced inside this BH.
Their behavior pattern is something like this.
The will start their insect catching works as early as 7:30 am.
The moment they arrived they will continue until less insect were outside the entrance hole or above the BH.
They will soon fly to other locations but will return for another session.
This same routine will be repeated for the whole day.
The deficiency of this BH was that it plays no external sound.
The birds were given a free food but were not invited into the BH.
If the owner should just put a simple sound that can pull those birds inside this BH will be a winner.
I am not sure what kind of insect the owner is breeding but I am sure they are those fruit flies.