Birds are returning to breed and maybe, you will find chicks in the nests unless you did harvest all the nests most recently.

Also, Now, the ripe time for those who wish to increase their birds by drawing other birds into your houses by sound or smell....and using smell, now is the time as otherwise, without any bird around, it shall be wastage of solution and time.

I shall not recommend any perfume in the market as most are useless or expired due to their shelf life. Smell must be fresh and to use in the right time and place to be successful. Smell play an importance part in the new BHs but then to waste your money by buying useless perfume is rather waste of money and stupid.

If you spray some liquid of aroma in to your BH and immediate, the birds flying overhead feel the urge to drive in; that a good smell!!!!

I am old and so I don't have time and energy to climb up and do the research so I shall need young men around here to do these experiments and provide us with the feedback.........if they are willing to share as we are to share cos there is really nothing to lose for sharing as I did for the past tens of years to many successful breeders. Remember that we maybe doing but God is seeing so for helping others in need we are gaining more rewards and happiness that money cannot buy.

As always, I remind all that we shall be grateful to the one who give especially the swiftlets and we shall be rewarded cos being good, I am blessed with everything that money can buy and also money cannot buy and I hope that you  can, too.

Many swiftlet 'farmers' make money from selling 'miracle' sounds and not from their nests. Not all sounds work, some work better than others and some work for a short while only. A sound that works for your neighbour might not work for you.

Where is your location, maybe some locals ranchers can help.