My main reason being it have the height that those birds are can reach much faster without flying downward.
The second reason being the protruded part of the monkey house or I should say the extension above the roof area will give those birds a kind of playing area.
They love to fly in a circular motion usually anti clockwise.
When they became intoxicated with the external sound, they will start to locate any hole to enter.
This is where the main entrance hole become the most important channel to bring these birds inside your BH.
I prefer a big size window about 3 feet wide and 4 feet high.
My main reason is that the big size will make them feel very safe during their first visit to the BH.
You might think that when it is too big a size those owls will surely have no problem to enter your BH.
This is true but we have to make the right decision for those swiftlet first.
In the meantime we have to get ready with various gadgets that you can make them scared of venturing into your BH.
Once the door was widened, it was installed with special wooden frame to make it easier during tweeters mounting operation.
One new method of arranging those external sound tweeters is to use my favourite "pole tweeters".
A unit of it is made up of three bullet tweeters made by Tecnik AG 35.
I put one each on the left and right wooden frame facing the opening but slightly slanting towards the sky.
This will be my most important gadget to draw those birds into the monkey house.
As for getting those birds to the monkey house I like the use of hexagonal tweeter located precisely above the roof (1.5 feet up above the roof) but located in the middle of the window.
To make it more exciting or magnetic I insisted in the installation of power tweeters about 2 each on the wall of the four walls of the monkey house.
Once these interesting monkey house preparation is done I can guarantee you that those swiftlet will get into the state of frenzy when a good sound is played.
They don't only fly around the monkey house but start to cling to the all these tweeters installed.
Some gone carried away and cling to the entrance hole perimeter.
Just see this this picture: