It was very obvious the main reason why this 8 years old BH was not performing.
I found out that the BH housed four owl nests.
Two inside the monkey house latch and two on the roof of the monkey house.
While trying to figure out how to install those external sound tweeters (hexagonal, power tweeters and bazookas) I came out with a drastic idea to totally removed the roof of the monkey house.
It ceiling was already covered with cement slab so the function of the asbestos made roof was redundant.
I instructed by workers to find their ways up to the roof and dismantle the wooden trusts and the asbestos.
It was during this time they found out that the roof was with two owl nests.
One of it was with 4 fresh eggs.
Well this was nothing new since this BH is surrounded with padi fields and more often the agri department encourage padi farmers to release those owls.
Another surprised was when my workers was trying to open a new entrance hole inside the monkey house.
The monkey house was with this 1/2 cement slab that was used as a working platform.
However due to some reason it was occupied by another two owl nests.
This make me feel that if the owner know how to tackle this owl issues his BH should have been well populated.
What I suggested for him to consider was to increase the number of owl traps.
I already installed one and I suggested that he install a few more (may be another 1-2).
Another predator that were not considered serious were those cockroaches.
To my surprise this BH has an acute number of nesting areas of those big fat cockroaches.
Their favorite were in between the nesting planks and the cement walls or slab.
They also seems to love those small triangular shape hole created by corner covers.
BH owner should be aware about cockroaches in their BH.
Wise to spray the BH with insecticides on a regular basis.
If your BH faced a similar problem please call me to inspect and tell you what to do.