According to Mr. W, the consultant who had built this Bh couldn't be found anymore. This what he had left behind for Mr.Wong. Now Mr. Wong has to so solve the puzzle that the consultant himself couldn't put together.
Mr.W had called me many times. He wants to know why birds are not staying in his Bh which located in a Prime Birds Area. As far as he is concerned he had tried his best to solve whatever problem he knows, but still unable to make the birds stay.
By observing from outside it can be clearly seen that the entrance hole is not properly done. I don't favor the size. There shouldn't be dangling wires around it which could obstruct bird's fly path.