Your house is not empty. It has just stopped growing.
Last year the count was that number. This year the count is the same number. In between you swapped the sound, added tweeters, bought a bottle of aroma. Nothing moved.
Houses that stall tend to share one habit. The sound keeps getting replaced, and the figure never budges.
What you are actually looking at
Birds still fly. They still come home at dusk. Nests are not dropping off the planks either. They are simply not adding up.
The newer runs of plank sit bare while the same handful of old ones are packed shoulder to shoulder. You have been up there more than once, come back down no wiser, and eventually landed on a thought. This is probably all the house has in it.
That thought is the costly one. Believe it, and the house really does stop there.
The wrong read: swap the sound one more time
Sound is the one thing you can change without climbing anything, breaking anything, or leaving your chair. So an owner who is stuck reaches for it first.
Count it up yourself. How many sets have you been through? Did the figure ever shift?
If years of swapping has not shifted it, you already have your answer. Whatever is wrong is not sitting inside the thing you keep replacing.
Four directions below. Half of each one is visible the moment you walk in.
One, stagnant air
A house that climbs to some figure and then parks there is the signature of this one.
Airflow bites at both ends, and either way the birds will show you.
Too much of it and they back off, visibly. Every nest goes as high as it can get, tucked hard under the plank so the plank takes the wind for them. A ceiling row crowded solid at the top while everything lower stays bare is not luck. That is the birds telling you the wind is too much on that side.
The other end is nothing moving at all. We call it stagnant air. With nothing fresh coming in, the house climbs to some figure and parks, and whatever you do afterwards it stays parked.
Which means you read airflow off the nests, not off a wind meter. Where they chose to build, and the figure the house froze at, is the reading. The birds handed it over already.
An exhaust fan on the wall is not the same thing as airflow
Plenty of houses have one. Not many are running it properly.
The hour it runs. Some owners have it going before first light. A house that already runs cold only gets colder, and the eggs do not hold.
Round the clock, then? A house has to keep a certain smell in it before birds settle, and pulling air out without stopping pulls that out along with it. Spray as much water in as you like, the place still ends up too dry. Strong airflow is not something swiftlets want in the first place.
Bigger, surely? No. Size and quantity follow the house and the number of birds living in it.
There is a rule underneath this that matters more than the fan does. Exhaust fans, tweeters, partitions, every one of them has to sit in the right place. More of them is not better.
If what you have is heat rather than air that will not move, that is its own topic and I wrote it up in what temperature should a swiftlet house be.
Two, the sound coverage is wrong
The word matters. Nobody is asking whether it sounds nice. The question is where it lands.
Look at whether the nests give the tweeters a wide berth, or sit tucked in behind one. Either way round, that tweeter is pushing birds off rather than pulling them in.
Three, the layout cannot keep up with the flock any more
Back when the flock was small, the layout suited it. The flock grew, the layout did not, and now it is the thing holding the house back.
A kampung works the same way. One road carries a few families without complaint. That same road at rush hour does not.
Four, the state of the planks
A plank gone old, gone dirty, gone mouldy will let a bird in and still give it nowhere it wants to sit.
Of the four, this is the only one you can start on this afternoon. Nothing knocked down, nothing structural touched. I wrote it up on its own, in swiftlets nesting on the walls but not on the planks.
When equipment finally comes into it
By now you want me to name which of the four it is.
Not from here. They get fixed in four different ways, and picking the wrong one burns another year before you find out.
It is also why nothing gets pushed at you before we have seen the house. Picture a doctor writing the prescription before he has asked you a single question. You would not swallow that. So we do not sell you anything with no diagnosis behind it.
That is the work the MDK Swiftlet House Diagnosis Method does. Diagnosis first, prescription second.
Your next step
Two free things, today.
Go up and read the nests. Crowded at the very top and pressed against the plank means too much wind. A house parked at one figure with the newer positions never taken means stagnant air. No measuring involved. Looking.
Take your phone in, record, then listen back. Back off to roughly 12 feet from a tweeter and record a bit. Do it again at 10 feet, then again at 8 feet, saying the number out loud each time. Play the three back at home. Messy, distorted, smeared together. Your own ears will tell you, and no instrument is needed.
If you want me to look, one video will do. Film your way in from the entrance hole, talking as you go, and record the internal sound and then the external sound. A phone is fine.
Send them over, free. If we need more after that, we will ask you then.
A house stuck for years is usually stuck in one single place. What is missing is not a method. It is that nobody has ever read it from the start.