The weather turns hot and most farmers do the same thing. They turn the misting system up. Some run it from nine in the morning to nine at night. Ask why, and the answer is always the same. The birds are scared of heat.
I have been hearing that line for more than ten years. Half of it is right. The other half is how a man wrecks his own house with his own hands.
What you are actually looking at
You walk in during the afternoon and you are wet with sweat. The planks feel damp. The nests are getting yellower, some with a bit of mould at the base. Stand outside at dusk and the bird traffic looks the same as always. But the nest count does not move.
You put all of that under one word. Heat. So the misting runs longer, the house gets damper, and the thing gets worse instead of better.
The wrong read: using a misting system as a cooling machine
A misting system adds moisture. It does not cool.
For water to cool anything, it has to take the heat and then leave. Think of standing in a draught after a shower. If your house has no way to move that air out, the water you spray in just sits there.
What spraying is really for is the nest, to keep it from drying out, cracking and falling. It was never the tool for temperature.
Run it all day and the damp has nowhere to go. Nesting planks take in water. Spray for twelve hours and they soak for twelve hours, and they do not dry back out overnight. Then comes the list you already know. Mould on the planks, mould in the droppings, yellow nest bases, odd shaped nests, a musty smell through the whole floor. That is the point where birds start leaving for real.
Temperature has two ends, not one
Everybody repeats 28 degrees. The temperature they grow fastest at is 32. Above 34 is what counts as too hot.
That is where the trouble starts. You spend the whole day forcing the house down to 28, so the walls never store any heat. Once the sun goes down, the house loses roughly one degree every three hours, and it is still falling at three or four in the morning.
A house held at 28 in the daytime, what is left by then? 25, 26.
In those hours the chicks are in the nest. They cannot fly, cannot move somewhere better, cannot tell you. In a house that does not have many birds yet, that stretch is what hurts you.
So the dangerous hour is not one in the afternoon. It is three in the morning, and you never see it, because you are asleep.
I ask farmers one question. Do you know how cold your house gets at six in the morning? Nine out of ten cannot answer. They can tell me the afternoon, because the afternoon is the only time they ever go in.
Heat collects, it does not simply shine in
A swiftlet house takes heat from three places. The roof, the walls, and hot air blowing in from outside. The roof is the big one.
We have measured it. With the roof tiles sitting at around 40 degrees on the surface, the space between the roof and the ceiling can reach 50 something. The heat cannot get out, so it piles up there and presses down onto the ceiling.
So the first move on heat is not insulation. It is giving that trapped air somewhere to go. Open vents front and back so fresh air keeps coming through, then add insulation on top, and the ceiling comes down. Insulation with no ventilation just locks the heat inside the roof.
And there is a kind of heat that is really damp
Sometimes the house is not hot but you still cannot stand being inside. That sticky kind has little to do with temperature. The air holds too much moisture, your sweat cannot leave your skin, so you feel hot. You get it before rain, near the coast, and badly in a house misted all day with no air movement.
Mix these two up and you keep repairing the wrong thing. Real heat is a roof and airflow problem. The sticky kind is your machine running too long.
How to check, and in what order
One, start at the roof. Heat rises, and the roof is the biggest share. Does that space have a way to let heat out.
Two, look above the entrance. If there is a hanging ceiling board above the entrance, hot air rises into it and gets held there. Add weak ventilation and the house feels stuffy the moment you step in. We have students who took that board out and the temperature went back to normal.
Three, look at the exhaust pipes. Heat always collects at the top. Whether your house is trapping it shows up fastest here.
Four, cut back the hours on the misting system. Give the house a chance to dry out, then see whether that sticky feeling is still there.
Not one of those four asks you to spend real money.
When equipment finally comes into it
Same word, heat, and yet one man needs to bring it down while another needs to hold it in. Houses on higher ground have the opposite problem. They get too cold for the birds to nest, and what they need is heat kept in, not more ventilation. Copy an installation without understanding it and you can end up doing the exact opposite of what your house needs. That includes copying your own other house, the one that is doing well.
We have tried heaters. The electricity bill is frightening. Not the answer.
So equipment sits behind diagnosis, always. Work out where your heat is coming from, then decide whether anything needs to be bought. That is the whole idea behind the MDK Swiftlet House Diagnosis Method. Diagnosis first, prescription second.
If your nest count falls a little more every year in a house already ten years old, that is a different topic, and I wrote about it in why your swiftlet house production keeps dropping.
Your next step
Do not rush out and buy a thermometer.
Every temperature post I wrote years ago ended with me telling you to go and buy a temperature gun. I am crossing that line out myself today.
It is not that numbers are useless. The order was wrong. Most thermometers on the market are not accurate, and if it hangs in the wrong spot the number will mislead you. That is worse than not measuring at all.
Here is the free thing you can do today. Go and see whether your house has a proper way to let hot air out. Hot air always collects at the top.
If you are not sure, take two photos. One of your exhaust pipes, one of your second entrance (the second door that birds will pass through in your bird house). Send them to us and I will take a look. Free, and you do not have to buy anything first. If we need more after that, we will ask you then.