She doesn't, however once the eggs start to pip and crack the wet chicks will make the RH% go up.
The only bird that I have ever seen that would work to keep the RH% high was a Muscovy duck. The hens will come off the nest and get a quick bite to eat and get wet before going back to the nest. They will shake most of the water off but still you can feel the nest material (we use wheat straw) would be damp.
Our bodies are how much percentage of water? We give off some moisture and a hen's body would hold in moisture well. When the eggs start hatching that moisture would not be lost. When they hatch in our incubator especially a forced air the moisture is lost to the dry air circulating in. Unless your in the desert we also usually are running air conditioners or heaters in our house which dry out the air even farther. At least here there's a huge difference between humidity outside and inside.
Quote:Ok... sounds reasonable. How come this same principle does not apply in a 'bator?
Actually it does. We have several large cabinet incubators. (gqf sportsman). When we are hatching we don't change anything. They only thing I do is mist the eggs when we open the door to take out chicks.
Ours runs about 100 degrees and we use the same settings for everything, chickens, guineas, ducks, turkeys. often they are all in there together.
On the day to stop turning we pull out the flat as quick as possible, close the door, put all the eggs in the hatching tray and stick them back in quick. About 3 to 4 squirts of the mister and cya. Then we don't open the door again until the hatch is done, you can see the rh% rise as they hatch.
On a smaller 'bator our method might not work due to not as many eggs, less mass to hold heat and rh% etc etc. We started with a hovabator and hovered over it to make sure we didn't miss anything. Now we put eggs in, candle at 7 days(if we remember) and come back at the stop turn date. The hatch rates are great.
Hi Chickabee. The way I like to think about it is it's about how much humidity you are letting out of the egg. At 40-50% you are letting a good amount of humidity out of the egg. At 70-80%, you would be letting very little humidity out of the egg.
The bator and the egg like equal % of humidity, and will try to equal it. If the bator is 50% humidity, the egg will let out humidity trying to get to 50% to be equal with the air in the bator.
At 70% humidity in the bator, the egg is probably not far from that % so it would let out very little moisture, and the egg would at least have 70% like the air.
Have you ever picked up a broody hen? There's alot of humidity under her. The longer she sits, it seems the warmer it gets and the more skin/egg connection and more humidity. How does a chick know when to pip? I think it is all just nature.
Nature can be explained. Chicks are triggered to pip for one by the noises of the hen if they are being hatched by a broody and the noises of other hatched chicks. Second the lack of oxygen triggers the hatching muscle to contract making the chick peck. After pecking out of the membrane they get some fresh air in the air cell and can rest. Then when they start to run out of oxygen they will again be triggered to peck and start breaking through the shell. That's one reason why helping a chick hatch can cause complications and mean you have to hatch the chick completely. If they are getting unlimited oxygen they may not be triggered to try and keep hatching. I think that's partially what happened to one of my buttons. It zipped and I removed all the other chicks so with no peeping and plenty of oxygen it just kinda gave up and sat there. 2 days later when I cleaned out the incubator and realized it was still alive it was too late. The chick was stuck in the position it was in the egg and it's tendons and muscles never recovered.