How do hens do it?

[cchardwick]

I'm wondering how the sitting hen knows it's the last three days of incubation and how it raises the humidity? This doesn't make sense.

 

[Tammy N]

Mother Nature ,
also when they sit on the eggs and so many hatch then the others do not they get off when the last live baby hatches or they crack the bad eggs .... The smell they have better noses then we do and mother nature have not given them anything but what they know to survive ,
No tv,no bad news links , nothing just the way things are for these animals . even mistreated hens in the egg plants know they are unloved . thats the sad part they did nothing but where born . . we humans have left the box of wisdom closed too long.

 

[sumi]

My guess would be because the eggs are not exposed entirely to air like in an incubator it has less chance to dry out, so humidity is not an issue under an hen. Hens will also pluck the feathers from their undersides a bit when they sit. I've heard that hens' body temperatures go up a bit when they are sitting. They create a perfect environment for the eggs to hatch in.

 

[cchardwick]

Yes but you would think that their temperatures and humidity levels would be fairly constant. As I understand it the increase in humidity in the last three days is essential. It would be interesting to see if anyone has determined the changes in humidity under a hen as she sits on an egg. To me it would seem like a constant humidity would be better, or perhaps a constant increase over the entire time. I woudl imagine that is how it would be under a hen...?

 

[Elke Beck]

The reality is the chicken does it better than we do. We have to fiddle around with humidity and temperature because eggs were designed to be hatched in nests by hens. There was an article on one of the threads about how hens and the chicks in the eggs are constantly communicating with each other from pretty early on, so the hen moves the eggs around to speed up the ones that are developing slowly and slow down the ones that are ahead of the others to make sure they all hatch close together. We cannot match that with even the most advanced incubators.

Just today my mother and I were marveling that my Buff Orpington is such a great mother. This is the first time she hatched eggs, and aside from one that she broke when I first gave them to her (my fault, 10 eggs is a lot for one hen), she had 100% hatch. She is a hatchery bird, and was raised by me from the time she was day old, so she has no role model for how to do this, but she does it flawlessly. Her chicks are over two weeks old now and growing like weeds without heaters, draft shields or chick starter. No pasty butts here!

I think good mother hens intuitively make many small adjustments based on tiny changes in the eggs and environment, so having less than perfect temperatures or humidity does not have as much of an impact as it does in an incubator that has a one size fits all approach to environment.