Possible Broody Hen

[Ridgerunner]

With that ventilation I'd leave her alone. If ventilation were a problem or if she was somewhere the sun was creating an oven I'd be worried.

In those temperatures make sure all your chickens have access to clean water and shade.

 

[Evadig]

Another question...you count the days beginning the day after the hen started sitting, right? If Jen started sitting on Monday May 6 at 10 am, with a brief interval on Tuesday when Viv kicked her out, I calculate prospective hatch day from Tuesday, right?

 

[Ridgerunner]

Yes. It takes 24 hours for the egg to have one day's worth of development so you say "1" the day after you set it. A way to check your counting is the day of the week you set them is the day of the week the 21 days are up. In your case you started them on Monday May 6 so the 21 days are up Monday May 27.

Eggs can hatch as much as 2 days early or late, under a broody hen or in a calibrated incubator. There are a lot of different reasons for that. Don't be surprised if it is not exactly 21 days.