Humidity under a hen. A scientific report with a table

[Akane]

When the chicks break the membrane to start hatching they raise the humidity on their own. I would suspect that under a broody hen the humidity is just not lost as easily as in our incubators. The chicks starting to hatch would raise the humidity for themselves. I've had humidity spikes up to 20% more than the humidity had been at since day 18 when several chicks hatched at once.

Were these broody hens without eggs or actually hatching something? I notice they go 13weeks in the first table.