do hens know when 21 days is up if nothing hatches?

[pinkyglory123]

Have a broody that ended up setting on a huge pile of eggs without me realizing it. Do hens know when it is futile to set any longer if nothing hatches? Will they eventually give up?

 

[TwoCrows]

Yes, they know when to stop setting. It is built into the hen and at some point she will either know the eggs are viable or not. Sometimes they will kick out bad eggs. But if the entire batch is full of duds, she will know and get off the pile of eggs.

 

[song of joy]

A broody hen may stay on the nest for 1-2 weeks past the normal 21-day incubation period before giving up.

 

[aart]

Agrees they may stay on eggs for a long time past 21 days...up to the keeper to monitor and remove old eggs that may explode.