How long will a bird sit on an unfertilized egg before they learn it won't hatch?

[bravevline]

???

 

[Ridgerunner]

It depends on the hen. It could be a few months.

 

[thebanthams]

Some hens are immature , A good broody hen will sit tight . you can candle the eggs, and mark them..

 

[chickenlver2013]

It will sit 21 days just like a hen would with fertilized eggs. BUT it will set and set and set your hen won't come off that egg until it hatches hens are known to set themselves to death which means they'll set until they die. She doesn't know the egg is unfertilized. The only way she'll leave it is if there is fertilized eggs to hatch.