Pile up prevention

[CKNNWBEE]

I have 4 11 week old pullets that are piling crudely on top of each other. It is just chilly and they have only one 'window' for full air to come in. Are they too cold? Does this behavior last forever? They do have one long perch, do they each need their own perch? I have read some previous posts and will try settling them on their roost when I put them to bed.

 

[ChickensAreSweet]

Sounds like they are cold.