Curling feathers

[Gazoo]

Hi everyone, I'm hoping someone has some advice. I have been breeding black show level Orpingtons for a while and have just started breeding blues. They were hatched in August and are looking full grown, most have started laying. They are housed with brown shavers that are a little younger but laying.
They are fed layer pellets and they have access to extra grit. They are penned in a large outdoor area with indoor sleeping space.
The feathers on there tail area have all gone curly and I have no idea why?
Anyone know what the reasoning behind this may be?

 

[NatJ]

Could they be squishing the feathers against something while they sleep at night? You might take a look at them when they are roosting, so see if they have plenty of space behind and above their back ends.

Chicks molt several times as they grow up, with the last one being when they are almost adults (not too long before they start laying.) Do you know if the feathers grew in like that after their last molt, or if the feathers grew in normally and then changed later?

Other than that, I don't know what might be causing it, but I agree that the feathers look odd. Since it is all of them, it does make sense to look for something they have in common that could cause a change like that.