My chickens do this too. Its called a dust bath. Its an integral part of their self-care routine.

This one’s in dirt right now but most of them really love my kids sandbox if I let them out of their area. They treat it like a spa. Good thing my kids are too big for a sandbox now.

She was really in it though…stretching out those feathers and getting it in the little crevices. Rolling around. Just having a grand old time.