Rusty takes a Sand Bath

I only knew owls took water baths until one day several years ago I saw Iris thrashing around on the floor of her pen. I thought she was having a seizure, but realized she was trying to take a dust bath. So we added a pan filled with sand, and occasionally the owls now take sand baths. I think this is the best video we have of a sand/dust bath, since Rusty was nice enough to do it during daylight hours for us. Why do they do this? Good question. Perhaps it can help control ectoparasites like lice and flat flies. Or maybe it just feels good. No idea.