4 of the 5 are Silkie chicks. Should I bathe them? If so how often? Should I also bathe the 5th chick? It is a Lafleche/black mottled d’uccle cross.
Should you bathe them?
Yes, if they get lots of oil all over themselves.
Maybe, if you're going to take them to a show.
No, in almost all other cases.
As several other people have said, chickens like to take dust baths. They lay down and scratch around on the ground and get dirt all through their feathers, then lay there and take a nap and look dead for a while, then get up and shake off the extra dust and go on about their day.