Feather loss and staggering
Featured Stories on BackYard Chickens
Make sure that she is not being deprived of food and water (which can start a molt) and that she is not being feather-picked or bullied. Look for any paralysis of her legs, which could be a sign of botulism (which can cause feathers to come off easily.) Botulism comes from eating rotted vegetation, maggots, or dead animal remains. It is very deadly. Hopefully she just needs some fluids and electrolytes. I would probably bring her inside in a cage for 24 hours for observation, and give her some egg and poultry vitamins/electrolytes in her water.