We have two RIR hens that may have an illness. One has lost quite a few feathers. This happened about a month ago and it was not from a predator. She has kept to the coup and only comes out occasionally. Since she lost the feathers she does not socialize with the other chickens but has an appetite. Maybe not an illness, but molting? The other hen now walks like a duck. She is socializing and eating normally. Our egg count of 4 per day is down to 2 per day. So that would indicate that the two chickens are not laying. We have 4 RIR hens and a Barred Rock rooster. Happy Holidays! Andrew RIR hen with lost feathers. She has lost more since this was taken. The RIR that walks like a duck. Another shot of her.
Your first hen looks and sounds as if she is going through a typical molt. As long as she is eating well she should do fine. You might want to increase her protein to aid in regrowing feathers. You can buy a higher protein feed - such as flock raiser - or feed her high protein foods like scrambled eggs. Just to be on the safe side, examine her to make sure she doesn't have lice or mites, which can also cause feather loss. Your second hen looks as if she is egg bound. Here's a link to a thread with information on how to treat her for this (post #3). You can also search this site for more information on this condition. Good luck to you https://www.backyardchickens.com/forum/viewtopic.php?id=502419
