How old is she? I'd guess that she's molting.

I second what Erin said...molting? Hens can look positively frightful whe they molt, also they suspend egg laying when molting so don't be surprised if that happens, too. If she is broody, sometimes broody hens will pull feathers from their chest area to help expose their skin directly to the eggs thay are sitting. Is she acting strange or sick at all? Is she eating and drinking OK, have normal poops?

I have one duck and he eats the same food as the chickens, and growing up on our farm we had a bunch of mallards that also ate the same chicken feed as the chickens. I'm sure one of our duck experts here can give you more help though. :)

Velvet

Ducks aren't supposed to have medicated feed. so long as your chicken feed is unmedicated it's okay for them to share. Usually (but not always) the molt starts with loss of feathers on their back, but some chickens go almost completely bald and others you hardly notice at all. But I do agree with all that Velvet and Erin said. You might also want to check for feather mites. I dust my girls once or twice a year to be safe.

What do you all think of hens with missing tail and neck feathers? My girls were losing their tail feathers badly but I thought it may just be the rooster. He is long gone and they are still missing them pretty badly. They were about a year when it first started and they did suspend laying but have been laying again now for some time and the feathers don't seem to be coming back very well. I guess I should dust them...but the others look fine it is just my two Australorps and they are the two bosses of the flock. Suggestions?

Thanks all. No dust mites that I can see, but I'm going to dust anyways. Not sure how old Liberty is, since I saved her off a chicken truck....my guess is she's about 1 to 1 1/2 years old now. She has stopped laying quite a bit recently, so that is another sign you pointed out.

I read recently about making sure the feed was unmedicated, so I've verified that (before purchasing of course....LOL). Just wanted to make sure that that was all I really had to look out for before getting some kind of laying feed like Layeena.

Thanks again