One of my Barred Rocks, I noticed when I pick her up, is really light in weight. She's almost 4 years old. The other 3 barred rocks are of their normal weight, 5 or 6 pounds…. but for some reason she seems to have lost her poundage. I'd say she weighs about a pound…. she is really light. She's not always been this light and so something is going on with her. Any thoughts? Thanks.