So I'm still new when it comes to raising ducks, but I have been having issues with hens recently. My drake is a Khaki/Mallard mix that we received from a friend almost a year ago, and he is just as happy and playful as ever. However, we also had a Swedish blue hen that was doing great for a while, but she died suddenly and I still don't understand why. We had a vet do a necropsy that showed she had lesions in her stomach and broken egg fragments in her abdomen, but no conclusive reason as to why this happened. Now we have another Khaki female that I'm very worried about, as she might be acting the same way our previous hen did before she died, although it's very subtle and I tend to be paranoid, so I can't be sure. Basically she is not as interactive with me or the other duck, and is a lot quieter, though she is still eating and drinking. She is also laying eggs as normal, but I believe she stopped laying on her nest like before (granted she wasn't consistent about it anyway, but there were signs of brooding.) Something else I noticed is that I can hear an odd grinding noise coming from her, like two stones rubbing together; I had also heard this from the Swedish blue, but never our drake. It's fairly loud and very alarming to me. I'm wondering if this have anything to do with eggs specifically. Their diet currently is standard duck mash and the grass that they graze from our yard. I had hoped to get some kind of calcium supplements soon, but as far as I know it hasn't actually been long enough for a lack of those to cause problems, and her eggs themselves are very strong and healthy. Does anyone know what might be causing this (assuming there's a problem at all), and what I should possibly be doing differently for hens compared to drakes? Any advice is appreciated.