Approximately 4 weeks ago, when I went out to feed, one of our runners was acting strange. He seemed a bit lethargic and wasn't at all interested in the greens I was giving to the rest of the flock. My ducks all love greens and will usually "attack" me for them. He didn't seem interested at all and just stayed at a distance. He also seemed to not really be able to quack normally. I had to leave and the next day when I went out, he was dead in the pen. He was only a couple years old. Then last week, my absolute favorite duck, a sweet Pekin named Yangtze who comes when called and is usually a very silly, very active duck, was acting the same way. She wasn't interested in food, wasn't quacking normally - would just make a few small quacks - of course, being a Pekin and with her fun personality, she normally quacked a lot! She was still drinking so I just decided to wait and see if she felt better the next day. She was doing worse the next day - more lethargic and not really drinking so I would put her beak in water so she would take some sips. Thought she might have gotten into something bad so tried the epsom salt flush but couldn't really get her to even drink much of that. I did get her to eat a few worms - that was the only thing that interested her. Then, the 3rd day, she wouldn't eat or drink and wouldn't even get up. I brought her in the house and let her soak in a warm tub (she didn't even play, just floated around), then wrapped her in a towel and held her on my lap for a couple hours. She vomited up a teeny tiny bit of foul-smelling stuff and I knew she was going to die, so I just held on to her. About 10 minutes later she died in my arms. She was about 4 years old. I am at a complete loss as to what is going on... here's my thoughts and discrepancies on everything... They were not even in the same pen (pens are about 20 feet away from each other) nor had any recent access to each other as they have been cooped up for a few months due to the garden being planted. It was super hot temps when the runner died, but not very hot at all when Yangtze died. It was fairly dry weather when the runner died, but saturated when Yangtze died as we had just had several days of rain in a row. They all eat organic layer crumbles and I throw them organic garden produce once in a while. The ducks only get organic greens. They don't even like anything else. All other ducks seem fine at the moment but I thought the runner was an isolated incident as it was 4 weeks later before Yangtze showed the same symptoms. Could they not be getting enough grit? They haven't been out of their pens in a few months so maybe there's not enough "dirt" in there? I have had chickens and ducks for years and never provided grit - they just get it by foraging around the yard. Is there some disease that ducks get? I know they are sensitive to mold??? Maybe Yangtze could have gotten some from all the rain we've been having, but it was pretty dry when the runner got sick - unless some mold was growing under their water dishes?? The food is all protected and seems to be fine. I would never feed moldy food if I detected it. I am at a complete loss! Any ideas!! I don't know what to do if I start losing more!