I am at a complete loss. I have discussed our situation with our feed store, a poultry major from TX A&M and now her professor. I am still scratching my head and would love some feedback. Our string of dead birds stared several weeks ago with a hen who was attacked by a hawk and 3 crows. Its possible the crows were just opportunistic. We were not home at the time and when we did get home the 4 were eating her. About a week later our largest roo, mate to the murdered hen, was acting funny. Walking the property with a droopy tail, lethargic movements, etc. I had read about roos becoming depressed and I thought this behavior change might have been due to the loss of his hen. Over the course of that week we noticed that the other two roos had also divided up all his ladies between the two of them, thus possibly adding to his depression. I don't know. He had been the top roo prior to all this, so there was definitely a change in the pecking order. I had our son separate him from the herd for observation and his safety (at that time our herd was 42 hens & 3 roos). He was in my garden for a week and it was decided he might have gone to battle with the hawk to save his hen. He did not seem to be outwardly injured, so we assumed internal damage of some sort. We thought about putting him down but he appeared to get better over the course of a week and he was such a good roo, I hated to put him down needlessly. When he seemed to recover we moved him back in with the flock. This was April 18th, the weather was not going to be good and we wanted him to have shelter in the chicken barn/yard. The 18th and the 19th the weather was rainy and mucky. My son came in the afternoon of the 19th to report that one of the other roos, a polish, was walking slowly about the yard and not really himself. It was rainy and he typically hates the rain and looks pretty pitiful with his head feathers all wet and droopy during drizzly days, so I did not give it much thought. Very early the next morning, the 20th, he was dead. That same day we noticed a hen to be showing the same symptoms and when the weather cleared we moved her and the original roo back to the garden to separate them from pecking within the flock. At this time it was obviously not a battle injury and we started running the list of possibilities. We had recently changed watering systems, from old style plastic water buckets to a drip system with a tank and buckets that had been equipped with nipples. Because this was the only change we had made to the flock, we were advised that they might just be dehydrated, not fully understanding or liking the new water system. So we went back to the original buckets. The hen and roo who were suffering seemed to be perking up, but they had been separated from the flock and the new water system for a time and on the old buckets. This confirmed in our minds that it was indeed the new water system. Needless to say we were relieved, sad to have lost a roo, but relieved that we had caught it in time to save the flock. The next morning, the 21st the hen was dead. Saturday morning, the 22nd the original roo was dead. We were told that the effects of being dehydrated could have made a huge impact on their overall health. However, this morning my last roo began showing the same symptoms. He was fine yesterday but then today while I was in the yard I observed him with faded comb, tail tucked and when he would walk quickly he fell forward onto his face. I put him down. I am hoping that someone here might have an idea of what could be causing our troubles. I am pretty heartbroken as you can imagine.