Over the past 4 days, we have had two of our young chickens mysteriously die. On Thursday we left on vacation. On Friday, our housesitter notified us that one of our chickens had passed away. No signs of illness, no blood, nothing to indicate what could have happened. Today we returned home and another one had died. The first bird to die displayed no signs of illness. The second bird had been somewhat "lazy" in that it seemed to sleep a lot, but I hadn't thought anything of it at the time. Here's the overall situation we have for our chickens: -We had 17 chickens (now 15), 2 of those are roosters. 9 of those are laying age, 6 were still very young (fully feathered and old enough to be outside without a heat lamp, but no where near laying age). We have purchased all our chickens from the same location at "coop-ready" age. The two that died were from the 6 we most recently purchased. Is there a chance they came to us already sick and not well? -They have both oyster shell and grit available to them freely. Their food is a chicken grower crumble. We do have some laying pellets in the coop, but they are higher up and I haven't seen the younger chickens show any interest. Is there still a chance they got too much calcium in their diet and that killed them? -Would the older chickens have picked on them and possibly killed them? We didn't see any signs of blood, but under all those feathers it is hard to know for sure. Should we separate our younger chickens? -The temperature has been around 90 degrees the past few days, but they have lots of water available and plenty of shade. Any idea what is going on or what we can do to prevent more deaths??? I would hate to think something we've done has caused this!