Thanksgiving morning we went out to find our only Buff Orpington dead on the floor of the coop. Today (Saturday), we went out and found our White Silkie Bantam dead too! Background: We use the deep pine shavings method in the coop and a couple days before, we discovered an ammonia smell. My husband had put a little to much water on the "composting bedding" and it activated the ammonia. We left the windows open, but our Buff either was smothered in a corner or got too much ammonia during the night. So we think that is what killed her. We had planned on cleaning it all out in the morning, which we did early Thursday morning (6:30am), put in new pine, cleaned, etc. The run is sand, but we have a half a bale of hay in it to trap bugs and just let the chickens play in it. Most of it is tied up, but they pull it out, etc. The chickens free range every day for a few hours but we are always out there with them. By the way, they are all between 5 1/2 months old and 7 months old. Our 3 bantams started laying about 3 weeks ago, our Ameraucana laid her first egg yesterday, and one other full size (we don't know who) also laid yesterday; and all of the rest of the chickens seem to be okay. Five of our chicks did get the Mareks shot at the hatchery we brought them from. Could this be residual ammonia poisoning? We have had them all on Tetroxy HCA-280, due to the weather changes here (Burbank, CA); the weather has been fluctuating wildly, hot, cold, rain, sun--all in any weeks time. Some chickens had a bit of runny nose, a couple were sneezing, so we put this in their drinking water and they have been on it for about 3 weeks. We are city folk and have not a clue about these deaths. There seems to be no outward physical signs of abuse by the other chickens, but I am having my husband check out their vents, etc., to see if there is any problems we can see. Is there anything else we can do; does anyone notice anything in the above that we shouldn't be doing? We have the Storey's Chicken Book, but we're still lost. As too feed, they are on organic crumble and regular scratch, and we give then oyster shell mixed in the scratch. The do get some lettuce from our garden and we give them raw corn on the cobs on occasion, apples, bananas, etc. We keep a list of what not to feed them by the coop, so friends don't accidentally feed them something wrong. We do have 4 avocado trees in the back yard, but I make sure there is no fruit on the ground from them to peck at. HELP!