I had 7 Black Austrolorps, then someone gave me 3 chicks they had gotten for easter, and then the wife brought home 4 bantam chicks. Now I only have 4 Austrolarps, and 3 bantams. No sign of sickness, all seem healthy but when I check them I find a dead one. What's up with that? Temp is fine, plenty of food and water. They are almost ready to go outside.