Chicks are almost 6 weeks old. Several different breeds. Yesterday about sunset I moved them from my first house to a coop at my new house. Coop was inspected by me & adult son (inherited with the property). There are no gaps or holes that we could see. This AM I checked on chicks. All there & accounted for. Eating fine, scrambling for mealworms, had 2 waterers. Between 9-ish & 3-ish when I checked on them again I found a dead chick. Between 6 & 10pm when I JUST checked them -- another dead chick. The chicks are completely whole, seem uninjured, & no blood. Just lying on the straw on the coop floor. They look "wet" around the head/neck area though. The waterers are 1 standard chicken waterer & 1 nipple waterer. No way for them to get into water & coop is completely dry. They were both lying near the middle of the floor, not in a nest box or under a perch. All chicks seem alert, drinking & eating well, & hopping up into the nest boxes. No sickly-looking ones. 2 different breeds were dead. No change in food or methods of feeding. Any ideas? I'm baffled.