We had 6 chicks in a horse water trough brooder box, with a screen cover. Yesterday they were all there. Today when we went to check 2 live chicks were there and 1 dead. 3 chicks are missing, they were about a week old, too small to get out on their own. The building they were in is locked with a padlock, we searched the building with no sign of dead or live chicks. They were laying chickens, and fairly large. Could a snake have gotten in and ate them, could they have gotten out on their own?