I had a run full of quail that i thought was fox/vermin proof so i didnt shut the house door at night,the run was fully enclosed with very fine chicken wire but i kept losing the odd one and then all gone,couldnt understand it so then as space was short moved a hen with 6 chicks in to the same pen next morning all gone will never make that mistake again now i always make sure that i shut them in at night,it could have only be a rat.