Something I learned in Ohio where we boarded horses. The owners of the stables brooded hundreds of chicks every year. I would help the stable owner with catching predators. One thing I learned is a fox or coyote will dart in steal a bird and dart out leaving a feather trail. 1 bird at a time. They will keep coming back until you challenge them Only 1 animal in my opinion will stay long enough to kill every single living bird. A young raccoon. Of all the episodes they had with predators there was nothing like a young raccoon who goes on a murder spree. For whatever reason they killed every single bird in the barn for no reason. When I say no reason i mean they couldnt possibly eat everything they killed. Some of the chicks would have bites taken from their necks or heads but most were just dead with no bite wounds. If you lost that many birds in 1 or 2 nights its my opinion your dealing with young raccoons. Probably more than one.