We are raising chickens on 1 acre. While letting them free range in the yard, four of them were taken. We did not see the predator. Now we do not allow them out of their fenced in run. We back up to a farm so I suspect either fox, raccoon or coyote. Their run does have a 1 foot border or hardware cloth under mulch that does successfully keep out nightly diggers. Can we do anything to deter the daytime predators?
My best guess is fox or coyote but more likely fox. They are feeding their young now and become quite aggressive, often taking chickens during the day. Raccoons almost always attack at night and usually leave something. If it's foxes, you can sometimes find a pile of feathers some distance from where the chickens went missing. Sometimes not. Unless you can make their run very tight, the best thing you can do otherwise is not let them out when you are not home. Some people resort to getting a livestock dog, but make sure you get one that is trained to chickens if you do. Sometimes the dog can be the biggest enemy. Good luck. I know it's a challenge. Feel free to call me at the extension office 502-633-4593 if you wish more info.