I live on 10 acres out in the country. Surrounded by woods, crop fields and pastures. Right now have 20 or so chickens, the dang fox has picked off half my flock since spring. Otter came up from the creek and killed all my ducks summer before last. I’ve got two dogs but they’re not much account for keeping the varmints at bay.
Sorry to hear about the loss of your flock. I've been relatively lucky this year (knock on wood). The last dog attack my flock suffered was in 2011, when two dogs massacred half of my birds. I shot one of the dogs and litigated against the owner of the second dog.
I frequently see 'possum, raccoon, and skunk, but haven't had any losses to them. Neighbors tell me that they've seen fox, and there is rumor of a cougar in the area.
I think I'd be setting some traps or engaging in out-of-season fox and otter hunting.