Don't try to herd. Just don't feed them for a day then put food in the coop, only- works best if they had been habituated to getting their feed in the coop already. If they are hungry, most will run into there immediately then simply shut the door. I have some chickens so shy or saavy they cannot be caught by hand at all so I just have a 'trap cage' that is right by the feeding area at all times.. when I need to trap a particular chicken I just put feed in it and nowhere else(very helpful in catching Phoenix, such spooky birds they are..)
Most of my chickens, turkeys and some peafowl are completely free range and sleep in trees too. I also notice most of them much prefer to roost in trees, so you may need to keep them shut in without any free ranging at all for a couple weeks to 'break' them from trying to go back to trees.
There is a chain link fence all around the property, I refuse to do this without having that.. coyotes are very quick to learn about coming around very early in the morning and in evenings too to snatch something on the ground. However, dogs allowed to roam free always were a much worse problem so the fence really is primarily to keep dogs out..
The fence does not stop bobcats though.. had no problems for years then suddenly a bobcat killed the entire flock of muscovies and geese in a single night. Another bobcat came by a few years later and that one did make off with chickens.. I don't know if it went up the tree during the night or caught them early in the morning.
Owls certainly can and do take prey from trees- it's very common for tree roosting guineas to be lost to owls, my friend in Albuquerque says if any chicken tries to sleep in a tree or on top of coop, it is completely gone the next morning due to owls taking them. We have owls here too however they just don't seem to do anything to my birds.. peafowl are very terrified of barns, but way too curious about great horneds(they go right UP to those! But honk and freak out upon seeing any barns. Weird)
However.. there are no raccoons here, and everybody who has raccoons present in their area can have major problems, and these climb trees extremely well.. so if they are in your area, they definitely are a concern. Also must coon proof the coop.
