Hawks! I think???
I am in Colorado and see multiple hawks circling often above the prairie dog field by where I work.
If you have seen them on the coop or on the ground by the coop then they may see your chickens as plentiful targets and share the hunting space.
I don't care much for them eyeing my chickens at all. I have had a few encounters with them trying for the gals with me right there in the yard with them. They get a bead on a chicken and don't even see the human it seems. Even a small American Kestrel was after them.
Be careful letting the gals out.
This guy was hanging out for weeks in my area.
Not a great pic I know.
I like having the real crows in the hood here. They often chase hawks off and I think of them as my little helpers.
I have done the shiny cd's hanging in the trees and the ribbons on sticks on top of the run. It seems to work for a while but they get used to them eventually.
If you have the space perhaps you can do a pvc tractor or such so they can get some scratching done in areas other then the pen without as much worry.
My yard is in the middle of town so not much space for a tractor. My gals have to rely on me to bring them everything. Not how I wanted to have to keep them but much safer then the alternative.
Today I have to clear more snow out of the run so they can even come out of the house. I think I will get them a couple bales of straw to give them something to do in the run.
I keep seed out for the doves and see an occasional crow munching on some corn but not much.
I know I should not feed the doves. I feel bad for them when it is winter though. One got stuck in the run fencing so if not feeding them they go for the chicken feed. Better to lure them away lol.
I heard that the fake owls do work but you have to move them every couple days or they get used to it.
I had a huge hawk try for my Delaware hen a while back. I was building them a new coop and had the door off to make adjustments. I stepped into the shop for only a couple seconds when something banked coming around the apple tree. I ran out to see a hawk on top of the Delaware in the corner of the garden. She is fine but has yet to lay another egg after that event. That was about 18 months ago.
Hawks freak me out when the girls are out.
I have a lot of chickens too so understand tractors are not always the answer.
I just had a red-tail take one of my Cayuga drakes last night apparently while the birds (chickens and ducks) were putting themselves to bed going into the coop last night. I found him this morning. Cayugas are much bigger than chickens, so now I've stepped up my yard patrol on my acre. I will also hang out in the evening so they all get in the coop successfully. Good luck, they will take your birds.