Where are you posting from?
Any chicken with a crest on its head, feathers obscuring its vision, or having trouble running or flying is fox food for sure if a hungry fox comes around.
An electric fence about 4 foot high and with wires about 3 inches apart, alternating from top to bottom between a hot wire and a ground wire should convince any pesky foxes or maybe even stray neighbors to give your property a wide berth.
I'm in Central Texas.
The Silkies are hatchery Silkies, so their top knot is almost non existent. The Polish have their top knots cut at the sides and front or tied up. The Silkies don't stand a chance with a predator because they basically have no wings. A winged Ameraucana can run faster and use its wings to jump/fly.
The Ameraicamas also try to roost 15 or 20 feet up in my trees at night and one night my son didn't get them down in time so they spent the night in the trees. I don't know if that was when they were killed. I count my chickens every night when I put them to bed, but no one else does. I was away for the week the two cockerels went missing so I don't know when they were killed. I had surgery on my hands around when the Silkie went missing and didn't take a head count one day. She was missing the next night.
I'm not sure how to make an electric fence work with my deer problem. My neighbor feeds the local starving deer, so I have up to 10 spending the night on my property. There are probably about 40 or 50 who make the corner of my property and my neighbor's home base. Everything on my property that is edible (including the "deer-proof" plants) have a fence around them which the deer regularly crash into and demolish. I don't think the electric netting will last even one night. The boundary between my property and my neighbors is where the fox or whatever is crossing into my property. It is also the fence the deer use to get in and out of my neighbor's property.
I'm thinking of tying 40 inch chicken wire to the fence and running a live strand or two just over top of that, but I have to worry about the deer getting hung up on it. I've cut a few deer down from my fence before I took down the top strand. Maybe an electric fence right next to the farm fence, but if I use chicken wire, the fox will just climb up the farm fence side and jump clear of the hot netting. It might get stung on the return trip, but that is a little late for my chickens. The hot fence will have to be really close to the farm fence or the deer will destroy it.
In the mean time, I'm outside a lot especially near dusk. Now that it is cool at night, I leave them in longer in the morning. Unfortunately, they don't go to bed early. I'm going to get some scratch and try to train them to go to bed early.
My neighbor says she hasn't had any luck trapping the fox. I'm going to try with a really big trap and bait the trap, first outside the trap to get the fox (or whatever it is) desensitized to the trap and then slowly moving the bait into the trap. I'll put the trap just outside my fence so my dogs/cat won't get into it. What kind of bait would you use for a fox or raccoon? I was thinking cat food or maybe sardines. I'll start leaving bowls of dry cat food out by the trap as a start. A well fed predator is not as likely to go to the trouble and risk hunting where there is a fence and dogs, one being a pit bull.
I think another attack on my chickens is imminent since I know I haven't lost a chicken since I came home Sunday evening. Unless it caught something else, it must be getting hungry and nothing can be easier to catch than a little Silkie hen. The two cockerels it took were very big birds and it took those in the last 11 or 12 days.
Thanks for any advice and suggestions.