Most predators have a sense of smell at least 150 times better than humans, for many animals it is scent that they become aware of first.
There is no way to totally mask the scent of prey animals, but you can add some confusion to the odiferous air waves.
If you were to plant barrier rings of things like marigolds, garlic, onions, or other strongly scented plants that are known to deter animals (deer for example) then you might find that predators are less willing to get close enough to become a problem.
Dogs are a fairly good way to add a scent trail that will deter some of the predator animals.
Apparently Raccoons are an exception, since we have one that comes into our yard (which has dog scent all over it) to eat any left over dog food. (found this out by using a game camera). Now if the Dogs are outside, they will usually attack any wild predator that tries to come into their territory. So, you could put your chicken coop/run inside the dog's area (fenced so the dogs can't get in the coop/run) and that might be enough to keep the predators away.
In my experience, no matter what you do to try and keep them away, if there is the low risk, high reward element in play, the predator will not be deterred. Make it more high risk, low reward and then you have a fighting chance.
The best methods involve electric fencing, both high and low, with enough voltage/ amperage to instill fear in the predator who touches the hot wires. I have seen cases where the voltage/amperage was stepped up to the point that it fried the offending critter on the spot.
With our own list of predators missing only weasels and bears, we have been thinking about using hot wires at the top and bottom of our fencing (two or three at the bottom and one or two up top). I tend towards the aggressive side of the equation wanting about 220 volts at 3-5 amps for sure fire, OH- NO- YOU- DON'T! energizing of the hot wires.
Of course this means I also have to put up "Danger High Voltage" signs for two legged offenders, but I can do that.
Note: since it is the amperage that kills, it is possible to use 110 volts combined with large amperage to instantly stop any critter, even a bear. I have not noticed any two legs trying to act like a predator on our farm as yet, so I am all good with using a traditional 10-20 mile charger on any electric fencing we need to put up. The big trick to using hot wires is keeping them free of any plant materials that could render the wires ineffective.
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Thanks for all the info and advice! I had no idea these predators could do so much damage! It's just my rookie ignorance. We do have a dog and he used to patrol the coop all the time, he is so good with our birds, but he's recently become hard of hearing and his age is catching up to the poor guy. We'll be investing in a pup soon, hoping our old guy can teach the new pup the ropes. Our coop is close to our garden so my husband and I are constantly around the coop, but a few days before the attack I had been out of town and my husband hurt his back and hadn't been outside...Add our noisey rooster to the mix and our chattering ducks and the stars aligned perfectly for this attack. Lessons learn and hopefully we can set up traps and surveillance to catch and learn more about these predators.
