We had motion sensor lights at our old house, and raccoons regularly set them off (on?). However, the raccoons just went on about their business--I think the lights made it easier for the little bandits to see our garbage cans. Don't know how it would work with possums, coyotes, and skunks.
The lights might also upset your chickens, which are not the most sane and calm beasts on earth. If you try the lights, let us know the results.

in one of my dual motion lights i replaced the bulb with a screw in outlet adapter. i plugged in a cheap $5 alarm clock radio. its shining on my garden and my chicken coop behind the garden. so whenever something triggers the light the radio comes on too. my vegetables get to listen to music while it scares off critters.

That radio thing is a great idea! I might think about adapting that. My chickens are in a fortress at night, but racoons and groundhogs regularly eat my fruit and veggies. It would have to be set in the daytime too, to ward off the groundhogs. Interesting idea!

The raccoons and other predators would get used to the light going on and off and just kill em anyway. Best thing is to build a secure coop with a good door to keep them out.

And, if you build a secure coop & pen the cost of raising them will exceed the price you pay in the stores. The benefit is you know what you are eating. You could supplement with grass/comfrey/clover clippings during the growing season.

Find a CO-OP near you for best grain prices if you'll be supplementing, maybe sell any extra eggs to offset costs.
Brendasue

I don't use them as my dogs are itching for a fight with anything that gets close enough but you can get solar powered infared lights that make predators think that there is already a predator in the area and so they leave. I have heard that they work really well.
I *think* I've seen them in Mcmurrey Hatchery and QCSupply catalogs but I don't have either on hand at the moment so I could be wrong.