Last year I bought several lights called Nite Eyes that were guarenteed to scare away preditors from my birds. These lights came on at dusk, flashed bright red like a pair of eyes, and then shut down at dawn. The research stated that these lights frightened preditors like Coons, Fox, and Opossums because they would think another preditor was in the area.
I bought four of these and installed according to the instructions. To test them, I placed a live trap within 25 feet of one of the lights and directly facing it. since January, I've trapped two coons, and seven Opossums in that trap less than 25 feet away from the light. My conclusions are that the preditor lights advertised are totally ineffective and I won't waste any more of my money on another.