I don't know what the attraction to styrofoam is, but I haven't found a chicken yet who would pass at the chance to dine on styrofoam when given half a chance.
I made the mistake of building a chicken tractor with a sheet of exposed insulation on the interior. It took three feathered eating machines just a few days to eat a big hole right through the insulation (because it was on the interior of the tractor, I didn't see what they were doing until they had eaten a nice size hole in the insulation). I had to pull them out of the tractor for a few days, till I could cover the insulation up with some thin plywood -- let's see them eat THAT!
Another time, a styrofoam cup flew into their chicken yard from a neighbor's place, and they had eaten the better part of the cup before my wife found it and took it away from them.
But all of our feathered styrofoam eaters have survived the experience.