We have lots of rabbits here, but they seem to not bother the irises. We had (until we finally, recently, fenced them out) lots of deer, too. Deer definitely don't eat the irises.
That said, something has eaten the foliage on some of my irises down to the ground. We also have gophers, so I am thinking that land-traveling gophers is the problem.
Raccoons will sometimes tear a patch of iris apart, in search of worms or grubs, but they won't eat any of it. They just leave the rhizomes lying scattered on top of the ground.
I hope that you can find (and fix) your critter problem!
