It is really common to find it in my area. There is a certain type of little finch bird that lives around here that loves to peck at the screens covering the "bird holes" in freeze blocking. Then they build nests inside the attics. The rats come after the eggs and then take up residence. I've seen brand new houses with chewed up insulation on cables. Dust mask is not good enough, wear a real resparator, and gloves.
