Gnawing noises are heard in one general area of our house. It is most obvious coming from forced air vents located in the shared void between a lower level ceiling and the floor of the living areas above. Two professionals have not been able to ID the animal (not mouse, not squirrel, not rat, or raccoon) and there appear to be no visible entry points from outside to this area. Baits and snap traps (peanut butter, bacon) for mice, live traps or baits(untouched) for chipmunks haven't eliminated the cause of the sound. I have opened the ceiling in numerous area and inspected the floor joists without seeing the animal, droppings, or actual damage.

Members of my family often wake with the loudness of the noise at night. However, the noise is day and night but stops after any sharp noise occurs in that area, as if an animal is startled. Soon after the noise resumes. Our home is built into the side of a hill so the affected areas are 4-6 feet above outside ground level and have been consistent for about ten weeks. I wonder if it could be a chipmunk or vole in an adjacent wall with the sound traveling to multiple areas close by.

There has been heavy construction (i.e. pile driver) two blocks away that began at the beginning of last fall. We do have bird feeders, squirrels, chipmunks and maybe meadow voles(?) in our yard all year. This is a new situation in the 19 years we have lived here. Any observations/suggestions you have would be appreciated greatly. Lee Johnson

An IDNR district wildlife biologist provided this reponse: A gnawing noise would be from some type of rodent, (e.g., field mouse, white-footed mouse, chipmunk, vole, rat or squirrel). The likely suspects would be smaller animals that have less desire to move inside and outside during this weather time-frame. Rodents gnaw to keep their teeth from continuing to grow, which they do without maintenance. If the culprit is active anywhere around the ventilation system, that is like a transmission line for noise. The animal could be gnawing in one end of the house, but due to the design of ventilation corridors and ducts, the sound may travel throughout the building. My suggestion would be to purchase some "sticky traps", they are not scented and will work efficiently, but they may need to be placed in multiple areas. Traps baited with bacon or peanut butter will eventually mold, but the sticky traps do not have that problem. On the other hand, a snap trap baited with peanut butter (recommended over bacon) will let anyone know during the night if it is successful. The next step is to ascertain on the outside where these animals may be entering the home. It does not take a very large opening, maybe the size of a quarter for a mouse or vole to enter. Some type of caulk can be used to seal any openings of descriptive nature and prevent further unrest."