Wildlife Matters Presents: 10 Steps Towards Critter-Proofing Your House

The following information is an overview of typical wildlife problems and some techniques used in humanely dealing with nuisance wildlife. Before attempting these methods yourself you may want more detailed information. Call Wildlife Matters at (703) 534-8180. In-house consultations are available; telephone consultations are free! Or check with your local humane society or nature center for recommendations.

1. Birds nest in attic vent louvers: check nest for babies. If present check weekly until vacated, then proceed. Clean out debris and screen entire vent with l/2 inch mesh hardware cloth.
2. Squirrels chewed through into attic: Check inside attic to make sure squirrels are outside before screening vent with hardware cloth. You may need to wait for bad weather to clear or for baby squirrels to grow big enough to leave the nest. Ammonia or mothballs can help get the squirrels out temporarily, but you must follow up with repairs within 24 hours.
3. Raccoon in chimney: Flue needs a sturdy cover. The raccoon will leave every night at dusk. In the spring, check for young. If present you must wait until mid- to late summer when they are big enough to follow the mother out. Install flue-cap after raccoon has left (you'll need a good flashlight).
4. Bird nest in stove exhaust fan vent: usually starlings are found here. They may raise young year-round but typically are active from early spring through early fall. When young have vacated (and before next clutch is laid), clean out debris. A vacuum cleaner hose is helpful. Cover vent opening with hardware cloth.
5. Bats entering attic through unscreened attic vent and under fascia board: To safely evict bats yourself you will need more detailed information than what's given here. During June and July there may be baby bats in the roost than cannot fly. You must be sure all bats are out before sealing entry/exit. Watch outside the house at dusk to see where bats are exiting. Any openings into attic 1/4 inch of larger must be sealed. Caulk along fascia board and stuff steel wool in large gaps.
6. Mice entering garage under door: Mice can enter 1/4" gaps. Check doors for weatherstripping. If chewed through, wrap metal flashing around bottom edge of door. Caulk/fill in any cracks around foundation of house.
7. Opossum eating pet food: Do not feed pets outside or if absolutely necessary, leave food out during daylight hours only.
8. Woodchuck burrowing under concrete slab (porch): Do not attempt to evict woodchucks during winter months (they hibernate) or spring to mid-summer when there are babies. When appropriate, bury an empty soup can in the floor of the burrow so that the lip of the can is flush with the floor. Fill can half full of gasoline. The fumes drive the animal out in approximately two to five days. When you are sure the animal is gone, dig a trench along the slab 1-1/2 feet wide and 1-1/2 feet deep. Fold appropriate length of three-foot-wide hardware cloth into "L" shape and bury in trench. Tamp soil firmly and cover with a layer of one inch of gravel, six inches wide and six inches deep.
9. Snake entering basement around duct to dryer vent: Check around pipes, wires and ductwork that lead from inside to outside of the house. Caulk around all openings and fill large gaps with steel wool.
10. General housekeeping hints: Keep shrubs trimmed at least one foot away from the house; trim tree branches away from the house. Keep grass cut short. Check window screens for tears; check attic vent for screens. Check concrete patios and porches for signs of soil erosion away from sides and line with one inch size gravel if necessary. Screen exhaust fan vents with hardware cloth.