Nuisance Wildlife

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Evicting Animals from Buildings

Occasionally a raccoon, skunk, tree squirrel, or other animal will find a suitable shelter in or under a house, shed, or other structure. These animals may occupy an area sporadically, using the site only two or three consecutive days or nights usually until available food sources are exhausted. However, some may choose to overwinter there if the surroundings remain favorable. During the mating and nesting season, females attracted to warm, dry, easily defended areas may attempt to den or nest in these settings.

You may choose to let the animal use the area if it doesn’t pose a direct problem to you, your family, or your pets and other animals. However, its discarded food, urine, or droppings may create odors and become a potential health hazard. Animals also may make considerable noise, chew on building parts, or destroy insulation during the nest building process.

Should you choose to remove the animal, you can complete the process yourself or hire someone to do it (see Hiring a Wildlife Damage Control Company). A wildlife damage control company is recommended for work that poses health or safety hazards. Examples include removing a large accumulation of droppings, removing a mother and/or her young in emergency situations, or working in a precarious location.

Note: State wildlife offices do not provide animal removal services, but they can provide names of individuals and companies that do.

If the animal you are trying to evict appears sick or injured, call a nearby wildlife rehabilitator for assistance (see Wildlife Rehabilitators and Wildlife Rehabilitation for more information).

To encourage an animal to move on its own or to evict it from a place where it is undesired, follow the steps below. (For information on evicting bats, see Bats.)

Click to enlarge Figure 1. The house and yard can provide homes for wild animals in the form of shelter and cover. An overhanging branch (a) can provide access to a roof, while the tree itself may be used as a refuge. An uncapped chimney (b) or broken vent (c) can provide access to warm, dry living quarters. Entry for small mammals can occur where wiring or pipes enter the house (d) and (e), vents are uncapped (f), doors are improperly fitted (g), ground-level window sills, foundations (h) and bulkhead doors (i) have gaps. Shelter can be found under decks (j); burrowing animals may tunnel beneath patios (k) or wood piles (l). (Adapted from Hodge, Wild Neighbors: The Humane Approach to Living with Wildlife.)

A Seven Step Strategy to Conflict Resolution

Before anything else occurs in a wildlife/human conflict in or around a structure, it is absolutely necessary to be sure of the following: the species involved, where the animal(s) are entering, and whether or not young animals are present. After that it is important to proceed in such a way that is humane and prevents the problem from reoccurring.

Step 1. Try to identify the suspect
Identifying the species of animal causing the conflict is vital to resolving the problem. Note the time and location of calls, cries, or scampering noises heard coming from inside the structure, and have a look outside for the animals themselves. Tree squirrels (except flying squirrels) and marmots are heard exiting around sunrise and returning from late afternoon until dark. Both can be seen outside during the day. Flying squirrels, raccoons, river otters, skunks, and opossums are heard rummaging around shortly after dark until just before dawn, and are generally seen outside at night.

If the animal isn’t seen, try to identify it from its method of entry, odor, tracks, droppings, or any damage it is causing. (Read the appropriate handout in this series for specifics on any suspects.) Always be cautious around animal droppings; they can contain organisms extremely harmful to people.

Step 2. Do some detective work to locate the animal’s method of entry
Inspect the outside of the structure for visible entrances. More than one entry may be used, and entry holes are often smaller than expected. (Small native squirrels enter holes 2 inches in diameter; Eastern gray and fox squirrels chew open baseball size entries.)

Common points of entry are around utility cables and pipes that come into a structure, attic louvers, and roof vents, as well as holes in roofs, siding, soffits, and foundations (Fig. 1). Raccoons often leave scratches, tracks, and body oil stains where they shimmy up downspouts, trees, or the corners of buildings to access roofs. Rats, skunks, and marmots often dig under foundations or concrete slabs.

Use a bright flashlight to locate holes in shadowy areas, and a ladder to search for holes high on a structure. You know there is a hole when you shine the light at an area and it remains black. (This is because the light is entering the hole, instead of reflecting back to you off the structure.)

Step 3. Determine the animal’s main entry
Indications that you’ve found the animal’s main entry include a newly dug hole or dirt stains, nest materials, and/or hairs stuck around a narrow hole in the roof, siding, or foundation. Fresh animal tracks may be found in dry soil near the entry.

To verify that an entry is being used, lightly stuff wadded-up newspaper, burlap, or dirt in the entry and watch daily to see if the material has been moved. (Don’t use this technique if you think it may be bats or birds entering; they will get trapped inside.)

An alternative approach at ground level is to spread a tracking patch outside the entry, covering an area large enough to record footprints as the animal enters or exits. A tracking patch is a light layer of an inert material such as unscented baby powder, fine dirt, or sand. Don’t use flour; it may attract a hungry animal.

If you can’t find the entry, during daylight and with a strong flashlight or headlamp containing fresh batteries, very carefully enter the attic, crawlspace, or other area. Wear gloves and a dust mask or a respirator, and be on alert for animal life. From inside, you can better inspect the screening on the vents for signs of entry. Turn the light off to reveal light coming through any potential entry holes in the roof or walls. Securing something in these holes will make locating them from the outside easier when it comes time for repair.

Step 4. Determine if young are involved
After finding the main entry you need to verify that no young are inside before proceeding with the eviction process. Because each situation and each animal is different, do this even if it seems early or late in the year for young to be present. Failing to do so can lead to major problems from an unhappy female animal separated from her young.

Reenter the attic, crawl space, or similar place and search for a nest or young. Focus on the area near the active entry or where you have been hearing noises. Squirrel nests are often made of insulation and other material that is torn up or piled within 20 feet of the entry, and close to the outer edges of the attic. Raccoons, skunks, and river otters don’t make an obvious nest.

To get the young to move or make noise and alert you to their presence, pound on a floor joist, ceiling joist, or wall. A stick may be used to search for babies in hard-to-reach places, such as in a wall between studs.

Note: Use care to prevent injuring any animals, and never approach a mother with her young; her protective instincts can make her very dangerous.

Step 5. Evict the family only when necessary
If young are present, the most humane thing to do is to leave the family alone until they move on their own. Squirrels, raccoons, opossums, and other young mammals generally leave the nest area eight to ten weeks after being born. Occasionally one of the young may stay behind, in which case the eviction methods described in Step 6 may be used.

If the young need to be moved, you will want to get the mother to move them on her own using one of the techniques described below. Even in an emergency, females can often be persuaded to move their young, thus avoiding the need to trap or euthanize families.

Note: Anytime you try to evict a mother animal and her young there is a chance that she may leave some or all of her young behind. If the young end up as orphans they will not survive in the wild without mom. In such a case, they should be taken to a local wildlife rehabilitator. Do not attempt to care for the animals yourself. Not only could you further harm the animals, it may be illegal for you to do so. (See Wildlife Rehabilitators and Wildlife Rehabilitation for information.)

Note:State wildlife offices have requirements that you’ll need to follow, including mandatory euthanasia of certain species, such as skunks, Eastern gray squirrels, and opossums.

If you are lucky and the weather is fair, the mother may move her young, even newly born ones, to an alternate den within an hour or so after they have been disturbed. If the weather isn’t favorable, or she has to find a new den or build a new nest, it may take a couple of days.

Each animal is different, and river otters in particular tend to be quite stubborn when they have young with them. To help the eviction process go smoothly, keep children and pets away from the animal’s entry.

If steps taken to evict the family are unsuccessful and the young must be moved immediately, the female can be live-trapped and the dependent young placed in a weather-protected releasing box. Place the box outside and adjacent to the point of entry after the entry has been sealed to prevent reentry. This will allow the mother to relocate her young at her own pace. It is recommended that a wildlife control company experienced with live trapping and releasing boxes complete this procedure.

Step 6. Begin the removal process
If no young are present, an option at this point is to live-trap the animal (see Trapping Wildlife).

Because trapping presents additional problems for both the trapper and the animal, the preferred option is to get the animal to leave on its own. This will require effort on your part in the form of encouraging the animal to leave, and then following up to make sure the animal doesn’t return, or a different animal take its place.

Begin the removal process by sealing off all entries but the active one. First, carefully seal any potential entries, as the animal will seek other ways to get back inside. Use wood, ¼-inch mesh galvanized hardware cloth, sheet metal, aluminum flashing, or another sturdy material that will prevent the animal from entering. Small holes in hard-to reach locations can be plugged with wadded-up wire, copper Stuf-fit®, or copper or stainless steel mesh scouring pads (steel wool quickly corrodes after becoming wet). High-quality and reasonably priced bulk material is available for larger jobs. If necessary, foam or caulk the openings to seal them. Paint will help hide the repair job.

To create a barrier along a foundation to prevent skunks and other species from burrowing, refer to Figure 3b and “Preventing Conflicts” in Skunks.

After all entries except the active one are sealed, and during a period of fair weather, encourage the animal to leave using one or more of the following methods:

Seal the remaining entry hole while the animal is outside feeding. Note: Do not do this if young are present; they will be separated from their mother, which will quickly create other problems.

First, have all materials ready that are needed to seal the entry. Next, place wadded-up newspaper in the entry or use a tracking patch as described in Step 3 to determine that the animal has gone outside. For squirrels and other species that are active during the day, look for the signs that they have exited early in the morning; for raccoons and other nocturnal species, begin the surveillance an hour after dark. Survey the entry frequently, as animals will return to rest or escape bad weather. When you are certain the animal is outside, seal the entry to prevent the animal from reentering.

An alternative approach and one to use if mobile young are present is to lightly pack the active entry hole with wadded-up newspaper, burlap, or dirt, and repack it whenever you see it open. Just block the hole enough so the animal must expend energy to reopen it, but not get trapped inside. When the barrier has not been removed for three days during fair weather, the animals have gone and repairs can be made to prevent reentry.

Harass the animal. Simply banging on the ceiling, wall, or floor in the vicinity of the animal may cause it to vacate; also, your initial search for young may have already made the animal uncomfortable enough to leave.

Alternatively, with a powerful flashlight or headlamp containing fresh batteries, and wearing gloves and a dust mask or respirator, carefully enter the area where you think the animal and/or its young are sleeping. Shine the light on the adult animal, bang on a rafter, clap your hands and tell the animal to leave, or do anything that doesn’t put you or the animals in danger. If the adult is outside, gently tamper with the nest, pull off the top and/or slide it over a foot or so.

In addition, roll rags into tight balls and secure them with twine or tape. Sprinkle the rag balls with predator urine available from farm supply centers, hunting shops, or over the Internet, and throw or place them near the nest. Sprinkling stinky kitty litter around the nest will also create an unpleasant atmosphere; Raccoon Eviction Fluid® works well on raccoon families.

The animal(s) may leave within the hour or it may take a couple of days. Revisit the area to see if the young are gone, and to make sure the adult didn’t move them elsewhere within the structure.Use wadded-up newspaper as described above to verify that the animal is gone, and make the necessary repairs to prevent reentry.

Intensely harass the animal. Using a mechanic’s bright droplight (grid enclosed bulb) or other portable light located away from burnable objects, light up the sleeping area being used by the animal. (A fluorescent light will conserve electricity and keep the heat level down.) In addition, put a radio in the area and play a talk station as loud as you can tolerate. If the animal moves to an unlit area, move the light and radio to that area, or install an additional light and radio.

(There is no scientific evidence that commercially available ultrasonic devices will drive animals from buildings. Animals quickly become accustomed to the noise or move to a noise-free area because the devices do not penetrate objects, and the sounds quickly lose their intensity with distance.)

Leave the lights and radio on 24 hours a day to interrupt the animals’ sleep. Use a visual verification, a one-way door (see “One-Way Doors”), or the wadded-up newspaper or tracking-patch approach described above to verify that the animal has gone. Be patient it may take several days for the animal to make the move, especially in urban areas where animals are used to lights and noises.

Step 7. Follow up
If you hear noise coming from inside the enclosure after sealing the entry, an animal may be inside. Reopen the area and repeat Step 6 until all the animals have departed. Then reseal the entry. If for some unknown reason an animal will not leave the area, it can be live-trapped (see Trapping Wildlife).

Make frequent inspections for two weeks to make sure an animal hasn’t tried to get back inside using the original entry or a new entry. Where one animal enters, a scent trail is left which others may find and use. This scent lasts for several months, sometimes longer. As a preventative measure, pepper spray or a commercial taste repellent such as Ropell® can be applied to the area. Applications will need to be repeated if the area is exposed to damp weather.

Consider hiring a wildlife damage control company to inspect for piles of droppings and other contaminants. If an animal has spent a lot of time in an area with exposed wiring, inspect the area for wire damage or have an electrician inspect it. (You should also inspect for damage done to insulation and heating ducts.) In the meantime, check your smoke detectors to make sure they are functioning in case of a fire.

One-Way Doors Figure 2. A ready-made one-way door can be set to evict animals that burrow under houses and concrete slabs. (From Hodge, Wild Neighbors: The Humane Approach to Living with Wildlife.) An active entry can be fitted with a one-way door so an animal can exit but not reenter. A one-way door takes time and effort to install correctly, but is effective at evicting squirrels, raccoons and other animals above the ground on buildings where they have gained access. Ready-made one-way doors that trap burrowing animals (Fig. 2) are available from companies advertising over the Internet (search for “Animal Control” or “Animal Traps”). A one-way door must be used only when you can be sure that no young will be trapped inside after the adult is evicted. Thoroughly inspect the area for young prior to installation. Leave the one-way door in place for seven days (longer during particularly cool or rainy weather). To verify the one-way door’s success, look for scraping or digging on the outside of the door this means the animal is out and can’t get back in. For further proof, place a tracking patch on the outside of the one-way door, as described in Step 3, and keep an eye out for prints. After all animals have been excluded, remove the door and immediately seal up the exit. A simple one-way door can be constructed from plywood, sheet metal, or 1/4-inch mesh hard ware cloth. Attach the top to the structure with strap hinges (wood) or fence staples (sheet metal, hardware cloth) to create a flap door that opens easily and closes completely. The door should extend out at least 6 inches from all sides of the exit hole. To help prevent the animal from reentering, the bottom of the door can be weighted with a piece of rebar or a similar heavy object. To further help prevent an animal from trying to open a wire-mesh door, the wires around the edges can be bent out to create sharp points. On angled areas (trim, eves, etc.) where gravity would keep the door open, use two small screw-eyes below the door, and run fish line from the bottom of the door through the screw eyes. Weight the ends of the line with a few metal nuts or whatever is needed to pull the door closed. Click to enlarge Figure 3. To prevent animals from digging back into an area where they are being evicted, one-way doors (a) are often used in conjunction with an L-shaped footer made of welded wire or hardware cloth (b). (Drawings by Jenifer Rees.)

Adapted from "Living with Wildlife in the Pacific Northwest"
Written by: Russell Link, Urban Wildlife Biologist