Site Inspection

Learning Objectives

  1. Describe the inspection process.
  2. List the proper tools needed to do the job.
  3. Explain when to use those tools.
  4. List the right questions to ask the client to obtain needed information.

Terms to Know

Damper  The metal plate that controls the size of the opening between a fireplace and chimney.
Sill plate  In a building, a horizontal (usually wood) member anchored to a foundation. It secures the wall to the foundation.


A thorough site inspection is the foundation of an effective IPM approach to control wildlife damage. Failure to spend enough time on the initial visit can result in hours of additional work and could prevent the NWCO from properly understanding the problem.
The first thing to do is find the source of the customer’s problem. That means you need to understand the type of damage and how bad it is. You have to identify the culprit. Look for clues that will help you figure out what attracted the problem animals to the site. Remember the two key enticements, food and shelter.

Signs of Wildlife Presence

Use your knowledge of animal behavior. Wild animals usually provide many signs of their presence. Once you’ve gained experience in reading these signs, the clues you gain from your site inspection and customer interview should help you identify the species, estimate the number of animals present, and find the areas where they’re most active.
Visual sighting. This is one of the easiest ways to identify the species, if you can trust the observer. If nocturnal animals are seen often during the day, the animal may have young and is feeding more often, or the local population is high, especially with rats and mice. If dealing with a bat colony, you may have a hard time locating the entry holes. Stand outdoors at dusk or dawn, and watch where the bats enter or leave the building. There’s the hole! A more detailed description of how to conduct a bat watch can be found in the Bat species section.
Sounds. Listen for various squeaks, growls, cries, hisses, chitters, and screeches; gnawing; or clawing, scampering, and climbing inside the walls, above the ceiling, between the floors, or underneath cabinets. Learn to tell the sounds of adults from those of young.
Odors. You may smell the droppings, urine, or body oils of wildlife that are living indoors. With a little experience, you can tell the odor of a house mouse from that of a rat. Skunks have a well-known scent, but woodchucks also can be identified by their odor. Dens of other animals, including raccoons, have their own scent.
Droppings may be found along runways, near shelters, in piles near an entry hole, or in other places used often. Fresh droppings are shiny and often soft, while old ones are dry, lighter in color, and hard. Old droppings crumble easily.
Urine. You can see rodent urine using an ultraviolet light — urine glows blue-white. Unfortunately, other materials also glow, which can be confusing until you become familiar with the typical background fluorescence of a home or office. In regular lighting, you may notice discoloration on building materials in attics or crawl spaces. It is caused by a large amount of urine, which could indicate the presence of raccoons, flying squirrels, or a large bat colony.
Food caches. Nests and food caches sometimes can be found when cleaning garages, attics, basements, closets, and other storage places. Rats, squirrels, and other rodents often store food in attics.
Entry sites. The location, size, and condition of the entry sites, such as holes, cracks, and loose siding are important clues to the species involved.
Burrows. Woodchucks, chipmunks, moles, voles, and Norway rats can dig burrows. You can learn to tell their burrows apart. Other animals, including raccoons and skunks, will use burrows but they don’t make them. The location of the burrow, its size, the type and number of entrances, and objects located near the burrow will help you identify the species.
“Leftovers.” Sometimes you can find the remains of a meal near an animal’s den. You may be able to identify what the animal was eating, and that can help you identify the animal using the den. For example, often you can find rabbit fur, bones, and feathers near the den of a fox or coyote. If you can’t find sign of prey, then you’re probably dealing with a herbivore, such as a woodchuck.
Runs. Look for smooth or worn trails next to walls, along fences, or under bushes and buildings. Runs within buildings may be well-polished trails that are free of dust. Trails through insulation are common.
Smudge marks often are seen in the animal’s run where it rubs against a surface during its travels, leaving behind dirt and oil from its fur. Look on pipes, beams, walls, and the outside edges of holes.
Tracks and claw marks. Footprints, tail marks, and wing prints may be found in dusty surfaces, sand, soft soil, and snow. If the surface doesn’t show tracks well, you can sprinkle nontoxic tracking dust (such as chalk powder or unscented talc) in a likely area, and return later to look for tracks. When used outdoors, the dust must be protected from wind and rain. You may find claw marks on woodwork, trees, or in dust. Consider photographing and labeling the images after you have properly identified the species.
Hair, feathers, or shed skins. You may find tufts of hair on a fence or baseboard, feathers in an attic or above a dropped ceiling, or, less often, the shed skin of a snake. With practice, you may be able to identify the species from these signs. To improve your identification skills, consider making hair sample charts. Clip a tuft of hair from an animal you’ve dispatched, and attach it to the chart with the appropriate label.
Gnawing. Look for evidence of chewing (wood chips, tooth marks, holes, shredded fabrics, frayed wires). Some wildlife will gnaw to enlarge a crack or enter a space. Wood chips may be seen near baseboards, doors, basement windows, kitchen cabinets, furniture, and stored materials. You could find shredded clothing, or see tooth marks on pipes. Rodents and raccoons often chew on the insulation around wires. The size of the tooth marks will frequently help you tell whether you’re dealing with mice, rats, or squirrels.
Pets become excited. When cats or dogs hear or smell rodents in a wall or other inaccessible space, they may become very interested and whine, sniff, or scratch at the spot.
Access routes. Walk around outside and try to imagine the route the animal might have used to gain entrance to a building. Are trees or utility lines near the roof? Could the animal have crawled under a porch, up a chimney, or along a downspout? Is there an attached garage that might have been left open? These clues point to likely culprits. Skunks, for example, aren’t going to jump from a tree branch onto the roof, and squirrels aren’t as likely to wriggle in underneath a porch.

Information from an Interview
and Inspection

Your knowledge of the habitat preferences and behavior of wildlife will help you estimate how many animals might be present. For example, if a customer complains of noises in the attic in March, you’d expect to find not just 1 squirrel, but probably 3 to 8, because that’s when female squirrels are raising their young. If you see a female mammal, you may be able to tell if she’s nursing because her nipples would be larger. This is hard to see on some of the small, fast-moving animals like flying squirrels. If it’s any time near the breeding season, assume that young may be present.
Other aspects of the animal’s lifestyle that help you answer the question, “How many?” include its social habits, daily movements, and whether or not it hibernates or migrates. Is the animal generally found alone, or in a group? How fresh are the signs? Is this problem new or is it well-established? How large is the property, and how many individuals of that species would you expect it to support?
You are more than a wildlife detective, however. You also have to nose around in your customer’s home, and ask questions to find out if the inhabitants or their neighbors are causing the problem. People sometimes feed or house wildlife without realizing it. Squirrels, for example, may be attracted to spilled seed at a bird feeder. This may not be a big problem, but once nearby, they may run across the roof and find a hole that gives them access to the attic. The animal may decide this is an ideal place to raise its young. To solve this conflict, you may have to remove the food source and repair the building.
You will have to learn more about your customers before choosing a strategy. For example, do they let pets roam freely in the area? Are garbage containers tightly secured?
So, Sherlock, how do you proceed? Most NWCOs interview their customers and inspect the premises to look for clues.
Here are some questions you’ll hope to answer using clues gained from the interview and the inspection:

  • Which wildlife species is causing the problem? Is more than one species involved?
  • How many animals might be present?
  • Could young be present?
  • Is this the first time they’ve had a wildlife problem? If not, what happened before?
  • How long has this problem existed?
  • Are the culprits readily accessible or hard to reach?
  • How risky is this situation for you, your customers, and their neighbors?
  • Can you target only the offending animals?
  • Will it be easy to be discreet or will your control activities be in public view?
  • If you repel or exclude the animals, where might they go?
  • Does this look like a short-term problem or one that is likely to happen again?
  • Given the location of the problem, are there any local laws that would affect your management options?
  • Do you see any signs that could predict future problems?

The Interview

First, it is best to talk to the right person — whoever knows the most about the problem and the property. Ask both general questions and some very specific ones. A general question might be, “Please describe what you know about the problem,” or “Have you noticed any problems since my last visit?” This type of question gives customers a chance to share their information, which could trigger other questions that might guide your inspection.
You will develop your own style when interviewing people, but here are some questions to probe for specific information. Ask the customer when they first noticed the problem. How often does it occur? Did they see any animals or signs of animals? You might want to prompt them by asking whether they’ve heard noises. Find out if the noises are heard during the day or night. Can they locate the noise? You may want to ask several questions about the noises they are hearing, because sometimes people mistake mechanical sounds, such as the beeping of a smoke alarm with a low battery or a swaying utility line, for animal noises.
Remember to ask if they’ve ever had any trouble with wild animals before. If they say yes, have them describe that situation in more detail. When did it happen, did they identify the culprits, and what did they do?
Ask a few important questions about the household. Are any children or pets present? Their presence might limit which wildlife control techniques you choose. Did anyone have any direct contact with a wild animal? This is especially important if dealing with bats, raccoons, and skunks, the species that are most likely to carry rabies. If there has been contact, you’ll have to follow health department guidelines. It’s the law.
Inspections seek to answer 3 related questions:

  1. What is the nature of the problem, and is it really a problem?
  2. How can the problem be resolved?
  3. What potential future problems can be prevented for the client?

Shortcuts in any area will result in less than adequate inspections.
Effective site inspections require
coordination of 3 elements:

Persistence, knowledge, and equipment.


Wildlife damage inspections can put a strain on NWCOs and their equipment. Professional wildlife control operators may work in hot summer heat and in the cold winter months with snow and ice. It takes time to conduct a thorough inspection, so plan accordingly based on the environment and the weather.
While pest control technicians often do not need to perform outdoor inspections in poor weather, NWCOs likely will. It takes effort to remove a ladder from a truck many times during the day. Cutting corners during wildlife control work can result in embarrassing and costly call backs. Call backs are unprofessional, unproductive, and expensive for the NWCO.


An inspection is a process, not an event. The inspection frames the nature of the problem and the behavior of the problem animal. While many jobs may appear to be routine, avoid cutting corners. Familiarity can lead to complacency and new situations occur all the time. Discipline yourself to follow the entire inspection process every time.

Site Inspection Equipment

Essential Equipment

  1. High-intensity spotlights should emit at least 500,000 candle-power, and preferably more. Service flashlights are adequate when you are close to the target but are useless when inspecting a space from a distance. Use a high-intensity light to illuminate dark spots around eaves and gables. If a hole exists, it will remain dark when a light shines on it. If the building surface is intact, light will reflect back to you.
  2. A telescoping mirror can be made from a stainless steel plate or traditional glass mirror (Figure 1). This tool is essential for looking around corners and above fireplace dampers. Learn how to shine a light into the mirror to illuminate your target.
Figure 1. Inspection mirror. Photo by Wildlife Control Supplies, LLC.
  1. Safety equipment, including respirators, gloves, and goggles.
  2. Ladders and ladder hooks (also known as ridge hooks).
  3. Binoculars, preferably 8-power with a 30° or greater field of vision.
  4. Multi-purpose tool such as a Leatherman™.
  5. Extension painter’s pole at least 10 feet long.

Recommended Equipment

  1. Basic tools, such as a power drill and drill bits, claw hammer, chisel, screwdrivers, ratchet, adjustable wrench, hex-wrenches, pliers, and vice-grips are useful during an inspection.
  2. A digital camera with a minimum of 3 megapixels, self-contained lens cover, 3x optical zoom, built in flash, macro mode, neck or wrist lanyard, and small enough to fit in a shirt pocket (Figure 2) is important for documenting inspections.
  3. Fiber-optic scopes provide an easy way to investigate walls and crevices (Figure 3).
  4. Fiber-optic scopes provide an easy way to investigate walls and crevices (Figure 3).
  5. A stethoscope can be helpful in identifying the location of sounds within a wall.

Figure 2. Pocket-sized digital camera.
Photo by Stephen M. Vantassel.

Figure 3. Fiber-optic scope.
Photo courtesy of Wildlife Control Supplies, LLC.

  1. Magnifying glasses with 5-power lenses help in the identification of small sign.
  2. Black lights are helpful on difficult mouse jobs when used with fluorescing, non-toxic, tracking powder.

The Inspection Process


We encounter many distractions that prevent us from observing, or REALLY looking at something. Critical observation, the kind necessary for WDM inspections, requires you to focus on a single spot at a time. Peripheral or broad vision simply is not enough. Narrow your focus to see cracks, crevices, holes, and changes in the color of a surface. This may take extra effort, but you must make the process second nature early in your career.
Fortunately, to enter a structure most wildlife use openings that are large enough to see easily. In fact, the animals you will be required to control cannot enter a gap smaller than 1/8-inch, with the exception of small snakes.
We emphasize the size of the hole because it is one of the best signs for identifying a problem animal. While tracks and scat are helpful, they usually are not available in urban settings. Furthermore, tracks are difficult to read on compacted soils and asphalt.
Keep the following sizes of holes in mind as you inspect a structure:

  1. pencil-width for mice, bats, voles (Figure 4);
  2. golf ball-sized for rats, flying squirrels, red squirrels, chipmunks;
  3. baseball-sized for gray and fox squirrels; and
  4. grapefruit-sized for raccoons.
Figure 4. Bats require only a 3/8-inch gap to enter a structure (as shown in circle). Photo by Erin Bauer.

Step 1 – Pre-inspection

An inspection begins before you reach the location. Collect as much information as possible from the initial call without overburdening the client. Ask the following questions both to avoid making a second trip and to ensure that you have the right tools on the truck.
Pre-Inspection Questions

  1. What is the nature of the problem?
  2. Does the client know what animal is causing the problem?
  3. How long has the problem been occurring?
  4. How severe is the problem?
  5. Where is the problem? Is it in the attic, yard, basement, or wall?
  6. Can the problem be observed from the ground or will a ladder be needed?
  7. What time of day does the problem occur?
  8. Did the problem start with bad weather?
  9. Has the client taken any actions to resolve the problem? What were those actions?

When setting up the appointment, ask the client to ensure that access is available to areas of the house that likely will need to be investigated. For example, attic problems require the homeowner to ensure that the hatchway is clear for you to enter.

Step 2 – Site Visit

Inspections should begin from outside the building. Generally, it is easier to identify access points for wildlife from the exterior, and your control efforts usually are done from the outside. Avoid setting traps inside a building because you become dependent on the schedule of the client. Wildlife problems typically are better dealt with outdoors.

  1. As you approach the location, consider the neighborhood and the habitat it contains. What are the ages of the buildings?
    Are buildings in good repair?
    Is the neighborhood tidy and neat?
  2. Observe the home. Is it in good repair? Are tree branches hanging over the building (Figure 5)? Are the gutters clean (Figure 6)?

Figure 5. Tree branches near a roof line provide easy access for wildlife. Photo by Stephen M. Vantassel.

Figure 6. Vegetation in gutters suggest the home could be maintained better. Photo by Stephen M. Vantassel.

  1. What shelter and sources of food for wildlife can you identify (Figure 7)?
Figure 7. Squirrel feeders provide food for wildlife. Photo by Stephen M. Vantassel.

Exterior Inspections

Stand far enough from the structure so you can see the roof line. Observe all vents, chimneys, and other structures on the roof (Figure 8). Animals typically enter where a break has occurred in the underlying structural materials. For example, squirrels are more likely to chew at the junction of two boards than in the middle of a single board.

Figure 8. Sites on a house that wildlife typically use to enter structures. Image by Stephen M. Vantassel.

Look at the gutter line. If you can see the fascia board behind it, the gutter inspection is simple. Otherwise, try to inspect it from below. Use binoculars if necessary.
If you cannot see the fascia boards from the ground (Figure 9), use a ladder.
Figure 9. The snow and canopy prevented observation of this gap in the fascia board from the ground.
Photo by Stephen M. Vantassel.

Inspect the roof line.
Ridge vents (Figure 10), eaves, and gables are vulnerable to entry by animals.
Figure 10. End caps often are missing on ridge vents. Photo by Stephen M. Vantassel.

Check vents (Figures 11 and 12).
Figure 11. A vent bent by a raccoon.
Photo by Stephen M. Vantassel.

Figure 12. Stove vent filled with nesting material.
Photo by Stephen M. Vantassel.

Inspect window wells (Figure 13).
Figure 13. Window wells can become pit traps for wildlife. Photo by Stephen M. Vantassel.

The Chimney Inspection

Chimneys are a special concern because clients may believe their chimney is capped, so wildlife cannot enter (Figure 14). In reality, the chimney may have no cap, or the cap could be damaged, allowing wildlife to enter. Vents also need careful inspection to ensure that the mosquito netting or window screen is intact.
The presence of mice only can be confirmed through an internal inspection. Generally, if you perform a quality inspection and do not note anything, the culprits are flying squirrels or mice.

Figure 14. Chimney with two open flues.
Photo by Stephen M. Vantassel.


Always check to see if the chimney needs a cap. Flat screens or other devices over the top are a fire hazard (Figure 15); advise the client to upgrade the cap.

Figure 15. A milk crate placed over a flue tile does NOT meet fire code standards. Photo by Stephen Vantassel.

Typically, chimneys do not need to be thoroughly inspected from the inside unless the client complains of noises coming from the chimney, or you are dealing with raccoons. A typical chimney includes several structures that wildlife use (Figure 16). Feces on the roof and dark smudges on corners of the structure or the downspout are clues that raccoons are present.
Wildlife may enter double-walled metal flues (Figure 17) from one of two entry points. They may enter the main flue and drop down to the damper where they can be released if someone rescues them in time. If an animal falls between the external and internal cylinder, the only way to release it is by opening up the wall surrounding the flue and removing the animal (a service for which most clients are not willing to pay). One animal is unlikely to be a threat. If animals continue to fall in, however, carcasses may obstruct the air flow needed to keep the exterior pipe cool. Over time, the increased heat could lead to a fire.
Figure 16. Cross-section of a chimney. Image by UNL.

Steps for Chimney Inspection
and Animal Removal

  1. Inspect flues from the top. Use caution, particularly when a ladder is needed to reach the top of the chimney, as the chimney may collapse under your weight. Shine a light down each flue, looking for broken cobwebs, smudge marks, and the eye shine of animals. Listen for sounds.
Figure 17. Double-walled, metal flue chimney.
Photo by Stephen M. Vantassel.
  1. If your findings are inconclusive, inspect the chimney from the damper. Use extreme caution, as the animal may escape and damage property. You will need a respirator, eye protection, gloves, a clean drop cloth, flashlight, propane torch, lighter, inspection mirror, hand net, snake tongs, trash bag (large enough to place the trap inside), and suitable sized cage.
  2. Before opening the damper, seal off as many portions of the house as possible, including closet doors. Have the client remove valuable and fragile items.
  3. Spread the drop cloth, put on safety equipment, and light the propane torch.
  4. Allow the heat of the torch to go up the chimney. Listen for stirring. The purpose of the torch is to create an updraft. Do not allow the flame to get within 1 foot of the damper.
  5. Open the damper approximately 1 inch. Look and listen for movement and sign to help you identify the culprit:
    • squirrels may “chrrr” or bark,
    • raccoons may chatter,
    • birds may flutter, and
    • all may scratch.
  6. If you still are unsure, open the damper another inch, or to its next setting. At this point, you should have enough room to use your mirror to look behind the damper and up the flue.
  7. You should be able to determine what the animal is, if one is present.
    • If it is any bird other than a chimney swift, it will need to be rescued. Use your gloved hands or a net. Be careful of raptor claws.
    • Squirrels should be trapped. Open the flue wide, set a baited trap inside the fireplace, and seal off the opening so the squirrel cannot escape.
    • Young raccoons can be removed with gloved hands after the mother has been secured. Typically, you will have to remove the damper.

Interior Inspections

Effective interior inspections include looking at unfinished portions of the home. Attics, crawls spaces, and utility rooms should be the main focus.


  1. Wear PPE and practice safe attic entry.
  2. With a spotlight, look along the eave line. Check the vents for mosquito netting or window screen. Is the material intact?
  3. Look at the insulation. Do you notice droppings? Are some areas disturbed? Are there trails where the insulation has been packed down? Remove some insulation to reveal the ceiling and check for droppings.
  4. Does light enter the attic? Light could indicate holes where wildlife might enter.

Crawl Spaces

  1. Wear PPE and practice safe entry.
  2. With a bright light, look along the sill plate.
  3. Look at the insulation. Do you notice droppings? Are some areas disturbed?
  4. Inspect stored boxes and materials. Are they damaged?
  5. Turn off your light. Is any light entering the space?


  1. Wear PPE and practice safe entry.
  2. With a bright light, look along the sill plate. You may need a ladder.
  3. If you can see insulation (Figure 18), do you notice droppings? Are some areas disturbed?
  4. Inspect stored boxes and materials. Are they damaged?
  5. Look above ceiling tiles for droppings, acorns, seeds, and other signs of wildlife.
  6. Pay special attention to areas that are remote, or near sources of heat or water.

Figure 18. Check along the sill plate and insulation for signs of animal activity. Photo by Jan Hygnstrom.

Mystery Situations

Sometimes you will not be able to identify the source of the problem. Select from the following techniques that are most suitable for your situation.

  1. Set a cage trap with bait that is attractive to a wide range of species.
  2. Create a track trap with nontoxic tracking powder or talc. Protect a track trap from the elements by covering it with a board, sheet of plastic, or a bait station.
  3. Plug questionable openings with newspaper. Newspaper is easy for most animals to remove, except for bats and bees. NEVER secure a hole (with a board, wire mesh, plaster, etc.) unless you are certain it no longer is being used. If the paper is undisturbed for 5 days in good weather conditions, you can be reasonably certain the opening no longer is being used.
  4. Install a trail camera that can take photos in the dark when a motion sensor is triggered.
  5. Ask the client to monitor the situation.