Site and Damage Inspection

Module 4      Site Inspection

Learning Objectives

Terms to Know


Gathering Information

Signs of Wildlife Presence

Discuss the problem with the client 

Site Inspection

The Inspection Process

Interior Inspections

Learning Objectives

  1. Describe the steps in the inspection process.
  2. List the tools needed to inspect a site.
  3. Explain the relationship between prevention and maintenance.
  4. List questions to ask the client to obtain needed information.

Terms to Know

Inspection The process of identifying the location of animal damage and animal entry points.

Damage Identification  The process of identify the type of wildlife damage and quantifying the extent of the damage and number of animals involved.

Damper   The metal plate that controls the size of the opening between a fireplace and chimney.

Sill plate   A horizontal (usually wood) member anchored to a foundation in a building. It secures the wall to the foundation.


Wildlife management is often thought of in terms of protecting, enhancing, and nurturing wildlife populations and the habitat needed for their well-being. However, many species at one time or another require management actions to reduce conflicts with people or with other wildlife species. The objective is to identify and quantify the wildlife damage and locate the animals.

Identifying damage from wildlife is an important skill in resolving human-wildlife conflicts. Sometimes it is easy to identify the wildlife species and even its location, many times it’s not. A thorough site inspection is the foundation of an effective WDM approach to control and mitigate wildlife damage from all wildlife species. This module focuses on structural site inspection; homes, out buildings, barns, and small commercial buildings. Farm animal predation and crop damage inspections require similar investigative skills with the focus on minimizing crop damage and protecting farm animals from predators. Take the time to investigate every wildlife damage complaint thoroughly with a focus on damage prevention and damage management.

Survey the property to find the location and identify the species that is causing the customer a problem. You need to understand the type (chewing, digging, feces, parasites) and the extent (one, many, or major infestation) of the damage and you must identify the problem animal(s) in order to create a solution. Look for clues that will help you figure out what attracted the problem animal(s) to the site. Animals are attracted to food, water, and shelter, and if you can take these away and exclude future animals, then you may solve the conflicts.

Gathering Information

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 one 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 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? What about animals coming from neighboring properties?

You are more than a wildlife detective, however. You must also look 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 (habitat modification) and repair the building (exclusion). Sometimes you will have to install a one-way door or trap the squirrel.

You may have to pose multiple solutions to your customers so they can choose the one that works for them. For example, do they let pets roam freely in the area? Are garbage containers tightly secured? What non-target animals are around? What behavior patterns will have to change? Traps and toxicants can be dangerous.

How do you proceed? Most WCOs interview their customers and inspect the premises to look for clues.

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 frequently are seen 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 is in the Bat species section of this manual.

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.

Nests and 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 an 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 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.

Fence lines. Walk the fence lines and look for damage or openings in the fence that can allow animals to enter. Sometimes trees can create access routes for animals. Check to make certain the fence goes all the way to the ground and that there are not depressions under the fence that allow small animals to pass.

The following questions will help you formulate a solution while you perform your inspection.

  • Which wildlife species is causing the problem?
  • Is more than one species involved?
  • How many individual 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, and any non-target species?
  • Can you capture 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 building or firearms laws that would affect your management options?
  • Do you see any signs that could predict future problems?

Discuss the problem with the client

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.

Site Inspection

Site and damage inspections need to answer the following questions.

  • What is the extent of wildlife damage?
  • What species is involved?
  • What control measures will be required?
  • What is the long-term solution?

Take the time to look for wildlife damage and signs of the animals that caused the damage. Shortcuts can result in poor inspections, cause additional expenses, and can undermine your customer’s confidence in your ability to diagnose and solve the problem.

Identifying damage locations in buildings and the signs of animals takes equipment, persistence, and knowledge of building structures and wildlife habitat.

Wildlife damage inspections can challenge WCOs and their equipment. Professional operators may work in all types of weather conditions such as hot, cold, rain, snow, and ice and need the clothing and equipment to do the job in the field. It takes time to conduct a thorough inspection, so plan on the current environmental conditions. Work until you find the damage, identify the species, and propose a solution to the problem. Help the client understand that finding and capturing the animal may take time.

An inspection is a process that never really ends as you must monitor the solution. The inspection outlines the extent of wildlife damage, the species, and the behavior of the problem animal. While many jobs may appear to be routine, make sure your solution fits the problem. Wildlife are intelligent and adaptive so assume things may change with each job. Observe the details, correlate them with your past experience, and propose a solution.

Site Inspection Equipment – Essentials

  1. Safety equipment, including respirators, gloves, and goggles.
  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. Ladders and ladder hooks (also known as ridge hooks).
  2. High-intensity spotlights. 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.
  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 can be useful during an inspection requiring access to portions of the building structure.

Figure 2. Pocket-sized digital cameras or Smart-Phones are useful. Photo by Jan Hygnstrom.

  1. A digital camera with a neck or wrist lanyard, and small enough to fit in a shirt pocket (Figure 2) is important for documenting inspections. A smart-phone may be sufficient, although a lanyard is helpful so you don’t drop it from a roof while taking a photo.
  1. Fiber-optic scopes provide an easy way to investigate walls and crevices (Figure 3).
  2. A stethoscope can be helpful in identifying the location of sounds within a wall.
  3. Magnifying glasses with 5-power lenses help in the identification of small sign.
  4. Black lights are helpful on difficult mouse jobs when used with fluorescing, non-toxic, tracking powder.

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

The Inspection Process

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.

When setting up an appointment for the inspection, ask the client to ensure that access is available to areas of the house that may need to be investigated. Attics and basements may need to be decluttered for you to do your work.

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? If so, what were those actions?

We encounter many distractions that prevent us from observing or focusing our attention on the details around us. Critical observation, the kind necessary for WDM inspections, requires you to focus on the details of a building structure. Peripheral or broad vision simply is not enough. Narrow your focus to see cracks, crevices, holes, and changes in the color of a surface.

Look for obvious gaps in the building envelope as animals you may exclude cannot pass through a gap smaller than 1/8-inch, with the exception of small snakes and insects.

Keep the following sizes of holes in mind as you inspect a structure:

Figure 4. Bats require only a 3/8-inch gap to enter a structure (as shown in circle). Photo by Erin Bauer.

  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. grape-fruit-sized for raccoons.

The size of the hole is important 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 or even see on compacted soils and asphalt.

The presence of mice only can be confirmed through an internal inspection. Generally, if you perform a quality inspection and do not find anything, the culprits are flying squirrels or mice.

Step 2 – Site Visit

Inspections should begin from outside the building. It may be easier to identify access points for wildlife from the exterior, and your exclusion efforts are most often done from the outside. Avoid setting traps inside a building if you do not have access to the building. Habitat modifications and exclusion generally occur outside.

Figure 5. Tree branches near a roof line provide easy access for wildlife. Photo by Jan Hygnstrom.

  1. As you approach the location, consider the neighborhood and the habitat it contains.
    1. What are the ages of the buildings?
    2. Are the buildings in good repair?
    3. Does the neighborhood any brush piles, vegetation, or other types of shelter?
  2. Observe the home. Is it in good repair? Are tree branches hanging over the building (Figure 5)? Are the gutters clean (Figure 6)?
  3. What shelter and sources of food for wildlife can you identify (Figure 7)?

Figure 6. Vegetation in gutters suggest the home could be maintained better. Photo by Jan Hygnstrom.

Figure 7. Bird feeders provide food for many species of wildlife; some may be unwanted. Photo by Jan Hygnstrom.

Exterior Inspections

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

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.

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).Animals will often enter the home through vents or use them as shelter for dens or nests.

Figure 11. A vent damaged by a raccoon. 
Photo by Animal Control Specialists Inc.

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. Here, some species of wildlife could fall between the wood slats that were meant to be a deterrent. Photo by Jan Hygnstrom.

Chimney Inspection

Chimneys are a special concern because they are an entry point for wildlife that may become trapped (Figure 14). Vents need careful inspection to ensure that the mosquito netting or window screen is intact. 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.

Chimneys may not need to be 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.

Figure 14. Chimney with one covered and two open flues. 
Photo by Jan Hygnstrom.

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

Figure 16. Cross-section of a chimney. Image by UNL.

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 17. Double-walled, metal flue chimney. 
Photo by Jan Hygnstrom.

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 reflection of animal eyes. Listen for sounds.
  2. 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.
  3. 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.
  4. Spread the drop cloth, put on safety equipment, and light the propane torch.
  5. 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.
  6. 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.
  7. 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. You should be able to determine what the animal is, if one is present.
  8. 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.
  9. 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.
  10. 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, but focus on attics, crawls spaces, and utility rooms.


  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 cause of the problem during your inspection. 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.

A structural inspection of the home is just one type of site and damage inspection. You may be asked to investigate holes under out-buildings or remove birds’ nests in carports. You may have to walk a fence line to look for breeches in the fence that allow animal entry. Or you may be asked how a predator was able to get into a chicken coup.

The goals of site and damage inspection remain the same. Identify the location and extent of the damage, identify the species causing the problem, and formulate a long-term solution.