Introduction to Methods

Overall learning objectives for this chapter

  1. Understand the best practices approach to solving wildlife conflicts.
  2. Know how to interview people and inspect sites to figure out what caused the problem.
  3. Describe the different management options available to your customers.
  4. Be familiar with the techniques used to remove wildlife from buildings and outdoor areas.
  5. Identify the different euthanasia methods, and
    know when and why you might use each one.
  6. Understand how to prevent wildlife damage.
  7. Know why it’s important to evaluate your practices, and what you can gain from this effort.


Learning objectives

5.1         List the five steps involved in the best practices approach to solving wildlife conflicts.

5.2         Give one example of why it’s crucial to properly identify which species is causing the problem.

The best practices approach to solving a wildlife damage problem includes five steps:

  1. Assess the situation
  2. Choose management options
  3. Do it (tools and techniques)
  4. Prevent future problems
  5. Evaluate success

As a wildlife professional, we hope you’ll help your customers understand that they can protect their homes and businesses from wildlife damage without banishing all wildlife from the community. Whenever possible, use best practices and encourage your customers to solve their problems for good—not just temporarily.

Remember, in chapters one and two, we described a best practice as an effective method for solving a nuisance wildlife problem that also minimizes risks to the environment and our health and well-being. This decision-making strategy balances concerns about safety; the humane treatment of wildlife; practicality; landowner rights; the protection of wildlife popula­tions and habitats; and ethical, legal, financial, and aesthetic issues. Often, the most effective long-term solution involves the use of several best practices, such as a combination of removal and exclusion.

This manual focuses on best practices but in some circumstances, legal techniques that aren’t described in this manual may be appropriate. For example, in an emergency, the need to ensure safety may be so pressing that a technique which doesn’t satisfy all of the criteria well enough to rate as a “best practice” is considered the best choice for that situation. That’s one of the strengths of the best practices approach: it’s flexible and offers many options.

Some methods that seem questionable today could be perfected and achieve the status not only of best practice, but also become standard operating procedure. For that reason, we have included discussion of some practices that have not yet been well-researched, but seem promising. If you’re won­dering about the merits of a tool or technique, seek information from a trustworthy and current source. (Again, you may wish to check the online version of this manual at

Now, with your understanding of the best practices decision-making strategy, and the legal and safety issues you may confront on the job, we’re ready for the details, the tools and techniques that form best practices. This is when you get to play detective: investigating the situation, and then using your expertise to solve the puzzle.

Sounds like a lot of trouble! Is it worth it? Yes. Here’s a real-life example that shows why. In one case, night herons were raiding a fish hatchery. Researchers wanted to know if they could fake out the birds, so they played a tape of a propane cannon explosion to drive them off (that’s much easier than using the real thing). But six nights later, the birds were used to the noise and settled back down to their dinner. Then the scientists tried a recording of night heron distress calls. Bingo! More than 80% of the herons left the pond, and six months later, this technique still worked. Here’s the crucial bit: most birds only react to distress calls from their own species. So if the researchers hadn’t bothered to properly identify who was causing the damage, they might have used the wrong sounds.

Maybe you don’t handle agricultural problems, but don’t worry, you’ll encounter many cases of mistaken identity. Some customers may confuse raccoons for badgers (which aren’t even found in New York), woodchucks for muskrats, or moles for voles. Is it a young Norway rat or an adult house mouse? The techniques used to deal with those animals differ. Proper identification is the first step to identifying the source of the problem.

Resist the temptation to jump to conclusions, too. Just because an animal is seen at the “scene of the crime” doesn’t mean it’s the culprit. For example, turkeys are sometimes blamed for crop damage that was actually caused by raccoons. Why? Turkeys are active during the day, so people are more likely to notice them in the fields. Raccoons are primarily nocturnal so fewer people are aware of their activities.

A note about this chapter’s organization. It’s long and there’s a lot of important information, so we’ve broken it into five sections, to match the five steps of the best practices approach.

Higher, deeper, further…· Start your own “wildlife: who is it?” file, for those species that customers often misidentify, such as moles and voles. Jot down a few quick questions you could ask over the phone to help identify the species correctly.


Before you move on to the next section, you may wish to review the learning objectives for this section:

5.1         List the five steps involved in the best practices approach to solving wildlife conflicts.

5.2         Give one example of why it’s crucial to properly identify which species is causing the problem.

Review questions

  1. Your customer believes there are rats in their apartment. You find smudge marks on the wall and dry, hard droppings that crumble when you touch them. The table lamp’s wire is frayed. You want to put down nontoxic tracking powder to determine if there’s still an infestation, and if so, whether it’s rats or mice. This upsets your customer, who wants you to put down traps immediately. How do you explain your strategy?
  2. My traps are expensive, so I don’t take them out unless I’m sure they’re needed.
  3. To do the best job for you, I have to be sure whether it’s rats or mice because the techniques for catching them are different. For example, I’d use a smaller trap for mice.
  4. I charge more for rats so I’d need to know before I write up the contract.
  5. I’m writing a book and need a good photograph of rat tracks. Do you mind?
  6. Pick the 5 steps involved in the best practices approach to solving wildlife conflicts:

___ assess the situation

___ order pizza for your crew

___ take photos of the whole site for your records

___ choose management options

___ do it (use those tools and techniques)

___ clean-up all the signs of the animal’s presence

___ kill the animals

___ prevent future problems

___ evaluate your success


  • b (In addition to using a bigger trap to catch rats, you also need to pre-bait because rats are afraid of new objects. Mice are curious and will investigate traps).
  • The five steps to best practices for nuisance wildlife control are: assess the situation; choose management options; do it (use those tools and techniques); prevent future problems; and evaluate your success.


Learning objectives

5.3         Describe two benefits of doing a thorough inspection.

5.4         Give an example of a question you’d ask to figure out whether a problem was caused by a raccoon or a squirrel.

5.5         Describe four kinds of animal sign that you’d look for during an inspection.

5.6         Your knowledge of wildlife habits helps you estimate how many nuisance individuals may be present— before you even get to the site. Describe two biological facts that led you to this conclusion.

5.7         You’ve just noticed something that’s going to change the way you deal with this situation. What was it?

The very first thing you need to do is find the source of the customer’s problem. That means you’ll need to understand the type of damage and how bad it is. You have to identify the culprit. You’ll look for clues that will help you figure out what attracted the nuisance animals to the site. (Remember the two key enticements, food and shelter).

Wild animals usually provide numerous 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.

Best practices for solving a wildlife problem, step-by-step

  • interview
  • inspection
  1. Choose management options
  2. Do it (tools and techniques)
  3. Prevent future problems
  4. Evaluate success


  • Visual sighting. This is one of the easiest ways to identify the species (if you can trust the observer). You may also find carcasses. If nocturnal animals are often seen during the day, this may mean that the animal has young and is feeding more often, or that the local population is high, especially with rats and mice. If dealing with a bat colony, you may quickly identify the species but have a harder time locating the entry holes. You can use this to your advantage. Stand outdoors at dusk or dawn, and watch where the bats enter or leave the building. There’s the hole!
  • Various squeaks, growls, cries, hisses, chitters, 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.
  • You may smell the droppings, fermenting 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 can also be told by their odor. Dens of other animals, including raccoons, have their own perfume.
  • 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 soft in texture, while old ones are dry, lighter in color, and hard. Old droppings crumble easily.


You’ll often see a pile of bat droppings under the main entry hole

Urine. You can see rodent urine using an ultra­violet light—it glows blue-white. Unfortunately, other materials also do this, which can be confusing until you become familiar with the typical back­ground fluorescence of a home or office. You may also notice discoloration on building materials, of­ten in attics or crawl spaces. That’s 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 can sometimes be found when cleaning garages, attics, basements, closets, and other storage places. Rats, squirrels, and other rodents often store food in attics.

Top: Notice the urine stains on the chimney (from bats).

Bottom: Animals often gain entry under the eaves, as did a squirrel in this home.

Burrows. Woodchucks, chipmunks, moles, voles, and Norway rats burrow, and 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.” You’ll sometimes 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, you’ll often find a fair amount of prey remains, such as rabbit fur, near the den of a fox or coyote. If there’s no sign of prey, then you’re prob­ably dealing with a herbivore, such as a woodchuck.

Runs. Smooth or worn trails may be found 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.

The smudge on this wall and the slight depression in the ground where an animal has squeezed under the shed. It’s important to locate the animal’s travel routes and find the place where it enters the building. If you’re going to remove the animal, those are among the best places to set a trap. In many cases, when you’re done with the job, you’ll block that entry hole to make sure animals can’t get back into the building.

Tracks and claw marks. Footprints, tail marks, and wing prints may be found in dusty surfaces, sand, soft soil, and in snow. If the surface doesn’t show tracks well, you can sprinkle nontoxic tracking dust (such as chalk powder, flour, or unscented talc) in a likely area, then return later to see if there are any 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’re sure you’ve properly identified the species).

A raccoon climbed this pipe to gain entry to the attic. See the marks?

Buildings are vulnerable at their joints. Check carefully for smudges that show an animal’s been going in and out.

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 this sign. To improve your identification skills, consider making some hair sample charts. Clip a tuft of hair from a nuisance animal you’ve dispatched, and attach it to the chart with the species identified.

  • Gnawing (wood chips, tooth marks, holes, shredded fabrics, frayed wires). Look for evidence of chewing wherever wildlife might try to enlarge a crack or enter something. Wood chips may be seen near baseboards, doors, basement windows, kitchen cabinets, furniture, and stored materials. You could find shredded clothing, or see toothmarks on pipes. Rodents and raccoons often chew on the insulation around wires. The size of the toothmarks (or of a hole chewed in a baseboard) will frequently help you tell whether you’re dealing with rats, squirrels, or mice.

  • Smudge marks are often seen in the animal’s run where it rubs against a surface during its travels, leaving behind dirt and oil from their fur. Look on pipes, beams, against walls, and on the out­side edges of holes.

  • Entry sites (holes, cracks, loose siding). The location, size, and condition of the entry sites are important clues to the species involved.

A squirrel, trapped in a basement, tried to chew its way out. It tried to squeeze underneath the door that led to the basement, gnawing and scratching at the bottom of the door and the rug. See the bits of wood and shredded fabric?

A squirrel chewed on the window in the basement, hoping to escape that way. The squirrel chewed most of the mullions down to bare wood. See the bits of wood on the ledge?

Pets become excited. When cats or dogs hear or smell rodents in some inaccessible spaces such as a wall, they may become enormously interested, whining, sniffing, and scratching at the spot.

Access routes. Walk around outside and try to imagine the route the animal might have used to gain entrance to the building. Are there trees or utility lines near the roof? Could it 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.

Your knowledge of the habitat preferences and behavior of wildlife will help you estimate how many animals might be present. For example, if your customer complains of noises in the attic in March, you’re probably expecting to find squirrels, and not just one—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. So if it’s the breeding season for that species, assume that young may be present. And be careful, because individual animals may give birth outside of the textbook breeding season.)

Other aspects of the animal’s lifestyle that help you answer the question, “how many?” include its social habits (generally found alone, or in a group?), daily movements, and whether or not it hibernates or migrates. 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?

But you’re more than a wildlife detective. 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. Maybe not a big problem. But once nearby, they may run across the roof and find a hole that gives them access to the attic. Perhaps they decide that’s an ideal place to raise their young. To solve this conflict, you’ll probably need to remove the food source and repair the building.

There are other things you need to know about your customers before you choose a strategy, such as whether or not there are any pets roaming freely in the area. So, Sherlock, how do you proceed? Most NWCOs interview their customers and inspect the premises to look for clues.

Here are the questions you’ll hope to answer with clues gained from the interview and the inspection:

  • Which wildlife species is causing the problem? Is there more than one species involved?
  • How many individual animals might be present?
  • Could there be young 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 would 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’s likely to happen again and again?
  • Given the location of the site, are there any local laws that would affect your management options?
  • In addition to this problem, do you see signs that could predict future problems?


First, it’s 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. That could trigger other questions that might guide your inspection.

You’ll develop your own interviewing style, but here are some questions to probe for specific information. Ask the customer, when did you first notice this problem? How often does it happen? Did you see any animals or any signs of animals? You might want to prompt them, by asking whether they’ve heard noises, for example. Then be sure to find out if the noises are heard during the day or at night. Can they locate the noise? You may want to ask several questions about the noises they’re hearing, because sometimes people mistake mechanical sounds such as the beeping of a smoke alarm that has 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?

There are also a few important questions to ask about the household. Are there any children or pets present? That might limit which wildlife control techniques you choose. Did anyone have any direct contact with the wild animal? What about pets? This is especially important if dealing with bats, raccoons, and skunks, the species in our area that are most likely to carry rabies. If there’s been contact, you’ll have to follow health department guidelines. That’s the law.


Before you can confirm the problem and contemplate solutions, you’ll usually need to inspect the property. Take a good look at the whole landscape, and the neighborhood. This is the big picture that could explain why the problem developed. With the added information from an inspection, an experienced observer can provide management options for problems associated with uninvited animal guests.

Follow appropriate safety precautions throughout the inspection. Before you start your inspection, think about the space you’re entering and the typical hazards associated with it. In an attic, you might worry about heat stress; ladder accidents; airborne diseases stirred up from rodent, bat, or bird droppings; and scratches from nails that might expose you to tetanus. Heat stress and airborne diseases are also concerns when entering a crawlspace, but you may not encounter nails or need to use a ladder. (See chapter four).

Find out where the property lines are, and whether the caller owns or rents. If it’s a rental, talk to the property owner or manager to secure permission. (If the renter refused to pay, the managers might not be willing to if they didn’t authorize the work.)

During your inspection, you might focus on the specific problem area but there are some benefits to inspecting the entire building or property. A “problem-specific” inspection takes less time and addresses your customer’s immediate concern, but a more thorough inspection may identify other problems that your customer doesn’t know about. For example, you might be called for raccoons in a chimney and find that the animals have also entered the attic. Or maybe they haven’t made it into the attic, but you suspect it’s only a matter of time because the type of roof vent on this house is very vulnerable to raccoon damage. Rotted soffits, trim, and roofs are also vulnerable to animal entry.

A thorough inspection will also reduce the likelihood of overlooking some aspect of the current wildlife problem. What if there’s more than one species involved? Even if the customer didn’t ask you to look for that, they might not be happy if you missed it.

Detective tools (inspection equipment)

  • good flashlight with extra batteries and bulb
  • small, flat pry-bar
  • stepladder, larger ladder
  • binoculars (useful for tall buildings)
  • mirror, TV camera, or fiber optic scope attached to a long, flexible pole (for viewing hard-to-see areas such as wall voids)
  • ultraviolet light for detecting rodent urine stains
  • digital or instant camera (so you can show your customer exactly what you found)
  • inspection form for recording information
  • identification guides, including those that show animal sign (tracks, scat, nests)
  • plastic bags for collecting animal sign (to show evidence to customers)

“I had a job where a raccoon was living in one of two spaces in the attic of a large house. If I’d limited my inspection to the area where the customers regularly heard the raccoon making noise, I would have missed the actual entry site. This raccoon got into the building through a hole that wasn’t visible from the outside. Then it traveled through a small wall void into the second crawlspace area, where it was most active.”

—Lynn Braband, former NWCO in New York

Take pictures during the inspection, using a digital camera or instant camera so the images are available right away. It’s much easier to explain the situation to your customers if you can show them pictures of the damage, the animal sign, and the entry holes. In fact, you may want to create a photo album that shows structural problems, typical animal damage, manage­ment options, and prevention techniques. That’s a handy resource to keep in the truck. Consider offering fact sheets to customers, too. This could save you time while reducing the odds of misunderstandings. (Make sure the information is reliable! Dependable sources include the state wildlife agency, health department, and Cooperative Extension.)

It’s just as important to take notes during the inspection. Write down your management recommendations, either on the inspection form or the contract. Give the customer a copy of the inspection report and remember to keep one for your­self. Once you’ve reached agreement on the approach, you and your customer may want to sign a contract that clearly describes the work, your fees, and terms of payment. Many NWCOs also collect a deposit at the beginning of a job, although this is usually most practical with private individuals. Different arrangements are often made with corporate accounts.

Another tip that may save you time later is to be systematic as you conduct your inspection. It’s easier to remember whether or not you’ve checked a particular area if you always work in the same pattern. After you’ve done a few inspections, you’ll develop your own style. Here’s an example of a thorough inspection of a building for existing or potential wildlife problems.

Start inside the building at the top and work your way to the bottom. Within each room, move either clock­wise or counterclockwise. Pay special attention to the corners, and spaces underneath and behind furniture. If there are suspended (“dropped”) ceilings, push up the panels in a few places to check above the ceiling.

Inspect attics; basements; the areas underneath sinks; the places where pipes, cables, and wires enter the building; and crawl spaces. Look inside closets and built-in drawers.

Use light to your advantage. During the day, turn off the lights and look for places where the daylight shines through walls and floors. If light can get through, so can some small animals.

Once you’re done with the inside of the building, move outdoors. You can use light to your advantage here, too. At night, turn the lights on, then go outside to see if there are places where the lights shine through the walls or roof. Again, start at the top and work your way down. Use binoculars for a good view of the roof.

What’s the condition of the eaves, dormers, windows, vents, ledges, chimneys, and roof corners? Animals often gain entrance at joints and places where different building materials meet. Give careful attention to the foundation, because that’s a vulnerable area. Check beneath decks, porches, and crawl spaces. Don’t forget the garage; barns; sheds; the places where they store garbage cans; dumpster areas; compost heaps; and piles of firewood, lumber, or junk.

One size does not fit all!

Your chosen strategy for dealing with beavers might change dramatically depending on the site and the needs of the customer.

For example, beavers may not be tolerated at all in a reservoir used to supply the town’s drinking water, while the same level and type of activities might not bother a private landowner. Each nuisance wildlife situation presents different challenges and requires a customized solution.

Higher, deeper, further…

  • Ask a friend to pretend to be one of your customers. Interview your friend about the problem, then inspect the premises and share your advice.
  • Jot down a few questions you might ask customers that would help you identify which animal is causing the damage.
  • Go to a bookstore or library to browse through the latest field guides to animal signs.
  • Visit a zoo or nature center that exhibits some of the animals you might encounter in your job. Spend some time watching them. Close your eyes, and pay attention to the odor. Talk to staff about the species’ habits. How would they know if that critter was present?
  • Start your own wildlife sample charts, to help you identify species by their fur, feathers, or shed skins. You can collect samples from the animals you trap.


Before you answer the review questions, you may wish to think about the learning objectives:

5.3         Describe two benefits of doing a thorough inspection.

5.4         Give an example of a question you’d ask to figure out whether a problem was caused by a raccoon or a squirrel.

5.5         Describe four kinds of animal sign that you’d look for during an inspection.

5.6         Your knowledge of wildlife habits helps you estimate how many nuisance individuals may be present— before you even get to the site. Describe two biological facts that led you to this conclusion.

5.7         You’ve just noticed something that’s going to change the way you deal with this situation. What was it?

Review questions

  1. You’re called to a home to deal with a rodent problem. Your customer has three dogs and a toddler. That makes you think:
    1. No wonder the place smells
    2. I should attach the mouse traps to beams, where the dogs and the child can’t reach them
    3. Why aren’t these lazy dogs taking care of the mice?
    4. I could set out live traps, which would be safer for the kid
    5. Answers “b” and “d” correct
    6. Answers “b,” “c” and “d” correct
  2. When you first talk to your customer to gain information about the nature of the wildlife conflict, you might ask:
    1. “What can you tell me about this problem?” and “Why didn’t you call earlier?”
    2. “What’s going on?” and “Can you pay for this?”
    3. “What have you seen and heard?” and “When do you notice the problem?”
    4. Very little, because they always lie
  3. There’s a noise in the dropped ceiling. Your customer’s not sure what it is, but you know it could be a rodent or a bird. Your truck is packed tight, so you want to make sure you bring the right equipment for the job. What question do you ask her?
    1. When do you hear the noises, during the day or at night?
    2. How loud is it?
    3. Where are the noises coming from?
    4. You mind if I leave this skunk in your driveway while I finish up my route? That would make it easier for me to fit everything into my truck without going back to the office.
  4. Your customer just bought an old house. They’ve been told there’s a bat or two in the attic, but they were too scared to check. They want to know how many are up there, and have them removed before they move into the house, which they’re planning to do the first week in July. Because you’re the wildlife Sherlock Holmes, you tell your customer you’d be glad to help, but:
    1. This time of year, there’s a good chance there’s more than one or two bats in the attic. There could be a whole colony of females raising their young.
    2. You can start now, and make sure that the bats can’t get from the attic into the living spaces. But you’d like to let this batch of young leave on their own, which they’ll do by mid-August. Once they’re gone, you can finish bat-proofing the house.
    3. The bat’s probably long gone. Don’t worry about it. You’ll never go into the attic, anyway.
    4. Answers “a” and “b” are correct.
  5. You think there’s a mammal in the office. While inspecting the kitchen, you’d look for these signs

(check all that apply):

___ gnaw marks on the cabinets

___ droppings in drawers and by the kickboards

___ smudge marks on the baseboards

___ urine stains on walls and woodwork

___ holes chewed in cereal boxes and other stored foods

___ burrows

___ piles of nuts and seeds in a cabinet that’s not used often

___ odors

___ fur

___ tracks

___ noise

___ the creature

___ pets scratching at a wall

___ livestock remains

___ broken egg shells

___ nest

___ crop damage


  1. e
  2. c (these questions will help you identify which species is present. Some of the questions address reasonable concerns, but in a tactless manner.)
  3. a (rodents and birds might be active in some of the same places. Most birds are diurnal. All of the ones most likely to cause problems in homes are. Rodents may be active at night, too).
  4. d
  5. Most of these signs are made by rodents, except for livestock remains, broken egg shells, and crop damage, which you wouldn’t expect to see in a kitchen. Rats do burrow, but usually outside.