Principles of Wildlife Control

Prepared by the National Wildlife Control Training Program. Research-based, wildlife control information.

1  Principles of Wildlife Damage Management

Learning Objectives

  1. Learn when and why an animal becomes a pest.
  2. Learn why wildlife damage management (WDM) is about managing damage from wildlife, and not just the capture and control of wildlife.
  3. Understand the definition of a wildlife control operator.
  4. Explain the differences between biological and cultural carrying capacity, and how each relates to WDM.
  5. Explain the 5 key objectives addressed when applying IWDM methods.
  6. Learn why biological knowledge of wildlife species and habitat is important.
  7. List the major strategies for resolving human-wildlife conflicts.
  8. Learn why considering public attitudes and values towards wildlife is important.
  9. Learn why training makes a wildlife control professional more competent in the field.
  10. Know that wildlife control is highly regulated and that wildlife control professionals contribute to the conservation and management of wildlife species by working closely with state agencies.

Terms to Know

Biological Carrying Capacity   The maximum number of animals of a given population that an environment can sustain.

Cultural carrying capacity (CCC)   The number of animals that a human or human community will tolerate in a given area.

Diversion   Luring animals away from protected sites, usually with a food attractant.

Exclude   To prevent access, such as with the use of fences, netting, or securing holes.

Integrated pest management (IPM)   An environmentally-responsible approach to pest management that involves the timely use of a variety of cost-effective methods to reduce damage to a tolerable level.

Relocation   Moving an animal, but keeping it within its home range.

Repel   To drive away.

Translocation   Moving a nuisance animal from one place to another outside of its home range.

Wildlife and wildlife habitat are important to all of us. Based on the 2016 National Survey of Fishing, Hunting, and Wildlife-Associated Recreation, over 103 million US residents fished, hunted, or watched wildlife in 2011. They spent almost $157 billion pursuing these recreational activities. Unfortunately, wildlife can damage property, be a nuisance, and pose threats to human health and safety. Economic losses associated with wildlife damage approach $3 billion annually, demonstrating a clear need for effectively addressing negative impacts. The purpose of this manual is to provide the information needed to help people resolve conflicts with wildlife. Wildlife damage management is a form of wildlife management and conservation and is highly regulated by federal and state laws.

This training manual is designed to help professionals manage wildlife problems by developing solutions based on the principles of integrated pest management (IPM) or Integrated Wildlife Damage Management (IWDM).). The emphasis is on controlling damage and protecting wildlife. Changes to the habitat or modifications to a building may be followed by capture or other control measures.

The training covers the basic skills needed to effectively deal with a variety of wildlife issues. It focuses on wildlife identification, knowledge of wildlife habitat and the skills to modify the habitat or capture, contain and dispatch an animal. Most people can master the techniques required to resolve wildlife conflicts using the methods of wildlife damage management.

Managing, controlling, and capturing wildlife is a highly regulated activity. Whether the conflict with wildlife is simple or complex, your response should follow be professional and ethical. Federal, state, and local laws and regulations must be obeyed. Safety practices should be followed. You will need knowledge of the biology, habitat, signs, and damage caused by various species and you must be an advocate for the wildlife. Be sure to review the species information after the training modules.

This training is important because animal capture, handling, containment and control techniques must be learned, practiced, and mastered. If an animal must be killed or euthanized, then the operator must be skilled in humane dispatch.

Wildlife damage management is founded in the traditions of hunting and trapping. A historical perspective dates back to the days when fur harvesting and the fur markets were dominant and bounty hunters killed wildlife to protect new settlements. Many state and federal regulations regarding the control of certain species are based on hunting and trapping regulations. Protected status, open seasons, legal capture methods, and disposition are all influenced by state hunting and trapping laws, and the conservation predictions of wildlife biologists.

Do not hesitate to contact state and federal wildlife officials if the damage situation is complex or if safety issues exist. If you have concerns about your ability to handle a wildlife problem with appropriate care and diligence, do not hesitate to work with other qualified WCOs.

Many states may require a trapping license to capture wildlife, professional certification and licensing for animal removal, transport, and disposition. The use of regulated toxicants almost always requires a separate pesticide applicator license. or some type of permit for trapping and removal.

wildlife control operator (WCO) is an individual trained to solve problems from wildlife conflicts and nuisance wildlife situations, usually for profit. In some states, a WCO may be called an Animal Damage Control Agent (ADC), Animal Control Agent (ACA) or Wildlife Damage Control Agent (WDCA). Technically, a WCO is a specialist in vertebrate pest management with the ability to capture, transport and dispatch an animal, and repair and prevent the damage from occurring again. In this book we use the term WCO to include all technicians trained in WDM methods.

In today’s urban environment, nuisance wildlife are abundant and wildlife damage management professionals are in demand. State hunting and trapping laws need to be supplemented with nuisance wildlife control laws. The training and skills required to hunt and trap are similar to some of the control methods for WDM such as knowledge of wildlife and its habitat. A different set of skills, however, is also needed to manage wildlife in urban and suburban settings such as building maintenance and public relations.

A wildlife control operator (WCO) is a professional trained to solve problems from wildlife damage and nuisance wildlife situations, usually for profit, and licensed or permitted by the government.

The management of wildlife causing damage has ethical, economic, social, and biological dimensions. Concerns about animal welfare, property damage, safety, species diversity, and habitat destruction pose philosophical questions that must be answered professionally, fairly, and legally. Public awareness, appropriate legal oversight, and research by wildlife professionals are required to make sure that human-wildlife conflicts are managed properly.

People appreciate wildlife and often enjoy seeing animals around. You might ask “what makes an animal a pest?” Animals are protected by the public trust in many cases protected by additional laws, and even when they can be lethally removed, it should be done to resolve an unacceptable amount of damage or risk. It is important to recognize that any animal that may currently be a pest to one or more persons, may at the same time be either desirable, or of neutral value to someone else. There is no such thing as good animals and bad ones. Whether an animal is beneficial, neutral, or undesirable depends entirely upon one’s relationship with it.

Wildlife damage management (WDM)
is the application of methods to resolve conflicts
 from vertebrate species that cause damage, create safety issues, or are considered a nuisance.

Principle 1 – Wildlife are not Pests

Animals are not considered pests until they create a conflict with humans, their habitats and resources, and/or values.

Principle 2 – When Animals become Pests

Animals can be called pests when they cause:

  1. Damage to food, crops, fiber, crops, buildings, vehicles, landscapes, and other natural resources;
  2. Safety issues from wildlife attacks, threats to human health, vehicle and safety issues from diseases, collisions, and
  3. Nuisance from noise, odors, excrement, and other unwanted behaviors.

Wildlife that have unwanted behaviors are deemed pests and can be controlled outside of typical hunting and trapping seasons, sometimes with special permits, by wildlife control operators following all local, state, and federal regulations.

Principle 3 – Prevent Wildlife Damage

The objective of wildlife damage management (IWDM) is to mitigate or prevent the conflicts caused by the animals, and not just the control or elimination of the wildlife itself.

Principle 4 – Objectives of Control

Objectives when applying WDM methods:

  1. Reduce damage to a tolerable level;
  2. Use methods that are low risk for people, non-target animals, and the environment;
  3. Implement control and habitat modifications efficiently and economically;
  4. Use humane and ethical methods when capturing and disposing of wildlife; and
  5. Follow all local, state, and federal laws.

Reduce Damage to a Tolerable Level

Integrated Pest Management (IPM) uses all appropriate pest control strategies to reduce pest populations to an acceptable level. WCOs perform integrated wildlife damage management (IWDM).

Set reasonable goals. Propose a solution that solves the problem. WCOs should avoid creating fear in clients, as this could lead to an overreaction to wildlife on their property. People should accept that there is a difference between a raccoon living in an attic and a raccoon walking through the backyard (Figure 1).

Figure 1. Young raccoons on a deck. Are they a threat? Photo by Steve Stronk.

Be respectful and listen when clients explain their feelings about an animal. Do not reinforce inappropriate stereotypes or become drawn into a “problem” that does not need to be solved. On the other hand, don’t use your clients’ fear of animals just to sell a job. Using the clients fear to sell a job is unethical.

The focus of IWDM is to reduce or eliminate damage, not just reduce the number of animals. Remind your clients that the goal is to solve a specific problem, not remove all the animals in the area. Target only the animals causing the conflict, and not all the animals themselves.

IWDM problem-solving framework

  • Identify the problem species and damage.
  • Consider a variety of solutions.
  • Implement the least harmful, most cost-effective strategies first.
  • Monitor the problem to ensure that it has been solved.
  • Evaluate the effectiveness of the solution.

Use Cost-effective Methods

If the expense of resolving a problem is more than the cost of the problem itself, it may not be practical to control the animal causing the damage. On the other hand, a $250 stainless-steel chimney cap may seem expensive, but when a client understands that the chimney cap will protect a chimney from animal entry for decades, the cost may be reasonable. If the cap lasts 20 years, the annual cost of the cap is just $12.50. Thus, a chimney cap provides a long-term, inexpensive, and permanent solution, and provides clients with a tested method for excluding wildlife from chimneys.

Use Safe Methods

People dealing with wildlife damage may be under stress, which could lead them to encourage the use of hazardous or illegal techniques. Just because a technique or method works does not mean it should be used. For example, mixing strychnine with cat food or putting out a bowl of radiator antifreeze may be effective in killing opossums and raccoons. These techniques, however, are irresponsible and illegal. Poisoning non-target animals can result in unnecessary suffering. Recommend only the techniques that are most appropriate, effective, legal, and safe for resolving the problem.

Use humane and ethical methods

Wild animals are part of the public trust and need to be treated with respect. People want to control damage from animals, not kill and hurt animals by neglect and inhumane dispatch methods.

Follow all local, state, and federal laws

Wildlife control is regulated in most states. If there are no permitting requirements for WCOs, there are still hunting and trapping laws. WCOs must make every effort to follow government laws and regulations.

If a client requests something beyond what you know to be legal, ethical, or safe, you should suggest more reasonable alternatives, or consider declining the job.

Principle 5 – Be Knowledgeable of Damage

People conducting IWDM need to be knowledgeable of both the animals and the associated damage that they may cause, and have the ability to:

  1. Identify common wildlife species;
  2. Identify the damage caused by wildlife, and which species is responsible;
  3. Be aware of the variation in damage in agricultural, urban, and suburban environments; and
  4. Know the different problems associated with native vs. introduced wildlife.

Principle 6 – Be knowledgeable of Biology

People conducting IWDM need to be knowledgeable about the biology of wildlife so that they understand basic population dynamics, including carrying capacity and overabundance. A common species does not become overabundant until it creates conflicts with people or runs out of resources.

Knowledge of wildlife basic biology includes:

  1. Litter size and time of reproduction
  2. Behavioral and seasonal characteristics
  3. Typical home range size and habitat use
  4. Common human-wildlife conflicts
  5. Potential of animals to spread diseases


Overabundance occurs when the population of a species of wildlife has exceeded both the biological and cultural carrying capacity. For one reason or another, the environment cannot handle that number of animals. Too much food and shelter may create overabundance.

The biological carrying capacity (BCC) is the number of animals in a population that an environment can sustain without long-term detrimental impacts. For example, when white-tailed deer become overabundant, a browse-line appears on shrubs, trees, and ornamentals. Plants will have few live branches below 6 feet, undergrowth will be dramatically limited, and plant diversity will be reduced due to over-browsing. Eventually, the deer population will decline due to starvation, disease, and competition. Long-term environmental damage will occur long before the deer population declines.

Cultural carrying capacity (CCC) refers to the number of animals in a population that people are willing to tolerate, based on the balance of environmental and social benefits and costs. For example, some people are willing to tolerate a lot of deer damage, and they are influenced by the benefits experienced from viewing and hunting deer. Some people cannot tolerate a single snake or a wild animal in their yard.

Population Dynamics

Problems with wildlife typically are greater when suitable habitat (food, water, and shelter) are available. As the habitat changes, so does the wildlife population. When a client asks, “Why did the animals choose my house and property?” the simple answer is because their home and landscape supplied necessary resources (e.g., food, cover, water, and resting areas). Environmental or behavioral factors eventually will limit animal abundance (Fig. 2).

Figure 2. For many ground-nesting birds, safe nesting sites often are limited. Image by Paul D. Curtis.

However, people’s tolerance may be exceeded long before animal numbers reach levels where environmental or behavioral factors limit population growth.

Wildlife populations are not static. Wildlife populations may fluctuate dramatically, both within and among years. Reasons for the fluctuations vary but the populations usually go up with food, shelter, and good weather. Rodent and other prey populations frequently increase in numbers responding to suitable environmental conditions such as sufficient rainfall and mild winters. As the number of prey animals increases, the number of predators can increase, although usually in the following year. Local wildlife populations may change due to human activity such as residential development, the addition or removal of bird feeders or gardens, and improper trash storage.

Will Predators Solve the Problem?

A common misconception is that wildlife is “out of balance” with nature because humans have removed predators from the system. While it is true that populations of many large predators have been reduced dramatically, it is unlikely that restoring their numbers to pre-settlement levels would solve many human-wildlife conflicts. Often, human tolerance of damage by wildlife is quite low. Homeowners do not want to have fewer squirrels in their attic; they want NO squirrels in their attic. Predators typically do not control populations of prey. If a predator substantially reduces prey populations, the predator would threaten its own existence by eliminating its source of food.

Predator-Prey relationships. Image by NPS.

Even a cat that is skilled at catching mice often cannot control a rodent infestation in a house . In addition, many predators are not selective in their choice of prey, so non-target animals likely will be taken, for example cats may also like to kill non-target birds.

Figure 4. While often recommended, cats are not very effective at controlling rodents. Image in Pixaby.

Principle 7 – Strategies to Resolve Conflicts

IWDM includes many methods to reduce wildlife conflicts. They are generally classified into the following categories:

  • Habitat management and sanitation. Clean up and reduce the carrying capacity of the area, which will reduce the number of animals the habitat can sustain over time. Remove food, water and shelter that attracts animals.
  • Exclude or prevent animals from accessing locations like decks, soffits and vent pipes or garden and crop areas. Use fencing for large agricultural areas and netting for bird control.
  • Repel or divert animals from the area using methods that frightening or are aversive by using sound, visuals display, smell, and by chemical repellents that are sticky or physically noxious.
  • Reduce the number of animals by lethal and non-lethal control methods such as: trapping, shooting or the use of toxicants.
    1. Trapping;
    2. Shooting; and
    3. Chemical methods.
  • Other (e.g., fertility control, biological controls, guard animals, raptors, etc.).

Strategy 1   Habitat Management:
Reduce Biological Carrying Capacity

Remove food, water, or shelter to reduce the biological carrying capacity and thus, the number of animals in an area. For example, if someone is having conflicts with mice, thorough clean up and removal of available food likely will reduce numbers (Figure 5). You could aggressively trap to reduce the population, but mice likely will reproduce faster than your trapping efforts can control them, particularly when plenty of food and shelter are available.

Strategies to Reduce Wildlife Damage

All methods for WDM fall into 4 strategies.

  1. Clean up. Reduce the carrying capacity of the area, which reduces the number of animals the habitat can sustain over time.
  2. Exclude or prevent animals from accessing a location.
  3. Repel or divert animals from the area.
  4. Reduce the number of animals by lethal and non-lethal control methods.

Strategy 1. Clean Up Sites to Reduce Carrying Capacity

Remove food, water, or shelter to reduce the biological carrying capacity and thus, the number of animals in an area. For example, if someone is having conflicts with mice, implementing rigorous clean up and removal of available food likely will reduce mouse numbers (Figure 5). You could aggressively trap to reduce the population, but mice likely will reproduce faster than your trapping efforts can control them, particularly when plenty of food and shelter are available.

Strategy 2. Exclude Animals

Prevent access of animals to potential damage sites and to provide long-term protection from damage. Exclusion techniques include closing entry holes in buildings, installing bird nets over fruit trees, and constructing deer-proof fences around orchards. Development of exclusion techniques and devices is an active area of entrepreneurship, with new and interesting products frequently appearing in the market. Exclusion techniques typically require building skills like those of a carpenter. Tools and craftsmanship play an important role in professional WDM exclusion services. Poor exclusion methods can create problems with clients and the public image of WCOs.

Strategy 3   Repel or Divert Animals

Another IWDM strategy is to repel or divert animals from a location. Repellents are based on pain, fear, touch, or conditioned aversion. Several repellents and frightening devices are available, depending on the problem. Many of these products, however, have not been tested adequately under research conditions and may fail to prevent damage. Most repellents provide short-term control of wildlife conflicts.

Diversion is the process of luring animals away from protected sites, usually with a food attractant. Although this may sound good in theory, few practical applications exist. First, you need to find a food source that is more attractive than what the animal is currently using. Also, by increasing the availability of food, population levels may increase, adding to the potential for damage on the property. The effectiveness of diversion often is questionable. As for repellents, the effectiveness of diversion is almost always is short-term.

Strategy 4   Reduce or Eliminate the Number of Animals in an Area

The number of animals can be lowered using toxicants, trapping, or shooting. Such actions typically lead to a rapid decrease in the population to a level in which they, or their associated damage, can be tolerated. Lethal control alone, however, often fails to reduce long-term damage. As long as suitable habitat and food resources are available, populations may rebound quickly. Well-fed animals often have larger litters and greater success in raising young to maturity. Population reduction sometimes fails because animals often move into an area that has been vacated (Fig. 6).

Figure 6. A problem raccoon can be removed by trapping, but unless openings to an attic or chimney are sealed, another animal may quickly move in and become a problem. Image by Paul D. Curtis.

For example, you may have successfully removed voles from a particular property at a given time. However, your client did not understand that other voles would quickly move in from neighboring properties where you did not have permission to work, and soon occupy the habitat previously used by the voles you removed. Some pest problems need to be managed by multiple property owners in order to provide a lasting solution to the problem.


Once you have captured and animal, you must do something with it. The law forbids WCOs from keeping animals in traps for more than a short time. In many cases, the law does not allow moving the animal to another location.

Translocation” means moving a nuisance animal from one place to another outside of its home range.

Relocation” refers to moving and releasing an animal within its home range. This is sometimes referred to as onsite release and is usually is a short distance away from where it was captured.

Moving animals by translocation is not recommended. Moving animals may spread disease or cause problems in new places.  If an animal must be moved, it should be moved as short a distance as possible. For the best chance of survival, the animal should be released within its home range.

Moving an animal may spread disease or create damage problems in new places. Translocated animals rarely stay in the area of release and often have low survival rates because they cannot find suitable habitat. As a result, these animals often experience a slow and stressful death, as opposed to a quick and humane death administered by a trained NWCO. New York State law prohibits relocating or translocating wildlife, except when animals are removed from inside dwellings or structures and released in the immediate vicinity outside these buildings on the same property. However, licensed NWCOs are allowed to relocate most species of wildlife with written permission of the landowner where the wildlife will be released. NWCOs also must contact the county health department before relocating any rabies vector species (bats, raccoons, or skunks).

Humane Dispatch and Disposal

Humane dispatch refers to humanely terminating an animal’s life, if possible using veterinary approved methods for euthanizing animals. The body must be disposed of safely, legally, and ethically.

Principle 8 – Conflict is Inevitable

Some wildlife species thrive and adapt to urban and suburban environments. We share food, water, and shelter. We invite wildlife into our space. Conflict is inevitable. People performing IWDM provide a valuable service for stakeholders and the community. WCOs play an important role in the conservation and management of wildlife by practicing wildlife damage management.

Whose Home?

Many people believe that wildlife cause damage to property because “humans have taken away their homes” or that urbanization has destroyed their natural habitats. When resources are available, wildlife is abundant and the animals are very comfortable in urban environments. Urban sprawl has reduced habitat for some animals such as forest birds and large predators, but it has created and supplied habitat and food for other more adaptable species such as gulls, raccoons, squirrels, rodents, and deer. Wildlife removal, exclusion work, and wildlife damage management are necessary services.

Principle 9 – Respect Public Attitudes

Peoples’ attitudes about wildlife vary greatly. Many people enjoy seeing wildlife, and species are protected by the public trust. Clients’ wishes should be considered when they are safe, legal, and practical.  All IWDM should be performed humanely, ethically, and as transparently, but discreetly, as possible. Resolve conflicts rather than just remove offending animals.

Principle 10 – Regulation is OK

Licensing and training standards improve the working environment of wildlife control operators by applying consistent standards of professional behavior and knowledge, both legal and practical, of wildlife control methods, as well as standards for humanely dispatching and disposing of wildlife.

Study Questions for Principles of Wildlife Damage Management

Questions for Reflection

  1. Explain why the statement “balance of nature” may be misleading.
  2. A client does not want to modify a bird feeder to reduce rodent access to bird seed. What would you tell the client about the benefits of doing so?
  3. After recommending trench-screening to protect a deck from skunks, your client expresses resistance over the price. How would you help the client appreciate the value of the exclusion?
  4. You have had difficulty in removing muskrats from a pond. The client, angry over the damage to the water levee, suggests dumping motor oil in the water to eliminate the muskrats. How would you respond?

Questions for Reflection

  1. Explain why the overabundance of some species may not be a problem.
  2. Animals are not pests until they become unwanted. There are benefits to modifying bird feeders to reduce rodent access to bird seed. How do you explain this to people who want your service to remove squirrels?
  3. Why is it important to have definitions for what constitutes wildlife damage?
  4. Why is cost effectiveness important in resolving wildlife damage problems?
  5. Why are public attitudes and values important?
  6. Why is it important to have continued training in the field of wildlife damage management?
  7. Name at least 2 reasons why an animal would be considered “nuisance wildlife”.

Objective Questions

  1. A goal of WDM is to
    1. change the habitat
    2. remove animals
    3. reduce damage to a tolerable level
    4. do whatever the client pays for
    5. none of the above
  1. Select the correct term – Cultural or Biological
  2. __________carrying capacity relates to when wildlife conflicts have reached a level people will not tolerate
  3. __________ carrying capacity relates to when habitat is harmed by the wildlife
  4. Habitat modification
  5. reduces the total number of wildlife that can be present.
  6. reduces wildlife numbers over the long term.
  7. is considered a non-lethal form of management.
  8. all of the above.
  1. All of the following can be reasons why a wildlife control program might fail EXCEPT
  2. animals moved into the area.
  3. you reduced the amount of food and shelter available.
  4. the devices you used did not frighten the animals.
  5. you did not catch the target animals.
  6. True or false – Residential development will only reduce the number of animals in an area because it removes habitat for wildlife.


  1. c
  2. a cultural b. biological
  3. d
  4. b
  5. false