Principles of WDM

Module 1   Principles of Wildlife Damage Management

In this Module:

Learning Objectives

Terms to Know

WCO Education Core Curriculum

Principle 1 – Wild animals are not Pests. 4

Principle 2 – Problem animals are unwanted. 4

Principle 3 – Prevent Wildlife Damage. 4

Principle 4 – Objectives of WDM… 4

Principle 5 – Understand Wildlife Biology. 6

Principle 6 – Knowledge of Wildlife Biology and Habitat is Required  6

Principle 7 – Use Multiple Strategies to Resolve Human-Conflicts  8

Principle 8 – Conflict is Inevitable. 10

Principle 9 – Respect Public Attitudes. 10

Principle 10 – Education and Regulation Promote Competency and Professional Behavior 10

Study Questions. 11

Learning Objectives

  1. Understand when and why an animal becomes or can be classified as a pest.
  2. Learn why wildlife damage management (IWDM) is about managing damage from wildlife, and not the management 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 wildlife agencies.

Terms to Know

Attitude – a personal way of thinking or feeling about someone or something, typically one that is reflected in a person’s behavior.

Competence – the ability to do something successfully or efficiently.

Conservation and Management A conservation management system (CMS) is a procedure for maintaining a species or habitat in a particular state. It is a means whereby wildlife biologists, state, and private agencies protect wildlife for the recreational use and enjoyment of all citizens.

Damage – physical harm caused to something in such a way as to impair its value, usefulness, or normal function.

IPM – Integrated Pest Management (IPM) is an ecosystem-based strategy that focuses on long-term prevention of pests or their damage through a combination of techniques such as biological control, habitat manipulation, modification of cultural practices, with the goal to reduce damage to a tolerable level. WCOs perform integrated wildlife damage management (IWDM).

Pest – A plant, insect, or animal that sickens or annoys humans, hampers human activities, damages crops or food products, harms livestock, or causes damage to buildings.

Regulation – a rule or directive made and maintained by an authority.

Training – the action of teaching a person a particular concept, skill, or type of behavior.

Wildlife – Wildlife traditionally refers to undomesticated animal species, but has come to include all organisms that grow or live wild in an area without being introduced or controlled by humans.

Wildlife are wild animals collectively; the native fauna (and sometimes flora) of a region.

Wildlife Control – the methods and processes of excluding, repelling, capturing, and removing nuisance animals

Wildlife Control Operator (WCO) – wildlife control operator (WCO) is an individual trained to solve problems from wildlife conflicts and nuisance wildlife situations, usually for profit.

Wildlife Damage Management – 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.

Wildlife is a valuable resource. 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 several billion annually, demonstrating a clear need for effectively addressing negative impacts. The purpose of this manual is to provide the basic information needed to help people resolve conflicts with wildlife.

WCO Education Core Curriculum

This course content is designed for instruction and assessment of technicians according to performance-based learning objectives related to competent, safe, legal, respectful, and responsible trapping/capture, animal containment, transport, dispatch as well as damage prevention techniques for long-term animal damage control.

The course content is designed to train people about wildlife control options and:

This training program is designed to help professionals manage wildlife problems by developing solutions based on the science and 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 including lethal techniques.

A 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 program we use the term WCO to include all technicians trained in WDM methods.

The goal of WCO education is to train safe, competent, responsible, respectful, and law-abiding WCOs. WCO education is important because it:

These materials cover the basic skills needed to effectively deal with a variety of wildlife issues. They focus 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 detailed knowledge of the species causing the conflict 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, trapping, handling, containment, and control techniques must be learned, practiced, and mastered. Field work is recommended to complete your training. If an animal must be killed or euthanized, then the operator must be skilled in humane dispatch. Proper disposal and carcass handling procedures are required. If a building or other structure needs repair to prevent future conflicts, carpentry and building skills are needed.

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 guidelines of wildlife biologists.  

To truly understand the basis of most state and federal laws around wildlife you should:

Recognize the central principles of the North American Model of Wildlife Conservation.

WCO’s play a role in wildlife conservation

A WCO’s Role in Wildlife Conservation can include:

Do not hesitate to contact state and federal wildlife professionals 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 may also be required. The use of regulated toxicants almost always requires a separate pesticide applicator license.

In today’s urban environment, abundant wildlife create many human-wildlife conflicts, 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 for recreation are similar to some of the control methods for WDM, such as knowledge of wildlife and its habitat. However, a different set of skills is also needed to manage wildlife in urban and suburban settings such as building maintenance, managing clients, 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 like wildlife and enjoy seeing animals. Problems occur when animals engage in dangerous behavior or damage crops, domestic animals and property.  Animals are protected by the public trust, and in many cases protected by additional laws, even when they can be lethally removed. Wildlife control should be conducted 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 animals that  cause damage, create safety issues, or are considered a nuisance.

Principle 1 – Wild animals are not Pests

Animals are not considered pests until they create a conflict with humans, their habitats, property, pets, health, resources, or values.

Principle 2 – Wildlife can be unwanted

Animals may have to be controlled when they threaten human infrastructure or conflict with humans, their habitats, their resources, or their values in the following ways.

Animals become problems when they cause:

Wildlife that have unwanted behaviors are deemed pests and can be controlled outside of typical hunting and trapping seasons. This may require special permits for wildlife control operators, who follow all local, state, and federal regulations.

Principle 3 – Prevent Wildlife Damage

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

Principle 4 – Objectives of WDM

Reduce Damage to a Tolerable Level

Integrated Pest Management (IPM) is an ecosystem-based strategy that focuses on long-term prevention of pests or their damage through a combination of techniques such as biological control, habitat manipulation, modification of cultural practices, and use of resistant varieties. 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 deer living in the woods and deer eating plants in the backyard.

Figure 1. Deer in the woods. Are they a threat? Photo by Jan Hygnstrom.

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

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 home 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 and many unprotected species cannot be taken without a valid nuisance complaint. 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 – Understand Wildlife Biology

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

State resource agencies typically classify wildlife species into several categories including big game, small game, upland game, migratory game birds, furbearers, non-game and endangered/threatened or special concern species.

Problem wildlife can be legally trapped in many areas. WCOs must be able to properly identify their target species. Additionally, understanding the habits and habitats of each species helps WCOs build better exclusionary controls, locate good trapping locations and make successful sets.

Characteristics to consider when identifying wildlife include:

Principle 6 – Knowledge of Wildlife Biology and Habitat is Required

People conducting IWDM need to be knowledgeable about the biology of problem 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 in its habitat.

Knowledge of wildlife basic biology includes:

Population Dynamics

Factors that affect wildlife production and survival include:

Problems with wildlife typically are greater when suitable habitat (food, water, and shelter) are available. Habitat is the most important factor affecting wildlife survival. It can change over time through natural succession or management, and provides benefits to different species at different stages of growth. Habitat loss can have permanent or lasting effects on wildlife populations. Many wildlife species are comfortable in urban/suburban environments (urban exploiters). Understanding wildlife ecology promotes professional behavior.

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).

Biological basis of wildlife control

Limiting factors are characteristics that can alter population growth. Examples include disease, predation, weather, and a lack of habitat. (Fig. 2).


Overabundance occurs when the population of a species of wildlife has exceeded the biological or cultural carrying capacity. For one reason or another, either the environment cannot handle that number of animals, or animal numbers exceed human tolerance levels. Good quality food and shelter contribute to overabundance.

The biological carrying capacity (BCC) is the number of animals in a population that an environment can sustain without long-term detrimental impacts from lack of food and other resources. 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 may 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 in their yard, or a bat in their attic.

Figure 2. Many people enjoy seeing Canada Geese but are not tolerant of feces and damage. Image by Paul D. Curtis.

Often, people’s tolerance for wildlife 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 may also 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?

Figure 3. Predator-Prey relationships. Image by NPS.

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 (Fig. 3). If a predator substantially reduces prey populations, the predator would threaten its own existence by eliminating its source of food.

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. Raptors may have some effect in mitigating large bird populations. Image by Paul Curtis.

Principle 7 – Use Multiple Strategies to Resolve Human-Conflicts

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

Strategy  1   Habitat Management:
Reduce the 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 (Fig. 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.

Figure 5. Spilled bird seed will attract rodents, often leading to structural damage and entry into homes. Photo in public domain.

Strategy 2   Exclude Animals

Prevent animals from accessing 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 by 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 or eliminated. 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 new animals often move into an area that has been vacated (Fig. 6).

For example, you may have successfully removed voles from one 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.

Coon in trap

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


Once you have captured an 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.

Translocationmeans moving a nuisance animal from one place to another outside of its home range.

Relocationrefers 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.

Translocated animals rarely stay in the area of release and often have low survival rates because they do not find suitable habitat elsewhere. As a result, these translocated animals often experience a slow and stressful death, as opposed to a quick and humane death administered by a trained WCO. Many states prohibit translocating or relocating almost all species of wildlife, except when animals are removed from inside dwellings or structures and released in the immediate vicinity outside these buildings.

Humane Dispatch and Carcass 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. Human activities provide food, water, and shelter. People invite wildlife into their space. Conflict is inevitable. People performing IWDM provide a valuable service for stakeholders and the community. WCOs play an important role in wildlife conservation by controlling problem wildlife and practicing integrated 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 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 and exclusion work is an essential occupation. WCOs performing wildlife damage management provide important and 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. Wildlife are protected by animal cruelty laws. 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 – Education and Regulation Promote Competency and Professional Behavior

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. Training and licensing are an important part of wildlife damage management.

Continuing education at conferences and workshops promotes collegial behavior and provides the opportunity to learn new and effective strategies for controlling wildlife from practicing wildlife professionals.

Study Questions for Principles of Wildlife Damage Management

Questions for Reflection

Objective Questions

  • is the number of animals that a human or human community will tolerate in a given area

  • s the maximum number of individuals of a given population that an environment can sustain.


1. c 

2. a cultural b. biological 

3. d 

4. False 

5. False