Prepared by the National Wildlife Control Training Program. Research-based, wildlife control information.
Module 1 Basics of Wildlife Damage Management
Module 1 covers the basic principles of wildlife damage management such as key definitions, important objectives and social and ethical considerations.
- Explain 3 reasons why wildlife damage management (WDM) is necessary.
- Describe 3 objectives of WDM.
- Explain why the concept of “balance of nature” is misleading.
- List the 4 major strategies of WDM.
- Provide some reasons why the removal of wildlife could fail to control the damage.
Wildlife is an important resource in the US. According to the 2006 National Survey of Fishing, Hunting, and Wildlife-Associated Recreation, 87.5 million US residents fished, hunted, or watched wildlife in 2006. They spent over $122 billion pursuing these recreational activities, contributing to millions of jobs in industries and businesses that support wildlife-related recreation. In addition to hunting and fishing, fur trapping is an important industry. Usually, wild animals are not a problem and people enjoy seeing wildlife around their homes. However, some wildlife species do well in the landscapes we create and cause conflicts with humans.
Wildlife damage management is founded in the traditions of hunting and trapping. Many state and federal regulations regarding the control of certain species are based on hunting and trapping regulations. Wildlife pest control or wildlife control operators (WCOs) are an outgrowth of urbanization and human-wildlife conflicts and the movement of problem wildlife into suburban backyards. Laws or regulations pertaining to hunting and trapping may or may not apply to wildlife damage issues. The training and skills required to hunt and trap are similar to some of the control methods for WDM. A different set of skills, however, also are needed to manage wildlife in urban and suburban settings.
The management of wildlife damage has moral, 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.
Wildlife may become pests for 3 main reasons.
- Economic – personal and social costs associated with damage.
- Safety –wildlife attacks, vehicle collisions, and transmitted diseases.
- Nuisance –noise, defecation, odors, and unsightly impacts.
Wildlife damage management is defined as the process of resolving conflicts associated with vertebrate species that:
- cause damage to food, fiber, personal property, and natural resources (e.g., feral pigs cause $800 million of damage to US crops each year)
- threaten human health and safety through disease, strikes, and attacks (e.g., tick-borne disease associated with deer); and
- become a nuisance (e.g., geese on golf courses, skunks under your deck, and phobias related to snakes).
The objectives of WDM are to: (1) reduce damage to a tolerable level, (2) use methods that are low-risk for people and the environment, and (3) implement control methods in a cost-effective way. A WCO is an individual trained and licensed to solve wildlife damage and nuisance wildlife situations, usually for profit. Many common problems associated with wildlife, however, can be resolved by the landowner using exclusion or habitat modification. This manual will focus on methods to prevent wildlife damage. Contact a trained professional for situations in which safety is a concern or the wildlife problem is complex.
Look for practical solutions to human-wildlife conflicts
Homeowners should set reasonable wildlife management goals. Be respectful and prudent when people explain their negative feelings about an animal. Do not reinforce inappropriate stereotypes or be drawn into a “problem” that does not need solving (Figure 1).
The focus of WDM is to prevent or resolve the cause of a specific problem. The goal is not to reduce the number of animals in an area. Landowners should target only the animals causing a specific conflict and prevent the situation from recurring.
Act legally and morally
Is the pest protected? Is legal permission required to remove or contain it? Is certification needed or are permits required? Homeowners experiencing wildlife damage may be under severe stress and suffering high economic losses, which could lead them to encourage the use of dangerous or illegal techniques. Just because a method works does not mean it should be used. For example, mixing strychnine with cat food or setting out a bowl of radiator antifreeze may be effective in killing opossums and raccoons. However, these techniques are illegal and irresponsible, and can result in the poisoning of non-target animals and unnecessary suffering. Recommend the techniques you believe to be most appropriate for solving the problem. If a homeowner requests something beyond what you believe is legal, reasonable, moral, or safe, suggest appropriate alternatives.
How much will it cost to execute and maintain a strategy? People have limited financial resources. Be sure to evaluate costs and benefits over the long-term. If the expense of resolving a problem costs more than the problem itself, it may not be practical to control the damage. The true cost of a method, however, must be considered over time. For example, it would take truckloads of vegetables and many years to recover the cost of installing a $500 fence to protect a garden from hungry animals. However, installing a $250 stainless-steel chimney cap to keep raccoons and other wildlife out of a chimney is inexpensive, given the cost of their removal. If the cap lasts 20 years, the annual cost of the cap will be just $12.50.
Patience is needed to deal with clients, wildlife problems, and potential solutions. Some problems may be very complex and require you to coordinate costs, timelines, and legal requirements. Other necessities include:
- preparation – Be prepared to understand the wildlife problem in the context of the environment, landscape, or building.
- knowledge – Have knowledge of the biology and basic behavior of the species.
- resources – Know what will be needed to deal with the problem safely and effectively. Have the right protective gear and specific tools to safely exclude or remove the target species.
- skills – Have the skills to manage the methods and equipment to effectively resolve the concern.
Specific methods to manage damage will be repeated throughout this manual and form the basis of most effective strategies. Prevention typically is the best, safest, and most effective approach to WDM. It is important to understand and apply prevention and control methods properly – they are listed in the accompanying species information chapters.
Methods for WDM often are classified into four categories:
- habitat modification – reduce the availability of food, water, and shelter to reduce the number of animals that can be sustained over time;
- exclusion methods – prevent animals from accessing a location;
- repellents and frightening devices – repel or divert animals from a location, and
- lethal control – reduce the number of animals through shooting, trapping, and the prudent use of toxicants.
The number of animals the land can sustain, known as the carrying capacity (symbolized by the letter “k” in Figure 2), can be reduced by decreasing resources necessary for population growth. For example, if someone is having conflicts with mice, removing available food by reducing spillage of bird feed, protecting food storage bins, and securing trash and compost will slow the increase in the number of mice. While you could aggressively trap to reduce the number of mice, your efforts would yield short-term results without also addressing the availability of food, because populations of mice can rebound quickly.
When practical, physically preventing access of target animals to an area of concern often is the best long-term solution. Exclusion techniques range from simply sealing entry holes on buildings to installation of bird exclusion to animal-proof fences around large properties. Although exclusion initially may cost more than trapping, it provides a long-term solution to prevent further problems and damage.
Repellents and frightening devices
Another WDM strategy is to repel or scare animals from a location. Repellents are based on pain, fear, touch, or conditioned aversion. The effectiveness of the technique greatly depends on how motivated animals are to access the protected location or food sources. The impact of repellents and frightening methods almost always is short-term.
The number of problem animals can be lowered using lethal control methods, such as toxicants, trapping, or shooting. Such actions typically lead to a quick decrease of the target population to a level in which they, or their associated damage, can be tolerated. Lethal control is especially appropriate when animals pose risks of disease or safety. However, animal removal usually brings short-term results if suitable habitat remains.
Habitats with plenty of food and shelter allow animals to live well. Well-fed animals often have larger litters and greater success in raising young to maturity. The killing of animals may be effective in reducing damage, but habitat modification often is necessary to prevent future damage.
Wildlife dispersal, the movement of an animal from where it was born and reared, also may cause population reduction to fail in some cases (Figure 3). For example, a person may have a chipmunk problem in a yard. Four chipmunks are trapped and removed, yet several weeks later the person complains that the problem is back. The action was effective, as the chipmunks residing on the property were removed. What the person may not understand was that other chipmunks moved in from neighboring properties (the reservoir) and occupied the habitat previously used by the chipmunks that were removed.
The WDM process
When presented with a wildlife problem, inspect the site. Search landscapes and buildings for signs of wildlife activity. One or more of these methods – habitat modification, exclusion, repellents and frightening devices, and perhaps lethal control – will fit into an overall or long-term WDM plan.
Once animals gain entry to buildings, homeowners must use WDM methods appropriate to the situation. Monitor animal activity to observe the effectiveness of the selected method. Be certain that the problem is truly resolved or effectively contained. If it is not, select another method.
Will predators solve the problem?
Wildlife populations are not balanced (Figure 4). People suffering from wildlife damage often wonder why the problem is happening now. While reasons vary, it is important that homeowners understand that wildlife populations fluctuate, sometimes dramatically, both within a year, and from year to year. For example, rodent populations frequently increase in response to improved rainfall, because the enhanced growth of plants produced more food. As prey numbers increase, predator numbers also may increase, although usually in the following year.
Locally, populations can change due to human activity such as construction, and the addition or removal of bird feeders, trash receptacles, and gardens. The bottom line is that environmental issues often are out of the control of your clients. Help homeowners refocus on their property and how they can make appropriate changes to reduce wildlife damage.
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 top-level predators may be present in low numbers or even absent, it is unlikely that restoring their populations would solve most human-wildlife conflicts. Human tolerance of damage by wildlife often is quite low. Homeowners do not want to have fewer squirrels in their attic; they want NO squirrels in their attic. If a predator substantially reduces prey populations, the predator would threaten its own existence by eliminating its food source. For example, having bats in a backyard will never make the yard free of insects, and even a cat that is a great mouser cannot control every rodent living in a house (Figure 5). In addition, many predators are not selective in their choice of prey, so non-target animals likely will be taken as well.
Many people believe that wildlife cause damage to property because “humans have taken away their homes.” Although this logic is understandable, many species (e.g., raccoons and squirrels) actually do well in suburban areas and animal densities may be much higher than in nearby rural areas. Urban sprawl has created and supplied habitat and food for species that often cause damage. In fact, some animals thrive in human-impacted environments because:
- urbanization creates new shelter such as attics, chimneys, crawl spaces, decks, woodsheds, and more;
- urbanization provides food for animals through bird feeders, trash cans, compost piles, fruit trees, and pet dishes;
- environmental legislation has allowed some wildlife populations to rebound; and
- lethal control of wildlife (e.g., hunting and trapping) may be illegal in some areas due to safety concerns and local regulations.
Populations of white-tailed deer (Figure 6), for example, have increased dramatically across much of the US for several reasons:
- expansion of their preferred edge habitat (e.g., mixed lands, woods, and fields),
- subsidized food sources such as garden and ornamental plants or bird feeders,
- reduced hunting pressure (fewer people hunt and more land is closed to hunting), and
- lower numbers of natural predators (automobile strikes, however, kill hundreds of thousands of deer each year).
Who Can Perform WDM?
Anyone can perform basic strategies for wildlife damage management. Prevention of problems is the preferred solution. If you want to properly manage a wide variety of wildlife concerns, you must gain skills and competency in safe practices, site inspection, use of equipment, and communicating with clients and local authorities. In addition, you must be knowledgeable of species biology, legal requirements, and ethical considerations.
- Explain why the statement “balance of nature” may be misleading.
- A homeowner has a rodent problem but does not want to stop feeding birds that are constantly scattering bird seed. What would you tell the person?
- You recommend installing screening under a deck to protect the area from skunks. The added protection of burying the base of the screen increases the cost. The homeowner expresses resistance over the price. How would you help the person appreciate the value of the exclusion?
- A client calls in complaining about muskrats in a pond. The landowner, angry over the damage to his earthen water-control dam, suggests putting toxic baits near their burrows to eliminate the muskrats. How would you respond?