Control Methods

Wildlife Control Methods


Learning Objectives


  1.  Learn how to apply the principles of integrated wildlife damage management (IWDM).
  2. Explain IPM problem solving methodology.
  3. Be able to explain each of the basic methods to control and resolve wildlife conflicts.
  4. Describe methods to reduce animal damage before using lethal control methods.
  5. Understand and explain the details of each type of damage prevention and control method and describe situations where different control methods may be applied.
  6. Explain how fencing and other exclusion tactics often can prevent a vertebrate pest problem.


Terms to Know


Integrated wildlife damage management (IWDM)  The timely use of a variety of cost-effective, environmentally safe, and socially acceptable methods to reduce human-wildlife conflicts to a tolerable level. IWDM is a problem-solving methodology based on international standards for integrated pest management (IPM).


Habitat modification   Changing the habitat of an animal to limit its access to food, water, or shelter..


Exclusion   Techniques and products that prevent wildlife from entering an area.


Frightening device   Typically, a non-chemical tool designed to cause animals to avoid areas through the use of fear.


Repellent    A chemical that causes animals to avoid a given location. Repellents come in 3 main forms: oral (taste), tactile (touch), and olfactory (smell) repellents.  


Toxicant   A chemical substance that is designed to kill an animal.


Use a Framework for Applying Damage Prevention and Control Methods


Wildlife damage management includes a variety of damage prevention and control methods which include strategies, methods, and tools to reduce wildlife conflicts to tolerable levels. A wide range of techniques and equipment are needed because no single control method will resolve all wildlife conflicts. There are many different types of wildlife from rodents to reptiles and birds to carnivores. The diversity of species and conflict situations often require some form of wildlife damage management resolution. Animals can damage many things that are important to humans and they can be a safety risk from injury or disease. WCOs should use whatever control strategy works best, with an emphasis on damage prevention and long-term conflict resolution. Exclude animals from where they do not belong and modify the habitat so that wildlife don’t want to hang around. It is better to use a variety of control methods to address long-standing damage situations.


Wildlife damage control is an increasingly important part of the wildlife management profession because of expanding human populations and intensified land-use practices. Concurrent with this growing need to reduce wildlife-people conflicts, public attitudes and environmental regulations are restricting use of some of the traditional tools of control such as toxicants and traps. Agencies and individuals carrying out control programs are be /wp:paragraph –>

Repellent    A chemical that causes animals to avoid a given location. Repellents come in 3 main forms: oral (taste), tactile (touch), and olfactory (smell) repellents.  


Toxicant   A chemical substance that is designed to kill an animal.


Use a Framework for Applying Damage Prevention and Control Methods


Wildlife damage management includes a variety of damage prevention and control methods which include strategies, methods, and tools to reduce wildlife conflicts to tolerable levels. A wide range of techniques and equipment are needed because no single control method will resolve all wildlife conflicts. There are many different types of wildlife from rodents to reptiles and birds to carnivores. The diversity of species and conflict situations often require some form of wildlife damage management resolution. Animals can damage many things that are important to humans and they can be a safety risk from injury or disease. WCOs should use whatever control strategy works best, with an emphasis on damage prevention and long-term conflict resolution. Exclude animals from where they do not belong and modify the habitat so that wildlife don’t want to hang around. It is better to use a variety of control methods to address long-standing damage situations.


Wildlife damage control is an increasingly important part of the wildlife management profession because of expanding human populations and intensified land-use practices. Concurrent with this growing need to reduce wildlife-people conflicts, public attitudes and environmental regulations are restricting use of some of the traditional tools of control such as toxicants and traps. Agencies and individuals carrying out control programs are being more carefully scrutinized to ensure that their actions are justified, environmentally safe, and in the public interest. Thus, wildlife damage control activities must be based on sound economic, ecological, and sociological principles and carried out as positive, necessary components of overall wildlife management programs.


Wildlife damage control programs can be thought of as having four parts:


  1. problem definition; 
    (species, damage identification, habitat)
  2. ecology of the problem species;
  3. control methods application; and
  4. evaluation of control.


Problem definition refers to damage identification, determining the species and numbers of animals causing the problem, the amount of loss or nature of the conflict, and other biological and social factors related to the problem. Ecology of the problem species refers to under-standing the life history (cycle) of the species, especially in relation to the conflict. Control methods application refers to taking the information gained from parts 1 and 2 to develop an appropriate management program to alleviate or reduce the conflict. Evaluation of control allows an assessment of the reduction in damage in relation to costs and impact of the control on target and nontarget populations and the environment. Increasingly, emphasis is being placed on integrated pest management (IPM) whereby several control methods are combined and coordinated with other management practices in use at that time.


Integrated wildlife damage management (using IPM to solve WDM problems) involves the appropriate use of a variety of cost-effective, environmentally safe, and socially acceptable methods to reduce human-wildlife conflicts to a tolerable level. Attempt to fix the problem before you kill or capture the animal. There are only a few methods that you can use to stop wildlife damage before your emphasis turns to trapping and removing the problem wildlife. To be socially acceptable, you must use methods that are “humane,” which means that you cause no unnecessary pain or stress to the animal. Through each stage of your work, whether capturing, handling, excluding, transporting, or disposing of wildlife, act respectfully.


Remember that wildlife are not pests, rather they come into conflicts with people when they damage property, create safety or nuisance issues, or endanger human lives. Use the basic principles of wildlife damage management to solve the problem.


Acting humanely does not mean that you only use nonlethal techniques to solve a wildlife conflict. In some situations, a nonlethal technique may be considered less humane than killing the animal. If you must kill an animal, do it humanely. Catching snakes with glue boards would be a good example of an inhumane, nonlethal method. In addition, some nonlethal techniques that are meant to frighten the animal, or get it to stop a certain behavior, may cause some stress or pain, but for a good reason (e.g., electric fences).


Consider these 6 questions when choosing capture, handling and containment, transport, and humane dispatch methods for wildlife:


  1. Is it safe?
  2. Is it legal?
  3. What are the environmental impacts?
  4. Is it practical?
  5. Is it humane?
  6. What are the public attitudes?


Some complex wildlife conflicts are difficult to manage. What works well in one case may be inappropriate in another, especially when trapping and lethally removing animals. Neighboring populations of animals over which you have no control may be a problem. Using toxicants can be dangerous to non-target animals and the environment. The effects from frightening and repellents may be short lived. Habitat modifications may not be possible. Exclusion can be expensive. Laws regarding the discharge of firearms may limit humane dispatch options. Thoughtful solutions to resolving wildlife conflicts can be challenging. After defining the problem and considering the unique factors in each wildlife conflict you’re ready to select a management strategy.


What are your options when confronted with a wildlife damage situation?


  1. Do nothing; let the problem resolve itself.
  2. Make the environment less attractive by environment manipulation and habitat modification.
  3. Keep the animal out (exclusion).
  4. Scare the animal away (frightening).
  5. Capture or kill the animal.
    1. Trap and dispatch
    2. Shooting
    3. Toxicants (license required)
    4. Translocation (not recommended)
  6. Reduce the local breeding population.


Regardless of which strategy you favor, keep the following points in mind. First, a combination of techniques almost always works better than relying on one method. Be as selective and discreet as possible. Proper timing will increase your success. You wouldn’t try to monitor a nocturnal animal during the day, would you? Take advantage of behaviors that are a weakness for the species (lures and attractants). Always watch out for risky conditions and dangerous animal behavior.


Avoid Creating Wildlife Orphans


Before you repel, remove, exclude, or kill an animal, take steps to prevent the orphaning of young wildlife. A lot of WCO work happens when wildlife are raising their young, so this is an important consideration.


Many people assume that den and nesting sites are plentiful and that a female usually has several from which to choose. Perhaps this is true for some species, in some areas. It certainly is not true in all places. How often does the female find a suitable den site in time? How easily does the family recover from the stress of the experience? Do a reasonable number of the young survive to adulthood? We don’t always have the answers for these questions.


The best way to prevent orphaning is to convince your customers to wait until the young are mobile before removing, repelling, or excluding the family from the site. If that’s not acceptable, you can try to capture and remove the female and all of her young and hope that she will retrieve them and continue to care for them.


When is this most likely to work? Let’s apply a little biological common sense. Older, more experienced females probably are better at finding resources than younger females. As the young age, the bond between the mother and young strengthens, so she’ll be less likely to abandon them. You can’t change the ages of the animals you’re dealing with, but you might wait a little longer if you think your chances of success are poor.


Some WCOs are refining removal techniques to increase the chances that the female will retrieve her young. Consider the following: time your activities to match the normal habits of that species. The sooner the female finds the young, the better. If they’re left alone too long, they may die of exposure. For a nocturnal species, start at dusk.


Remove the female, preferably using a direct-capture technique, such as a catch pole. Place the female and young in a release box (opinions differ on cardboard, wood, and plastic) in a secure location on the same property; it may be illegal to translocate wildlife to a different area. Make sure you’ve excluded the animals from the structure they were removed from by repairing or installing barriers to access points.


Match the size of the box and its entrance hole to the size of the species. Use a smaller box with a smaller hole for squirrels and a larger box with at least a 7-inch hole for raccoons.


Cover the hole to ensure the female and her young cannot get out of the box immediately. Move the box to a quiet place outdoors. Unless they’re likely to be disturbed, keep the box at ground level. Remove the cover so the female can get out of the box. Another option is to build a box with a sliding door. Leave the door open about an inch, to keep the heat inside but make it easy for the female to slide it fully open so she can retrieve her young.


Some WCOs prefer to use heated release boxes when it’s cold outside. Make sure that the box doesn’t get too hot. You may want to provide heat in just one area. Assume that if you put something in the box, the animals will chew on it. If you choose to use a household heating pad, make sure the animals can’t reach the wires. You can build the box with a double floor and place the heating pad in the space between the floors. Other options for heat sources include microwaveable heating pads and warm soap-stones.


If you can’t catch the female, put the young in the release box and place it as close to the entry site as possible.


Knowing the biology and habitat of the animal will make you a more effective and humane wildlife control operator.


Wildlife Damage Management uses
Damage Prevention and Control Methods


Wildlife damage management attempts to eliminate damage from predator threats, disease, safety issues, structural and agricultural damage, as well as other nuisance problems by using 
Damage prevention and control methods.


  • Habitat Modification
  • Exclusion
  • Frightening Devices
  • Repellents
  • Trapping
  • Shooting
  • Toxicants
  • Other Methods


Preventing damage, modifying the habitat, and excluding animals from areas they don’t belong are goals of WDM. Frightening devices and repellents may have minimal long-term effect and are most effective on transient populations. Toxicants, trapping, and shooting are lethal ways to remove the animals and should only be used if other methods are ineffective or the animal is sick or dangerous.


Habitat Modification


All animals need water, food, and shelter. Reducing or eliminating any of these vital resources can reduce the carrying capacity of a species in that habitat. Modifying the habitat or environment to reduce access to food, shelter (denning space) and water can effectively change wildlife behavior by causing them to seek an alternative habitat. Even small modifications can enhance the effectiveness of other techniques. Using a good squirrel-resistant bird feeder and picking up spilled seed, as well as trimming branches near the bird feeder, will help to control squirrel problems.


Figure 1. Rock around a building foundation will reduce the availability of food, water, and shelter. 
Photo by Jan Hygnstrom.


Most habitat modifications are subtle, but they play an important role in long-term management of wildlife damage. Changes to habitat to reduce the carrying capacity for one species, however, may encourage population growth in another species. For example, mowing tall grass to reduce the presence of voles may encourage Canada geese to feed in an area.


Remove artificial food sources


If anyone is feeding the nuisance animals, persuade them to stop. It may even be illegal. Why? Because an easy food supply can attract a crowd. The wildlife might become dependent on the food source and learn to associate people with food, which could lead to other problems. Also, unnatural crowding is a set-up for the spread of wildlife diseases. The 2003 ban on deer feeding, for example, was put in place to try to prevent the spread of chronic wasting disease to New York State. Report illegal feeding of wildlife to DEC Bureau of Wildlife or law enforcement staff.


“Animal-proof” the trash. In general, this means you can either keep garbage cans and dumpsters in protected locations, or use strong containers with secure lids. Obviously, a container that’s strong enough to keep out mice may not even slow down a bear, so match your approach to the species. Attaching cans to posts will make them harder to tip over.


Clean garbage cans, chutes, and dumpsters often. Check for cracks and holes. If you find any, repair them.


Don’t leave trash out all night for a morning pick-up. Many of the nuisance species who rummage through trash are nocturnal. If you can, put the trash out right before it’s due to be collected.


Enclose compost piles in a framed box using hardware cloth, or in a sturdy container. Don’t compost meat products or cooked food.


Feed birds during the fall and winter and gradually stop by April. Use sturdy poles for bird feeders. Keep the area underneath the feeder clean. Or use natural landscaping to provide good bird habitat instead. (See the National Wildlife Federation’s backyard wildlife habitat program for information.)


  • Feed pets indoors. Any food left outdoors should be removed at night. Bring the food bowls indoors.
  • Clean up spills of food, bird seed, grain, garbage. Promptly.
  • Remove and properly dispose of livestock carcasses immediately.
  • Store food, bird seed, pet food, and grains in strong containers. Keep stored items off the floor and away from walls.
  • Near buildings, rake up and remove fruits and nuts that fall off trees.
  • Keep livestock feeding areas and grain storage areas as clean and secure as possible.
  • Remove dog, cat, and horse droppings daily. (Feces are food to other animals.)
  • Eliminate pools of standing water.
  • Keep livestock in protected areas, especially when they’re ready to have young.
  • Switch to landscape plants that the nuisance animal doesn’t find as tasty.


Limit their shelter


  • Maintain a foot-wide gravel border around the foundation that’s free of plants (best) or at least keep foundation plantings well-trimmed. Don’t stack anything against the foundation.
  • Remove brush piles, junk piles, and clutter. Keep woodpiles away from buildings.
  • Keep a clean border around any vulnerable area (building, garden, field, orchard). Mow the grass often. Trim shrubs.
  • Mow openings through large patches of thick ground cover. Some animals don’t like to cross areas where they can be easily seen. Canada geese, however, would make good use of such openings, so don’t use this technique if geese are, or could become, a problem in the area.
  • Trim or thin trees to reduce their appeal as roosts.
  • Cut trees that brush up against the building and limbs that overhang the roof.
  • Wrap guards around trees to keep animals from climbing them. (Best done in late fall, when the wild animals have finished nesting in the tree. Keep the wrap loose so it doesn’t girdle the tree.) This will only prove effective if the tree is insulated enough that animals cannot climb a nearby object and leap into the tree.
  • Plus all the exclusion techniques to keep animals out of buildings, gardens, livestock areas, or any other vulnerable location.


Typical habitat modifications include:


  1. removing attractants such as bird feeders, unsecured trash cans, or outdoor pet food; or the deliberate feeding of wildlife.
  2. removing brush, woodpiles, and debris;
  3. cutting back bushes and trees to reduce cover and access to structures; mowing lawns,
  4. covering openings in buildings, sheds; and
  5. using wildlife-resistant plants.


Habitat modification can provide long-term solutions to difficult human-wildlife conflicts. Unfortunately, some habitat modifications can be expensive, so expect some client resistance. When the long-term effects are considered, however, habitat modification usually proves to be cost-effective.


Exclusion


Exclusion includes the use of barriers, fences, netting, sealants, and other methods to prevent wildlife from accessing areas and causing damage.


  1. Identify common ways that wildlife enter structures and surrounding areas.
  2. Explain how to determine whether an opening is being used by wildlife.
  3. Give examples of manufactured items used for excluding wildlife.
  4. Know techniques that should be avoided.


Exclusion can provide immediate, long-term, and high levels of protection. Exclusion sometimes can be a cheap and effective solution. It also can be costly, even prohibitive when large areas need protection. Exclusion is a powerful damage prevention and control method that provides clients with cost-effective ways to mitigate conflicts with wildlife permanently. Some experts consider exclusion to be a part of habitat modification, but it is more than environmental manipulation Exclusion typically requires carpentry and building maintenance skills.


Exclusion as Prevention


Exclusion is a great damage prevention and control method, not only for WCOs, but for anyone that needs to co-exist with wildlife. Exclusion does not use chemicals that may harm non-target animals or people and exclusion provides immediate, long-term, and, frequently, complete protection. A disadvantage of exclusion is the cost as it may expensive and require expertise, particularly when large buildings and areas need protection (Figure 2).


Figure 2. Fences are effective for excluding deer from areas but can be expensive. Photo by Paul D Curtis.


Protecting Structures


Knowledge of how to exclude rodents from structures provides a foundation for understanding how to use this technique on other animals. As valuable as exclusion techniques are, property owners should be made aware that excluding rodents from a structure will not guarantee rodent-free buildings forever. Rodents can gain access to a structure by gnawing a new hole or getting carried in with a box or appliance, or will walk right in if you leave the door open. Therefore, exclusion techniques should be part of an overall integrated pest management (IPM) program that includes sanitation, population control, and monitoring.


Know the Animals


Effective exclusion requires knowledge of an animal’s behavior and physical capabilities. Does it climb, jump, chew, or fly? Generally, an entire structure must be secured to prevent access by climbing animals, but only up to 4 feet to prevent access by those that cannot climb. Exclusion of birds requires consideration of the entire building, especially perching and nesting locations.


Holes and Openings


A thorough site inspection is necessary for any exclusion technique to be effective. All potential entry points must be located. Rats need slightly more than a ½-inch gap to enter; mice need slightly more than a ¼-inch gap. Do not ignore small crevices, as gnawing rodents can enlarge them quickly.


Screen, plug, or secure openings, but only after you are certain that animals are not using them. When uncertain about whether animals are using an opening, plug it with rolled up newspaper and monitor it for at least 3 consecutive days of fair, warm weather (Figures 3a to 3c). If the newspaper is untouched after 3 days, it is reasonable to assume that the opening is no longer in use. Do not use this method if bats may be present.


Next, consider whether a potential opening may be filled or if it must be screened. If airflow is needed, use a screen. If the gap can be filled, several options are available.


Secure holes up to ½ inch in diameter with caulk or other sealant. Sealants have greater elasticity than caulks and are preferable where movement in the substrate is expected, such as joints. Gaps larger than ½ inch require a backer to help hold the sealant. Backer rod, Copper Stuf-it™, and Xcluder™ have the flexibility to be wedged in crevices. They also provide enough structure to support the sealant as it dries.


Caulks and sealants come in several formulations. When selecting a caulk or sealant, choose the one that is appropriate for the substrate, exposure to weather, and aesthetics. It is common for WCOs to carry several formulations of sealant.


Figures 3a to 3c. Place paper on the end of a painter’s extension pole to plug holes without using a ladder. Do not use this technique near power lines or electrical wires. Photos by Stephen M. Vantassel.


Fill large openings, such as holes made by squirrels, first with expanding foam or other insulation to prevent leakage of air. It is thought that by inhibiting air movement and potential heat loss, animals will be less attracted to the structure as a possible nest or den site. After sealing the hole(s), install a gnaw-resistant barrier over the gap to prevent entry.


  Materials recommended for animal-proofing.


Concrete: reinforced – minimum thickness of 2 inches; if not reinforced – 3¾ inches
Galvanized sheet metal: 24-gauge or heavier. Perforated sheet metal grills should be 14-gauge
Brick: 3 ¾ inches thick with mortar-filled joints
Hardware cloth (wire mesh): 19-gauge, ½- x ½-inch mesh to exclude rats; 24-gauge, ¼ x ¼-inch mesh to  exclude mice
Aluminum: 22-gauge for frames and flashing; 20-gauge for kick plates; 18-gauge for guards


For openings less than ¾ inches in diameter that cannot be secured by other means, wedge copper or stainless steel wool tightly into the gap. Coarse steel wool will work temporarily but may eventually rust. Never rely on expanding foam alone to secure an opening as animals can chew through it.


Chimneys


Every flue in a masonry chimney should be protected with a professionally manufactured chimney cap that meets all requirements in your local fire code. Chimney caps are sold in single-flue (Figure 4a) and multi-flue designs (Figure 4b).


Figure 4a. Single-flue cap. Photo by Hy-C Co., Inc.


Purchase and install only professionally manufactured chimney caps made with stainless steel or copper. Galvanized-steel caps do not provide sufficient savings to justify their use. Chimney caps have solid roofs that protect the chimney crown from water damage. Check existing chimney caps fo cannot be secured by other means, wedge copper or stainless steel wool tightly into the gap. Coarse steel wool will work temporarily but may eventually rust. Never rely on expanding foam alone to secure an opening as animals can chew through it.


Chimneys


Every flue in a masonry chimney should be protected with a professionally manufactured chimney cap that meets all requirements in your local fire code. Chimney caps are sold in single-flue (Figure 4a) and multi-flue designs (Figure 4b).


Figure 4a. Single-flue cap. Photo by Hy-C Co., Inc.


Purchase and install only professionally manufactured chimney caps made with stainless steel or copper. Galvanized-steel caps do not provide sufficient savings to justify their use. Chimney caps have solid roofs that protect the chimney crown from water damage. Check existing chimney caps for damage. Ensure that animals are not residing in flues prior to capping. Chimney screens (also called raccoon screens) provide the same protection against animal entry as do chimney caps, but without a solid roof. They are less expensive and can be placed on flues closer than 6 inches apart.


Figure 4b. Multi-flue cap. Photo by Hy-C Co., Inc.


Under no circumstances should hardware cloth be used to protect a chimney. Wire mesh eventually rusts and the screen may allow water from snow, rain, or exhaust fumes to freeze, thereby blocking the exhaust gases and forcing them into the home.


Figure 5. Screen for a mushroom vent. 
Photo by Hy-C Co., Inc.


Vents


Consult state regulations before modifying vents. Vents require special care because they must allow air flow. As a rule, metal screening is best placed on the exterior of a vent so that mosquito netting may be protected from damage. Screen with a mesh size less than ½- x ½-inch may significantly reduce airflow.


Roof and attic vents are best secured from the outside to prevent animal entry. Professionally manufactured screens (stainless steel and galvanized; Figure 5) are available.


Stainless-steel screens are preferable for roof vents. Follow manufacturer recommendations for securing the screen to a roof to prevent leaking and ice damming. Check state regulations before securing vents. Although screens installed from inside an attic are effective and often easier to install, avoid using this option when protecting mushroom vents and other large vents. While your screen will prevent entry into the attic, squirrels and birds may build a nest on top of the screen under the protection of the mushroom vent.


Ideally, screens should have a mesh size of ¼ inch to prevent entry by bats and mice, although size should be balanced with air flow considerations. When installing vents, particularly on a roof, it is critical to seal screws to prevent leaks. Place a bead of roof sealant under and on top of the shingle where the screw is to be placed. After driving the screw through the sealant, cap the screw with a final dab of sealant. Consider whether snow or ice may be blocked by the screen. You may need to install barriers to shift snow and ice to one or both sides of the screen.


Figure 6. Weep vent cover. Image courtesy of Wildlife Control Supplies, LLC.


Weep vents are gaps that are purposely placed in brick walls to allow moisture to vent outward. With brick-veneer construction, a gap often is placed behind the brick where drywall does not come completely down to the bottom edge. Small animals can move freely behind the brick and find entry into the home through the gaps.


The act of securing these openings must balance the need for moisture to vent with the need for preventing insects and wildlife from entering. Use of ¼-inch wire mesh is discouraged as it will not prevent entry by insects or snakes. Devices such as Retrofit Weep Hole Covers™ (Figure 6) or a section of Xcluder™ material placed in the gap will limit access by insects, snakes, and mice. 


Ridge vents frequently have missing end-covers that provide openings for wildlife (Figure 7a). Use Copper Stuf-it™ or Xcluder™ (Figure 7b) and sealant to secure the ends. Add hardware cloth to the spot to increase its resistance to animal entry.


Figure 7a. The end of this ridge vent is open to wildlife entry. Photo by Stephen M. Vantassel.


Figure 7b. X-cluder™ fill fabric. 
Photo courtesy of Wildlife Control Supplies, LLC.


Dryer exhaust vents require special consideration, as improper screening hastens the build-up of lint and increases the likelihood of fires. Although some screens have air-activated flaps that seal when not in use, the flaps often fail as they become jammed with lint. Consider installing a dryer-vent cover with a simple removable screen (Figure 8a).


Figure 8a. Screen for dryer vents. Photo by Lambro Industries.


Whatever method is chosen, be sure to follow all state and local codes and ask homeowners to check their screens monthly. Use professionally manufactured screens whenever possible (Fig.8b).


Figure 8b. Dryer Ventguard™. Photo by Hy-C Co., Inc.


Homemade screens can be constructed in limited circumstances, such as when mouse exclusion is the priority, if legal. A large box (1 cubic foot or larger) constructed of ¼-inch mesh can be used to protect dryer vents. The large size is necessary due to reduced airflow, restricted by the mesh. Install a re-sealable flap to enable removal of lint. Inspect the screen at least monthly to ensure that lint does not obstruct airflow. Snow and ice buildup also are concerns. These screens may be used on shower vent exhausts, as well.


Sewer vents may attract squirrels that occasionally enter vents, thus raising the possibility of blockage. Crown-vent guards are designed to prevent animal entry. Ensure that exhaust pipes meet Consumer Product Safety Commission standards. Properly seal gaps between pipes and structures to prevent rodent entry.


Bathroom exhaust vent covers made from plastic are sufficient to protect bathroom exhaust vents from entry by birds.


Other vents on a wall may be secured with galvanized ¼- to ½-inch wire mesh. Cut the mesh at least 2 inches wider than the size of the vent to provide space to secure the screen to the structure. For triangular vents, measure the base and height of the triangle, add 2 inches or more to each measurement, and cut a rectangle or square. Place the mesh against the vent, outline the remaining sides of the triangle with a black marker, and then cut it (Figure 9).


Screens may not be acceptable in livestock buildings or other structures where ventilation is needed. In some locations, ¼-inch screens can become clogged with dust or ice. A screen with a larger mesh opening sometimes is preferable to no screen at all. For most homes, however, ¼-inch wire mesh is sufficient.


Figure 9. Outline of a triangular vent screen. 
Photo by Stephen M. Vantassel.


Secure a screen in several places with screws to prevent animals from pulling it off the structure. Screws with washers or expanded heads prevent the screen from popping over the screws. Use staples to secure the screen between the screwed areas. If aesthetics are a concern, paint the screen, screws, and washers to match the building. Though leaks are less of a concern with side screens, place a bead of water-proof sealant at the spot where the screw will pierce the structure. Add cross bars for support if the screen is very large (4 x 7 feet or more). If the opening is an access way, install the screen on a hinged frame.


Cover window wells 4 inches deep or greater to prevent wildlife entrapment (Fig. 10). Window well covers are easy to install and effective. Covers, caps, and screens prevent wildlife from entering specific structures such as chimneys, attics, vents, doors, windows, and window wells, all of which can provide wildlife easy access into structures.


Figure 10. This cover prevents wildlife from falling into the window well. Photo by Jan Hygnstrom.


Crack and crevice sealers include materials such as caulk, foam, mortar, and fabric (Figure 12) to fill cracks, crevices, voids and openings to prevent animals from entering structures. While rodents can gnaw through foam, its insulating properties play an important role in assisting more permanent exclusion methods. Foam degrades when exposed to sunlight.


Figure 11. Seal around a pipe with Todol foam. 
Photo by Erin Bauer.


Caulk and sealants cost more than foams, but provide a more durable seal for cracks and crevices. The products are sold in a variety of formulations and colors. Have several available for the most common applications in your area. Caulk should only be used for openings ½ inch or less in size. Larger openings need filler, such as hardware cloth or a professional sealant, or should be secured by another means (Fig. 11).


Sealants allow limited movement and are used when closing gaps between two surfaces that you expect to move relative to each other, such as during seasonal freeze-thaw events.


Figure 12. Copper Stuf-itTM is used to fill cracks and crevices. Photo courtesy of Wildlife Control Supplies.


Copper Stuf-it™ consists of woven copper mesh that is durable and highly flexible. It can be inserted around pipes and into small crevices with a flat-head screwdriver. Its woven nature allows caulk or foam to easily penetrate and lock the material in place. Cut the fabric to the desired length with tin snips or heavy-duty scissors. Be aware that rodents can gnaw through this material. X-cluder™ fill fabric consists of nylon fabric impregnated with strands of stainless steel wire. Wear gloves when handling it to prevent injury. The material is flexible, but not as flexible as Copper Stuf-it™. The impregnated stainless steel fibers may provide greater resistance to gnawing by rodents.


Exterior Doors


Doors should fit tightly enough so that the distance between the bottom of the door and the threshold is less than ¼ inch. It may be easier to build up the threshold than to modify the door. Steel pipes make good rodent-proof thresholds and allow doors to swing freely. Install flashing or a metal channel on the lower edge of doors, particularly softwood doors. The flashing should extend to within 1/inch of the door edge at the sides and bottom.


Mechanical door-closing devices save time and reduce the likelihood of a door getting propped open. Doors that are left open for ventilation should have rodent-proof screen doors added, or modified so the upper half can be left open for ventilation.


Foundations and Floors


Gaps or flaws often exist along building exteriors where the wall framing or siding meets the foundation at the sill plate. These gaps provide easy access for rodents. Rats can burrow beneath the floor or foundation of a building that rests on piers or shallow foundation walls. Prevent their entry by extending foundation walls at least 36 inches belowground. The potential for damage from frost also will be reduced. Alternatively, place 18 inches of compacted sharp gravel under the slab to discourage rodent burrowing. Repair cracks in foundations with concrete or masonry grout. If rodents have access to the crawl space of a building, modify the floor to prevent them from getting into the walls.


Figure 13. Crushed stone can be an effective deterrent to burrowing animals. Photo by Stephen M. Vantassel


Maintain a clean, 3-foot wide, weed-free area around building foundations, concrete slabs, and footings to discourage rodents from burrowing. This makes it easier to see holes, burrows, or other wildlife signs as well. Maintain the buffer by mowing vegetation regularly or by applying 1½ inches of crushed rock to a depth of 3 inches along a 24-inch-wide strip (or wider) around the structure (Figure 13).


Climbing Animals


Prevent squirrels, mice, and rats from climbing a structure by installing a 12- to 18-inch wide aluminum sheet metal band at least 36 inches above the ground. Seal openings in walls and floors with sheet metal. Cut two or three lengths of Model S Nixalite® spikes (1 foot each, Figure 14) and install them 4½ inches apart as measured from each base. The lowest row should be 8 feet above the ground to prevent accidental impalement. Never use spikes with an active raccoon infestation.


Figure 14. Model S Nixalite® spikes


Protecting Decks, Sheds, and Foundation Crawl Spaces


Structures that lack full foundations (e.g., trailers, sheds, and decks) are vulnerable to entry by skunks, woodchucks, raccoons, and other burrowing animals. Crushed gravel is not sufficient for these situations. Instead, use shallow trench-screen to prevent animal access (Figure 15).


Figure 15. Trench-screen will protect a crawl space. Image by Michael S. Heller.


Increase the depth and skirting of the screen in locations subject to frost heaves or with wildlife that have a tendency to dig aggressively. Use ½-inch mesh if more airflow is needed. Pay special attention to corners to ensure that they are properly protected. Overlap screens 4 to 6 inches to prevent any gaps that could be exploited by digging animals.


Special Situations


Some products are designed to address specific problems. Many homes with vinyl siding allow rodent access at the bottom of corners of the structure. Kritter Kaps™ provide an easy way to secure these openings (Figure 16).


Figure 16. Kritter Kap™ used to secure vinyl siding. Photo by Stouffert Technologies.


Protecting Structures from Birds


Figure 17a. Cat Claw® (top) and Nixalite® spikes (bottom) are two of many models of bird spikes. Photo by UNL.


Nets are useful for preventing access to joists and trusses. Nets also can be installed vertically to prevent birds from accessing walls and ledges. Several ledge products such as spikes (Figures 17a and b), coils, wires, electrical shock tape, and slants are available to exclude birds from ledges. Grid wire systems on flat roofs may prevent birds from nesting and roosting.


Figure 17b. Bird spikes prevent birds from landing on a window ledge. Photo by Jan Hygnstrom.


Other Exclusion Methods


Cone guards keep pests away from birdfeeders and nest boxes on poles. These barriers are round, flat sheets of metal with a hole in the center. To install a cone guard, place the metal sheet on top of the pole. The pole should go through the center hole in the metal sheet. Position the metal sheet between the ground and the birdfeeder or nest box. When pests try to climb the pole, the metal sheet usually will prevent them from reaching the feeder or the nest box.


Rollers are long, cylindrical wheels with supports on each end. They are mounted on peaks of roofs, signs, ledges, and other narrow locations where birds loaf. Birds land on the rollers. When the wheels roll, the birds fall off. This drives some birds away from the site.


Other methods include lines, wires, flappers, slants, spikes, coils, and shock tape. Each method has been developed for use in specific situations such as over water, in wastewater treatment systems, or on ledges.


Protecting Individual Trees and Plants


Use wire or plastic tree guards to protect trees from trunk girdling by wildlife. More expensive wire guards provide longer-term damage prevention. When using tubes to protect plants, place screen over the top to prevent entrapment of cavity-nesting birds. Use nets to protect trees and other plants from bird depredation. Ensure that the nets reach the ground, as birds may try to fly or walk underneath.


Protect young trees from animal damage by installing a 1- x 2-inch wire mesh fence around the tree. Wire or plastic mesh will protect plants from deer (Figure 18). Anchor the fence securely to posts, as animals will bend it to reach branches or the trunk. The fence should be 4 inches away from the trunk for beavers and 4 inches away from the branches for deer. Extend the fence 4 feet high for beavers and 6 feet for deer. Bury the lower edge of the fence 6 inches into the soil to prevent beavers from digging under it.


Figure 18. Plastic mesh fence protects a shrub from deer. Photo by Paul D Curtis.


Fences are the most reliable exclusion technique for preventing damage to nursery stock, gardens, and crops.


Fencing Large Areas and Crops


Non-electric barriers prevent access to many species and have the added benefit of low maintenance. Dimensions and the type of fence depend on the species to be excluded (Table 2).


Unfortunately, fences can be expensive if large areas need protection. While requiring lower maintenance than electric fences, non-electric fences typically cost much more to install due to the high cost of woven wire, posts, anchors, braces, fasteners, and labor.


Electric fences act as behavioral deterrents. They use a painful but harmless shock to interfere with wildlife movements. They often have lower initial construction costs but require higher continued maintenance. Electric fences fail to prevent wildlife damage when unsuitable designs are used, they are not installed according to manufacturer specifications, or maintenance is inadequate. Frequent monitoring and vegetation control are required to maintain sufficient shocking power (at least 3,000 volts) on the fence.


Electricity can be used exclusively with a fence, as with the poly-tape fence, or in conjunction with a non-electric fence. Electric fence technology has improved dramatically over the years.


Types of fences to exclude wildlife


Species Fence Type Minimum fence dimensions
Deer Non-electric 8 ft high
Deer Electric 2 strands, 1 ft and 4 ft from surface.
Rabbit Non-electric 1-in mesh buried 4 in in the soil, extending 2 ft above the ground
Raccoon Electric 1-in mesh buried 2 in and extending underground 1 ft or more. Fence should extend 4 ft above ground with an electrified wire 6 to 8 in below the top. Or 2 strands of electric wire 5 & 10 in off the ground.
Woodchuck Non-electric 1-in mesh buried 2 in, extending underground 1 ft or more. Fence should extend 4 ft above ground and have 1-ft overhang to prevent climbing.
Woodchuck Electric Install non-electric fence without overhang. Place a strand of wire 6 to 8 in below the top. 1-in mesh buried 2 in and extending underground 1 ft or more. Fence should extend 4 ft above ground with an electrified wire 6 to 8 in below the top. Or a strand of electric wire 4 to 5 in off the ground.


Figure 19. Solar and battery-powered fence chargers may power polytape fences. Photos by Jan Hygnstrom.


Fences can be powered using electrical outlets, disposable batteries, or rechargeable batteries connected to a solar electric panel (Figure 19).


Modern low-impedance chargers deliver pulses of electricity that produce a painful, but not continuous, jolt of electricity. The gap in the pulse allows people and animals to move away from the fence. While the shock generally is considered safe for adults and older children, always consider the presence of young children in the area. Some powerful electric fence chargers can do serious harm to young children and people with heart pacemakers. Most chargers used in large agricultural settings can power over 200 miles of fence. Electric fences can be used to protect home gardens from deer and woodchuck damage during the growing season. Electric post-and-wire applications can be used to exclude birds from roof tops and ledges.


Supplies


This section highlights only a sample of the products available to help property owners and WCOs manage conflicts with wildlife by using products for exclusion. Technicians are encouraged to obtain product catalogs from wildlife control supply houses. Search the internet for additional supplies and information. Membership in trade associations and participation in trade shows will help keep you informed of new products reaching the market.


Frightening Devices


Frightening devices scare wildlife from a location through non-chemical means. Frightening devices fall into four categories: visual, audio, audio-visual, and biological. Wildlife often quickly get used to (habituate to) frightening devices, except perhaps, those that are biological.


The act of hazing is a technique in which dogs, hawks, falcons, or radio-controlled aircraft or boats drive problem animals from a site. Canada geese can be hazed with border collies to remove the birds from golf courses, public parks, and similar locations. Occasionally, hawks are used to chase other birds from airport runways.


Birds cannot be hazed in their nesting areas during the nesting season because of the Migratory Bird Treaty Act. Also, do not haze geese during their molt (usually June 15 to July 15), because they are vulnerable and cannot fly. Secure a permit that allows the taking of geese before beginning hazing activities. Even a well-trained dog might accidentally injure a goose while chasing it. Without a permit, this would be a violation of the Migratory Bird Treaty Act.


Visual Frightening Devices


Visual devices use sight to frighten wildlife.


Visual frightening devices include scarecrows, effigies (e.g., plastic owls), scary-eye balloons, and Mylar® tape. Visual devices vary dramatically in price, sophistication, and effectiveness. For example, some scarecrows actually move. These animated human effigies tend to work much better than the home-made kinds, which are better considered as garden decorations.


Figure 20. The owl effigy on this roof does not distress the gulls. Photo by Stephen M. Vantassel.


Stationary visual frightening devices are the least effective, as birds tend to habituate to them in a few days (Figure 20). Whenever possible, choose a frightening device that moves (e.g., sways in the wind, Figure 21).


Strobe lights are marketed to frighten wildlife such as squirrels and raccoons. Manufacturers claim the lights interfere with circadian rhythms, but this claim is untested. Geese and crows can be dispersed from a night-time roost by pointing a spotlight, laser pointer, or high intensity laser light at them.


Figure 21. Scary-eyes balloon. Image courtesy of Bird-X.


Audio Frightening Devices


Audio devices use sound to frighten wildlife.


Audio devices include propane cannons and distress calls. No evidence is available that supports claims that ultrasonic devices are effective in repelling wildlife. Propane cannons (Figure 8) emit a loud boom that is suitable only for rural settings. Distress calls have more versatility and can target specific species, such as crows. Volume can be a concern for neighbors. Check local ordinances and consider the effects on neighbors before using any noisemakers.


Audio-visual Frightening Devices


Audio-visual devices use sight and sound to frighten wildlife.


Fireworks-based noisemakers (a.k.a. pyrotechnic devices) include the items on the following list. Each must be fired by a person at the site.


Bangers (or bird bombs) emit a loud bang. They are launched from a hand-held pistol launcher. Bangers can be used at medium range (100 to 150 feet).


Screamers emit a long, drawn out whistle. They can be launched from a hand-held pistol launcher. The shell flies out about 100 feet, screaming and whistling all the way.


Figure 22. Propane cannon. Photo by UNL.


Audio-visual Frightening Devices


Audio-visual devices use sight and sound to frighten wildlife.


Fireworks-based noisemakers (a.k.a. pyrotechnic devices) include the items on the following list. Each must be fired by a person at the site.


Bangers (or bird bombs) emit a loud bang. They are launched from a hand-held pistol launcher. Bangers can be used at medium range (100 to 150 feet).


Screamers emit a long, drawn out whistle. They can be launched from a hand-held pistol launcher. The shell flies out about 100 feet, screaming and whistling all the way.


Shell-crackers (or crackers) make a loud bang that soundslowing list. Each must be fired by a person at the site.


Bangers (or bird bombs) emit a loud bang. They are launched from a hand-held pistol launcher. Bangers can be used at medium range (100 to 150 feet).


Screamers emit a long, drawn out whistle. They can be launched from a hand-held pistol launcher. The shell flies out about 100 feet, screaming and whistling all the way.


Shell-crackers (or crackers) make a loud bang that sounds like an M-80 firecracker. The shells are fired from a 12-gauge shotgun and explode 75 to 100 yards away.


Propane cannons with spinners are audio-visual frightening devices. Unlike the bangers, screamers, and shell crackers, propane cannons can be used with timers so a person need not be present.


In 2011, the US Bureau of Alcohol, Tobacco, and Firearms increased the restrictions on the purchase of these devices. In addition, these devices usually require permits in urban and suburban areas. They may pose fire hazards and risks of bodily injury.


Biological Frightening Devices


Guard animals such as dogs and llamas sometimes are used to protect livestock, especially sheep, from predators.


The livestock and the guard animal must be kept within a fenced area. Dogs can protect orchards, Christmas tree plantations, or vineyards from deer or turkey damage. Dogs within an invisible-fence system may reduce deer damage to home garden and landscape plantings.


Repellents


A repellent is a chemical that deters an animal pest from a specific location or from damaging activity. In most states, repellents are considered pesticides when used in commercial applications and must be applied by a certified applicator.


Chemical repellents may be:


  • Oral: A chemical that tastes unpleasant or even causes pain (spicy hot).
  • Tactile: A chemical that feels unpleasant (gooey or sticky).
  • Olfactory: A chemical that smells unpleasant or promotes fear of a natural predator (ammonia or rotten-egg odor).


When used properly, chemical repellents are not toxic to target animals. The effectiveness of repellents often is highly variable, depending on the motivation of problem animals, alternative resources, previous experience, and active ingredients of the repellent. Repellents work best if alternative food and shelter are available to the pest and pest populations are low.


Repellents typically are sprayed on vegetation until it starts to drip off the leaves. Most repellents are available as liquid sprays, but some are available as granules, powders, and sachets. Repellents may have to be reapplied after rainfall or to protect new plant growth.


Oral Repellents


Apply oral repellents to vegetation, seeds, or fruit. The bad taste of these chemicals may discourage birds, deer, and other pests. The effectiveness of oral repellents depends on the availability of other food. When food is scarce, repellents are less effective because the animal has few or no alternative foods. This means the animal is more likely to eat the high-value food in order to survive.


Capsaicin is an active ingredient responsible for the heat in peppers. When used as a repellent, it causes pain to animals that eat it.


Another oral repellent, Flight Control™, contains anthraquinone that causes gastrointestinal distress. When geese eat the treated vegetation, they vomit. The repellent changes the ultraviolet reflection of the grass where it is applied. After eating treated areas and becoming sick, when geese see the reflection, they may learn to avoid treated areas in the future. This repellent, registered for geese in some states, is available for turf grass, ornamental plantings, and landfill areas.


Tactile Repellents


Tactile repellents are most useful in keeping roosting birds away from buildings. You can apply most of them with caulk guns. Others are available as liquids, aerosols, nondrying films, and pastes. The mixtures work by making the birds’ feet uncomfortably sticky.


Improper or excessive application of tactile repellents may foul the feathers of non-target birds. It also can entrap birds on ledges or other sites. Dead birds that stick to ledges will decay and are difficult to remove. This not only violates label laws, it can create a sanitation problem as well.


Apply sticky repellents about 1/2 inch thick in rows spaced no more than 3 to 4 inches apart. Increase or decrease row spacing depending on the size of the pest birds. Birds should not be able to land between the rows without contacting the repellent. Treat all roosting and loafing surfaces in a problem area or the birds will move a short distance to an untreated surface. When applying tactile repellents to buildings, clean the surfaces first. Then cover the surfaces with tape and apply the chemical to the tape. The tape will act as a barrier between the chemical and the surface. Otherwise, some materials may be difficult to remove or may stain the building.


Tactile repellents often become less sticky over time, especially in dusty areas. Usually, these materials will repel birds for less than one year before a second application is necessary. Always read the label for specific information and application instructions for each repellent used.


Olfactory Repellents


Olfactory repellents try to deter mammals through certain odors. Human hair, predator urine, soaps, and chemical-based rotten-egg repellents sometimes have this effect. For example, coyote urine may cause herbivores to flee due to fear. Naphthalene (the active ingredient in mothballs) may work to repel vertebrate pests. However, you may only use naphthalene-containing products that are specifically registered for vertebrate control.


Figure 23. Representatives of 3 different formulations of rodenticide bait. Photo by LiphaTech®.


Toxicants


Toxicants are chemical compounds used to intentionally kill or impair target species.


In nearly all states, a pesticide applicator license is required to recommend or use of chemicals and toxicants to kill wildlife. Training for the use of toxicants should come from the requirements for the pesticide applicator license. The information provided here and in the module on pesticide safety are an overview of the use of toxicants.


“Target species” refers to animals that are the target of management. “Non-target species” or “non-targets” refer to wildlife, livestock, pets, and people that are not the target of management and could be harmed by toxicants.


Toxicants can impact non-targets through primary exposure (direct ingestion), or secondary exposure (consumption of an animal that has eaten the chemical). When misused, misapplied, or sometimes due to unfortunate circumstances, toxicants can pose a threat non-target species. Safeguards may be in place to minimize these risks, but in many situations, it is best to use reduced-risk alternatives to toxicants.


Toxicants can be beneficial and effective tools for controlling vertebrates such as house mice, Norway rats, pigeons, starlings, and house sparrows. Vertebrate toxicants can be applied in many forms and delivery methods to protect structures, turf, landscapes, cropland, rangeland, and other sites.


Public attitudes toward toxicants vary greatly. Some pest management professionals rely too heavily on pesticides when alternative, reduced-risk approaches may be just as, or more, effective. Excluding rodents from buildings is more effective in the long term than setting up toxicant bait stations. Alternatively, some people are so opposed to the application of chemicals in the environment that they oppose all use of toxicants. Opposition of this sort can be short-sighted in situations where damage is severe, human health concerns are high, and pesticides can be applied safely with minimal risk to the environment.


There are few toxicants other than rodenticides and some bird control products that are registered for use on mammals and even then, these toxicants may only be administered by federal agencies or with special permits.


Toxicants can be an important component in an IWDM strategy to reduce overall damage when implemented with other control methods, such as sanitation and exclusion.


Review the module on Pesticide Safety for more information on the use of toxicants.


Shooting


Firearms include pistols, shotguns, rifles, and air rifles (high-end pellet guns).


Shooting is appropriate for use with medium to large mammals (squirrel-sized and larger), birds, and reptiles. Shooting requires training and skill. Safety concerns and legal restrictions must be considered before shooting. For proper training in the use of firearms, attend a hunter education course or a training course sponsored by the National Rifle Association (NRA).


If an animal is restrained, shooting may be one of the fastest and most practical ways to humanely kill a wild animal.


General tips for the use of shooting


  1. Take the time you need to take the best shot.
  2. The type of firearm you choose and the ammunition should be matched to the size and species of the animal.
  3. In most cases, small-caliber, low-energy projectiles are best. A .22 caliber rifle is adequate for most small mammals. Air rifles may be used on squirrels and birds. Among the most effective types of ammunition are hollow point bullets or low velocity .22 rimfire cartridges, such as shorts or CB caps, which are also quieter.
  4. Pay attention to the surface underneath, around, and behind the animal. Could a bullet ricochet? Bullets are less likely to ricochet off softer surfaces such as dirt or grass than off hard surfaces like concrete, asphalt, or rocks, or water.
  5. You must follow both state and local firearms regulations.
  6. Make sure the situation is safe. If a crowd has gathered, disperse them before you shoot the animal, or take the animal elsewhere.
  7. Some species continue to move after they’ve been shot, such as squirrels, birds, raccoons, opossums, and woodchucks. This is a reflex but can be difficult to explain to someone who’s watching. A good reason to be discreet.


Guidelines for shooting mammals


If you need to do a rabies test, don’t shoot the animal in the head. You might destroy so much brain tissue that the lab wouldn’t be able to do the test, and you could spray potentially contaminated brain tissue into the air, which might expose you to the virus if the tissue came into contact with your eyes, mouth, or nose. (Rabies virus by itself is not airborne.) Instead, aim for the heart and lungs. The heart/lung target may also be a better option if dealing with a free-roaming animal, such as a deer.


Target areas for the brain or heart/lung shots shown on a fox (illustration not to scale). The target areas are the same for most mammals, with the exception of the opossum.


Target areas for the brain or heart/lung shots shown on a fox (illustration not to scale). The target areas are the same for most mammals, with the exception of the opossum.


What if you shot an animal in the head, and later learned that a rabies test is needed? Don’t panic. Submit the specimen. In many cases, the specimen will be adequate. What about that worst-case scenario, when it’s not possible to do an accurate rabies test? Then, as a precaution, the exposed person or animal would receive the post-exposure rabies vaccinations. That’s not fun, and there’s a limited supply of one of the drugs that’s given as part of this series, so don’t be cavalier about the quality of the specimens you submit for rabies tests.


Although the head shot (aiming for the brain) is often considered faster and more humane than the heart/lung shot, this isn’t necessarily true. Please note that few people would be able to ensure a proper head shot at anything except close range.


To properly target either the brain or the heart/lungs, you must think in three dimensions. Without proper aim, the bullet could deflect off the skull. For the brain shot, the barrel of the firearm should be a few inches from the head. Ideally, aim so the bullet will travel through the brain and spine and lodge in the animal’s body. If the animal’s head is turned so you don’t have the right target, you may be able to distract it and get it to move its head by tossing a rock.


Target areas for the brain or heart/lungs shots shown on a opossum (illustration not to scale). Opossums have very small brains housed in a reasonably large skull. This means the target area- the brain – is actually much smaller than you’d imagine, just from looking at the size of the animal’s head. Their brain is about the size of a pea.


Opossums also have a very big crest that runs down the center of their skulls, called the “sagittal crest”. It’s very strong to deflect bullets. Unfortunately,, if you try to aim slightly off to the left or right to avoid hitting the crest, you miss the brain entirely. A side target might be a little easier. Imagine a line drawn between the eye and the ear, and aim closer to the base of the ear.


Guidelines for shooting birds 
(unprotected species)


House sparrows, starlings, and pigeons can become trapped within large buildings such as malls, warehouses, and airport terminals. These structures often have food, water, and even nesting resources that allow the birds to survive. One of the most effective ways to remove a small number of birds from a large building is with an air rifle. Choose a higher end model with a scope for improved accuracy and performance. Most often, you’ll shoot the birds when the building is closed to the public. (Although pellet guns are not as powerful as gunpowder firearms, there are still risks to human safety, and to property.) Learn where the birds roost, then choose a position that will provide you with good shots. The building management may have a lift that will provide you with an elevated platform.


Advantages of shooting


  • shooting is one of the fastest and most humane methods for killing wildlife
  • it will work with many different species, under many conditions
  • minimizes the handling of a live animal


Disadvantages


  • may splatter brain tissue, saliva, or blood, which could expose someone to wildlife diseases
  • may interfere with the collection of the tissue sample needed for the rabies test
  • cannot be done everywhere. There are legal restrictions and safety concerns that limit its use
  • requires skill and proper equipment
  • can be dangerous to people and other species


Firearm Safety


  • Treat every gun as if it is loaded
  • Control muzzle direction
  • Be sure of your target & beyond
  • Keep barrel & action clear of obstructions
  • Unload firearms when not in use
  • Never point a firearm at anything you do not intend to shoot
  • Don’t climb a fence or tree, or jump a ditch with a loaded gun
  • Never shoot at a flat, hard surface or water
  • Store firearms & ammo separately
  • Avoid alcoholic beverages when using guns


Rules of firearm safety that apply to WCOs


Many WCOs carry firearms to shoot animals caught in traps. Take a hunter education course to learn about firearm safety. Practice safe habits around firearms at all times


When working in the field it is generally a good idea to keep your firearm unloaded until you need to use it. It can be difficult to maintain control of a firearm when you are carrying gear and making sets.


When you shoot a firearm at an animal in a trap be careful about ricochets off the trap or rocks. If you are working with companions, everyone should stand behind the shooter.


Always look beyond your target when shooting a firearm and only shoot if it is safe. Keep the muzzle under control and pointed in a safe direction at all times, even when the gun is not loaded.


Figure 24. Shotguns and rifles are important tools in WDM. Photo by UNL.


Trapping


Traps are devices that can capture wildlife without the WCO being present.


Traps are the tools most often used by WCOs to remove wildlife. The information on trapping that is provided in this section is important to WCOs for managing problem wildlife in urban environments.


You can take the AFWA basic trapper training program at http://conservationlearning.org .


Figure 25a. Cage trap. Image courtesy of the Best Practices for Nuisance Wildlife Control Manual.


Live trapping


A live trap is meant to capture an animal without killing it. Live traps include cage traps (Figure 25a), box traps (Figure 25b), multiple-capture traps, foothold traps, nets, cable-restraints, and a variety of bird traps.


Live-trapping has many advantages. For example, you can see what you have captured and demonstrate success to the client. It prevents animals from dying in inaccessible locations, which is a hazard of using toxicants. With live-trapping, you avoid the foul odor caused by decay that could attract other pests and is a nuisance itself. In most cases, if you are using a live trap you can release non-target animals that are caught accidentally.


Figure 25b. Dura-Poly plastic catch box trap. 
Photo by Wildlife Control Supplies, LLC.


Live-trapping has disadvantages, as well. It usually is labor-intensive and you may capture the wrong animal. If a live trap is used improperly, an animal may die in it from lack of food or water; capture stress; from weather extremes ranging from heat in summer to cold in winter; or from attacks by wildlife, pets, or people. Some animals might hurt themselves because of the stress of being restrained, or while trying to escape.


If you’re not experienced with live traps, we strongly recommend that you seek hands-on training—especially before using foothold traps. There are several excellent courses, including the DEC Trapper Education Course, and the Trapper’s College and Furbearer Management Short Course offered by Fur Takers of America. Sessions on trapping techniques are often incorporated into seminars, conferences, and conventions sponsored by NWCO associations and trapping associations (see the resource list for state and national contacts). There are opportunities for one-on-one instruction, too. Experienced trappers often advertise such services in trade journals. You’ll also find many books, videos, and magazines about trapping.


Tips for live trapping mammals in an attic using a cage trap


  • Set the trap on the roof, as close to the entry hole as possible. Why not in the attic? Because adult raccoons seem to be less wary of traps on the roof than they are of traps placed in attics or on the ground.
  • With a roof set, you can safely use a few baits that wouldn’t be recommended for a ground set, such as pet food, because non-target animals aren’t as likely to go up on a roof. Avoid oily fish products such as sardines, because they might stain the roof.
  • With a roof set, you can also check the trap from the outside of the building.
  • How will you keep the trap from sliding off the roof? If the owner agrees, drive screws part way into the roof, then wire the trap to the screws. Once the trap is secure, finish driving the screws into the roof, then dab some roof sealant onto the heads of the screws.


Tips for live trapping mammals on the ground using a cage trap


  • Set the trap in the animal’s travel path, or in an area the animal uses often. (Look for sign.)
  • Choose a bait that will appeal to the target animal but not attract unwanted animals. For example, pet food attracts raccoons—and cats and dogs. If you want to trap a raccoon, a better option might be marshmallows, which aren’t as enticing to cats. Eggs are sometimes used as bait for skunks. Apples or raw vegetables are good woodchuck baits.
  • Covering the bottom of the trap with soil or leaves may also convince an animal to enter.
  • Raccoons may respond to a visual attractant such as a piece of aluminum foil suspended from the roof of the trap.
  • There are many commercially available scent lures. Just be aware that lures may attract unwanted species, too. NWCOs tend to use lures when they’re dealing with a trap-shy individual, or must set their trap away from the nuisance animal’s favorite areas.
  • After you have the trap set and baited, “dry fire” or trip the trap. Make sure the trap door(s) close smoothly and firmly.


Cage and Box Traps


Cage and box traps are important pieces of equipment for most WCOs. Cage traps often are made of wire while box traps often are made of solid material. The traps are available in many sizes and styles and may open on one or both ends. For example, squirrel-sized cage traps can fit into woodstoves and chimney pipes. Customers may call cage traps Havaharts® after a popular model, but many designs and manufacturers exist, including Tomahawk® and Safeguard®.


Cage and box traps are easy to set and double as animal carriers. An animal enters a cage or box trap and steps on a treadle, which causes the door(s) at the end(s) of the trap to close. Typically, little site preparation is needed. They generally present little risk to children and pets. Most people think they are humane, but some animals may hurt themselves because of the stress of being restrained or while trying to escape. Most cage traps are bulky and are difficult to conceal because of their size and shape, making them vulnerable to theft and vandalism. They are expensive and require frequent cleaning.


Cage and box traps are not universally effective in capturing animals. Some species, such as coyotes, may avoid themmost WCOs. Cage traps often are made of wire while box traps often are made of solid material. The traps are available in many sizes and styles and may open on one or both ends. For example, squirrel-sized cage traps can fit into woodstoves and chimney pipes. Customers may call cage traps Havaharts® after a popular model, but many designs and manufacturers exist, including Tomahawk® and Safeguard®.


Cage and box traps are easy to set and double as animal carriers. An animal enters a cage or box trap and steps on a treadle, which causes the door(s) at the end(s) of the trap to close. Typically, little site preparation is needed. They generally present little risk to children and pets. Most people think they are humane, but some animals may hurt themselves because of the stress of being restrained or while trying to escape. Most cage traps are bulky and are difficult to conceal because of their size and shape, making them vulnerable to theft and vandalism. They are expensive and require frequent cleaning.


Cage and box traps are not universally effective in capturing animals. Some species, such as coyotes, may avoid them. Even individuals of species that generally are easy to catch in cage or box traps, such as raccoons and gray squirrels, can be trap-shy, especially if they have been captured previously.


Foothold Traps


Foothold traps (Figure 26) are live traps and, as the name suggests, are designed to capture an animal by the foot.


Leg-hold, while a common term, actually is inaccurate, as animals should not be captured by the leg due to the risk of breaking bones. Footholds can be used in land sets, water sets (streams, lakes), and under ice. They are the most efficient tools for catching coyotes and foxes and often are important for trapping raccoons, beavers, muskrats, and nutria during wildlife control activities.


Several designs of foothold traps are available, including the coil-spring trap, which probably is the most common. To set a coil-spring trap (Figure 27), fully depress the spring levers, thereby compressing the springs.


Place the dog (trigger hook) across the nearest jaw until the tip of the dog fits into the notch of the pan. The dog holds the trap open in its set position. When an animal steps on the pan, it dislodges the dog from its notch, which springs the trap, and the jaws close around the foot of the animal.


Figure 26. No. 2 coil-spring foothold trap. 
Photo by Dallas Virchow.


In some cases, standard coil-spring traps can be modified by padding or laminating the jaws to reduce the chance of injuring the captured animal and possibly increase the effectiveness of the trap. Commercial models are available with these modifications.


Many WCOs add at least one swivel between the trap chain and the stake that anchors the trap to the ground. Swivels allow the captured animal to move around without binding the chain and twisting the leg. Most swivels within the chain are double, but single swivels usually are used at the end of the chain. Many WCOs modify their traps so the chain is attached to the center rather than the end of the trap. When used with the swivels, this can help align the trap at a better angle to prevent injury. Some trap manufacturers set their traps up in this manner, but most trapping suppliers sell hardware for the modification. Another modification is to have a shock-absorbing spring in the chain. Set the trap in an area that is free of anything that may entangle the chain.


Figure 27. A coil-spring foothold trap. Image courtesy of Best Practices for Nuisance Wildlife Control Manual.


Adjust the pan tension on coil-spring traps to reduce the chance of capturing the wrong species. An animal that weighs less than the target species should be able to step on the pan without triggering the trap. Adjust the pan tension by tightening or loosening the pan tension (adjustment) screw, which controls the amount of pressure needed to spring the trap. The tighter the screw, the heavier the animal must be to spring the trap. All of the tactics and modifications are used together or in various combinations to reduce injury to a trapped animal. While the overall goal is to reduce injury to animals, the opinions and sensitivities of clients and the public also must be considered.


Most states restrict the use of foothold traps, including jaw spread and where and how they may be set. The jaw spread refers to the distance between the two jaws when the trap is set, not counting the thickness of each jaw.


Enclosed Foothold Traps


Enclosed foothold traps (sometimes called species-specific traps) rely on the animal pulling rather than pressing on the pan or trigger. An enclosed foothold trap has the trigger in a tube, which reduces the capture of non-targets. Several traps are available including Lil Grizz® (Figure 28), Egg trap®, Coon Cuffs®, and Duffer’s Raccoon Trap®.


Figure 28. Lil’ Grizz Get’rz ® trap for raccoons. 
Photo courtesy of Wildlife Control Supplies, LLC.


Cable-restraint Traps


Cable-restraints, sometimes called snares, use a wire to capture an animal around the neck, body, or leg, and hold it without killing it. Sometimes the difference between a cable-restraint and a lethal snare lies only in the way the device is set.


Cable-restraints are either passive (gravity-operated) or active (spring-operated). Brands of cable-restraints include Belisle Footsnare® and Collarum® (Figure 29). Some states have restrictions on the use of cable-restraints for wildlife control. Check your local regulations.


Figure 29. Collarum® trap, primarily used for coyotes. Photo by unknown.


Body-gripping Traps


Body-gripping traps (Figure 30) are spring-loaded, lethal traps. They should be used only in areas where non-target captures are unlikely, especially domestic dogs and cats. Several sizes are available. They usually are square, but some specialized models are round. Body-gripping traps often are called Conibears®, which is the name of a popular model manufactured by Oneida-Victor, Inc. Several designs are available, including some with one-way triggers that are more selective and some designed specifically for squirrels.


When setting a Conibear-style trap, use the safety hooks or rings and a safety clip when positioning the trap. Be sure to release the hooks or rings and remove the clip before leaving the set.


Figure 30. Diagram of a body-gripping trap. Image by Best Practices for Nuisance Wildlife Control Manual.


“Magnum” or “zero tolerance” body-gripping traps are available. They are stronger and the jaws close very tightly, so they often kill faster and more consistently than standard traps.


They may increase the chance of a proper strike with squirrels, raccoons, or other small or flexible animals that might pull back if there is a slight gap between the jaws. Magnum versions are very strong (a No. 220 Magnum body-gripping trap can break bones), so consider using setting tools and safety devices and be very careful when setting this kind of trap.


To set a body-gripping trap, compress the spring until the tips nearly meet at the rotating point of the jaws. Hold both jaws open and fit the dog (a.k.a. the trigger hook), which is notched, into the notch located on the trigger. When securely in place, the dog holds the jaws open. In its correct position, the jaws of the trap close on the top and bottom of the neck or chest of the animal. Traps positioned to strike the animal on the side of the body do not provide adequate time to death in a non-submerged situation.


Stabilize the trap to keep it in this top-to-bottom striking position and to ensure that it cannot be knocked over easily. Anchor the trap. The traps are light enough to be carried off by predators that are attracted by the captured animal. Some models of body-gripping traps have safety hooks that hold the springs to prevent the trap from closing. If you use safety hooks, remember to release them after the traps are set.


When an animal passes through the jaws of a trap, it moves the trigger, which dislodges the dog from its notch and springs the trap, closing the jaws around the neck or chest of the animal. Ideally, the trap catches the animal directly behind the head, snapping the spine in the upper 1/3 of the neck (cervical vertebrae). A proper hit provides a quick death.


If you are trapping raccoons, skunks, squirrels, or woodchucks, modify the trigger to help ensure a top-to-bottom strike, which is more humane. These species do not tolerate anything brushing against their eyes or whiskers, so separate the trigger and center it on the bottom of the trap to prevent the animal from refusing to enter the trap. As with all lethal techniques, you should ensure that only the intended target animals are caught. Body-gripping traps often are set in front of an animal’s entrance hole because the animal must pass through the jaws of the trap to be captured (Figure 31), ensuring only an animal using the hole will be caught.


Figure 31. This No. 120 body-gripping trap was set over the entrance to a squirrel den. These traps should not be visible to the public. Photo by Stephen M. Vantassel.


Use hardware cloth to reduce the size of the entry hole or to block escape routes. Body-gripping traps often provide the quickest way to remove a raccoon or squirrel from an attic, but this trap is not appropriate for all settings. Use extra caution if you are setting a body-gripping trap on the ground because of the risk to people, pets, and other wildlife. Modify your technique and equipment to minimize these risks.


One way to lower the risk of catching a non-target animal is to use a vertical cubby set. The cubby set is a baited box that is open on one end with the trap set well inside, usually held in place by friction between the springs and a notch in the box. Use a model with two springs because those with a single spring do not stay in place. Anchor the trap so it will remain in the cubby after it is sprung. Place bait on a shelf near the top of the box. In set position, the trigger and jaws are within the box and the spring sticks out to the left of the box (Figs 32a and 32b).


Figure 32a. Body-gripping trap box with lid off showing placement of trap and bait.


Figure 32b. Body-gripping trap box with trapped raccoon.


The deep-notch box (Figure 33) is an alternative to the vertical cubby set. Center the trigger on the top of the trap. Place bait deep inside the box, at least 6 inches behind the set trap. By restricting the size of the opening, you reduce the risk that a dog will spring the trap. The opening height of a deep-notch box should be no more than 6 inches off the ground.


Figure 33. Deep-notch body-gripping trap cubbies can be made of square or round boxes. Photos by Best Practices


Although the vertical cubby set and the deep-notch box work on the same idea, and are interchangeable, they have different strengths. The vertical cubby is less likely to attract cats, unless the wrong bait is used, and is more dog-proof than the deep-notch box. Sometimes a raccoon will avoid a vertical cubby but investigate a deep-notch box. With a two-way trigger, a trap can spring regardless of which way the animal approaches. It can catch an animal on its way out of its den, which is what you want, but it might also accidentally capture an animal that stopped to investigate. In some cases, that might be a non-target animal. Commercial traps with one-way triggers are available.


Mouse and Rat Snap Traps


Figure 34. Mouse sized snap traps


The familiar mouse trap is a body-gripping trap (Figure 34). If the target is mice or rats, you will need several traps. Many options besides the traditional mouse snap trap are available.


Snap traps with expanded triggers and the clamshell design (Figure 35, left) are much easier to set than the traditional mouse trap.


Figure 35. Many styles of snap traps are available to trap mice. Photo by Jan Hygnstrom.


The Quick Kill Mouse Trap® made by Victor® has a lid over the bait cup. Only animals that seek the bait will lift the lid, which is what triggers the trap. An animal can accidentally step on the lid without setting off the trap. The bait cup is located to position the mouse in the perfect strike position. This trap is more selective and more effective than traditional snap traps.


Multiple-capture Traps


Multiple-capture traps can catch more than one animal without having to be reset. Most multiple capture traps are designed for mice. Some brands, such as the Ketch-All®, will catch animals up to the size of a chipmunk, although larger animals are likely to suffer harm. Some designs (e.g., Ketch-All® and Kwick Katch®) have a wind-up spring that powers a rotating mechanism. Other traps (e.g., Victor Tin Cat®) have one-way doors that allow mice to enter but not leave. Check live traps often enough, usually daily, so that animals are not stressed or exposed to extreme temperatures.


Mole Traps


Mole traps are available in several designs (Figure 36). They are all set on, in, or underground at the tunnel. The key to successful trapping of moles is to identify active tunnels. Look for ridges, molehills, dead grass, and soft spots in the lawn. Prepare the site and set the trap according to the instructions given for the trap. If there is no activity after a few days, move the trap. If moles are active near the trap but you are not catching them, add more traps or switch to another type of trap.


Figure 36. Harpoon-, scissor-, and choker-style mole traps (clockwise from top). Photo by UNL.


Glue Boards


Glue boards have a layer of long-lasting adhesive spread over a surface, usually cardboard or plastic. Small animals stick in the adhesive. Although some consider glue boards a live trap, they often are not used that way. Animals can be removed from glue boards by applying oil to the adhesive, but the oil may harm the animal. In practice, animals frequently are left to die on glue boards. Glue boards are not recommended as a general-use tool. They may be needed to deal with some severe infestations of mice or rats. Snap traps often are more effective than glue boards and are more humane, although setting them does take more effort. If you use glue boards, check them frequently and humanely kill trapped animals.


Figure 37. Trap for pigeons. Photo by Tomahawk Live Trap Co.


Bird Traps


Traps for birds are available in many designs (Figure 37). Some will capture one bird at a time, while others can capture many birds. Others capture specific species of birds. Remember to check federal regulations before trapping birds.


To increase your chance of success, habituate birds to the trap. First, put out some bird seed (shelled corn for pigeons) or other appropriate bait to habituate birds to feeding in the area.


When birds are regularly feeding at the site, place the cage trap next to the bait and prop it open with wires. Place bait outside and inside the trap to encourage the birds to enter the trap. If the birds do not come to the site, choose another area. Finally, when birds are accustomed to entering the trap, set the trap and place the bait only inside. Leave a captured bird inside the trap as a decoy. Give them shelter, water, and food daily.


Trapping Sets


A set encompasses the use of the trap and its entire placement. Trapping sets can be described as either lethal or non-lethal. Footholds, cable-restraints, and in some cases, cage traps can be situated in ways that allow the captured animal to die or live. Footholds, for example, can be attached to slide-wires that force the animal to enter deep water and drown. Cable-restraints can be set in areas with entanglements that cause the animal to get hung up and strangle. Set a cable-restraint in an area lacking in entanglements and with stop-locks and the animal will be alive when you arrive. Sets are categorized as blind, positive, or baited.


Blind sets rely on the movement of the animal to trigger the trap. No bait is used. Cable-restraints set along trails are classic examples of blind trapping. Blind sets can be used with foothold, cage, and box traps.


Positive sets place a trap directly over a den hole to force the animal into the trap (Figure 38). Cage traps with double doors can be positioned directly in front of a den hole and barricaded to direct the animal into the trap. Positive sets have an advantage in that you do not refresh bait. In addition, they substantially reduce the risk of capturing non-targets.


Figure 38. Raccoon-sized single-door cage trap set in positive trap style. Photo by Stephen M. Vantassel.


Baited sets are the most common. They rely on lure or bait to attract an animal to the trap. Use bait that selectively attracts the species. Marshmallows and sardines attract raccoons but marshmallows will not entice cats, so marshmallows are safer if you must trap where cats are free roaming. Cats are attracted to fat and protein-based baits, so choose sweet baits to reduce the likelihood of attracting cats. Mice are attracted by many types of bait that are appealing to other species but baits are not always necessary to attract mice. Instead, tie a cotton ball to the trigger. A cotton ball is an attractive bit of nest material to a mouse but is of no interest to many other species.


Trappers usually exploit an animal’s sense of smell.


Place baits or lures in a trap so that the odors can disperse into the air. One method uses a “Y” stick. Scoop out some of the bait with the stem of the “Y.” Insert the stem into the bait area of the trap so that the forked ends grab onto the trap mesh and allow the stem to dangle. With this method, the bait has very high exposure to the air around it while keeping the bait off the ground and away from ants. This technique allows the bait to remain attractive even if it rains. The small surface area makes it difficult for rain to wash it away and when it does, the bait falls to the ground where it may still be effective.


Figure 39. PVC pipe bait stick. Photo by Stephen M. Vantassel.


An alternative is to use a T-shaped plastic (PVC) pipe with holes in it (Figure 39). They are long-lasting and will not be thrown off center when you cover the cage with a cloth.


To use the PVC bait stick with liquid bait, attach a termination cap to the end of the PVC pipe. The location of the first drilled hole will determine the amount of liquid bait held. Use pressure on the end cap to secure it instead of glue to allow the liquid bait to seep out slowly, permeating the area with attractant.


Trapper’s wire and cotton balls are useful for liquid-based baits and lures in cage traps because cotton absorbs the bait or lure. Skewer cotton balls with wire and bend the wire so they will not slide off.


Make a loop in the other end to hang the wire from the cage. As with any hanging method, ensure that the stick or wire will not move much in the wind. Failure to consider this may allow the animal to grab the bait without getting close enough to depress the treadle. Hang the bait stick or wire towards the back half of the bait area.


In situations where hanging bait is not possible or practical, use eye appeal. One WCO uses Chef Boyardee® microwave lunch buckets. The small white plastic bowls have lids with holes. Bait is placed in the bowl and covered with the lid. The white bowl attracts the raccoon, the holes allow the smell to disperse through the air, and the lid helps protect the bait from being washed out in the rain. Yogurt containers with holes cut in the lids also work. Ensure that there is enough weight in the bottom of the containers so they aren’t blown over by the wind. Sight attractants are especially important for skunks or raccoons. Place marshmallows in the back of a trap to attract them in the dark.


Lures and Baits


Lures are concentrated odors and may be detected by wildlife from great distances. Trailing lures are helpful when traps cannot be set in the ideal locations due to safety or theft concerns. Lures can help bring the target animal to your trap. Lures tend to be liquid and fall into 3 categories: food-based, gland-based, and curiosity.


Figure 40. Paste bait. Photo by Tomahawk Live Trap Co.


Food-based lures trigger hunger and are scents that appeal to the animal’s appetite. Gland-based lures trigger sexual or territorial behavior. Urine is a gland-based lure. Urine should be treated as a biohazard. Do not expose your face or hands to urine. Curiosity lures are odors that likely are unfamiliar to the animal, yet attractive enough to cause the animal to investigate.


Baits typically are food-based materials used to attract animals into traps. They come in chunks, pastes (Figure 40), and powders. They are subdivided into sugary baits called “sweet baits,” or oil and protein baits called “meat baits.”


Direct Capture Control Methods


Some situations allow you to approach an animal, capture, and remove it in a single visit, without using a trap. Direct capture plays an important role in WDM. The proper equipment is important for safety of the WCO and animal.


A catch pole (snare pole) is a versatile tool for the capture and restraint of animals. It is a long stick with a noose on one end.


For most species, place the loop over the head of the animal and tighten the cable. Bobcats and housecats may suffocate if the loop is only placed around their necks. Place the loop over the head and one front leg if possible. Minimize the amount of time an animal spends in a catch pole. Some catch poles swivel, allowing the animal to twist without being injured. Commercial catch poles often lock after the cable is pulled tight, and also have a quick release.


Figure 41. Cat grasper. Photo: Tomahawk Live Trap Co.


Other hand-operated devices, often called cat graspers, incorporate a vice-grip closure on the end of a pole (Figure 41). They can be useful if you are trying to capture small animals or if you are not able to get a loop around an animal. Poles with a vise-grip closure usually do not have the restraining power of catch poles.


Gloves


We do not recommend grabbing wildlife using only gloves, except when dealing with juveniles.

Capture Nets


Capture nets, to be distinguished from nets used in exclusion, are available in varying designs such as throw nets, hoop nets, and mist nets. Throw nets are tossed over target animals. Hoop nets are attached to the end of a long handle and used to scoop up animals. The net should be deep enough to allow the hoop to be twisted to restrain the animal in the bottom of the net. A captured animal may climb out of a shallow net. The size of the mesh also is important. If the mesh is too large, the animal may force its head through and injure itself or strangle. If you must use a shallow net, immediately place the frame against a flat surface to prevent escape. You can further restrict the animal’s movement by carefully pressing on it with a stick. Encourage the animal to enter the net on its own, if possible. You may injure an animal while swinging a hoop net if you accidentally hit it with the frame.


Figure 42. CO2 net gun. Photo from Forestry Suppliers.


Mist nets are fine-threaded nets used to capture birds, such as sparrows and starlings inside warehouses. You will need training, skill, and federal and state permits to use mist nets to capture wild songbirds outdoors. Skill is needed to remove birds from the net without harming them. Mist nets should be monitored during use and removed immediately after use. Even veteran users can become frustrated trying to capture a sparrow or two in a net inside a large warehouse.


Snake Tongs


Snake tongs (Figure 43) are useful for grabbing a snake. Then, a snake hook can be used to pin the snake’s head to the ground. Use snake tongs carefully because it is difficult to tell how much pressure you are exerting; you could accidentally injure the snake. After the head is restrained, grasp the snake just behind its jaws with your thumb and forefingers and control the head. Support the body with your arm, a stick, or a pole while you carry it to minimize its stress and prevent the snake from thrashingthe loop is only placed around their necks. Place the loop over the head and one front leg if possible. Minimize the amount of time an animal spends in a catch pole. Some catch poles swivel, allowing the animal to twist without being injured. Commercial catch poles often lock after the cable is pulled tight, and also have a quick release.


Figure 41. Cat grasper. Photo: Tomahawk Live Trap Co.


Other hand-operated devices, often called cat graspers, incorporate a vice-grip closure on the end of a pole (Figure 41). They can be useful if you are trying to capture small animals or if you are not able to get a loop around an animal. Poles with a vise-grip closure usually do not have the restraining power of catch poles.


Gloves


We do not recommend grabbing wildlife using only gloves, except when dealing with juveniles.

Capture Nets


Capture nets, to be distinguished from nets used in exclusion, are available in varying designs such as throw nets, hoop nets, and mist nets. Throw nets are tossed over target animals. Hoop nets are attached to the end of a long handle and used to scoop up animals. The net should be deep enough to allow the hoop to be twisted to restrain the animal in the bottom of the net. A captured animal may climb out of a shallow net. The size of the mesh also is important. If the mesh is too large, the animal may force its head through and injure itself or strangle. If you must use a shallow net, immediately place the frame against a flat surface to prevent escape. You can further restrict the animal’s movement by carefully pressing on it with a stick. Encourage the animal to enter the net on its own, if possible. You may injure an animal while swinging a hoop net if you accidentally hit it with the frame.


Figure 42. CO2 net gun. Photo from Forestry Suppliers.


Mist nets are fine-threaded nets used to capture birds, such as sparrows and starlings inside warehouses. You will need training, skill, and federal and state permits to use mist nets to capture wild songbirds outdoors. Skill is needed to remove birds from the net without harming them. Mist nets should be monitored during use and removed immediately after use. Even veteran users can become frustrated trying to capture a sparrow or two in a net inside a large warehouse.


Snake Tongs


Snake tongs (Figure 43) are useful for grabbing a snake. Then, a snake hook can be used to pin the snake’s head to the ground. Use snake tongs carefully because it is difficult to tell how much pressure you are exerting; you could accidentally injure the snake. After the head is restrained, grasp the snake just behind its jaws with your thumb and forefingers and control the head. Support the body with your arm, a stick, or a pole while you carry it to minimize its stress and prevent the snake from thrashing.


Figure 43. Use snake tongs carefully so you do not injure the snake. Photo by Jan Hygnstrom.


CO2 powered net guns (Figure 30) are very effective for throwing light nests short distances.


One-way Doors (checkvalves)


Figure 44. Squirrel-sized one-way door. 
Photo by Tomahawk Live Trap Co.


One-way doors (Figure 44) allow an animal to leave but not re-enter a building, it is not a method to capture an animal. They come in a variety of designs, sizes, and materials. For example, plastic check-valves or nets are used for bats. Wire frames are designed to work with certain species and fit certain cage traps. Some WCOs build their own one-way doors. The advantage of one-way doors is that they do not require any handling of animals.


Before installing a one-way door, conduct a thorough inspection to make sure that all young are mobile. One-way doors only are effective if the animal can find and use the exit, but cannot find or force its way back through the door or find another way into the building. If a mother has been separated from her young and they are still inside, she will be highly motivated to find or create another entrance.


Here’s how a one-way door is used in bat control. A commercial checkvalve or simple netting is installed over the bat’s primary exit hole. All the other holes are sealed. Bats exit at the bottom of the one-way door, but when they attempt to return, their sense of smell guides them back to the hole. They land on the mesh (or checkvalve) near the hole, and stay there, sniffing around. They just don’t crawl down the mesh. After a suitable period of time, the one-way doors are removed, and the main entry sites are closed.


Chemical Immobilization


Chemical immobilization means using a tranquilizer to sedate an animal using treated baits or remote injection equipment such as blowpipes or darts. Chemical agents immobilize animals so they are unable to escape a human who approaches. Products such as alpha-chlorolose, ketamine, and telazol typically are available only to state wildlife agency, USDA-APHIS-Wildlife Services (WS), veterinary, local animal control, and academic personnel. Purchase and use of these drugs requires federal and state licenses that are generally impractical or impossible for WCOs to obtain.


Biological Control


Biological control typically involves the introduction of a disease or predator to manage a target population. Control with diseases is rarely used due to the risk of unexpected consequences. Predator control, although widely praised by the public, rarely works. For example, some people think that mice and voles can be controlled by placing perch poles around a field to encourage the presence of raptors. However, predators rarely reduce prey populations low enough to meet public expectations. Sheep dogs, however, have been known to aid in coyote control. Biological control methods are species and habitat specific and are usually used when other methods are not available.


Fertility Control


Population control is desirable when problem wildlife species are abundant. Fertility or reproductive control can also be considered a type of biological control. It is essentially birth control for wildlife. Most contraceptive methods require permits available only to researchers and veterinarians.


Some EPA-registered products, however, are available for feral pigeons that may stop them from laying viable eggs. For example, OvocontrolTM (active ingredient nicarbazin) is used to reduce the hatchability of pigeon eggs. These materials are not available in all states and may require training, permits, or a pesticide applicator’s license.


In some states, even food-grade corn oil is considered a pesticide when applied to goose or cormorant eggs to reduce hatchability.


Eggs can be “addled” by oiling, puncturing, or shaking so that they cannot hatch. Egg addling often is used to manage resident Canada geese in troublesome nesting areas. Permits from the USFWS are required Landowners may designate a third party, such as a WCO, but the permit must be in the landowner’s name and is time-specific. The USDA-APHIS-Wildlife Services administers the program, and also must submit an approval form. These rules are subject to change.


Figure 45. Wildlife contraceptives have been successfully given to species including deer, mice, elephants, donkeys and others. However, physical control of the animal and repeated dosing/boosters are required in order to be effective. Image by Texas A & M.


Studies have been done on surgical sterilization of deer in suburban settings. The results do not suggest that sterilization if an effective method to control over abundant deer.


Summary Questions and Answers for Wildlife Control Methods


What is Integrated Wildlife Damage Management?


Integrated wildlife damage management involves the timely use of a variety of cost-effective, environmentally safe, and socially acceptable methods to reduce human-wildlife conflicts to a tolerable level.


What are 2 ways to prevent orphaning wildlife?


The best way to prevent orphaning is to convince your customers to wait until the young are mobile before removing, repelling, or excluding the family from the site. If that’s unacceptable, you can try to capture and remove the female and all of her young and hope that she will retrieve them and continue to care for them.


What are the 8 broad categories of WDM methods?


  1. Habitat Modification
  2. Exclusion
  3. Frightening Devices
  4. Repellents
  5. Toxicants
  6. Shooting
  7. Trapping
  8. Other Methods


Habitat modification affects 3 necessities must animals have to survive. What are they?


All animals need water, food, and shelter.


What are the downsides to habitat management?


Changes to habitat to reduce the carrying capacity for one species may encourage population growth in another species. Unfortunately, some habitat modifications can be expensive, so expect some client resistance.


What are some examples of exclusion?


  • Nets can exclude birds from important crops and buildings and have become a more reasonable solution to complex bird problems.
  • Screens and barricades prevent wildlife from entering crawl spaces and buildings.
  • Fences prevent ground-dwelling animals from gaining access to landscapes like fields, gardens, airports, and structures such as decks, porches, buildings.
  • Covers, caps, and screens prevent wildlife from entering specific structures such as chimneys.
  • Crevice sealers include materials such as caulk, foam, mortar, and fabric to fill cracks, crevices, and openings to prevent animals from entering structures.
  • Cone guards keep pests away from birdfeeders and nest boxes on poles.
  • Rollers are long, cylindrical wheels with supports on each end, mounted on peaks of roofs, signs, ledges, and other narrow locations where birds loaf. Birds land on the rollers and fall off.


What are frightening devices? List 4 types.


These harassment tools scare wildlife from a location through non-chemical means. Frightening devices fall into 4 categories: visual, audio, audio-visual, and biological.


True or False. Birds can be hazed in their nesting area during the nesting season.


False. Most birds cannot be hazed in their nesting areas during the nesting season because of the Migratory Bird Treaty Act.


How do visual frightening devices work? Give examples.


Visual devices use sight to frighten wildlife.


Visual frightening devices include scarecrows, effigies (e.g., plastic owls), scary-eye balloons, and Mylar® tape.


What type of visual frightening device is least effective?


Stationary visual frightening devices are the least effective, as birds tend to habituate to them in a few days.


Geese and crows can be dispersed from a night-time roost by using what visual frightening device?


Geese and crows can be dispersed from a night-time roost by pointing a spotlight, laser pointer, or high-intensity laser at them.


What are some examples of audio frightening devices?


Audio devices include propane cannons and distress calls.


What extra steps should be taken when using audio frightening devices?


Check local ordinances and consider the effects on the neighbors before using any noisemakers.


What are audio-visual frightening devices?


Audio-visual devices use sight and sound to frighten wildlife, and include pyrotechnics (bangers, screamers, shell crackers, and propane canons with spinners).


What is an example of a biological control using fright?


Guard animals such as dogs and llamas sometimes are used to protect livestock, especially sheep, from predators.


What are repellents?


A repellent is a chemical that deters an animal pest from a specific location or from damaging activity.


Chemical repellents come in what 3 forms?


  1. Oral: A chemical that tastes unpleasant 
    (spicy hot).
  2. Tactile: A chemical that feels unpleasant (gooey or sticky).
  3. Olfactory: A chemical that smells unpleasant or promotes fear of a natural predator (ammonia or rotten-egg odor).


How do oral and olfactory repellents work?


Oral repellents deter pests by their bad taste when applied to vegetation, seeds, or fruit. Olfactory repellents drive mammals away through odors such as naphthalene, human hair, and predator urine.


How does one type of oral repellent teach geese to avoid certain grassy areas?


This repellent, registered for geese, changes the ultraviolet reflection of the grass where it is applied. When geese eat the treated vegetation, they vomit. The geese may then learn to avoid treated areas when they see the reflection of the grass.


Under what conditions are chemical repellents most effective?


Chemical repellents are most effective when alternative food and shelter are available to the pest and pest populations are low. Otherwise, the pest animals will be more likely to eat the high-value food in order to survive.


Why is it critical to use the right amount of tactile chemical repellent?


Improper or excessive application of tactile repellents may foul the feathers of non-target birds. It can also entrap birds on ledges or other sites. Dead birds that stick to ledges will decay and are difficult to remove. This not only violates label laws; it can create a sanitation problem as well.


What are 3 reasons that repellents may need to be reapplied?


Repellents may have to be reapplied after rainfall, to protect new plant growth, or because they lose effectiveness over time.


What are toxicants, and what are some examples?


Toxicants are chemical compounds used to kill problem animals. These chemicals include rodenticides, avicides, and lethal frightening agents. Toxicants also include toxic baits often used to control pest birds such as starlings (an avicide).


How can the effectiveness of a toxicant be increased?


Toxicants should be used with other control methods, such as habitat modification and exclusion, to increase their effectiveness.


What are some non-target animals that could be harmed by toxicants?


Considerable care must be used to minimize risks to non-target animals, including predatory wildlife, livestock, pets, and people.


What equipment commonly is used when shooting is selected as the damage control method?


Firearms include pistols, shotguns, rifles, and air rifles (high-end pellet guns).


On what species of animals is shooting appropriate?


Shooting is appropriate for use with medium to large mammals (squirrel-sized and larger), birds, and reptiles.


What are extra considerations when using shooting to control wildlife damage?


Shooting requires training and skill. Safety concerns and legal restrictions must be considered before shooting. For proper training in the use of firearms, attend a hunter education course or a training course sponsored by the National Rifle Association (NRA).


What is a benefit of using trapping to manage wildlife damage?


Traps are devices that can capture wildlife without the WCO being present.


What are 6 types of live traps?


Live traps include cage traps, box traps, multiple-capture traps, foothold traps, capture nets, cable-restraints, and a variety of bird traps.


What are some advantages of using live traps?


You can see what you have captured and demonstrate success to the client. It prevents animals from dying in inaccessible locations, which is a hazard of using toxicants. With live-trapping, you avoid the foul odor caused by decay that could attract other pests and is a nuisance itself. In most cases, if you are using a live trap you can release animals that are caught accidentally.


What are some disadvantages to using live traps?


It usually is labor-intensive and you may capture the wrong animal. If a live trap is used improperly, an animal may die in it from lack of food or water; from weather extremes ranging from heat in summer to cold in winter; or from attacks by wildlife, pets, or people.


What is the difference between a cage trap and a box trap?


Cage traps often are made of wire while box traps are made of solid material.


What are foothold traps?


Foothold traps are live traps and, as the name suggests, are designed to capture an animal by the foot.


What animals are foothold traps most efficient to trap?


Footholds can be used in land sets, water sets (in streams, lakes), and under ice. They are the most efficient tools for catching coyotes and foxes and often are important for trapping raccoons, beavers, muskrats, and nutria during wildlife control activities.


True or False. Mouse and rat snap traps are examples of body-gripping traps.


True. The familiar mouse trap is a form of body-gripping trap.


What modifications have been made to the traditional snap trap to make them more effective?


Snap traps with expanded triggers and the clamshell design are much easier to set than the traditional mouse trap. The Quick Kill Mouse Trap® made by Victor® has a lid over the bait cup. Only animals that seek the bait will lift the lid, which is what triggers the trap.


What is the benefit to using a multiple-capture trap?


Multiple-capture traps can catch more than one animal without having to be reset.


How often should one check a live trap?


Check live traps often enough, usually daily, so that animals are not stressed or exposed to extreme temperatures.


What is the key to successful mole trapping?


The key to successful trapping of moles is to identify active tunnels. Look for ridges, molehills, dead grass, and soft spots in the lawn. Prepare the site and set the trap according to the instructions given for the trap. If there is no activity after a few days, move the trap.


Why are snap traps preferred over glue boards in many cases?


Snap traps often are more effective than glue boards and are more humane, although setting them does take more effort.


How can you increase your success in trapping birds?


To increase your chance of success, habituate birds to the trap. First, put out some bird seed (shelled corn for pigeons) or other appropriate bait to habituate birds to feeding in the area.


What baits are attractive to raccoons, but not cats?


Marshmallows and sardines attract raccoons but marshmallows will not entice cats, so marshmallows are safer if you must trap where cats are free roaming. Cats are attracted to fat and protein-based baits, so choose sweet baits to reduce the likelihood of attracting cats.


What is the purpose of a lure?


Lures can help bring the target animal to your trap.


What are 3 categories of lures? Give examples of each.


Lures tend to be liquid and fall into 3 categories: food-based, gland-based, and curiosity. Lures are concentrated odors and may be detected by wildlife from great distances. Food-based lures trigger hunger and are scents that appeal to the animal’s appetite. Gland-based lures trigger sexual or territorial behavior. Urine is a gland-based lure. Curiosity lures are odors that likely are unfamiliar to the animal, yet attractive enough to cause the animal to investigate.


What equipment is useful for direct capture?


Gloves, however, we do not recommend grabbing wildlife using only gloves, except when dealing with juveniles


A catch pole is a versatile tool for the capture and restraint of animals. It is a long stick with a noose on one end. Other hand-operated devices, often called cat graspers, incorporate a vice-grip closure on the end of a pole. They can be useful if you are trying to capture small animals or if you are not able to get a loop around an animal.


Snake tongs are useful for grabbing snakes and a snake hook can be used to pin the head of a snake to the ground.


Capture nets, to be distinguished from nets used in exclusion, are available in varying designs such as throw nets, hoop nets, and mist nets.


What is chemical immobilization?


Chemical agents can be used to immobilize animals so they are unable to escape a human that approaches. Products such as alpha-chlorolose, ketamine, and telazol typically are available only to state wildlife agency, USDA-APHIS-Wildlife Services (WS), veterinary, and academic personnel. Purchase and use of the drugs requires federal and state licenses.


Why is one form of biological control, the use of a disease, to manage a target population rarely used?


Control with diseases is rarely used due to the risk of unexpected consequences.


What is fertility (reproductive) control? What is one example?


It is essentially birth control for wildlife. Eggs can be “addled” by oiling, puncturing, or shaking so that they cannot hatch. Egg addling often is used to manage resident Canada geese in troublesome nesting areas. Federal permits are required.


Study Questions for Wildlife Control Methods


Objective Questions


  1. Matching (items may be used more than once)
  2. habitat modification
  3. exclusion
  4. frightening devices
  5. repellents
  6. shooting
  7. trapping
  8. other methods


____ cat grasper


____ strobe light


____ nets


____ chimney cap


____ cable-restraints


____ modify bird feeders


  1. What are the basic types of trap sets?
  2. blind, positive, and baited
  3. two-door and one-door
  4. cage and box
  5. none of the above


  1. Which bait should be used to avoid catching house cats?
  2. sardines
  3. hamburger
  4. cheese
  5. marshmallows
  6. Before using a one-way door on a home, you must consider
  7. the condition of the home
  8. possibility of young
  9. possibility of reentry
  10. wishes of the client
  11. all of the above


  1. The trap type that will reduce non-target animal captures when trying to catch raccoons is
  2. 2, double-coil spring trap
  3. wire cage trap
  4. enclosed foot trap
  5. cable-restraint


Answers


  1. g, c, b, b, f, a
  2. a
  3. d
  4. e
  5. c