Vertebrate Pest Management PDF

FOR-121 Vertebrate Pest Management By Dave Pehling, Extension analyst, Snohomish County, Washington State University. Adapted for Kentucky by Thomas G. Barnes, Extension wildlife professor and wildlife Extension specialist, University of Kentucky. Revised by Matthew T. Springer, as- sistant Extensi...

FOR-121 Vertebrate Pest Management By Dave Pehling, Extension analyst, Snohomish County, Washington State University. Adapted for Kentucky by Thomas G. Barnes, Extension wildlife professor and wildlife Extension specialist, University of Kentucky. Revised by Matthew T. Springer, as- sistant Extension professor and wildlife Extension specialist, University of Kentucky. These factors can help you evaluate the situation. Not every In this chapter: conflict between humans and wildlife requires action—the goal is to solve a problem, not kill animals. Often, a bit more Problems with Home Remedies 01 human tolerance is all that’s needed; the situation may resolve itself, evident in the old saying, “Plant four seeds; one for the Prevention is the Best Solution 02 mouse, one for the crow, one to rot, and one to grow.” Even if Moles 03 you tried to kill all the wildlife in the group causing the problem, Voles 03 it would be almost impossible to control the entire population. The types of wildlife you are dealing with have very high repro- Chipmunks  04 ductive rates, live short lives, and have high death rates. They Cottontail Rabbit 04 are usually adaptable and opportunistic in their general habitat Deer and Elk 05 requirements, and we often create excellent habitat for them around our homes and in our gardens. For example, rabbits like Black Bear 05 nothing better than to eat from a well-tended, fertilized bean Skunks 05 patch rather than eat grass and clovers. Raccoons and Opossums 05 Tree Squirrels 06 Problems with Home Remedies Birds 07 People are ever-resourceful, so when it comes to wildlife conflicts we attempt to make our lives easier by designing For More Information 08 and developing new products, sometimes based on sound information and sometimes not. A perfect example of these new products is deer or wildlife “whistles” meant to keep deer M ost people enjoy watching wildlife around the home, or other creatures away from cars or structures by using high- whether it is birds at a feeder, butterflies on flowers, pitched sound. Research conducted in Europe has shown these or the occasional deer or turkey wandering through whistles have little effect. the yard. In some instances, wildlife come into contact with In some cases, gardeners and homeowners take matters into humans and are in the wrong place at the wrong time. For the their own hands and develop their own “home remedies.” Most gardening enthusiast, this encounter can create conflict. With such inventions may work for a short time, but be aware that weeds, insects, and other types of garden pests, you can just laws govern the types of chemicals you can put out to control spray a chemical and solve the problem, but vertebrate pests are wildlife. For example, many people will use mothballs to move considerably more difficult to deal with. Few poisons or repel- bats from a structure or from part of a building, such as an attic. lents are available for use. Also, vertebrate pests share similar Most of them do not realize that mothballs are carcinogenic physiology with humans, so chemicals designed to kill mam- to humans and that to obtain a concentration strong enough mals can potentially also harm us and our pets. Consequently, to repel bats would probably create a hazard for the human there is no standard approach to dealing with wildlife problems. occupants as well. Consequently, mothballs are not labeled for Each situation must be examined in terms of: use as a bat repellent. species of animal causing the damage Many states are becoming serious about the use of such severity of damage home remedies due to the toxic chemicals they contain and season and duration of damage the harm they can do to the environment, people, and pets. legal status of the animal Some states interpret using a home remedy as an illegal use of biological and ecological considerations a pesticide. Some will also invoke animal cruelty laws if wildlife wildlife value show signs of suffering and that suffering can be traced back to available types of prevention and control methods (non- an individual homeowner. For example, most homeowners rec- lethal and lethal) ognize that antifreeze attracts wildlife and that if wildlife drink economic considerations it, it will kill them. What they do not realize is that an animal dying as a result of this activity mimics an animal dying of rabies. CHAPTER 09 Vertebrate Pest Management It takes time for the animal to die and it wanders around the The next step in preventing damage is to examine your gar- neighborhood. Someone will most likely discover this animal den and landscape to see where barriers can be erected around and make efforts to help it. While this is most probably a case of the vegetable garden or over the grape arbor/berry patches, cruelty to animals, it is most definitely a violation of federal and which is where netting would be appropriate. You can also look state pesticide laws. If the homeowner who enticed the animal to see if you have favorite perches where birds roost (trees or to the antifreeze were caught, the case would be treated quite structures) and net them off. Or, you can use some other type seriously by the legal system. of structural deterrent (like porcupine wire or angled boards) It is better to use a product that has been tested and under- to keep the birds from perching near the gardens. gone scrutiny than to use something you or your neighbor heard If you are determined to live-trap and release wildlife from of through the grapevine. Unfortunately, many of the chemicals the garden, consider the following: that are labeled for wildlife control are “restricted use” products, You can’t release them on public land such as a park, wild- which mean you must have a specific license to use them. You life management area, forest, nature preserve, or any other must also realize that the directions on the product’s label are public land. the law, and failure to follow the label is illegal. You must obtain written permission from the landowner to release wildlife onto private land. It is not necessarily more humane to release the animal, as Prevention is the Best Solution they are often at a disadvantage when released. Members The best long-term solution to solving conflicts between of the same species may be aggressive to them or they may humans and wildlife is to prevent them in the first place. The become easy prey. Released animals may be injured in con- second-best solution is to keep the animals from the site and to frontations with these newly encountered individuals in the minimize any damage they might do. The solution of last resort area they were released. The injuries may not be limited to may be to capture and remove or kill the offending animal. the animal that was released, as those individuals that were A homeowner or gardener should first take stock of his or present are just as likely to be injured in a confrontation. On her property and at a minimum take some common-sense top of that, you do not know if the animal you are relocating precautions, like making sure the trash cans have lids that fit is potentially carrying a disease. Unnatural movement by tightly; not keeping dog or cat food out at night; inspecting the relocation can help diseases like rabies to be quickly spread home to ensure that all holes and entrance routes are sealed; not across the landscape, causing substantially more harm to the putting wildlife-attracting meat or fat scraps in the compost; species you are trying to protect. and picking up boards, debris, and other items from the ground Wildlife have incredible homing instincts. Unless an animal to minimize use by snakes, skunks, or other burrowing crea- is taken many miles from the point of capture, it will return tures. Clean up at the bird feeder—excess seed attracts not only to its original habitat. birds, but also chipmunks, squirrels, and rabbits. Finally, look Given these general guidelines, specific animal groups and at your perimeter fences and check for signs of where animals potential control options are presented in this publication. are moving from surrounding properties. Seek to make these travel routes uninhabitable. Mole 9-2  Vertebrate Pest Management CHAPTER 09 Moles Vole The much-maligned mole may be the greatest source of stress among homeowners. It is probably the number one lawn pest that people complain about. While moles do little actual economic damage except to golf courses and other expensive turf areas, many people consider it to be a significant problem. Moles are insectivores, not rodents, so they do not eat plant material. Their primary diet is earthworms and grubs. If you have a problem with grubs in your lawn, it is not wise to spray an insecticide to kill them, because the moles could switch their prey to something else and actually cause more damage. Ninety percent or more of a mole diet is earthworms, and the remaining 10 percent is other soil insects. If you have a grub problem, treat that problem, and if you have a mole problem, treat that problem. soil surface. Voles are plant eaters, so if you find bulbs, tubers, Most damage occurs when moles’ shallow burrowing activ- shrubs, or other plants gnawed on at ground level or just below ity, which is generally in the spring and fall, creates ridges or it, the culprit is likely a vole, not a mole. You might find one- hills of fine dirt in the lawn. It isn’t necessarily true that moles inch diameter holes in the turf, indicating the entrance to a are difficult to control. The key, whether trapping or using the burrow system. Prairie and meadow voles feed on tree bark, poison earthworm baits, is to find the active tunnels that moles primarily during the fall and winter. However, pine voles char- use most often. These tunnels are usually long and straight, not acteristically attack trees of all sizes in all seasons. Most pine branched. If you place your foot over a section of the burrow, vole damage occurs belowground, where the animals feed on it will usually be pushed up the next day. rootlets and the bark of larger roots. Voles breed from January The best time of year to use either baits or to trap is spring through October in Kentucky and can produce an entirely new and fall, when moles are more active in surface runs rather than generation in about 60 days. Vole numbers fluctuate from year deep runs and chemicals do not break down as quickly as in to year; under favorable conditions, populations can increase summer heat. (The chemicals in the earthworm baits are very rapidly. Voles often experience population booms and busts on heat sensitive.) Fumigation or gas cartridges are also available about a four-year cycle. It is during the boom years that lawn for control, but they are generally not effective. The mole runs and shrub damage is usually the worst. are so extensive that it is difficult to get enough gas into all Vegetation management is the key to managing vole popula- areas of the burrow system to kill the animals. More informa- tions. Because voles like thick, heavy mulch and grass, the key tion on using traps to control moles can be found in the UK is to not provide this type of habitat. However, limiting this Cooperative Extension publication Managing Mole Problems habitat can conflict with other objectives, such as applying in Kentucky (FOR-42) at http://www2.ca.uky.edu/agcomm/ mulch around landscape plants. To reduce the potential for vole pubs/for/for42/for42.pdf. damage, mulch should be pulled away at least 36 inches from The final option is to use a castor oil-based repellent. These the base of the plant material, and if possible, the ground should repellents have been shown to be somewhat effective; however, be kept clear of any vegetation or mulch, because bare ground they must be continually reapplied because they disperse into minimizes vole activity around plants. A thick, lush lawn, par- the soil. Also, they do not solve the problem; they only delay ticularly with fescue as the grass species, creates ideal habitat dealing with the long-term issue of actually controlling the for prairie or meadow voles. Lawns should be dethatched to animals. Furthermore, these products can be quite expensive. reduce potential vole problems. In the long run it will be more cost effective to remove the To protect individual landscape plants, place hardware cloth offending animals. cylinders (quarter-inch mesh) around the lower trunks and bury the cylinder’s lower edge six inches deep. Tree guards that Voles control rabbit damage do not discourage voles, since voles feed mostly underground. In fact, voles have been known to nest Often damage by voles is mistaken as mole damage, because under loose-fitting guards! For very small vole populations, meadow voles can create extensive burrow systems, particularly trapping may be sufficient control. Use ordinary mousetraps in lush, thick grass lawns. Voles, or meadow mice, are small, baited with peanut butter or apple. The traps must be placed compact mammals with stocky bodies; small, rounded ears; in the runs and then covered with boards. Check traps daily short legs; and short tails. When fully grown, voles are four to and reset as needed. This method is very time-consuming but five inches long. Their long, coarse hair can be blackish, grizzled, is often the only solution, as there are no chemicals labeled for or reddish, and they spend most of their lives just below the vole control in the landscape. 9-3 CHAPTER 09 Vertebrate Pest Management Chipmunks Cottontail Rabbit These small squirrels are not ground squirrels, although that A well-fertilized garden and lawn is a buffet for cottontail is a name commonly used for them. Kentucky has no ground rabbits. They love flowers, vegetables, and shrubs or trees that squirrels. Chemicals sold in Kentucky that are labeled for use provide ample nutrition. They often feed on bark and stems on ground squirrels are illegal to use for chipmunks. While during winter, when they cause a lot of damage to gardens and chipmunks are avid climbers, they spend most of their time on orchards, especially in peak population years. In spring and the ground or in underground burrows that can be up to six feet summer, they develop an appetite for flowers (particularly long and two to three feet deep. The entrance is typically a hole tulips) and vegetables. Rabbit-damaged trees and shrubs are eas- from one inch to one-and-a-half inches in diameter. No soil is ily identified by characteristic tooth marks. Rabbits clip tender mounded around it, and it closely resembles the entrance hole young shoots and terminal buds as well as gnaw on the trunk. for a vole. Chipmunk entrance holes are often around or at the The gnawing marks are larger than vole marks and appear as base of structures like a rock fence, a concrete wall, or sidewalk, clean, knifelike cuts at a 45° angle. and often the entrance is concealed with leaves or other debris. Because rabbits can’t climb and jump more than several No chemicals are labeled for chipmunk control in Kentucky, inches, the best method of solving rabbit problems is to place and homeowners are left with either excluding the animals or a mesh two-foot fence buried six inches deep around gardens trapping them. The best material to exclude chipmunks is quar- and flower beds where rabbits have been observed. Individual ter-inch hardware cloth. It should be buried at least six inches trees and shrubs can be protected with hardware cloth cylinders deep to prevent the animals from burrowing under it. The most that are at least two feet tall and buried six inches deep. Rabbits common trapping method involves using rat snap traps (which can also be deterred using a single high-tensile electric fence are much like a common mousetrap) or small live traps. Live with the wire placed four inches above the ground. Make sure trapping is usually an all-encompassing activity, because home- the system is well grounded and the vegetation under the wire owners trap and release not only the animals from their yards has been removed to ensure good contact between the wire but from surrounding yards as well. Therefore, snap trapping and animal. If the rabbits jump this fence, a second wire can be is the preferred alternative. To be successful, two traps should placed two inches above the lower wire. Live-trapping rabbits be used per entrance hole. The traps should be placed adjacent is not all that easy in the garden because there is such an abun- to one another and perpendicular to the hole, and they should dance of food, and it is generally ineffective. There are a number be buried so they are level with the surrounding environment. of commercially available chemical repellents for rabbits that There is no need to bait the traps at the entrance hole. Once are labeled for homeowner use. The only two available for use in place, some sort of structure should be placed over the top on human edible crops are Hinder and those made with cap- so that birds, pets, and other animals do not inadvertently step saicin (hot pepper). Generally speaking, repellents that make in the traps. Another viable alternative is to use PVC pipe six the plant taste bad are more effective than those that repel by inches in diameter. Cut it into one foot sections and place a making the area smell bad. To be effective, these repellents must trap in each pipe. Bait the trap with a mixture of peanut butter, be reapplied after a rain or heavy dew, and they are expensive oatmeal, and apple. For more information on chipmunk con- and labor-intensive to use. Always be sure to read and follow trol, see the UK Cooperative Extension publication Managing the label when using any chemical repellent. Chipmunk Problems in Kentucky at https://www2.ca.uky.edu/ agcomm/pubs/for/for41/for41.pdf. Chipmunks 9-4  Vertebrate Pest Management CHAPTER 09 of the fences to prevent the wires from grounding. These can be temporary fences that can be removed once the crop has been harvested or permanent versions. Other types of fences, such as a chain-link fence, may help deter bears, but they become much Elk more effective by adding a single strand of electric wire on the top. Hinder and hot pepper-type repellents are labeled for use on human edible crops, but no research has shown them to be effective at keeping bears from consuming crops. Skunks Skunks are another small omnivore common within Kentucky that can be problematic when maintaining gardens and landscaping. Skunks will feed on many types of produce within gardens, including corn and various types of berries. Fencing is a feasible option to help keep them out of gardens, as they are not adept at climbing. A chicken fence that is two to three feet high should suffice in keeping them from entering Deer and Elk specific areas. One of the major problems skunks can cause has to deal with their diet, specifically their love of larvae. They will Kentucky has abundant deer and elk populations in both dig up larvae from the soil, usually creating numerous holes urban and suburban environments. They are difficult for home- from three to four inches deep within flower beds or lawns. owners to deal with, because hunting is usually not a control This behavior is not all bad, as they are removing species that option in these environments. These two large mammals can are often viewed as pests. One of the easiest ways to deal with cause considerable damage, not only from their browsing of this type of skunk damage is to treat your lawns to control the plant material, but also from their movements and behavior. pest species itself. If there are no larvae present, the skunks will Furthermore, since fencing is really the only viable management not dig to find them. option that works, homeowners need to determine if they can deal with potentially unsightly fences around trees, shrubs, gar- dens, and other plantings. While repellents can provide some temporary relief, they are not viable management options in the long run. One potential solution is to select deer-resistant Raccoon landscape material. However, if a deer or elk population is stressed and hungry, it will devour these plants as well. More detailed information on managing deer problems is available in the UK Cooperative Extension publication Managing White- Tailed Deer Problems in Kentucky (FOR-57) at http://www2. ca.uky.edu/agcomm/pubs/for/for57/for57.htm. Black Bear Bears are the largest omnivore within Kentucky, and their range and population is currently expanding. Found mostly in the southeast and eastern counties, they can cause large amounts of damage quickly within your garden or other land- scaping. Bee hives, sweet corn, all types of berries, and orchard trees are especially attractive to bears. Because these species are Raccoons and Opossums quite adept at climbing, the best control is to use electric fencing These two mid-sized omnivore mammals cause most prob- around any areas you want to protect. The wires should start at lems when they get into the garden and raid fresh produce just six inches from the ground and be spaced about every eight to before it is ready to be picked. Sweet corn is especially attrac- 10 inches up to four feet off the ground. To ensure this method tive. Because these species are quite adept at climbing, the best is effective, you need a power source capable of providing an control is to use a two-strand electric fence around the garden. adequate shock to the animal; it is suggested to be between 6,000 The wires should be at six and 12 inches from the ground. To and 10,000 volts. In addition, all vegetation must be kept clear make sure this method is effective, you must have a charger that 9-5 CHAPTER 09 Vertebrate Pest Management supplies sufficient electricity to provide an adequate shock, and all vegetation must be kept clear of the fences to prevent the Tree Squirrels wires from grounding. These temporary fences can be removed Both the fox and eastern gray squirrel are common in once the crop has been harvested. Other types of fences, such Kentucky, and both can cause problems for gardeners by digging as a chain-link fence, can work, but adding a single strand of up plants, bulbs, or seeds; eating from fresh vegetables; gnawing electric wire on top makes them more effective. Hinder and off small branches and twigs; stripping bark; and raiding bird hot pepper-type repellents are labeled for use on human edible feeders. If they get into a house or another structure, they can crops and may deter the animals long enough for the vegetables cause significant property damage. Squirrels are easy to live trap to be harvested. If using hot pepper-type repellents, remember if the traps are baited with sunflower seeds, corn, peanut butter that they should not be sprayed on the actual vegetable you will and oatmeal, or other fruit-nut material. However, once squir- be eating but on the surrounding vegetation. rels are trapped, they are vicious. Dealing with them in a live trap can be troublesome and even hazardous. Furthermore, you may have many more squirrels than you first realize. Twenty- four squirrels were trapped in a single week at a residence in Lexington, Kentucky, and the population was still not depleted. Gray squirrel If you do want to catch and release the animals, pay strict atten- tion to the laws and regulations outlined previously. To more humanely move the animals, cover the trap in heavy canvas while transporting them (this method might also save one of your fingers!). If you have squirrels digging up bulbs, plants, or seeds, the best method is to place hardware cloth just under the soil so they can’t dig through the cloth and access the plant material that is underground. The cloth should be staked firmly, and it should be much larger than the immediate area to prevent the squirrels from getting at the edges and tearing the cloth out of the ground. Electric fencing, as discussed for raccoons and opossums, will also work to deter squirrels from a vegetable garden, and commercial repellents are available as well. If you want to treat birdseed to deter squirrels, a hot pepper-type repellent is available that can be placed on the birdseed. If you do feed birds, make sure you clean up any and all extra food that drops so that you discourage other animals. Squirrels can be kept out of fruit trees and other trees by placing six-foot sheet metal or plastic barriers at the base of the tree. At certain times of the year, squirrels will clip twigs and branches of trees for no apparent reason other than to sharpen their teeth. Don’t worry about this damage; it generally doesn’t harm the tree. Cage traps 9-6  Vertebrate Pest Management CHAPTER 09 Woodpecker Birds especially attractive and prone to damage. It is illegal to harm these birds. The best method is to place another material in the Birds, primarily crows, starlings, woodpeckers, pigeons, areas where they are drumming or cover the area with bird net- house (“English”) sparrows, and robins, can cause problems ting to create a different sound. If this method doesn’t work, a in gardens by their roosting, nesting, and feeding habits. Bird special sticky repellent available at hardware and lawn/garden management may present special issues, because woodpeckers, stores can be applied to deter them. Sometimes an infestation of robins, and songbirds are protected by law. Because of where carpenter ants or solitary bees can attract woodpeckers. If this Kentucky is located geographically, the state has tremendous is the case, take care of the insect problem and the woodpecker control issues with populations of both summer- and winter- problem will also disappear. roosting birds. The first step in dealing with this problem is to Perhaps the biggest threat to home gardens from birds is the select proper tree species for the landscape. For example, spe- damage to strawberries, cherries, blueberries, apples, grapes, cies with much branching, like the Callery pear, white pine, pin and hazelnuts. If you want any of these crops for harvest, you oak, and those of Zelkova, attract roosting species in the winter will most certainly have to place bird netting over them. It is because the birds can congregate closer and keep warm. For the cheapest, most environmentally friendly, and most effec- these species, the first line of attack is to trim up to 30 percent tive method of keeping birds from crops. Another alternative of the canopy and “open” it so that branches do not overlap is to use the chemical repellent methyl anthranilate, which is and more air moves through the canopy. Another option is to derived from grape skins, to deter the birds. However, using place bird netting over the tree. The final method would be to this repellent is very expensive, and, as with all repellents, you disperse the roost by using a bird distress tape call along with must reapply it after dew or rain. pyrotechnics. For more detailed information on dispersing a Various scare devices, including but not limited to fake roost, see UK Cooperative Extension publication Managing snakes and owls, scarecrows, hanging flashers, balloons, loud Urban Pest Bird Problems in Kentucky (FOR-62) at http:// noise, and ultrasonic or subsonic devices, may work for a day www2.ca.uky.edu/agcomm/pubs/FOR/FOR62/FOR62.pdf. or two, but the birds quickly become accustomed to them and If you have woodpeckers tapping on siding or trees in quickly return to their habitual behavior. the spring, it is usually a result of courtship. Cedar siding is 9-7 CHAPTER 09 Vertebrate Pest Management For More Information A list of UK Cooperative Extension publications on manag- ing vertebrates follows: Managing Muskrat Problems in Kentucky (FOR-51) Managing Beaver Problems in Kentucky (FOR-50) Managing Skunk Problems in Kentucky (FOR-49) Bats: Information for Kentucky Homeowners (FOR-48) Snakes: Information for Kentucky Homeowners (FOR-46) Managing Tree Squirrel Problems in Kentucky (FOR-45) Managing Woodchuck Problems in Kentucky (FOR-44) Managing Rabbit and Vole Problems in Kentucky Orchards (FOR-43) Managing Mole Problems in Kentucky (FOR-42) Managing Chipmunk Problems in Kentucky (FOR-41) Controlling Woodpecker Damage (FOR-38) Coyote Managing Coyote Problems in Kentucky (FOR-37) Managing Urban Pest Bird Problems (FOR-62) Managing Commensal Rodent Problems in Kentucky (ID-115) Kentucky’s Endangered and Threatened Species (ID-103) Revised 01-2024