Preventing Conflicts with Rats
In the process of seeking food and
shelter, Norway rats and roof rats can contaminate human or domestic animal
food with their droppings, destroy insulation, and create noise in attics,
walls, and crawl spaces. Rats also chew on electrical wiring and structural
supports in buildings. Norway rats occasionally burrow into dikes and dams.
Both species can damage garden crops and ornamental plantings.
Successful long-term rat control is not simple a continuing commitment to whatever solutions are adopted is required. Excellent exclusion work can achieve long term control. Within a population, some rats will be easy to control, some difficult. Complete control is often not possible in old barns and similar structures. Rat populations may also be a consequence of community-wide activities over which you have little control improper garbage disposal, building demolition, and poorly maintained bird-feeding stations.
If you think you can solve a rat problem with a house cat, remember that cats allowed to roam outdoors may also kill songbirds, chipmunks, snakes, lizards, and young rabbits and squirrels. In addition, although a cat may kill a young rat, after one experience with an adult rat, cats often prefer to seek easier prey.
The following recommendations ideally should be followed before rats enter areas where they are unwanted and before the numbers of rats becomes extreme.
Prevent rat access to food and water
This includes managing areas both inside buildings and their surroundings.
Store human and animal food in rat-proof buildings, rooms, or containers. Old World rats are very capable of chewing through heavy-duty plastic garbage cans when they can get started chewing on a corner or the lid or a handle. Use metal garbage cans where this is a problem.
Prevent raccoons and other animals from making garbage available. Keep your garbage-can lid on tight by securing it with rope, chain, bungee cords, or weights. Better yet, buy garbage cans with clamps or other mechanisms that hold lids on. To prevent tipping, secure side handles to metal or wooden stakes driven into the ground. Or keep your cans in tight-fitting bins, a shed, or a garage. Put garbage cans out for pickup in the morning, after raccoons have returned to their resting areas.
Prevent rat access to fruit and compost. Don't put food of any kind in open compost piles; instead use a rat-proof composter or a covered worm box. If burying food scraps, cover them with at least 8 inches of soil and don't leave any garbage above ground in the area including a smelly shovel. Keep all open or lightly covered compost piles the consistency of a wrung out sponge to make them unfavorable to nesting rats.
Pick up fruit that falls to the ground. Don't allow garden produce to rot on the vine. Compost it, or rototill or dig it into the soil.
Feed dogs or cats inside and clean up droppings. One of the most common attractants around homes is pet food. The strong smell attracts rats from a distance. Once they get a taste of these nutritious foods they will try to feed their daily. If you must feed pets outside, pick up food and water bowls, as well as leftovers and spilled food, before dark. Also, clean up pet droppings rats can subsist on a diet of droppings.
Prevent rat access to bird feed and feeders. Pet food and birdseed are the two items that attract the most rats around buildings. Once rats get a taste of these nutritious foods they will try to feed their daily. Place baffles above and below feeders to prevent rats from gaining access to feeder foods. Rats are attracted to the smell of seed hulls, so rake up the shells or offer birds hulled sunflower seeds (also known as sunflower hearts or chips).
Eliminate rat access to water. Fix leaky outdoor faucets and, where practical, eliminate access to other sources of ground water.
Prevent Rat Access to Shelter
In the long term, the most successful form of rat control is to build them out. Also called rat-proofing, this approach makes it impossible for rats to get inside or under a building where they could do damage.
Both Norway and roof rats may gain entry to structures by gnawing, climbing, jumping, or swimming through sewers and entering through the toilet or broken drains. While Norway rats are more powerful swimmers, roof rats are more agile and are better climbers.
It is always easier to keep rats out of buildings. Once they are inside, controlling them requires more work, cost, and aggravation.
Eliminate rat access into buildings. To enter a building, rats only require a hole 1/4-inch in diameter to chew larger and squeeze through. Seal openings around drainpipes, vents, power lines, cables, and other utilities that enter structures
Seal cracks and holes in building foundations and exterior walls (including warped siding) and roof joints. Seal all the above mentioned areas with 1/4-inch mesh hardware cloth, metal flashing, stuff-it, mortar, or concrete patch. copper or stainless-steel mesh scouring pads (steel wool quickly corrodes after becoming wet) into cracks, holes, and other openings.
Install commercially available vent guards to prevent rats from entering bathroom exhaust vents and dryer vents. Basement drains should be screened. If the drain is no longer used, seal it.
Rodent-proofing against roof rats usually requires more time to find entry points than for Norway rats because of roof rats' greater climbing ability. Roof rats often enter buildings at the roofline area so be sure that all access points in the roof are carefully inspected and sealed.
Prevent rats from climbing buildings.
Both roof rats and Norway rats are excellent climbers. Place metal or heavy plastic barriers around trees and over pipes and other places rats climb and gain access into buildings
If rats are traveling on overhead utility wires, trim tree branches at least 4 feet away from utility lines that lead into structures. Contact the utility company for information on measures that can be taken to prevent rats from using these lines. To prevent rats from climbing trees, install a tree guard
Remove vines, such as English ivy, which provide rats a way to climb structures and hide their access points. (Ivy also facilitates rats' entry into the tree canopy, where they can prey on nestling birds.)
Keep doors closed, especially at night. Rats can find easy access into buildings under doors (including garage doors) and through open or poorly fitting doors. Once in a garage, rats gain entry into the main structure via holes around pipes, furnace ducts, and drains. Cover door bottoms that are subject to gnawing with metal flashing or hardware cloth, and keep the openings no larger than 1/4 inch.
Prevent rats from tunneling under buildings. To prevent rats from digging under a foundation, slab, or other area, create a barrier such as underground screening
Keep ground areas around structures open. Keep a 4-foot wide space next to buildings mowed and free of thick vegetation, wood piles, and debris to allow for easy inspection. Materials stored in stacks or piles should be on pallets at least 12inches off the ground higher will allow for easier inspection. Ornamental shrubs next to the house should be pruned up at least 18 inches from the ground.
Remove the Existing Rat Population
If rat problems persist after you've eliminated all known sources of food and shelter, some form of population reduction, such as trapping or baiting, is almost always necessary.
Rats are wary animals, easily frightened by unfamiliar or strange noises. However, they quickly become accustomed to repeated sounds, making the use of frightening sounds, including high-frequency and ultrasonic sounds, ineffective for controlling rats in home and garden situations.
Rats have an initial aversion to some odors and tastes, but no repellents have been found to solve a rat problem for more than a very short time.
A one-way door allows rats to exit a structure, but prevents them from finding their way back in the same door. Unfortunately, a rat may try and enter the structure elsewhere.
Successful long-term rat control is not simple a continuing commitment to whatever solutions are adopted is required. Excellent exclusion work can achieve long term control. Within a population, some rats will be easy to control, some difficult. Complete control is often not possible in old barns and similar structures. Rat populations may also be a consequence of community-wide activities over which you have little control improper garbage disposal, building demolition, and poorly maintained bird-feeding stations.
If you think you can solve a rat problem with a house cat, remember that cats allowed to roam outdoors may also kill songbirds, chipmunks, snakes, lizards, and young rabbits and squirrels. In addition, although a cat may kill a young rat, after one experience with an adult rat, cats often prefer to seek easier prey.
The following recommendations ideally should be followed before rats enter areas where they are unwanted and before the numbers of rats becomes extreme.
Prevent rat access to food and water
This includes managing areas both inside buildings and their surroundings.
Store human and animal food in rat-proof buildings, rooms, or containers. Old World rats are very capable of chewing through heavy-duty plastic garbage cans when they can get started chewing on a corner or the lid or a handle. Use metal garbage cans where this is a problem.
Prevent raccoons and other animals from making garbage available. Keep your garbage-can lid on tight by securing it with rope, chain, bungee cords, or weights. Better yet, buy garbage cans with clamps or other mechanisms that hold lids on. To prevent tipping, secure side handles to metal or wooden stakes driven into the ground. Or keep your cans in tight-fitting bins, a shed, or a garage. Put garbage cans out for pickup in the morning, after raccoons have returned to their resting areas.
Prevent rat access to fruit and compost. Don't put food of any kind in open compost piles; instead use a rat-proof composter or a covered worm box. If burying food scraps, cover them with at least 8 inches of soil and don't leave any garbage above ground in the area including a smelly shovel. Keep all open or lightly covered compost piles the consistency of a wrung out sponge to make them unfavorable to nesting rats.
Pick up fruit that falls to the ground. Don't allow garden produce to rot on the vine. Compost it, or rototill or dig it into the soil.
Feed dogs or cats inside and clean up droppings. One of the most common attractants around homes is pet food. The strong smell attracts rats from a distance. Once they get a taste of these nutritious foods they will try to feed their daily. If you must feed pets outside, pick up food and water bowls, as well as leftovers and spilled food, before dark. Also, clean up pet droppings rats can subsist on a diet of droppings.
Prevent rat access to bird feed and feeders. Pet food and birdseed are the two items that attract the most rats around buildings. Once rats get a taste of these nutritious foods they will try to feed their daily. Place baffles above and below feeders to prevent rats from gaining access to feeder foods. Rats are attracted to the smell of seed hulls, so rake up the shells or offer birds hulled sunflower seeds (also known as sunflower hearts or chips).
Eliminate rat access to water. Fix leaky outdoor faucets and, where practical, eliminate access to other sources of ground water.
Prevent Rat Access to Shelter
In the long term, the most successful form of rat control is to build them out. Also called rat-proofing, this approach makes it impossible for rats to get inside or under a building where they could do damage.
Both Norway and roof rats may gain entry to structures by gnawing, climbing, jumping, or swimming through sewers and entering through the toilet or broken drains. While Norway rats are more powerful swimmers, roof rats are more agile and are better climbers.
It is always easier to keep rats out of buildings. Once they are inside, controlling them requires more work, cost, and aggravation.
Eliminate rat access into buildings. To enter a building, rats only require a hole 1/4-inch in diameter to chew larger and squeeze through. Seal openings around drainpipes, vents, power lines, cables, and other utilities that enter structures
Seal cracks and holes in building foundations and exterior walls (including warped siding) and roof joints. Seal all the above mentioned areas with 1/4-inch mesh hardware cloth, metal flashing, stuff-it, mortar, or concrete patch. copper or stainless-steel mesh scouring pads (steel wool quickly corrodes after becoming wet) into cracks, holes, and other openings.
Install commercially available vent guards to prevent rats from entering bathroom exhaust vents and dryer vents. Basement drains should be screened. If the drain is no longer used, seal it.
Rodent-proofing against roof rats usually requires more time to find entry points than for Norway rats because of roof rats' greater climbing ability. Roof rats often enter buildings at the roofline area so be sure that all access points in the roof are carefully inspected and sealed.
Prevent rats from climbing buildings.
Both roof rats and Norway rats are excellent climbers. Place metal or heavy plastic barriers around trees and over pipes and other places rats climb and gain access into buildings
If rats are traveling on overhead utility wires, trim tree branches at least 4 feet away from utility lines that lead into structures. Contact the utility company for information on measures that can be taken to prevent rats from using these lines. To prevent rats from climbing trees, install a tree guard
Remove vines, such as English ivy, which provide rats a way to climb structures and hide their access points. (Ivy also facilitates rats' entry into the tree canopy, where they can prey on nestling birds.)
Keep doors closed, especially at night. Rats can find easy access into buildings under doors (including garage doors) and through open or poorly fitting doors. Once in a garage, rats gain entry into the main structure via holes around pipes, furnace ducts, and drains. Cover door bottoms that are subject to gnawing with metal flashing or hardware cloth, and keep the openings no larger than 1/4 inch.
Prevent rats from tunneling under buildings. To prevent rats from digging under a foundation, slab, or other area, create a barrier such as underground screening
Keep ground areas around structures open. Keep a 4-foot wide space next to buildings mowed and free of thick vegetation, wood piles, and debris to allow for easy inspection. Materials stored in stacks or piles should be on pallets at least 12inches off the ground higher will allow for easier inspection. Ornamental shrubs next to the house should be pruned up at least 18 inches from the ground.
Remove the Existing Rat Population
If rat problems persist after you've eliminated all known sources of food and shelter, some form of population reduction, such as trapping or baiting, is almost always necessary.
Rats are wary animals, easily frightened by unfamiliar or strange noises. However, they quickly become accustomed to repeated sounds, making the use of frightening sounds, including high-frequency and ultrasonic sounds, ineffective for controlling rats in home and garden situations.
Rats have an initial aversion to some odors and tastes, but no repellents have been found to solve a rat problem for more than a very short time.
A one-way door allows rats to exit a structure, but prevents them from finding their way back in the same door. Unfortunately, a rat may try and enter the structure elsewhere.
This information was provided by the Washington State Department of Fish and Wildlife, Russell Link and Michael Holmquist
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