Norway rats, or brown rats, are non-native pest rats that are found in Colorado and across the rest of the U.S. Rats commonly live along the banks of creeks and ditches, and can sometimes move into developed areas where people live and work. The following information provides detailed directions for effective and nontoxic control of rats that you can use to keep your home, business or property free of rats—or remove them after they’ve appeared.
Norway Rat
Why are Rats Here?
Homes and businesses provide everything a rat needs to survive – food, water and shelter.
Rat reproduction peaks in the spring and in the fall. The average female rat has 20 or more offspring a year. Rats in cities and towns normally live for five to 12 months.
Rats will eat any food that people or their pets consume. They may store hoarded food in walls, furniture and appliances.
In cities, there is ample food from bird feeders, dog pens, vegetable gardens, chicken coops, garbage cans, dumpsters and
compost piles.
Unless disturbed, a rat colony may infest the same alley, basement or building year after year; construction and building
renovations may cause them to disperse to other areas.
Take These Steps to Rodent-Proof your Home or Business
Don’t give rats a place to hide
Manage exterior landscaping. Avoid low-lying shrubs and vines, such as creeping juniper, next to buildings and fences. Remove tree branches within five feet of the building. Mow tall grass and weeds.
Don’t give rats a home
Remove clutter both inside and outside the building. Remove boxes, rubbish and other debris that may have accumulated. Do not store firewood against house or a building. Remove old furniture, vehicles and appliances from your property.
Don’t provide food sources
Manage food sources. Store large bags of dog food or birdseed in metal or heavy-duty plastic cans. Pick up pet food dishes at night. Secure compost piles and recycling bins so that they are inaccessible to rodents. Remove animal waste (feces) every day from your yard. Animal waste contains undigested pet food that rats will eat.
Keep dumpsters and garbage cans clean and secure
Use a durable trashcan with a tight-fitting lid. Do not put out trash in plastic bags. Rats will chew through them and feast on your leftovers.
Dumpsters should be of adequate size so that there is no overflow.
There should be no leaks or breaks under or on the sides.
Lid covers should be in place (and used).
Drain plugs should be in place.
Dumpsters containing food trash should be stored 25 to 50 yards from buildings.
Do You Have a Rat Problem?
Inspect your home, business, yard and surroundings. If you answer yes to one or more of the following questions, you may have a rat problem.
Example of a rat burrow
Rat "runway"
View 2 Photos
Signs of a Rat Problem
Do you see rats traveling along fences or walls?
Rats forage for food mainly at dusk and again prior to dawn. But if the area is quiet and undisturbed, they may forage during the daytime. Have you found rat nests behind boxes or in drawers in the garage?
Have you seen rat droppings?
Fecal pellets are ¾ inches long and ¼ inch in diameter, smooth, rectangular in shape, dark colored and usually found in small groups. Look for droppings (one rat produces 40 to 50 pellets a day) in a 100-foot radius around outside dog pens or areas used to store pet food, birdseed or chicken seed. Are there rat droppings in your recycle bins or in/around your garbage cans?
Have you seen burrows and/or digging?
Rats live in subterranean burrows. Burrows are about 3 inches in diameter; the entrance looks compacted and smooth. An active burrow is free of cobwebs and debris. In urban and suburban areas, rats often burrow around buildings, beneath slabs and alongside building foundations. Junk and clutter on the ground, as well as areas with dense vegetation, are also favored. Look in these areas around both residential and commercial structures.
Alongside walls of gardens raised using railroad ties
Beneath low-lying bushes
Along fence supports where dense vegetation (ivy, Virginia creeper, etc.) is covering fence
Under slab walkways
Under low-lying decks, along garage walls or storage sheds
Under compost piles or chicken coops
Are there smooth, well-packed “runways,” such as worn-down paths in the grass?
Runways are used between the nest and food source, and the average distance a rat travels from its nest is 25 to 100 feet. Rats usually travel along structural lines, such as a fence or wall. Indoors, rats prefer continual body contact with at least one vertical surface such as a wall near ground or floor level. Have you seen gnawing damage around openings – shallow, parallel grooves left by incisors? Each mark is about 4 mm in width.
Are there defunct sewer system lines in your neighborhood?
These can be a source of rats.
Do you have woodpiles or wood stored on the ground?
Have you noticed remnants of rat nests when stacking or unstacking firewood?
Other signs of rats
Are there rub marks caused by the rats rubbing their fur along wall/floor junctions and at regularly used openings?
Have you ever had to remove a drowned rat from your swimming pool or hot tub?
Have you heard gnawing, scrambling or squeaking noises in the walls? Is there a musky smell?
Best Practices for Eliminating Rats—Use Snap Traps
Snap traps are lethal traps that quickly and humanely kill rats as they attempt to eat the bait. There are several advantages to using snap traps.
They provide a quick solution to a rodent problems.
Using traps will minimize the chances of decomposing rodent odors and fly problems.
Most mechanical traps can be reused many times.
They are nontoxic, which means they are less likely to harm the environment or other animals.
The least expensive option is the wooden snap trap, which looks like a standard mouse trap but is larger (see size comparison image on the next page); the single-kill plastic rattraps are easier to set and clean.
Snap traps are the safest and most effective way to control rats if used properly.
Using Traps Effectively
Although it takes patience and strategy, snap traps are an effective andnontoxic method to eliminate a rodent infestation. However, it is important that rat traps are used safely to ensure that people, particularly children, pets and non-target animals do not accidentally encounter the traps. When placing traps indoors, place traps in darkened corners, along walls or behind appliances and objects. If rat traps must be placed where kids or pets have access, place the snap trap in a tamper-resistant plastic or metal station, such as a Protecta bait station. Rats like a sheltered location, so these seem to have good results.
You may wish to hire a professional to install traps. But ensure that you understand the principles for effective trapping and don’t assume that a pest control service will use these techniques unless you require it when you hire them.
Step-by-step Guide to Effective Snap Trapping
Trap placement
Rats are cautious of new objects. Place the trap(s) in the location where there is the most rodent activity. For example, if there is a hole in the floor or wall used by the rodents, place several traps in the area, but away from the opening. You can also place traps 8 to 12 inches away from runways. Avoid placing traps directly in the line of frequently used travel lanes.
Monitor
Rats are cautious of new objects. Place the trap(s) in the location where there is the most rodent activity. For example, if there is a hole in the floor or wall used by the rodents, place several traps in the area, but away from the opening. You can also place traps 8 to 12 inches away from runways. Avoid placing traps directly in the line of frequently used travel lanes.
Trap spacing
Place rat traps about 10 to 20 feet apart. Use as many traps as are practical so trapping time will be short and decisive.
Timing
Place traps unset and baited for 2 to 3 days prior to setting the traps. Place baits in a small trail leading toward the snap trap, as well as on the edges of the trap. This lets the rat associate food with the new object.
Bait
Place different kinds of bait in traps. Divide up the traps with meats, peanut butter or even nesting material, such as soft strips of cloth. If rats are not attracted to the trap, try enticing them with a gourmet option, such as fresh meat or shrimp.
Whenever possible, eliminate the rat’s regular food source. Remember that rats are wary of new things, so, if there is abundant food elsewhere, it is not likely to try “new” food in a trap.
Inside buildings
In a building, place traps along a wall so that they extend from the wall at right angles, with the trigger end nearly touching the wall. Rats like to touch surfaces, like a wall, when they move.
Protect yourself
For personal hygiene, wear disposable gloves when installing or recovering any animal traps. However human odors on traps are not likely to deter most rodents.
Successful Implementation
If these steps are followed carefully, the majority of rats will most likely be caught on the first night. Install many traps at the beginning. Continue trapping for three to four more nights and continue watching for signs of rats.
Avoid another infestation
Make sure that you rodent-proof your property and follow the guidelines for removing food and shelter to prevent another infestation.
Avoid glue traps and live traps
Glue traps are not effective for trapping rats. Rats caught in glue boards may struggle and drag the trap around. Glue traps can also capture birds and other non-target wildlife.
Live traps are not recommended because trapped rats must be either humanely killed or released elsewhere. Rats are not native to the United States, and their presence in the wild is detrimental to native ecosystems, especially birds. It is against the law to release rats on OSMP property.
Other approaches that are not effective and should be avoided include ultrasonic machines and moth flakes (e.g. naphthalene).
The Dangers of Rat Poison - Risks to children, pets and wildlife
Poison baits or rodenticides (pesticides that kill rodents) are dangerous to children, pets, and non-target animals such as hawks, owls and other birds of prey, coyotes or bobcats, mountain lions, foxes and other wildlife.
Rodenticides can harm pets or wildlife by secondary poisoning - a pet or animal that eats a poisoned rat is also poisoned. Rodenticides are applied as a bait, which contains an attractive food laced with the poison. Rodent baits can be dangerous to children, pets or non-target animals from direct ingestion of the bait. Bromethalin is one type of rodenticide that poisons the central nervous system. Most other rodenticides are blood-thinning drugs called anticoagulants.
Anticoagulants damage capillaries and result in fatal internal bleeding. They are used at low levels and the onset of symptoms is delayed for several days. This usually results in the animal dying many days later at an unknown location, including inside buildings or in burrows. The stench of a dead rat in a building may require drilling a hole in a wall to remove the carcass. If not removed, the carcass can also attract flies, but the odor will usually disappear on its own in about a month.
Second-generation anticoagulants are generally used because they persist longer in the rodent’s body than first-generation anticoagulants. Anticoagulants have the same effect on nearly all warm-blooded animals. Dogs are more susceptible than many other mammals. Vitamin K1 is the antidote for anticoagulant rodenticides, although in cases of severe poisoning, whole blood transfusion is also used. Other rodenticides, such as the neurotoxin bromethalin, have no antidote or treatment.
Oxford University Press
Non-target animals can be die from consuming anti-coagulant rat poisons directly or through seocondary poisoing by eating rodents who've consumed poison bate.
Learn why rats are in Boulder and how to prevent an infestation or safely control them if you have a rat problem.