All about Roof Rats

The roof rat is dark brown to black in color and measures 13 to 18 inches in length including tail. They weigh 5-9 ounces, are slender, and their ears are large and nearly hairless. Their droppings are long and cylindrical.

Roof Rats
Roof Rats

Nesting Requirements

Roof rats nest outside in trees, woodpiles and debris, and in dense vegetation. Inside, roof rats prefer to nest in the upper levels of a building in the attic and ceiling.

Food Preferences

Roof rats are omnivorious, but tend to more vegetarian preferences. Typical food is fresh fruit, plant material, nuts and seeds, vegetables and even tree bark.

Natural Enemies

Roof rat didn’t just gnaw a hole in this dishwasher drain line, it chewed the entire length.

Dogs, cats, snakes, birds of prey, owls, coyotes and other rats.

Medical Importance

Rats can spread disease. Sometimes they transmit disease directly by contaminating food with their urine or feces or by biting people. Indirectly, they transmit by infecting as when fleas bite a disease-infected rat, then a person or other animal.

Potential Damage

Rat burrows can cause structural damage by undermining the foundations of buildings, roads and walkways, can cause damage by gnawing, damaging plastic and lead pipes, door frames, upholstery, and electric wires, and can cause damage through the destruction and contamination of stored foods.


ced36ebb1735051db8c768531a98a611Oleanders are the most common denominator for roof rats; the dark green hedge provides a safe refuge and an ideal path of travel. In Phoenix summers when attic temperatures rise over 130 degrees, roof rats find oleanders a cool place to nest. Roof rats can often be heard walking through the oleander as they travel over the dry leaves.

Understanding Roof Rat Behavior

Common signs of roof rat activity

  • Visual sightings on power lines, trees, bushes, patios, roofs, etc.
  • Hollowed citrus and other fruit
  • Rat droppings
  • Noises in the attic and walls
  • Gnawing sounds and gnaw marks around roof eaves
  • Damage to plastics and coverings on electrical wires
  • Unsettled pets

Places roof rats have been found

  • They have been found in swimming pools, laundry rooms, attics, garages, and patios.
  • They’ve been seen on power lines in the alleys.
  • Roof rats spend 90 percent of their life 4 feet or more off the ground.

Roof rat traveling patterns

  • Roof rats are strongly arboreal (tree inhabitants) and travel along power lines to trees, oleanders, vines, and roofs.
  • They can climb up brick, concrete block and other rough surfaces.
  • They can jump 2 feet up and 4 feet horizontally (double the horizontal distance if they are jumping from a height).
  • Ground covers and compost bins also provide safe travel routes and nests.
  • During twilight and nighttime hours, within a territory 200 to 300 feet from their daytime nesting locations.
  • They thrive in cool weather and are most active from November through May.

How roof rats enter homes

  • They enter homes, sheds, garages and other structures through any opening larger than a nickel, looking for places safe from predators and good for nesting.
  • They may follow pipes down from the attic, gnaw through drywall, to access structures
  • They may chew through wood, plastic, aluminum siding, sheet rock, and soft metals to gain access to interiors.
  • Attics provide a safe refuge, a nesting place for their young and routes into the home below.

What roof rats eat and drink

They love to eat all types of citrus and other fruits, and nuts, including:

  • Lemons
  • Limes
  • Grapefruits
  • Oranges (including ornamental oranges)
  • Tangelos
  • Tangerines
  • Figs
  • Pomegranates
  • Palm fruit, including Queen Palm fruit, especially in summer when citrus is not available
  • Nectarines
  • Peaches
  • All nut fruits like walnuts, almonds and pecans
  • Rats do not have a discerning taste for fruit like humans
  • Fruit can be green (unripe) or even rotted
  • Rats eat fruit more for their water content than for food sustenance

They’ll also eat:

  • Bird seed (both in feeders and stored in bags)
  • Dog and cat food (left outside after dark are favorites)
  • Stored grains
  • Vegetables in your garden
  • Insects
  • Lizards
  • Tree bark
  • Soap
  • Paper
  • Animal and taxidermy hides
  • Beeswax and candle wax

Water sources include:

  • Leaky faucets
  • Leaky sprinkler heads
  • Leaky irrigation boxes
  • Bird baths
  • Water fountains
  • Ornamental ponds
  • Irrigation lines
  • Air conditioner condensation drip lines
  • Saucers under potted plants
  • Pet water dishes
  • And remember, they will chew through metal and plastic pipes to reach water!

Dealing with Roof Rats

There are several steps homeowners can and should take to prevent and minimize the rodent’s length of stay and possible ensuing damage:

  1. HOME PROOFING: Seal House and Attic
  2. LANDSCAPE CARE: Trim and manicure trees and bushes.
  3. FOOD & WATER SOURCES: Glean fruit trees, secure pet food and water sources.
  4. PROTECTION AND ERADICATION: .Go to “eRATication that works!”
  5. WORK WITH NEIGHBORS: All of us helping each other and working together will clear our neighborhoods of this common enemy. Go to “Neighborhood Action”


  • The most extensive damage occurs when roof rats enter the home, so the first goal is to keep them out!
  • Caulk all holes, cracks, crevasses, or gaps (any opening larger than a nickel) on the exterior walls and underneath the eaves of block and/or wood constructed homes/outbuildings, sheds, etc.
  • Look for holes in exterior walls and near hot water heaters, washers, dryers, dishwashers, and under sinks.
  • Roof vents and attic turbine ventilators should be checked and screened if necessary.
  • Fireplaces need to be protected with the proper screening of a chimney cap.
  • Tile or wood shake roofs should be closely inspected for openings.
  • Pet doors, vents, and exterior door and window screens should be secured at night.
  • Use stucco diamond mesh or steel wool and a flathead screwdriver and push the material into prevent rats from climbing up the insulated pipe inside the cover. Look for scratch marks on the insulation, and then set a snap trap to catch them the next time they use that entrance.
  • Always shut doors when exiting/entering the home.
  • Screens placed on clothes dryer vents should be checked often and cleaned for accumulated lint. Not cleaning the screen could result in the malfunction of the dryer and/or possibly result in a fire.


  • Roof rats are not indigenous to Arizona, and therefore try to escape the heat by harboring in thick shrubs where there is moisture and protection; a clean yard is a deterrent.
  • Thin out bushes until daylight can be seen through them; oleanders and bougainvilleas are particularly prone to harboring roof rats.
  • Prune trees and shrubs up from the ground at least 12 inches so the ground beneath is open and visible.
  • Prune back all tree branches from all structures by at least 6 feet.
  • Rake dry leaves, old growth and weeds from under trees and shrubbery.
  • Thick ground covers should be thinned.
  • Keep palm trees trimmed. Roof rats nest in the skirts of old fronds, as well as in piles of debris and hollow trees.
  • Take down all vines/shrubs growing against the home or perimeter walls
  • Remove wood and brush piles from yard.
  • Eliminate piles of lumber and firewood, or store them at least 18 inches above ground and at least 12 inches from walls.


  • Promptly and completely pick all fruit (ripe or not) on citrus and other fruit and nut trees, and pick up fallen fruit every season.
  • Fruit and nut trees that touch other trees, houses, fences or power lines have more roof rat activity, so prune to isolate each tree.
  • If you can’t physically pick your trees, go through the yellow pages for landscapers who might. Those landscapers who will pick – not all do – typically charge between $20 – $45 per tree.
  • Residents can also call their faith community for youth groups who might be looking for community service work or Boy and Girl Scout troops are a good example.
  • Consider donating excess fruit to the nearest food bank.
  • With proper care, fruit and nut trees do not need to be removed, but you may want to consider this if upkeep is not possible for you.
  • Check for the seasonal citrus drop off program (generally from January to March each year). In a partnership between the city, residents and county agencies, the Arcadia Citrus Program makes citrus drop off possible, with viable fruit being distributed to food banks and county facilities.
  • Short of cutting a nut tree down, there is virtually no way to stop a nut bearing tree from being a roof rat’s food source. But the tree will make a good place for a bait station (see section on bait stations and snap traps).

Don’t unknowingly feed roof rats

  • Roof rats will eat anything to survive – this includes all domestic and wild animal food, garbage, and animal feces.
  • Keep all pet feces off the ground at all times.
  • Don’t leave pet food out, especially overnight.
  • Consider not filling bird feeders until all signs of roof rat activity have ended, or provide just the amount of bird seed that will be consumed in a day and sweep up fallen seeds before sunset.
  • Store bulk foods and seeds in metal, sealed, rat-proof containers. (Rats will eat through plastic bins.)
  • Keep garbage containers tightly covered.

Eliminate water sources

  • All water sources on private properties are a welcomed invitation to a roof rat. This can include birdbaths, dog/cat water bowls, fountains, water features, and pools.
  • Drain or empty all standing water sources except pools and spas. Draining standing water also helps prevent mosquito breeding issues.
  • Change pets’ drinking habits by training them to go inside for a drink, if your dog/cat is used to drinking water from a bowl outside.
  • Do not leave food or water outside for stray/neighborhood animals.
  • Keep pool water level at least 6 inches below the decking surface. If a rat falls in while getting a drink, it won’t be able to get out of the pool and can drown. Dead rats can be fished from the pool with a long-handled net and all questionable areas, to screen and seal all holes and air vents leading into the home or shed. It cuts and molds very easily. For aesthetic purposes, you can use paintable caulk to go over the areas containing the steel wool and then paint over the caulk.
  • If window or door screens are loose, either reinforce or replace.
  • Stuff the cover of the air conditioning line that runs from the outside unit into the attic with steel wool or copper mesh to disposed of in city trash containers.
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