Rats, like house mice, are active mostly at night. They have poor eyesight, but they make up for this with their keen senses of hearing, smell, taste, and touch. Rats constantly explore and learn, memorizing the locations of pathways, obstacles, food and water, shelter, and features of their environment. They quickly detect and tend to avoid new objects and novel foods. Thus, they often avoid traps and baits for several days or more following their initial placement. While both species exhibit this avoidance of new objects, this neophobia is usually more pronounced in roof rats than in Norway rats.
Both Norway and roof rats can gain entry to structures by gnawing, climbing, jumping, or swimming through sewers and entering through toilets or broken drains. While Norway rats are more powerful swimmers, roof rats are more agile and are better climbers.
Norway and roof rats don’t get along. The Norway rat is larger and the more dominant species; it will kill a roof rat in a fight. When the two species occupy the same building, Norway rats may dominate the basement and ground floors, with roof rats occupying the attic or second and third floors. Contrary to some conceptions, the two species can’t interbreed. Both species can share some of the same food resources but don’t feed side by side. Rats can grab food and carry it off to feed elsewhere.
Rats of either species, especially young rats, can squeeze beneath a door with only a 1/2-inch gap. If the door is made of wood, the rat might gnaw to enlarge the gap, but this might not be necessary.
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Is there evidence rodents are feeding on fruit/nuts that are in or falling from the trees in your yard?
Do you see burrows among plants or damaged vegetables when working in the garden?
Do you see rats traveling along utility lines or on the tops of fences at dusk or soon after?
Have you found rat nests behind boxes or in drawers in the garage?
Are there smudge marks caused by the rats rubbing their fur against beams, rafters, pipes, and walls?
Do you see burrows beneath your compost pile or beneath the garbage can?
Are there rat or mouse droppings in your recycle bins?
Have you ever had to remove a drowned rat from your swimming pool or hot tub?
Do you see evidence of something digging under your garden tool shed or doghouse?
Do you find rat droppings around dog or cat dishes or pet food storage containers?
Do you hear noises coming from the attic just after dusk?
Have you found remnants of rat nests when dismantling your firewood stack?
Does your dog or cat bring home dead rat carcasses?