Roof rats are slender and dark, with a tail longer than the head and body, and they live up high in attics, trees and upper walls. Norway rats are heavier and brown, with a shorter tail, and they burrow along foundations and live low in crawl spaces, garages and yards. Memphis has both. Where you hear them and what the droppings look like usually tells you which one you have, and that decides where traps go and which openings get sealed.
Size and body shape
The Tennessee Wildlife Resources Agency lists the roof rat at about 12.9 to 18.3 inches long including the tail, with a tail of 6.5 to 10 inches that is longer than the body, and a weight of about 5 to 10 ounces. Its fur is grayish-black, with a lighter belly.
University of California pest guidance describes Norway rats as stockier and heavier, about 7 to 18 ounces, with a tail shorter than the head and body. The TWRA notes the brown (Norway) rat has a more brownish color, a heavier build, smaller ears and a shorter tail than the roof rat.
A quick look is often enough: a sleek rat running along a power line is almost always a roof rat. A chunky rat waddling out from under a shed is almost always a Norway rat.
Droppings
University of Kentucky pest training gives clear sizes:
- Norway rat droppings: about three quarters of an inch long, capsule-shaped, with blunt ends
- Roof rat droppings: about half an inch long, with one pointed end
- House mouse droppings: an eighth to a quarter inch, with at least one pointed end
Where you find them matters as much as the shape. Droppings scattered across attic insulation point to roof rats. Droppings along the crawl space wall or garage floor point to Norway rats. See rat droppings identification.
Where they live and nest
University of California guidance says roof rats usually nest above ground, in shrubs, trees and dense vegetation outside, and in attics, wall voids and cabinets inside. The TWRA says they are almost always found around buildings, mostly in upper floors.
Norway rats burrow along foundations, beneath rubbish and woodpiles, and in gardens. Inside, they stay low: crawl spaces, basements, garages and ground floors.
That split shapes Memphis rat calls. Roof rats show up in the attics of tree-shaded older neighborhoods like Midtown, Central Gardens and East Memphis. Norway rats show up near rivers, creeks, alleys and restaurants, and under older homes on crawl spaces.
How far they travel
University of California guidance says roof rats routinely travel 300 feet or more for food, and Norway rats forage about 100 to 500 feet from the nest each night depending on conditions. That means the rats in your attic may be eating at a neighbor's bird feeder or a restaurant dumpster down the block.
It also means you cannot always find the food source on your own property. Sealing the house is the part you control.
Want a local technician to take a look?
(901) 256-2861Breeding
The TWRA says roof rats can breed year-round, with peaks in summer and fall. Gestation runs 21 to 29 days, litters have 6 to 12 young, and a female can have up to 5 litters a year. Memphis's long, warm seasons suit them.
That pace is why a small problem in early fall can be a big one by spring. Acting on the first signs costs less than waiting.
Why the difference changes the plan
Roof rats are a roofline problem. Traps go up on rafters, top plates and ledges in the attic. Sealing focuses on soffits, gable and ridge vents, roof returns, chimney chases and limbs touching the roof.
Norway rats are a foundation problem. Traps go along walls in the crawl space and garage. Sealing focuses on crawl space vents, access doors, pipe gaps, gaps at the slab and burrows, which may need burrow treatment.
Some Memphis homes have both. A good inspection checks the attic and the crawl space before anyone sets a trap. See rat control.
What each one eats
The TWRA describes the roof rat's diet as omnivorous with a preference for grains and cereals. In Memphis yards, that means birdseed, pet food, and the fruit and nuts from pecan, fig and other backyard trees. Roof rats often feed up high, on fruit still on the branch or seed in a hanging feeder.
Norway rats eat almost anything and are more likely to raid garbage, compost, dumpsters and pet food on the ground. That is one reason they cluster around restaurants, alleys and homes with open garbage carts.
Knowing the diet tells you which yard changes matter most. For roof rats, take down feeders and pick fruit and nuts. For Norway rats, lock down the trash and the compost.
Can you have both at once?
Yes. An older house with tall trees and a crawl space can have roof rats in the attic and Norway rats underneath. The two species tend to keep to their own levels. If you find large blunt droppings in the crawl space and smaller pointed ones in the attic, tell the technician; the plan needs to cover both.
Want a local technician to take a look?
(901) 256-2861