Roof rats (Rattus rattus) are a different animal from the fancy rats most people keep, and getting to know them is half the fun. Here is the practical picture: where they come from, how they differ from Norway rats, what they are like to live with, how long they live, and what they cost. For the bigger case that they are the next great pet rat, see Pet Roof Rats: The Next Fancy Rat?
Where roof rats come from
Roof rats (Rattus rattus) originated in South Asia, with related species in southeast Asia living in cane and rice fields. Like Norway rats, they’re considered a pest and invasive species, they exploit human agriculture and food stores and have followed us to colonize nearly every habitat people occupy. They’re intelligent, hardy survivalists that can eat almost anything, have several litters a year, and outcompete many native species. (To be fair, apart from the reproductive rate, we humans share a lot of those same traits.)
How roof rats differ from Norway rats
Roof rats (Rattus rattus) are a different species from the fancy or Norway rat (Rattus norvegicus): more arboreal and climby, leaner, and genuinely their own animal in temperament. For the full set of common questions on the differences, see our Roof rats vs Norway rats FAQ.
What makes roof rats special
- Vertically oriented, they sleep in hammocks, not on the ground, and need things to climb and jump on.
- They will chew anything chewable, so watch what’s within reach.
- They’re more active than Norway rats and rarely sit still unless they’re eating.
- They show affection differently: chittering while climbing on you is a sign of trust, and closing the eyes and tilting the head while being stroked means they’re enjoying it.
Roof rat lifespan and size
Roof rats usually live about 3 years, and can reach 4 or 5 with good care. I have never seen a mammary tumor in this colony, which keeps medical costs lower than they were with the fancy rats I used to breed. That is what I have seen in my own animals, and not an established difference between the two species. A female who is not pregnant usually runs 150 to 270 grams, and a male 230 to 350 grams, comparable in length to Norway rats once you include the tail. I put the ceiling at 330 grams for a pregnant female and 400 grams for a male, and neither is usual. These are what I see in my own animals rather than a published range.
Roof rat temperament
Young roof rats are often timid and wary until they acclimate, careful, alert, and ready to run and hide, all good survival instincts. They avoid fighting when they can. Once bonded, a roof rat will treat you like another rat (a big, dumb, stinky one): climbing on you, using you as a tree, stealing food, begging for treats, and gently nipping if a treat is slow to arrive. They’re highly food-motivated and easy to train. Two unfamiliar roof rats may fight; females are every bit as aggressive as males and will take on, and usually beat, a larger male.
Do roof rats need company?
Most are happier with cagemates, though some prefer to live alone or only with the opposite sex. Compatible companions will snuggle and groom each other. But never force an incompatible pairing, roof rats can badly injure or even kill each other.
What roof rats cost
The rats themselves are free. Plan on roughly $100–$200 for a cage and supplies, plus a few dollars a month for food. Veterinary care can be expensive, though I’m always glad to offer advice.
The bigger picture
These rats have been selectively bred for many generations to be calmer and friendlier than wild roof rats. They remain a bit more active and reactive than a typical Norway rat, they’re slender, athletic, tree-living animals, and that’s simply their nature. The goal is to keep improving them while respecting what they are.