Roof Rat Social Life: Other Rats & Pets

Should I keep more than one roof rat?

Some do, and some do not. We have tried very hard to find good cage mates for all of our roof rats, but some of them are not happy with cage mates no matter what we think is best for them. Roof rats do not really need cagemates the way Norway rats do, and a roof rat that lives alone will be fine if you spend a lot of time with him.

Are roof rats social or solitary?

Social, though not as hierarchical as Norway rats, and often preferentially solitary. Roof rats do not reliably follow the Norway-rat pattern where a properly introduced pair bonds for life: cage mates that have been together for a year or more, even littermates that have literally lived together their entire lives, can turn on each other overnight without any warning.

Do roof rats fight for dominance like Norway rats?

This is not to say that roof rats never engage in dominance behavior. Here is an example of one roof rat force grooming his brother, who was his cagemate. The brother does something similar to Norway rat boxing to try to ward off the unwanted grooming, which was apparently unpleasant (too rough, or not done in a nice way?). Notice how they both immediately stop when they realize I was watching them.

These rats genuinely seemed to like each other and bullying was rare. In a case like this, where neither rat is actually getting injured, it’s fine to keep them together.

You will see some pet-rat sources say roof rats are highly social and should be kept in same-sex groups and introduced just like Norway rats. That advice is borrowed from the fancy rat, and it does not match what we see firsthand: roof rats have no stable pecking order and will work to drive out an intruder rather than rank under it. We treat our own colony as the primary evidence here, and the true natural social structure of this species is itself an open research question, with the test for it on our open research questions hub.

How many roof rats can live together?

We recommend that you don’t keep more than 4-5 adult roof rats together in one cage.

Is it possible to add new rats to a cage with existing rats?

Yes, especially if the rats are both still younger than 4 months or so.

Roof rats seem to be socially different from Norway rats. Norway rats sort out a pecking order and then usually stay friends for life. Roof rats do not appear to work that way: they do not seem to have a stable hierarchy or any concept of an alpha. Every roof rat acts as though the territory is his. He may willingly share it with a rat he treats as a friend, but he does not defer to that rat, and he reserves the right to withdraw his acceptance at any time. So when roof rats fight, it looks less like sizing each other up and more like trying to drive an unwanted rat out of the territory.^[1]

Because of that, introductions between sexually mature roof rats are done with care, in a neutral space where neither one is trapped with the other. The first goal is simply that they do not immediately hate each other. Some adults are easygoing and rarely fight, others do not want any other adult, or even a youngster, in their space. If two rats fight right in front of you, take that as your answer and do not house them together. Adults fighting over territory do not gently box the way Norway rats do, two equal males often make what I call a rat ball and go for each other’s bellies, so separate them fast. A rat that clearly wants to live alone can just have his own cage. The Norway-rat rule that a rat must always have a companion does not reliably apply here. For the full method, see Introducing roof rats to each other in the Bonding & Behavior guide.

If they do seem to tolerate each other, you can cautiously try housing them together, and pull any rat that is getting injured right away. Roof rats are quieter by day and often save their fighting for the night when you are not watching, so check everyone for fresh injuries each morning. Often one pugnacious individual is the whole problem, and the simplest fix is to give him his own cage.

One important caution: do not introduce a very young female to unfamiliar adults, because an adult female may kill babies that are not her own. Wait until she is big enough to defend herself. Introducing very young males to adults usually goes much more smoothly. The honest bottom line is to go slow, watch closely, and accept that some roof rats simply will not live together and will need separate cages.

Do male roof rats get along, or do they fight?

It varies by individual, but our fertile males have grown more socially tolerant over the generations, we’ve watched established males calmly accept a young newcomer with no hostility at all. Selecting for temperament seems to help here too. (Introduce carefully and supervise regardless, see The New Roommate.)

Related: Care & Husbandry Guide · Winning Over Whiskers.

Thinking about keeping or breeding roof rats yourself? See Successor Breeders Wanted and What It Takes, or get in touch.

Can a roof rat live in a home with a cat?

Our cat and our roof rats share a home, but I never leave them together unattended, cats are unpredictable, and a rat gets stressed with a predator too close. Keep them separated and supervise any contact.

Can rats be friends with cats or dogs?

Yes, people have reported to us that their cat or dog and rats accepted each other and even become good friends!

It usually works best when they are younger so they can grow up together.  And it is very important to supervise your pets carefully whenever they are together until you are sure that they are friends.  Obviously, a cat or dog can injure or kill a rat, but it is also possible for a rat to inflict a very nasty bite if provoked.

Even if your pets seem to like each other, it is always possible for them to have a bad day and fight, so be careful (that is true with any animals that share the same space, regardless of species)

Tommy the Roof Rat friends with Explorer a 14 year old cat

Can Roof Rats and Dumbo Rats play together?

People often ask us if Roof Rats and Norway Rats can play together. Apparently, these guys can! BaoBao and Chill are Male Roof Rats, and Rollie and Brownie are Female Dumbo Rats. They got along just fine: there was some rear sniffing and urine marking, like you’d expect in any rattie playdate. A bit of playful chasing, but not much else. The male Roof Rats were similar in size to the female Dumbos, and they had similar activity levels, too. They actually seemed like good playmates for each other.

I introduced Cinnamon and Bear’s Dumbo rat babies to Bandito, an adult male Roof Rat.  The babies (mostly) seem just fine with Bandito and he has no problem at all with them.  He’s mostly just interested in eating a nut.  Roof rats are not aggressive towards babies: I’ve never seen an adult attack a baby of either species.

Can Roof Rats share a cage with Norway Rats (Fancy or pet store rats?)

It is physically possible, and there is no risk of accidental litters: roof rats and Norway rats are different species and cannot have babies together. A Norway rat will be bigger and stronger than a roof rat of the same age and sex, but a friendly, non-aggressive Norway rat can usually share space without fighting, and dwarf Norway rats are close to a roof rat’s size and activity level, so they can be an especially good match.

Even so, I do not recommend housing the two species together, and the main reason is disease. Beyond the risk of fighting, they can pass illnesses to each other that the other has little natural immunity to. The clearest example is mycoplasma: nearly all pet Norway rats carry it, and roof rats were never selectively bred to resist it, so a roof rat exposed to a Norway rat can catch something that is much harder for it to shake off. This is not hypothetical. If you keep both, house them separately. See Mycoplasma Respiratory Disease in Pet Rats for more.