Where this page comes from. Very little has been published about keeping roof rats, so unless a line says otherwise, the framework here is adapted from the literature on fancy rats and laboratory rats (Rattus norvegicus). Roof rats (Rattus rattus) are a different species. Where the two are known to differ, I say so on the page. Where something comes from my own colony, it is marked as mine.
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Roof rats as pets: a breeder’s care guide
A plain-language overview of what roof rats are and what they need, drawn from years of keeping and breeding them. For the deeper detail, see the FAQ and care lessons on the Care & Husbandry page.
More about what roof rats are really like »
Quick reference: roof rat husbandry basics
Cage size: Bigger is better, and these are the cages Brian actually uses: a KW Cages Rodent Cage 10 x 14 x 12 for bringing babies home and for early socializing, a Deluxe Rodent Cage 12 x 24 x 12 for one adult or for a doe who is pregnant or nursing, and a customised Pointer Hill BR804 for two to four adults. The Roof Rat Starter Kit cage is 18 x 24 x 18. All-metal construction, wire rather than plastic or wood, because they will chew both. Unless you really trust your rats, pick a cage whose door opening is smaller than the whole side: the lip of a smaller opening blocks a rat from darting straight back out past your hand.
Capacity per cage: Two to four adults in the Pointer Hill BR804, which is the cage he uses for a group. Mothers with litters need their own cage.
Social structure: Variable. Some males and some females prefer to live alone, so respect that. They can injure each other faster than you can intervene. Group housing is easiest when the rats are introduced young, around 5 to 8 weeks old, and even then it is not guaranteed. Do not force it, and be prepared to keep some rats separate.
Water: Provide in dishes, not bottles. These rats learn quickly how to push the valve on a water bottle open, and they really love playing in the running water. Once they learn, they do not stop, and their litter will be soaking wet every morning.
Sexual maturity: Females 2–3 months, males 3–4 months.
Recommended breeding age: 120 days to 6 months, depending on your breeding goals. Rats, especially females, can be bred successfully and safely at 120 days (females may be fertile sooner than that), and it is sometimes advisable to wait until they are older. We tend to wait longer before breeding males: they take longer to mature, they need to be physically larger than the females to breed successfully, and they have a longer fertile life than females (a male can breed as long as he is healthy, while females go through menopause). If you are breeding for tameness and are not sure about an animal (a marginal personality, or a lineage with a history of poor offspring), waiting longer lets the adult traits show first. And if the colony is overcrowded, waiting until rats are older before breeding them is one way to balance deaths against births without culling. This is up to the experience and intuition of the individual breeder, who knows their rats and their history: there is no absolute rule.
Breeding method: Weigh the female before pairing. House with the male for ~18 days. Weigh again; if she has gained weight, she’s pregnant, so move her to her own dedicated cage for the rest of pregnancy and weaning.
Gestation: 23 days. Published ranges for Rattus species are usually given as about three weeks; 23 is what Brian has seen in this colony, and it is the number the colony software counts from.
Weaning: Around 2 months. Litters remain with the mother until they are near adult size.
Handling young: We do not handle pups before they are running around and almost weaned. The reason is that handling-induced tameness can mask whether an animal is genetically tame. We need to see the natural temperament before deciding whether to include an animal in future breeding. There is a second reason, and it matters more if you are keeping rather than breeding: some mother roof rats get very nervous if their babies are disturbed young, and a nervous mother may carry them about looking for somewhere quieter until they are injured.
Climate: Target 76 to 80°F and above 50% relative humidity year-round. Those numbers are Brian’s own, from this colony rather than from a published standard, and in his own words the humidity figure comes with a hedge: “40-60% is OK. Above 50% is optimal to avoid ringtail, but sometimes that is not practical advice. Too high humidity can promote fungal infections. In practice, my actual colony’s environment is 40-60% and they are fine. 76-80f are the ideal targets (lowest metabolic energy consumption to maintain homeostasis.) Below 70f is dangerous. Not sure about upper limit as my colony never exceeds 85f, but in Florida wild roof rats can survive 90f but probably seek shade and use other strategies to stay safe. I suspect many wild roof rats also die from extreme temperatures, and our goal is that our rats do not get sick or die at all.” Ringtail is the reason the humidity matters: their long tails are vulnerable to injury when the air is too dry, especially in babies.
Explore the guide
This guide is split into focused sections so it is easy to find what you need. Pick a topic:
Cage, beds, litter, water, and fixing housing problems. Bonding, Training & Behavior
Taming, tricks, nipping, and meeting people and pets. Life Stages: Babies & Seniors
Raising babies and caring for older roof rats. Health & Common Issues
Common problems, early signs, and when to see a vet. Feeding
Diet, treats, and supplements: our full nutrition guides. About Roof Rats
What they are and how they differ from fancy rats. Common questions (FAQ)
Quick, targeted answers, indexed by topic.Colors & Genetics
Blonde, black, agouti, and the genetics behind them.Adopting a Roof Rat
How adoption works (free, via contact + vetting).