Rats

Common Name:

Rats

Scientific Name:

Rattus

Type:

Mammals

Diet:

Omnivore

Group Name:

Mischief

Average Life Span:

1 to 2 years

Size:

Body: 5 to 10 inches; tail: 7 to 8 inches

Weight:

2 to 14 ounces

What are rats?

Much like dogs, though not as beloved, rats are our constant companions. Of the dozens of species in the genus Rattus, the most familiar are those which commonly live among us: the brown rat (also known as the Norway rat or sewer rat) and the black rat (also called a house rat, roof rat, or ship rat).

Some rodents that we call “rats” are not true members of Rattus, including the pack rat, naked mole rat, and giant pouched rat.

Rats are notorious stowaways that migrated around the world along with humans; today they live wherever Homo sapiens are found, on every continent except Antarctica. Rats are not just an inescapable feature of city living: In some ecosystems, particularly on islands, the invasive arrivals have wreaked havoc on bird and reptile populations by devouring eggs and young, driving many species to extinction.

Diet and habitat

Rats are successful because they are adaptable. They dwell in sewers, landfills, fields, and basements. Although they live around and among us, rats are nocturnal and tend to stay underground, or at least under cover, when humans are most active. (Climbing black rats, however, prefer trees—or high floors in buildings.)

(How rats became part of city life.)

They forage and subsist on all types of foods from farm crops to trash, and one way or another their diet is frequently furnished by humans. When easier pickings can’t be found, rats will also prey on small animals including insects and fish. Rats can eat up to a third of their body weight in a day, and scientists found that one rat’s stomach contained traces of over 4,000 different items.

Reproduction and social structure

Another reason rat populations number in the billions is that they reproduce at a furious rate. During her six-hour estrus, when she is fertile, a female brown rat will mate up to 500 times with a number of different male partners.

A litter averages about eight pups, and because those blind, furless young will be on their own in just three or four weeks, each female may have seven litters in a year—up to 60 young rats. If conditions are ideal, and each of those young rats and their own offspring also reproduce at top rates, a rat mom can have 15,000 descendants in a year.

(Rats invaded paradise. Here's how paradise fought back.)

At home, rats are very social animals and live in large colonies, sometimes creating extensive burrows. The rodents work together, and studies suggest that social isolation has serious impacts on rat welfare.

Rat superpowers

A rat’s whiskers are more sensitive than our own fingertips, and they use them to touch and feel things much like we use our hands. Rats have sharp eyes that move independently of each other and can watch for predators directly overhead. They can hear high-pitched sounds that we do not. Impressively, their sense of smell is so acute that African giant pouched rats have been trained to detect tuberculosis and land mines, and perform search and rescue.

Rats can squeeze through a hole no bigger than the size of their head, which spawned a myth that they have flexible bones. They use long claws to scale vertical walls. Black rats are especially gifted climbers and can survive a fall of 50 feet.

(Animals dream too—here's what we know.)

And rats can dream. Not only do they run mazes when awake, scientists have learned that they run the same mazes in their sleep, possibly using an unconscious state to help learn travel routes. They also dream of a desired future, like a tasty treat, brain studies suggest.

Rat-human interactions

Despite their reputation as dirty animals, these rodents actually practice good grooming and spend hours licking their fur to keep it clean. Unfortunately, that grooming doesn’t prevent them from carrying lice and fleas, which can transmit many serious diseases like typhus and the plague. However, some studies suggest that rats were not actually responsible for spreading the medieval Black Death.

(Why plague is still a threat to U.S. wildlife.)

Rats are also destructive pests. Their large, yellow teeth grow continuously so they must gnaw on things to keep them trimmed. Their chew toys can include wood, plastic, drywall, and even brick! They also spoil crops and stored foodstuffs both by feasting on them and by contaminating the remains with their prodigious waste.

In many places, humans have seen enough. In 2023, New York City hired a “rat czar” to manage populations, while Alberta, Canada, is a model for keeping rodents out in the first place. Rats have been eradicated from more than a thousand islands, including South Georgia in the South Atlantic Ocean.

All hail the rat king?

The rat king is a legend in which a number of rats become fatally tangled together by their tails. The Guinness Book of World Records claims that the largest rat king was 32 black rats found entangled in 1828 in a German chimney. In 2021, another one was presented to Estonia’s University of Tartu Natural History Museum. But are these nightmarish groups actually natural, or just hoaxes?

Theories suggest that under extremely rare conditions, huddling rats’ tails might become coated with sticky saps or other substances, tangling in a knot that the struggling rats tighten with each pull. But rats have also been known to gnaw off their own tails when caught in traps, so it’s unclear why they wouldn’t chew themselves free. Because rat kings, real or not, are extremely rare, their true nature may remain a mystery.