They are diabolically clever animals. ~ English biologists A.H. Barrett-Hamilton & M.A.C. Hinton
Rats are extraordinary creatures: cunning, fearless, smart, and curious. Their capacity for viciousness is quite manly. If cornered, a rat will fight to the death.
Rats are nearsighted. Vision is quite poor beyond a meter. Living in close quarters does not reward excellent eyesight, except up close, where rats’ visual processing is at least as sophisticated as humans.
Rats otherwise have keen senses, particularly an astonishing sense of smell, excellent hearing and sense of taste, and an exquisite sense of touch, accentuated by extremely sensitive whiskers and body hair. Rats use their facial whiskers much as humans use their hands and fingers when finding their way in the dark.
Motion can be sensed 15 meters distant. By smell, rats can tell whether a predator is within that range, or another rat, and whether male or female.
Rats are immaculate. They spend up to 30% of their time grooming. Rats are good swimmers, and happily bathe when clean water is available.
Rats are strong and agile; capable climbers that can jump 10 times their height, and squeeze through tight spots.
Rats are omnivorous, with a high metabolism: consuming 1/3rd their body weight per day. Seeds, grains, seafood, and meat are favorite foods. Rats will not eat white flour, as it lacks adequate nutrition.
Rats prefer to dine in secrecy. They readily hoard food.
Rats are stealthy, wily hunters. They are fine fishers and gather shellfish when seaside. Small animals, domestic fowl, and wild ground birds are ready prey. Stolen bird eggs are an especial treat.
Hungry rats are bold. They will attack the newborn or sick of larger animals, whether a piglet or human infant, even an adult human that appears helpless.
A rat can survive 2 weeks without food but must have up to 40 milliliters of water a day. Rats typically build their nest close to supplies of water and food.
Rats have many predators, so it is crucial that they navigate their environment efficiently and flexibly. Rats are better at mazes than people, and superior at tasks requiring precise timing. Rats excel at remembering various inventories. They exceed human capacity in intuitively counting objects.
Rats make decisions based upon past experiences. They suffer regret from poor choices. Novel situations require more analysis before a decision is made.
A rat has its own personality and temperament. Some are hard workers, other are slackers. Some are good-natured and cheerful, others somber.
But all rats like being tickled, especially tummy tickled. It is a social joy. Rats tickle one another and chirp with glee. Tickling makes for a happy home. In contrast, being petted is not pleasing.
Rats certainly have a sense of pleasure. It is likely they have a sense of humor, though stolid researchers haven’t figured out a way to test for that.
Rats behave like people in numerous ways. They make facial expressions: grimacing with pain, sighing in relief. A rat can tell another rat’s emotional state by its facial expression. Rats dream of the day’s events and who knows what else.
Rats develop a sense of trust, or mistrust, in others. Rats are generally empathic, and selectively altruistic. Rats enjoy sex and know good sex from bad.
Rats are prolific, breeding year-round. Females gestate for 22 days and may mate again 2 days after giving birth. A female can produce 16 litters per year, 6–12 pups per litter (kittens is the European term for rat younglings).
Rats are very altricial. Pups are born completely vulnerable: blind, deaf, and helpless. A pup is weaned in 4–5 weeks. Rats reach sexual maturity by 2–3 months, if they live that long.
Mortality is high. Pups are sensitive to temperature swings or other environmental upsets. Predators are aplenty. Disturbed mothers commonly kill and eat their young.
Life as a rat is tough, regardless of age. Most live but 6 months to a year, though some survive to 5 years.
Rats congregate in large packs. Females share parental care, while all adults protect pups from danger.
Old World rats lived in Central and South Asia before furtively traveling the world with human explorers. Black and brown rats are the best-known species. As stowaways on sailing ships, by the 19th century, the adventurous rat had colonized the world.
Black rats originated in South Asia, descending from a tree dweller. They prefer high places.
Brown rats came from northern China and Mongolia. Once found in the forests, reliable food supplies lured them to farms and villages. Brown rats prefer to be underground, near water. They are avid burrowers.
Brown and black rats are mortal enemies. They will not crossbreed. They may live in the same house, but only so long as they remain apart: black rats upstairs, brown rats in the basement. War breaks out if they meet in between. The larger, more ferocious brown rat is likely to prevail.
Rats are wrongly dreaded for carrying diseases. A marked fear has been immigrants may carry illness from afar. But rats are hygienic, and fiercely territorial. Newcomers are rebuffed by residents.
It’s unlikely that a lot of diseases are going to be entering cities on rats walking into the local rat population. ~ American zoologist Jason Munshi-South