How Big Do Rats Grow?
WouterRats grow in different sizes depending on their environment. Most species are about five inches (12 centimeters) long, but some are much larger than that. According to the Integrated Taxonomic Information System, the world’s largest rat is the Bosavi woolly rat, discovered in the rainforests of Papua New Guinea in 2009. This species has the body weight of 3.3 lbs. (1.5 kilograms). Other species are smaller, such as the Osgood’s Vietnamese rat, which is around 5 to 7 inches (12 to 17 centimeters) long.
Rats reach sexual maturity at around five weeks of age. After reaching this age, female rats are usually ready to breed and have a litter of six to eight babies per year. Male rats, on the other hand, are much slower to reach sexual maturity. Gestation can take 21 to 23 days, but female rats can conceive within 48 hours of giving birth.
Adult rats grow to be between nine and eleven inches long, including their tail. Male rats weigh between 0.66 and 1.1 pounds, while females weigh between half a pound. However, the size of adult rats may vary slightly depending on their environment. Domesticated rats tend to be larger than wild rats because they are fed better and do not have to spend as much time hunting for food.
Some populations may be seasonal. They are most abundant in the summer and decline during winter. However, in southern Texas, the population size can vary greatly. For example, a recent study of the rice rat population in Mississippi found that flooding did not have a significant impact on its population. A flood caused a sharp decline in the number of rice rats there, but the numbers did not drop as much as expected.
