Rats

Average Norway rat is about 16 inches total length and weighs about 12 ounces or 340 grams. They reach sexual maturity in 75-90 days and their average litter is 6 to 14 pups. And they can easily have 3 to 6 litters in a year, but in perfect conditions, they can actually have between 10 and 12. Ideal means living inside a structure with no predators or whether to combat.