The underside is typically grey to yellowish-white. Rats will eat nearly any type of food, but they prefer high-quality foods such as meat and fresh grain. Rats have keen taste, hearing, and sense of smell. Rats have litters of 6 to 12 young, which are born 21 to 23 days after mating. Young rats reach reproductive maturity in about three months.
Breeding is most active in spring and fall.
The average female has 4 to 6 litters per year. Rats can live for up to 18 months, but most die before they are one year old. Good sanitation will effectively limit the number of rats that can survive in and around the home. Outside dog pens must be properly maintained, to reduce potential rat problems. On farms where food grains are handled and stored, or where livestock are housed and fed, it is difficult to remove all food that rats can use.