Pest Library

Characteristics

One of the most successful breeders around the world, these Norway rats are known to be found in any locations where humans are found. The Norway rat is also known as the brown rat because of its brownish to grayish fur. However, its color can also differ from white, pale brown or black.

This rat is also the largest rodent found around the world. It can grow up to 18 inches long with the male being larger than the female, and can weigh 31/100 to 1 lb. The tail is bald and is also shorter than its body. The ears are shorter and also bald.

Habitat

The Norway rats enjoy a variety of habitats that are beside the human population.

Their homes can be located in:
• Garbage cans
• Sewers
• Old buildings
• Basements
• Attics
• Barns
• Woodlands
• Ponds
• Any location where humans are present

Behavior

Although this species are known to be polygynandrous, which means they can mate many times with different males, they are still known for their social and cooperative behavior. They will breed in large groups, and can take care of their young pups together no matter who the mother is as long as that mother belongs to their group.

Food

This rat can eat anything that is edible. From grains, fruits, nuts, seeds, rice, eggs, fish, to mice, chicks, birds, and even lambs.

Life Cycle

Norway rats are known to be polygamous creatures and are prolific breeders. The female rat only has six hours of heat cycle, but this is just enough for her to mate at least five-hundred times to different male rats.A single female can give birth to 6 to 9 pups. In a year, this rat can give birth to up to 12 to 13times, which is why they can easily spread and create infestations. The young pups stay with their mother to be milk-fed for three weeks to a month, then will soon leave her, and begin the cycle of breeding again. The mother on the other hand, can mate right after giving birth to her pups.

Since these rats have easy access to our living conditions, they are now taking advantage of the different types of foods that are made available to them. As a result, Norway rats can live up to 4 to 5 years, as long as the conditions are favorable to them. However, rats that are found in the wild may just have 1 to 2 years to live.

Other Information and Tips

The Norway rat is considered a major pest in all parts of the world because of the many different damages it causes. These rats are responsible for fouling human food, property and electrical damage, and are known as a carrier of different diseases. They also carry lice and fleas that they can transfer to their human home.

To control these rats, various measures such as poisoning and trapping can be used for them, especially in places where their populations are bigger.

Photo: Brown Rat (Rattus norvegicus) by Martin Cooper, used under CC BY 2.0 / resized from original