Technical Papers

Norway Rats: The Common Rodent

Tuesday, September 30th, 2014 by Bill Cowley

norway rat

 

The Norway rat is the most common rat found in New Jersey, probably even throughout the United States. Also known as the brown rat, sewer or even street rat, it ranges in size from approximately seven inches to approximately nine and a half inches in length. The top of their body is covered with coarse brown fur that is sometimes scattered with darker, almost black hairs. Their underside is gray to white in color. The Norway rat has a long, relatively heavy body with a blunt muzzle. The tail of a Norway rat is scaly and semi-naked. Unlike many rodents, the tail of the Norway rat is shorter than the head and body combined.

How Do You Know You Have Rats in Your Home?

Rat droppings. The droppings from a Norway rat are pellet shaped with blunt ends. The average size of these pellets range from one half of an inch to three quarters of an inch in length. One rat can produce fifty of these pellets per day. Besides leaving behind fecal matter, the urine of a Norway rat is often noticeable. Their urine makes stains on woodwork and produces a musky odor.

Staining woodwork with their urine. A rat may leave greasy rub marks on the walls and baseboards of your home. The Norway rat has a keen sense of touch and very oily fur. It relies heavily on this sense of touch to direct it through the areas near its nest. Due to the fact that Norway rats prefer a stationary object on at least one side of them as they travel, they commonly rub against objects like walls and leave marks between their nests and their food sources.

Gnaw marks on the corners of walls, the corners and bottoms of doors, and on stored materials. You should take special note of any holes with wood shavings adjacent to them. Although gnaw marks in areas you frequent are the most obvious, it is important to realize that these rats will gnaw at almost any building material, including cinder blocks, aluminum, wood, glass and even sheet metal. It is important to look for gnaw marks in out-of-the-way areas like the basement and crawl spaces 

If you do see an actual rat in your home it will most likely be during the night. Norway rats are primarily nocturnal. They may come out of their nests as early as dusk to begin their search for food and water. If a rat is active during daylight hours it is usually due to a high rat population in your home, a disruption of their nest or when their food source is threatened. Rats are social animals that live in colonies. If you see one rat, there are most likely many more already in your home.

How Do Norway Rats Enter Your Home?

Norway rats will live in the wild but have adapted well to living in and around residences where shelter is available and food is in abundance. A rat can enter a home through holes in the foundation and walls. The body shape of a Norway rat allows it to squeeze into relatively small holes. The average Norway rat weighs approximately one pound, however it can squeeze through a hole the size of a quarter. Due to their amazing gnawing abilities, a rat can increase the size of a hole to gain entrance to the home. Although Norway Rats can climb, they prefer to inhabit the lower floors of multi-story structures.

Why Do Rats Enter Homes?

Rats enter homes to find shelter, food, and water. When Norway rats nest indoors they are most commonly found in basements, storage rooms, under floors, behind stored items, and in crawl spaces. Their nests are usually eight inches to twelve inches in diameter. When making their homes indoors, rats commonly use scavenged items like insulation, fabric, and shredded paper to line their nests.

Norway rats often enter a home in the fall when outside food sources become scarce. When it comes to food, the Norway rat is an opportunist. They prefer fresh food over garbage, but will make do with whatever is available. Once a rat is in a home pet food is often a source of sustenance for the rodent.

Norway rats also enter homes in search of water. They require a half of an ounce to one ounce of water per day when they eat dry food. They are able to survive on less water when they eat fresh food. Household garbage usually offers a fairly balanced diet and also satisfies their moisture needs.

How Do You Prevent a Rat Infestation?

Since rats can enter homes through relatively small holes (approximately the size of a quarter) it is important to seal all holes with heavy materials that will resist rodent gnawing. The best materials to use include concrete mortar, heavy-gauge hardwire cloth, silicone caulk, and galvanized sheet metal.

The Norway rat is the most common rat found in New Jersey, probably even throughout the United States. Also known as the brown rat, sewer or even street rat, it ranges in size from approximately seven inches to approximately nine and a half inches in length. The top of their body is covered with coarse brown fur that is sometimes scattered with darker, almost black hairs. Their underside is gray to white in color. The Norway rat has a long, relatively heavy body with a blunt muzzle. The tail of a Norway rat is scaly and semi-naked. Unlike many rodents, the tail of the Norway rat is shorter than the head and body combined.

How Do You Know You Have Rats in Your Home?

Rat droppings. The droppings from a Norway rat are pellet shaped with blunt ends. The average size of these pellets range from one half of an inch to three quarters of an inch in length. One rat can produce fifty of these pellets per day. Besides leaving behind fecal matter, the urine of a Norway rat is often noticeable. Their urine makes stains on woodwork and produces a musky odor.

Staining woodwork with their urine. A rat may leave greasy rub marks on the walls and baseboards of your home. The Norway rat has a keen sense of touch and very oily fur. It relies heavily on this sense of touch to direct it through the areas near its nest. Due to the fact that Norway rats prefer a stationary object on at least one side of them as they travel, they commonly rub against objects like walls and leave marks between their nests and their food sources.

Gnaw marks on the corners of walls, the corners and bottoms of doors, and on stored materials. You should take special note of any holes with wood shavings adjacent to them. Although gnaw marks in areas you frequent are the most obvious, it is important to realize that these rats will gnaw at almost any building material, including cinder blocks, aluminum, wood, glass and even sheet metal. It is important to look for gnaw marks in out-of-the-way areas like the basement and crawl spaces.

If you do see an actual rat in your home it will most likely be during the night. Norway rats are primarily nocturnal. They may come out of their nests as early as dusk to begin their search for food and water. If a rat is active during daylight hours it is usually due to a high rat population in your home, a disruption of their nest or when their food source is threatened. Rats are social animals that live in colonies. If you see one rat, there are most likely many more already in your home.

How Do Norway Rats Enter Your Home?

Norway rats will live in the wild but have adapted well to living in and around residences where shelter is available and food is in abundance. A rat can enter a home through holes in the foundation and walls. The body shape of a Norway rat allows it to squeeze into relatively small holes. The average Norway rat weighs approximately one pound, however it can squeeze through a hole the size of a quarter. Due to their amazing gnawing abilities, a rat can increase the size of a hole to gain entrance to the home. Although Norway Rats can climb, they prefer to inhabit the lower floors of multi-story structures.

Why Do Rats Enter Homes?

Rats enter homes to find shelter, food, and water. When Norway rats nest indoors they are most commonly found in basements, storage rooms, under floors, behind stored items, and in crawl spaces. Their nests are usually eight inches to twelve inches in diameter. When making their homes indoors, rats commonly use scavenged items like insulation, fabric, and shredded paper to line their nests.

Norway rats often enter a home in the fall when outside food sources become scarce. When it comes to food, the Norway rat is an opportunist. They prefer fresh food over garbage, but will make do with whatever is available. Once a rat is in a home pet food is often a source of sustenance for the rodent.

Norway rats also enter homes in search of water. They require a half of an ounce to one ounce of water per day when they eat dry food. They are able to survive on less water when they eat fresh food. Household garbage usually offers a fairly balanced diet and also satisfies their moisture needs.

How Do You Prevent a Rat Infestation?

Since rats can enter homes through relatively small holes (approximately the size of a quarter) it is important to seal all holes with heavy materials that will resist rodent gnawing. The best materials to use include concrete mortar, heavy-gauge hardwire cloth, silicone caulk, and galvanized sheet metal.

Proper drainage at the foundation of your house as well as gutters that channel water away from the structure will prevent ideal conditions in which house rats can nest. It is imperative to remove sources of moisture, especially in crawl spaces and basements, in order to keep your home inhospitable to Norway rats.

Why is an Infestation Dangerous?

Rats cause a great deal of damage when they gnaw. Rats may gnaw on wires that can spark electrical fires that destroy homes. Excessive gnawing by rats can even cause structural damage to a home.

Besides endangering your homes structure, rats can bring diseases into homes that make people very ill. Rats are able to carry many diseases including murine typhus, leptospirosis, trichinosis, salmonellosis (food poisoning), and ratbite fever. For the safety of the occupants of a home, it is important to keep your house rat free.

Proper drainage at the foundation of your house as well as gutters that channel water away from the structure will prevent ideal conditions in which house rats can nest. It is imperative to remove sources of moisture, especially in crawl spaces and basements, in order to keep your home inhospitable to Norway rats.

Why is an Infestation Dangerous?

Rats cause a great deal of damage when they gnaw. Rats may gnaw on wires that can spark electrical fires that destroy homes. Excessive gnawing by rats can even cause structural damage to a home.

Besides endangering your homes structure, rats can bring diseases into homes that make people very ill. Rats are able to carry many diseases including murine typhus, leptospirosis, trichinosis, salmonellosis (food poisoning), and ratbite fever. For the safety of the occupants of a home, it is important to keep your house rat free.