The Norway *Norwegian Rat (Rattus norvegicus)
Also known as the Brown rat, Sewer rat, or Wharf rat
Basic Identification
Distinguished by the Brown/Grey fur, A Blunt nose, small eyes, shorter Ears & a shorter, fatter appearing tail. (Not that you were looking that close at the time!)
Rattus Norvegicus
The head & body length, weight, etc are all available yet basic recognition is often all that is needed from our point of view.
Signs of Norway Rats
Keys signs that tell you that they are Norway Rats;
- Droppings are Blunt at each end
- Prefer to nest in the ground or lower stories of a building
- Tail-drag marks found on dusty surfaces
Blunt Droppings
Norway Rats' droppings are 3/4 -inch long and capsule-shaped, both ends are usually blunt; they often contain hairs.
You will find droppings where rats & mice are active, especially along their paths & trails.
An adult Norway rat produces about 35 droppings per day. You can get a quick estimate on the size of the infestation with the count.
Nest in the ground
Norway rats prefer to nest in the ground. Each nest will have several entrances, with one or two appearing to be covered over or not there. These are emergency holes for a quick escape.
Norway rats will also nest inside storage boxes or under cabinets (Kitchen Cabinet)
They also enjoy any form of insulation to nest in, such as furniture stuffing, inside mattresses, inside the wall, etc.
We have recently cleaned out & sanitized a Norway Rat Nest, found under the kitchen cabinet, tucked up into the far corner.
Tail-drag marks
Norway rats drag their tails as they walk, unlike the Black rat which will carry theirs.
You will see the footprints to the side & a sweeping tail mark in the middle. Normally found on plumbing pipes under the home, dusty ceiling voids, cupboards, etc
Norway Rat Foraging Facts
Rats & mice are generally nocturnal animals. They do however come out during the day when conditions require it
Conditions that bring rats out from the nest
- Resources such as Food & Water
- Human activity
- Finding a mate
Upon leaving the nest, they find pathways routes that provide as much concealment, protection & escape options as they can get while trying to find the shortest distance to food.
Food & Water
Necessary on all levels, rats are fixated on finding the next best supply of food & water. It does not have to be fresh, or even edible (in the human idea of food), it just has to be food.
They do however prefer oily/fatty food such as meat fat or oily fruit/veggies/nuts such as walnuts, avocado, and macadamia nuts.
Nuts, packed with great carbohydrates, oils, vitamins, and minerals are a great food supply to keep a rat healthy during winter.
On average, a Norway rat will forage will range up to 150ft 50m in diameter from the nest. The range will only increase when one of the resources becomes scarce. They may consider shifting the nest location.
Human Activity
Like most animals, movement is often around the change of light, an hr before dawn or an hr after dusk, (When all military personnel in the field are in their fox holes, actively watching for enemy movement) rats do the same, waiting for it to be quiet
Rats will come out during the day whenever it is required. Ideally, when humans are not around, we know of many stories where the rats have become very brazen & not care about people at all.
Finding a mate
Since rats cannot effectively *swipe right, rats still need to find a mate the traditional way. They still need to find a suitable place to build a nest & this keeps them out while they inspect new territory.
(This happens to be the time when pre-baited stations get them) in the words of the late Eric Clapton song *I shot the sheriff, … Kill it before it grows.
Mating Pair of Norway Rats
Norway Rat Habits & Abilities
Being able to eliminate Norway rats effectively, as well as preventing them from getting inside buildings, requires a true knowledge and understanding of their biological abilities & habits.
- Norway rats can jump/leap about 35inches or 88cm
- Very good at Swimming
- Burrowing & Digging
- Climbing vertical pipes, brick walls, etc
- A rat can handle being Dropped
Rats Leaping, Jumping, Climbing, Dropping & Swimming
A Norway rat will jump or leap across from a tree, fence line, pergola, drain, roof, etc without hesitation. A quick gauge that it can make the jump and woosh, it is gone.
Rats Leaping – Norway 36 inches 88cm
Black/Roof 34 inches 86cm
Rats Jumping - All rats approx 24 inches 60cm
Rats Climbing – All rats will climb anything they can grip onto incl vertical pipes < 4 inches 10cm
Rats Dropping – All rats can drop approx 50ft 15.5m without being hurt
Rats Swimming – All rats are very good swimmers, they can tread water for hours, and cover large distances. (Always a threat to our Island Bird Sanctuaries)
Norway rats are burrowers. They prefer to keep everything close to the ground. The burrow along with the wall foundations and into open drains or sewers if possible.
Norway Rat in full Leap
Active Exploration & Safety Protocols
All exploration & foraging activity is governed by the rat’s ability to sense its surroundings
Because a rat’s sight is fairly below par, they rely more on what they hear, feel, smell, taste, and sense and regular behaviors.
A rat will learn a path that is the safest possible. It will travel around structures and objects very quickly once the path is learned.
A rat passes the food preferences to its young in the mother’s milk & crumbs lying around.
A rat will become familiar with noises, vibrations & people.
Neophobia – A built-in safety device
A keen sense of everything
All rats are fantastic at smelling, sensing vibrations, feeling & hearing faint noises. These abilities give the rat a huge advantage over most of their predators in the wild and around our homes.
What is Neophobia?
Neophobia-A type of *fear response to do with the uncertainty of whether a threat exists or not.
A rat will map out the safest path to food or water and stick to it. They will travel this well-remembered path very quickly, only to stop when spooked or a new object is placed in the way.
They will not engage with the new object (ie bait station with bait inside) until their curiosity overtakes the possibility of a perceived threat.
Everything to do with a rat’s ability to survive is surrounded by threats (actual or perceived) & how they deal with them.
Rats Reproduction rates
In general, rats & mice have a high mortality rate, to prevent this from being detrimental to their survival, they have learned to multiply
Norway Rats in a Ceiling Void
Some quick figures to stun, silence & consider
Under normal conditions where all resources are available,
The Norway Female Rat is;
- Reproductively mature by 3 months
- She can have up to 7 litters per year
- Produce up to 56 young per year
- She will live about 1 year
- & The young leave the nest after 30 days
The true reproduction matrix goes further to presume that under normal conditions where the available resources are high enough to support the population;
From the 56 young per year, once they also start to breed, the population explodes into the 1000s quite quickly.
Norway Rat Control
Each situation is different. Consider a strip of flats where one end has a hedge and the other is next to a creek, each one is affected by rats differently.
To control Norway Rats, you will need to start thinking like a rat that likes to live in the ground would.
You will need to consider what would provide shelter? Where would be a good place to dig a tunnel? Where would be a safe place or path to travel? What food and water sources are available?
What disturbances are around, such as animals, people, earthworks or machinery, predators & threats.
You have options available such as trapping or baiting, toxic or non-toxic, kill or live traps, self-setting, or large bait capacity systems for unmonitored sites or situations.
Placement of the baits or traps is very important, as well as the number of baits or traps. You will need to move the devices around to ensure all possible *Rodent pathways are covered.
It is recommended that you seek good advice from your local, professional Pest Control company. They will understand your situation much better than most & have relevant advice to suit your needs.
