Pest Problems

Do Rats and Mice Live Together? Can Your Home Be Infested with Both?

Image sources: Szasz-Fabian Jozsef / Holger Kirk /

To the amateur observer, mice and young rats could look the same. They’re small, furry rodents which come out at night and cause trouble around the house. This could easily make you wonder if perhaps the two species have united and live peacefully under your roof.

Well, that’s what we will look into here. Although rats and mice have a lot of similarities in appearance and behaviour, they also differ very much. Knowing what kind of rodent is giving you trouble and sleepless nights is very important, in order to determine the right way to dispose of the little critters. The differences between a rat and a mouse are many as you will read in a second and these differences play a major role in their ability to coexist.

Who is this post for:

  • People dealing with rodent infestation;
  • Gardeners who have rodent problems;
  • People that can’t tell rats and mice apart.


In this post, we will be looking at the most common species of mice and rats, which populate the UK. Those two are as follows:

  • House mouse (Mus musculus)
  • Brown rat (Rattus norvegicus)

So, can rats and mice actually live together?

That would be extremely rare. As mentioned before, rats and mice may appear similar, but they are two separate species and both of them are highly territorial. This means that neither a rat nor mice can tolerate another species in the area where their food and water resources are. Given that the latter could be limited or hard to get, especially in urban areas, both type of rodents will fiercely guard their territory.

In fact, rats can become quite aggressive if they sense a mouse close by because they would see it as a potential competitor for their food and water sources. Rats can even kill mice. This is also why if a mouse catches a rat’s scent, it will relocate quickly to avoid confrontation. Given that rats are bigger, they could be considered the dominant species of the two, so it’s no surprise mice would prefer to avoid them.

So when it comes to urban areas, chances of having both rats and mice infesting your property are slim. In order for that to be possible, there should be plenty of available food resources and also a large enough territory, so the two species don’t compete. That would be hard to accomplish in a residential home. If let’s say, by some chance the rats settle into the basement and the mouse into the attic, there’s still a high chance of the two meeting at some point and competing for food in the kitchen or other parts of the house.

Mice vs rat: how to differentiate between the two?

If you happen to see a rodent running around your home and wonder what it is, there are a few features that can help you identify it. In terms of colour, both rats and mice look alike, that’s why you should consider other characteristics of appearance such as:

1. Differences in appearance

As we’ve already mentioned, rats are bigger. How bigger exactly we will look into here, as well as list some other specific features to keep in mind.


The ordinary house mouse can reach a length from 5cm (2 inches) to 10 cm (4 inches). That’s from the nose to the base of the tail, while the tail itself can be as long as 10 cm (4 inches). The average weight of this rodent is between 40g and 45g (1.4–1.6 oz).

The brown rat, also known as the Norway rat, can reach a length between 15 and 28cm (5.9 to 11.0 inches), while its tail can be as long as 10cm to 24cm in length (4-9 inches). When it comes to weight, this rodent can be as heavy as 140 to 500 g (4.9 to 17.6 oz).


Let’s start with the snout. A mouse’s nose is triangular-shaped, whereas a rat’s snout is blunter. This gives their heads a different look, the mouse’s being more pointy compared to the rat’s.


Given the larger size of the rat, it is only natural that the size of a rat’s teeth would also be larger than that of a mouse. You can easily use this as a telling sign when wondering whether there is a rat or a mouse in the house.

If you happen to find chewing marks on either object, the wall or the floor, just take a closer look at their size and shape. A rat’s bite marks are deeper and larger, while a mouse’s bite marks look more like scratches.

You may also like:
Pest Problems
Ways to Deter Rats and Stop Them from Coming Into Your Home


Rats have bigger ears than mice, but not in relation to their bodies. That’s why when you look at a mouse, you tend to notice its ears more. They look floppy and somewhat big for their bodies.


A mouse’s tail is very thin and covered in hair. It also appears longer in relation to a mouse’s body. A rat’s tail, on the other hand, is always hairless and also looks thicker but short in size.

Image source: torook /

How do you distinguish a grown-up mouse from a young rat?

  • The house mouse has larger ears and longer tail compared to its body length than the rat
  • A young rat has larger feet and head compared to a mouse
You may also like:
Pest Problems
House Mouse vs Field Mouse

2. Differences in diet and eating habits

What do mice eat?

This rodent prefers seeds, cereal grains and generally anything sweet. However, if certain conditions arise, the mouse will not hesitate to eat whatever is available including meat. As far as water goes, mice don’t need much of it.

They usually get the needed amounts from the food they consume but will drink about 3ml if the opportunity presents itself. They also tend to seek food in the same place they first found it.

What do rats eat?

Rats are omnivores, meaning they eat anything, however, their preferred food is meat. They would scavenge through your trash looking for leftovers and even attack insects. Rats drink about 30ml of water a day. They tend to look for food at different places, which makes them harder to catch.

3. Differences in droppings

It can be rather difficult to distinguish mouse from rat droppings, or any other kind of pest dropping for that matter. The place where you’d most often find them is along walls, but they might look like dirt and not like what they really are. Always keep in mind the size.

Size of mouse droppings

Mice droppings are between 1/8 – 1/4 of an inch long, smooth, elongated and with pointed ends. Mice produce anywhere between 50 and 70 pallets every day, so you will usually find them in groupings. The areas of your home, where you’re most likely to find faeces, are the attic, closets and areas near food, such as pantries and kitchen cabinets. However, you might also find mouse poop in crawl spaces and air vents.

Rat droppings size

Rat droppings are between 5/8 inch long, curvy and as large as an olive. Rats produce from 35 to 50 brown pallets a day and you are likely to find them in large groupings, as well. The places where rats poop includes attics, where the droppings usually get stuck to the insulation, along garage walls, behind storage shelves and behind boxes.

Seeing dropping in the house? Get help from a professional in identifying and removing the rodent. Learn more about our methods here.

4. Difference in mouse and rat behaviour

Mice and rats have some significant character differences when they’re not busy chewing on food. Surprisingly, mice are bolder and more curious than rats. They would usually explore new areas, where they’d never been before. This is important because it’s easier for them to walk into your carefully set-up trap.

Rats, on the other hand, are very careful and definitely not explorative. They tend to stick to routes they know are safe. When setting up a trap, you need to know these routes, otherwise, the vermin will not go near it.

As far as nesting goes, mice can easily inhabit all parts of your home even your attic, because they’re skilful jumpers and climbers. Brown rats, on the other hand, prefer the low-level parts of your home such as the basement and crawlspace.

5. Differences in breeding habits

Both rodents breed throughout the entire year with slight differences in their breeding patterns.

House mouse reproduction                  

  • Size of litter: 4-16 pups
  • Litters per one year: 7-8
  • Gestation period: 8-12 weeks
  • Sexual maturity: 5 weeks after birth

Brown rat reproduction                          

  • Size of litter: 7-8 pups
  • Litters per one year: 3-6
  • Gestation period: 10-12 weeks
  • Sexual maturity: 5 weeks after birth

A couple of true facts about mice and rats

  • Rats usually come for where pipe work is but may also come from overgrown gardens.
  • Rats are neophobic (afraid of new objects) and it takes 7 days to get used to the rodenticides.
  • Rats are a fire hazard – they can chew through cables, plasterboard, copper tubes just in order to have access to food and water.
  • Rats defecate up to 30 pellets (excrements) daily.
  • Rats can eat mice if given the chance. They prefer meat and are bigger in size, so a mouse can easily be included in their menu. A mouse’s killing by rats is also known as muricide.
  • Mice teeth never stop growing (the incisors) which is why they will never stop chewing whatever blocks their access to food.
  • Mice enter your property to search for food and to breed.
  • Mice have flexible skeletons and can squeeze into the tiniest spaces, like a gap the width of a pencil.
  • Mice are excellent climbers and they often go through kitchen tops and cupboards, if it is the shortest path to food.
You may also like:
Pest Problems
How Much Does a Mice Control Service Cost

How to prevent a rodent infestation

Dealing with pests like mice and rats is definitely not a fun activity. That’s why prevention methods are key if you want to avoid having furry neighbours lingering inside your house walls. Here are a few effective tips that will make your property a safer place:

Block access points

We’ve all seen those old Tom & Jerry cartoons. And where does Jerry live? That’s right – inside a hole in the wall. Such holes don’t serve only as homes for mice, but as entry points, as well. If you don’t want to have furry tenants running around your property, make sure to carefully expect it for holes and gaps. And if you happen to find any, seal them or call in a professional to do it for you. 

Store food in plastic containers

Why would mice invade your home in the first place? One word – dinner. And do you know what improperly stored food means? Fancy mouse feast. To eliminate all risks of organising such an event in your cupboard, make sure to keep food such as cereals, rice, etc. in plastic containers and tightly closed. 

Give tall plants in your garden a regular trim 

We know that this one sounds weird, but hear us out: mice can get really creative in terms of accessing your property, which can also include literally jumping from a tree. Ok, it’s not that dramatic, but still, make sure to keep tree branches trimmed, so they don’t act as a bridge leading directly to your home. The same goes for vines and shrubs located near your property. 

Keep your garden tidy

Autumn is a beautiful season, especially with all of those colourful leaves in your back garden. However, those exact same lovely leaves can serve another purpose – as nests for all types of rodents. That being said, make sure to clear any debris from your garden, including fallen branches and twigs.

It’s best to do this before it gets cold outside, in order to avoid finding a pest family that has already moved in under the pile of leaves.

You may also like:
Pest Problems
How to Get Rid of Rats and Mice in The Garden

Use potent smells to keep the rodents away

This tip is for those of you who suspect that are already mouse hosts and want to prevent the infestation from growing. But first, we need to explain a few things about how tiny house mice move in. It goes like this: when a mouse finds a space that covers all of its living requirements, such as nourishment, water and shelter to breed, the rodent leaves a special pheromone behind.

This scent trail helps the other members of the creature’s family to find the place and settle in, as well. Now – this is where the tip comes in:

If you spray potential mouse nest spots around your house with a potent-smelling product, such as ammonia, for example, it will destroy any pheromone trails that might have been left behind. 

Use metal screens to cover all of your drains

Rats have very interesting means of transportation – they can swim through damaged sewer pipes and enter your property through the toilet. Yup, you read this right – THE TOILET! We know this sounds like something taken out of a horror movie, but it’s true.

To avoid nasty, furry surprises popping up in your toilet and bathroom, keep the toilet seat lids closed and use metal grates to cover all of the drains in your property. And definitely, don’t forget the one in your basement. Also, it’s a good idea to check your pipework for damage from time to time and if you happen to find any – call an expert to fix them. 

Take care of potential water sources

When the winter months settle in, all rodents, including rats, start to look for food.  Rats, like all other animals, need their water supply, as well, and will search for a source until they find it. That’s why if you have any leaks around your home, it’s best to take care of them, otherwise, you risk finding a furry “friend” in your basement, bathroom, or attic. 

Hire a Fantastic rodent exterminator

If feel there’s an infestation going on in your home, but you have trouble determining what you’re dealing with for sure, give us a call. The Fantastic pest controllers will make a full inspection and find out what kind of nasty rodent is eating your food or trash.

You will either need mice or rat control, but not both. Book an inspection with a specialist!

Dealing with a rodent infestation?

You don’t have to do it alone, you can count on a seasoned exterminator.

Add a valid postcode e.g. SE1 2TH


  • Rats and mice usually cannot coexist in the same territory.
  • Rats are larger than mice and could kill them if they threaten their food and water sources.
  • Mice have bigger ears in relation to their body.
  • Mice love to explore and thus, can be trapped more easily, while rats are fearful and won’t fall for your trap once they discover it.


What is your experience? Have you ever had rodents infest your home, only to wonder whether they’re mice or rats?

4.6 7 votes
Article Rating
Notify of
Newest Most Voted
Inline Feedbacks
View all comments
Would love your thoughts, please comment.x