Do Rats Eat Mice? 14 Related (+Grizzly) Facts

Will a rat eat a mouse? That’s the question I’m going to dive into here and try to answer. But not only that, I’m going to offer up a series of facts all about rats and what they eat (including mice!).

Do Rats Eat Mice?

Rats do eat mice. They normally will eat a mouse if they are really struggling for other food sources, or if they see the mice as competition.

That fact that rats eat mice comes as no real surprise considering what a rat is like when it comes to getting something into its belly. However, there’s always a bit more to the story than simply saying they like to munch on a mouse.

With that in mind, let’s explore the facts.

Brown rat on soil

Fact 1 – Rats Eating Mice Has A Name

This act of a rat killing and eating a mouse has its very own name, and it’s called muricide.

Now, while it’s sometimes seen as being a rather general zoological name, most people use it in terms of what they see as being a natural instinct in rats to go out and kill mice.

So, if you ever see the word ‘muricide’ in the context of rats, then you will instantly know what it is that they are talking about.

Fact 2 – Rats Will Kill Mice as Competition

A rat is going to realize that it’s effectively competing with a mouse for the same food sources.

You must remember that a rat is going to try to eat anything it can, and it won’t take kindly to another rodent being in the way of its food.

For that reason alone, it’s going to be the case that a rat is going to be quite happy to attack and kill a mouse. Do remember that a rat is bigger in size than a mouse, and it’s also going to be more powerful. 

However, this won’t always happen, so just because a rat and mouse are in the same area won’t then always translate into a fight to the death.

Instead, they will prefer to get on with their own lives and not even bother one another. They are too focused on surviving, and also trying to avoid their own predators, to even be bothered with one another in the grand scheme of things. 

Fact 3 – It’s Not A Rat’s Main Source of Food

Don’t think for a second that a rat is always going to see a mouse and think that it’s only a source of food. That won’t be their first thought at all.

Instead, a rat is going to be focused more on their usual food sources. They want something that is easier to eat, rather than going through the process of catching a mouse, killing it, and then eating it.

They would prefer to munch on vegetables, seeds, and fruit, or even scraps you leave lying around. [Source]

That takes up less energy, it’s less work, and they are going to get lots of nutrition from it.

A rat is a scavenger. It will chew its way through anything it feels it can literally get its teeth into. It’s going to primarily be focused more on the regular food sources that it knows it can usually find in ample amounts. A mouse just does not fall into that category. However, that doesn’t mean it’s never going to be something that they think about or try to eat.

Fact 4 – It Tends to Happen Under Tough Circumstances

If a rat is starving, it’s going to go to some pretty extreme lengths in order to stop that starving feeling. It’s at that point where a rat may indeed encounter a mouse and feel compelled to go ahead and try to eat it. 

You need to keep in mind that there’s this whole process that the rat needs to go through in order to get a mouse for a meal. They need to feel as if there’s no other option to push them into this sort of situation. 

So, if food is scarce, for whatever reason, then a rat is going to be more likely to go ahead and eat a mouse if it’s able to catch one.

But even then, they won’t actively go out hunting for a mouse. Instead, it’s more a case of if they stumble across a mouse while they are trying to find other sources of food.

At that point, they may suddenly feel like having an alternative bite to eat.

Fact 5 – Rats Also Eat Other Rats

But don’t think a rat will restrict its rodent eating options to mice for a second. A rat in the same tough circumstances will also be quite partial to going ahead and eating another rat. [Source]

This is all just a matter of trying to survive in the wild. They will be pushed into doing almost anything if their very survival is going to depend on it. 

A rat is going to even eat another dead rat. This isn’t all about food.

It’s also all about effectively disposing of the dead body to prevent other predators picking up the scent of a rat, and that its home is in the area.

In that sense, they are doing it for a self-preservation act that is not only restricted to the consumption of food. With that, it’s quite a clever thing for them to do, and it makes a whole lot of sense when you consider the rat is pretty far down the list of predators that rule the natural world.

Fact 6 – Studies Show it’s Purely a Food Thing

This sort of behavior within rats has been the subject of a vast amount of study and research over the years, and do you know the result of all that research and study?

They have come to the conclusion that there’s only one reason why a rat is going to kill and eat a mouse because it’s a source of food.

Now, that’s hardly going to come across as being groundbreaking research. After all, it does kind of make sense that they would view a mouse as food, but it does eliminate other reasons that had been floating around as potential ideas.

Those reasons included competition for resources, so they basically kill them to get them out of the way. 

It’s not as if this is being done due to some natural hatred that a rat has for a mouse.

The only way in which it’s an enemy is because they both want to eat the exact same food. In that situation, the bigger and stronger animal is going to be the one that ends up winning the battle.

Fact 7 – Rats are Pretty Swift with the Killing Aspect

When it comes to the killing part, then it seems the rat is quite swift at delivering that all-important fatal blow.

What has been observed is that the rat is usually capable of killing the mouse with the very first bite. It seems they are very accurate, and the mouse is dead within seconds. 

Wild rat at night

Fact 8 – Rats Won’t Eat All of the Mouse

If you thought that the rat would eat every single part of the mouse, then you would be wrong. Instead, there are only certain parts of the mouse that will be seen as edible to the rat.

What this means is you will see what appears to be a half-eaten carcass lying around.

They will focus on the neck area as well as certain organs, including the liver and even the brain, while other parts of the body will be left behind.

However, this is all going to depend on various important factors, and the primary factor is how hungry the rat is at the time.

Be aware that this is only really going to be something that they will do when food is scarce anyway, so there’s also a sliding scale of how much they will eat of a mouse compared to how hungry they are.

If pushed, or really hungry, the rat will eat some of the carcass, but don’t expect there to simply be bones left, as that is never going to happen. Perhaps it’s best to see this a rat nibbling on something rather than viewing it as an entire meal.

Fact 9 – A Baby Mouse May Also Be Food

It also makes sense to learn that a rat is going to view a baby mouse as another potential source of food.

The same idea of this only being something done when the rat is very hungry does hold water here, and to the rat it’s clear they don’t see much difference between an adult mouse and a baby mouse.

To be honest, they may be aware that the baby mouse is going to be the easier option. It’s harder for the baby mouse to get away, so it’s an easier meal.

On the flip side, there’s less to eat due to their size. It basically amounts to how hungry the rat is at the time.

You need to remember that a rat is not going to want to expend too much energy. For that reason alone, it may see a baby mouse as being the better option. 

Fact 10 – It’s Tough to Catch a Mouse

The rat is going to find it tough to catch a mouse, as mice are hard-wired to be fearful of rats. It’s in their natural instinct to get away from an area if they even pick up the smell of rat urine in the area, so the rat has to work hard, or be lucky, to successfully kill a mouse.

Of course, you need to realize that if a rat is starving due to lack of food, then there’s every chance that the mouse is in the same boat. At that point, natural instinct can become somewhat rocky, and the mouse may let its guard down a bit since it has that drive to find something to eat.

That can be the point where the rat leaps on the weakness and manages to secure some food. Apart from those times, the mouse is going to be far too switched on to be caught up in this entire issue of becoming a meal for a rat.

Fact 11 – Mice Have Developed Differently on a Genetic Level as a Result

This does kind of dovetail into the previous fact, but it has been scientifically proven that mice have developed differently on a genetic level thanks to their relationship with rats.

It’s believed that there was a time when there wasn’t the same reaction to rats from mice, but they are now effectively being born with a gene that makes them very fearful of rats in particular.

They are so tuned in to the scents and smells of rats, thanks to their need to survive, that it’s amazing to think that this is something that has developed due to evolution.

This is a perfect example of evolution working.

Considering that all rodents have certain characteristics that are common across the entire spectrum of rodents, this is a surefire sign of how they have managed to adapt to their situation. It just turns out that the situation in question is a rat eating a mouse and what a mouse will do about it.

Fact 12 – It’s Something in the Brain of the Rat

While this is all about the need for food, additional studies have shown that there appears to be something going on with the neurotransmitters in the brain of the rat that makes them feel like they have to go ahead and do this.

Of course, those neurotransmitters can be going ahead and sending the signal out that the rat is hungry, and therefore, they need to find food somewhere.

The research doesn’t indicate if it’s a specific signal from the brain that is only linked to mice, or if it is the same signal with other potential food sources.

That kind of information would be important to better understand what is going on with the rat. However, the one thing we do know is that the brain of the rat will pick up on a mouse as a food source, and then implore the rat to act on that signal.

Fact 13 – What About the Body?

This is an important point to keep in mind, and it’s one that is often glossed over, but what about the body?

Remember earlier on when I said that a rat will eat other rats in order to dispose of the body and to keep predators away from the smell? Well, the same applies when they have a dead mouse on their hands.

They are not going to kill a mouse and consume it close to where they sleep. That’s asking for trouble from other predators, as they would then be left with the question of dealing with the body, and they just don’t eat enough of the body to stop that from becoming a problem.

That means they need to kill and consume the mouse elsewhere. Then, after they have finished with their meal, they will scuttle off to their home and sleep it off.

By doing that, they have the best of both worlds in that they are safe and sound where they stay, and they are going to have a full belly.

Fact 14 – Keep in Mind it’s Not Their Favorite Food

The last fact is simply a reminder that a mouse is not going to be the favorite food of the rat. It’s a last resort sort of option when nothing else is capable of satisfying the hunger that they feel. 

A city rat would much rather spend time eating garbage or scraps of human food.

In the wild, they would much prefer to be eating those seeds, nuts, plants, vegetables, or anything else they can get their teeth into.

If food is in abundance, then a rat is not going to be all that interested in a mouse. They would much rather spend their time chomping away on other things rather than dealing with all of the hassles.

The Summary

So, those are 14 different facts all to do with this concept of rats eating mice. As you can see, it’s not as clear-cut as you may have initially thought.

In saying that, it does happen in the wild, but you have nothing to worry about should you have a pet rat and a pet mouse. After all, they will hardly be in the same cage, so they won’t come into contact.

Also, don’t worry about wild rats getting in and trying to eat your pet mouse. Their cage will keep them safe and sound even if a rat did manage to venture inside. Also, there will be more than enough food options for a rat in your home without them feeling as if they need to turn to your pet mouse.

A rat eating a mouse is just the same as a rat eating another rat. It’s purely nature, and what goes on out there when pushed to extreme lengths. However, at least you now know the truth, even if it is pretty gruesome as a thought.

Barry Gray

Barry is a freelance writer from Scotland. He has written about pets for over a decade, and his work has been turned into a range of ebooks, courses, and material for diplomas. Barry is passionate about all animals, but particularly dogs, fish, rabbits, birds and spiders. You can find out more about Barry at

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