Rat vs Mouse: What’s the Difference?

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Most homeowners don’t really care about the difference between rat and mouse infestations – both types of animals are vermin, both need to be removed from the premises, both look similar, eat similar things, and are caught in similar ways. So, why is the Rat vs Mouse question important?

Despite the fact that most traps, poisons and other vermin control tools are marketed for rat and mouse problems at the same time, there are actually several quite significant differences between these animals. And when we say significant, we mean that they matter to your chances of catching them, killing them, or driving them off your property.

Obviously, there are a lot of physical differences between rats and mice, as well as almost as many differences between the different types of rats or mice. Some of the most common rat pests in the Western world include Norway rats, Black rats, Roof rats, and others, and they differ from one another in size, fur, color, and even behavior.

For example, Roof rats, as is evident from their name, avoid walking on the ground and prefer to keep to the higher levels of your house by walking on ceiling beams. Norway rats, on the other hand, are ground-level rats and are rarely seen too high.

Another example is the feeding habits of Brown and Black rats. While Brown rats tend to return to the same feeding locations they’ve been using for a while which makes them easier to catch, Black rats are smart enough to frequently change their feeding locations, which means that you need much more traps and other control tools to capture them.

These differences matter because they tell you where you should place the rat traps or the rat poison. For Norway rats, you want to place the pest control tools on the ground, where with Roof rats you want to place them somewhere high and near their travel paths.

There are other such behavioral differences, as well as a lot of physical appearance differences, but we won’t delve too deep into those here. Instead, let’s focus on the difference between rats and mice, in general, as it is even more drastic and crucial than the difference between different types of rats.

The physical difference between rats and mice

The most obvious thing to point out here is that rats are significantly bigger than mice. Depending on the type of rat, it can be multiple times larger than an average house mouse. In fact, as much as they are alike, house mice are actually a common prey and food source for most rats.

This difference is not enough to distinguish these animals, however, since you may encounter a young, small rat and mistake it for a mouse. So, without going too deep into the different types of rats and mice, there are several more basic differences between mice and rats, even if the latter are young and small:

  • Mice tend to have larger ears compared to the rest of their head. Different types of rats can also have bigger or smaller ears (Brown rats have smaller ears compared to Black rats), but with mice, it’s usually much more obvious
  • Mice have smaller legs compared to the rest of their bodies. Particularly the hind legs of rats are noticeable large and strong, while mice’s legs are thin and small
  • Most house mice have lighter coloring, whether grey or brown, with an even lighter belly. Rats an also vary in color, but they are usually much darker than mice
  • Mice have longer tails compared to the rest of their bodies (usually longer than their whole bodies) while with rats it’s typically shorter. There’s still a difference between different rat types – Black rats have longer tails than Brown rats, for example, but with mice, the tail is even longer comparatively

Of course, there are other more intricate physical differences, but as far as identifying those goes, these ones, together with the size difference are typically enough.


Photo credit: Rentokil

The difference between rat and mouse signs of the presence

Very often we don’t get a chance to see our unwanted guests and we have to make an educated guess about their nature based on the signs they leave behind. This includes observing the difference between rat poop vs mouse poop, as well as bite marks, scratch marks, locations, and so on.

Typically, here size matters as well. The most distinguishable difference between rat and mouse poop is its size, same with bite and scratch marks. As far as the location of burrows and holes, don’t be fool into thinking that a hole is too small for a rat – averagely sized rats can fit into cracks that are just half an inch wide. In other ways, however, the location of the vermins’ sightings can give it away, since certain types of rats such as the Roof rat tend to dwell in roofs and ceilings where mice and other rats rarely visit.

The physical difference between the offspring of rats and mice

Sometimes homeowners can find or even just stumble upon a rat or mouse nest. However, without the adult rodents present, it can be hard determining the exact nature of the nest and whether you’re facing a baby rat or mouse. Both types of animals reproduce extremely quickly, with mice producing approximately 10 litters per year, with 5 – 6 mice babies per litter for a total of ~60 mice annually. Rats, on the other hand, have about 6 litters per year, with up to 12 rat babies per litter, for a total of ~70 rats annually. Rats, however, develop much slower than mice – where a baby mouse will open its eyes on the third day and will have fur after about 10 days, a baby rat won’t open its eyes until the 6th day and will have fur at the start of its 3rd week. And, yes- rat babies are typically bigger than mice babies, although the exact size difference depends on the subspecies and the stage of development.

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Behavioral differences between rats and mice

This is the most significant and most commonly overlooked difference between rats and mice – their behavior. This matters because when it comes to rat and mouse traps, it’s not just the size of the trap that’s important, it’s also how and where you set it.

Typically, both mice and rats are not afraid to invade buildings that have a constant human presence in them. It’s even often said that rats are not afraid of people at all and will make every place their own despite us. And while that’s true in the sense that once they start reproducing they can overrun us with numbers, rats are generally more cautious than mice. Where mice will bravely go exploring even with people in the room, rats will be more likely to wait for us to go out. Similarly, mice are curious and love to pay attention to everything new they see, while rats will avoid new things sometimes even for days.

This is vital for our chances of dealing with these vermin as it tells us how to lay our traps. If you have a problem with mice, it’s smart to place the loaded traps right where you think the mice will pass through. With rats, on the other hand, it’s smart to first place empty and inactive traps for a couple of days so that they can start trusting the devices. Also, with rats, it’s important to frequently change the locations of the traps after each capture or kill, as they will learn to avoid the traps once again.

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