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4 Differences: Identifying a Large Mouse and a Small Rat

Updated on: January 28, 2021

Rodent infestations are very frustrating for homeowners since the pests carry several diseases and can cause damage around both indoors and outdoors. One method to help you eliminate these creatures is to determine what rodent species is present in your house or building. Learning about their differences helps you come up with better strategies to remove them. 

So how do you identify a large mouse from a small rat? Here are some things that help you determine what kind of rodent that is present in your house or building: 

  1. Physical appearance
  2. Behavior
  3. Lifespan
  4. Droppings

Difference Between a Large Mouse and a Small Rat

In the United States, rodent infestations are usually caused by Norway rats, roof rats, and the house mouse. Though these rodents generally look the same and belong to the same family of animals, they are two different species with key differences in the way that they look and act. Here are some of the differences that can help you identify which rodent species you’re dealing with at home: 

1. Physical Appearance

Physical appearance is one of the easiest ways to tell the difference between the two species. Looking at the following characteristics can help you determine whether you are dealing with a rat or a mouse: 

  • Size: One of the most obvious physical traits that help you differentiate a mouse from a rat is their size. This is easier to distinguish if you are dealing with adults, since adult rats tend to be larger in size compared to adult mice. The typical house mouse is normally 2-4 inches in length, while the Norway rat is 7-9 inches. 

    But if you are dealing with a “large mouse or small rat?” situation, then there are other things you can look at to determine the rodent you are dealing with inside the house or building.
  • Color: Mice are often white, brown, or light gray with softer fur. On the other hand, rats are gray, white, brown, or black with coarse fur.
  • Head: Mice have triangular shaped heads and have pointed noses, while rats have blunt and chunky heads. Rats also have a larger head in direct comparison with their body.
  • Ears: Mice appear to have large, floppy ears but this is because they have a smaller body. Rats have larger ears, but they tend to look smaller because of their body’s size.
  • Tails: Mice tails are thin, long, and hairy and are more likely to match the color of their body. On the other hand, Rat tails are hairless and scaly and are usually lighter in color. When it comes to their tails, a mouse’s tail appears longer because of how small their body is, but a rat’s tail is still longer than a mouse’s. 

2. Behavior

Aside from physical appearance, a rodent’s behavior helps determine if you’re dealing with a mouse or a rat. These are some of the things you want to look at:

  • Movement: One key difference between the two species is how they move around. Rats usually avoid new things in their way and take time to be familiar with their surroundings. Mice are the opposite; these creatures explore new things they encounter.

    These two creatures also prefer to find shelter in different areas of the house. Mice are smaller and more skilled in climbing, so they tend to live in high areas of the house like the attic. On the other hand, rats tend to find shelter in lower areas like the basement.
  • Damage Caused: Since rats are bigger creatures, they are likely to create more damage and can chew through tougher material. You may also determine what kind of infestation you’re dealing with by looking at the teeth marks they leave. Rats leave deeper teeth marks, while mice teeth marks usually look like tiny scratches.
  • Food Preference: Though both species are omnivores, there are some differences in the way these rodents eat. Mice and black rats prefer cereals and grains, while the brown rat prefers to feed on moist fruit. However, both rodents are willing to eat almost anything they can find.   

3. Lifespan

In general, rats have a longer lifespan than mice. However, it is important to remember that these creatures will live longer if they are provided with favorable living conditions. This is why rodents that are kept as pets live longer than those in the wild. 

  • Mouse lifespan: A mouse has a lifespan of around 1.5 to 2.5 years. They can sexually mature and breed 4-8 weeks after being born, and a female mouse can produce up to 400 offspring in her lifetime.
  • Rat lifespan: A rat lives for about 2-3 years. Both Norway and roof rats can sexually mature after 8-12 weeks of age. Rats usually give birth to 5-10 litters per year; Norway rats usually have 8-12 pups per litter and roof rats usually have 4-8 pups per litter. 

4. Droppings

The droppings, urine, and grease marks the rodents leave behind can also help you determine whether you are facing a rat or mouse infestation. Here are some things to look out for: 

  • Droppings: The droppings that rats and mice leave behind differ in size, shape, and color. Rats have more rounded, dark brown droppings around 10-20mm in length. On the other hand, mice leave behind black, pointier droppings, around 3-8mm in length.
  • Urine: Rat and mouse urine tend to have different odors. Rat urine usually has a muskier odor while mouse urine has an ammonia-like odor.
  • Grease Marks: Rats tend to have more oily fur than mice. More noticeable grease marks around the house or the building can indicate that you are dealing with a rat infestation. 

For easier reference, here is a table showing the differences between the two species:

RodentPhysical AppearanceBehaviorLifespanDroppings 
Rats- Bigger in size - Coarse fur- Blunt and chunky heads
- Light-colored tails
- Avoid new things- Find shelter in low areas- Causes more damage- Has a lifespan of 2-3 years- Leave behind more rounded dark brown droppings; 10-20mm in length
Mouse- Smaller in size- Softer fur- Triangular-shaped heads- Tails are the same color as the body - Explore new things- Find shelter in high areas- Teeth marks resemble small scratches- Has a lifespan of 1.5-2.5 years - Leave behind pointier black droppings; 3-8mm in length 

Importance of Determining the Difference Between Rats and Mice

Learning about the differences of rats and mice can help you create better strategies when it comes to eliminating them. Here are some things you can use to your advantage if you are looking to effectively remove these pests from both indoors and outdoors:

  • What they eat: Since rats and mice have different food preferences, you can use this to your advantage to come up with better bait to catch these creatures.
  • Where they stay: Learning about where the kind of rodent stays can be helpful in determining where to place traps. If you’re dealing with mice, then it’s better to place traps in the attic and higher areas of the house. But if you’re dealing with rats, you can place these in the basement and lower areas.
  • How they behave: This is helpful when it comes to setting up traps. Their difference in behavior can help you determine whether it’s better to place unset traps for a while or not. Since rats are more wary of their surroundings, it’s better to set unset traps for a while so that they can get used to it. 

Professional Pest Control With PermaKill Exterminating

No matter what kind of rodent infestation you’re dealing with, it’s best to call for professional help when it comes to eliminating the problem. Here at PermaKill Exterminating, we provide professional pest control services to all our clients. 

Our team is composed of skilled and friendly technicians who are eager to help you solve any rodent problem that you face. We promise to deliver excellent services that guarantee pest-free spaces. Call us to know more about our services and how we can help you. 

Read more: How to Get Rid of Mouse Urine Pillars

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