Baby Mouse VS Baby Rat: A to Z Information!

While from afar, there might seem no difference between a young rat and a mouse, but if it is observed keenly, there are specific properties that distinguish a rat from a mouse.

The three widespread species of rats and mice are Brown rats, Black rats, and House Mice; respectively.

Baby Mouse VS Baby Rat: A to Z Information!

Even when a rat is pretty young, it looks bigger than a full-grown mouse. Some distinctive features help in differentiating between a baby rat and a mouse. Rats relatively have broad heads and feet. They have a blunt nose and are usually black, brown, white, or gray. Their tails are thick, scaly, and without hair.

On the other hand, mice comparatively have smaller heads and feet. With a pointy snout, they are found in brown, gray, or white colors. Mice have a long thin tail covered with hairs and have whiskers on their face.

 House MouseBrown RatBlack Rat
Average Weight12-45 g250-350 g110-340 g
Size3-10 cm20-25 cm12.8-18.3 cm
Tail5-10 cm10.5-24 cm15-22 cm
Lifespan1-6 yrs2-4 yrs1-4 yrs

Nesting Habits

Baby Mouse VS Baby Rat

House Mice

They will usually be found on the ground or in nests in burrows as they are active and can jump quickly. Mice choose to build their nests near food as they do not go beyond 30 feet for eating. House Mice usually like to build their nests where it is dark and warm. It makes them feel secure during breeding.

Brown Rats

It is normal when Brown rats are seen scurrying through buildings, sewer systems, and outdoor areas. Unlike House Mice, they like wandering above the ground, and their nests are usually found inside walls, cabinets, or areas surrounded by shrubs.

Black Rats

These rats prefer building their nests on rooftops, trees, and holes because they are excellent at climbing. Their signs of living are easily detected as they leave smudge marks on the surface they walk on.


House Mice

House mice pretty much eat anything, but they especially like to have cereals, sweets, or seeds. While eating grains, they prefer the endosperm inside and do not consume the outer layer. Also, Mice do not require much water as they attain most of it from their food, but they drink up to 3 ml if it is available. 

It is preferred that baby mice are given cooked rice either diluted with some or goat milk until it goes soft. They can also eat human baby food or kitten food. Cooked soft vegetables are also an excellent food to them, like cooked carrots or peeled cooked peas.

Brown Rats

Brown rats are omnivores and eat almost everything like insects and birds’ fruits, seeds, and eggs. They can even consume young mammals. These rats also enjoy eating cereals. While having grains, they use their teeth in a way that the grains seem chopped. They can drink up to 60 ml per day. They consume about 50 grams of food each day and prefer being fed at night.

Baby rats depend on their mothers for approximately three weeks after they are born. Even when they start having solid food, they need their mothers for nursing.

Black Rats

Black rats can also eat almost everything, but they like having food with high contents of water. They prefer fruits, grains, and cereals. They do not feed at the same place on successive nights to make them hard to spot.


House Mice

Mice produce 40 to 100 droppings in a day near their nests. They are generally black and granule-shaped with pointy ends. The length of their dropping varies from 3mm to 8mm.

Brown Rats

Rat droppings are generally more significant than a mouse’s. Brown rats produce wide droppings that are dark brown. Their shape is that of a big grain of rice.

Black Rats

These rats produce 20 to 50 droppings in a day that are smaller than those of Brown rats’. With their lengths varying between 7mm to 9mm, they are long and thin. The ends are a bit pointy, and they are usually curvy.


House Mice

A female mouse produces 7 to 8 litters in a year. She can give birth to a second litter even after 25 days of the first one. On average, there are six pups in a litter. They are usually pink when they are born and can not even stand in the first few days. Initially, they are blind and hairless.

Brown Rats

Brown rats produce 3 to 6 litters in a year, and one litter comprises about 7 to 8 pups. The newborns take 10 to 12 weeks to mature fully.

Black Rats

These rats give birth to 3 to 6 litters per year, with the litter size varying from 5 to 10. The baby black rats take 7 to 8 weeks to mature.


House Mice, although smaller than rats, are much more inquisitive and tend to explore around. A male mouse can live with females and young mice, but two or more male mice tend to fight a lot unless they have been together since birth. They are usually scared of rats as rats mostly kill them.

Rats are a bit more careful comparatively and do not go about exploring. When kept as pets, they enjoy digging and pretty much chew anything in their reach when they are left to explore.


House mice are pretty active, usually during the night, and spend their day sleeping. Instead of hibernating, they look for warm places when it is cold. The smell of food attracts them. They are fast runners, and excellent climbers help them explore and usually keep them safe from traps. They are good swimmers too. 

Rats, when kept as pets, are active from dusk till dawn. Their eyesight is not very good, so they depend on their sense of smell and touch for exploring and usually like climbing.

Mouse VS Rat Skeleton

It is widely believed that mice and rats do not have bones because of their flexibility. However, it is not valid. Like any other vertebrate, mice, and rats also have bones and cartilage. 

The skeleton of a mouse consists of nearly all the bones present in any other mammal. The most important of them are the skull, ribs, backbone, pelvis, and limbs. In total, they have more than 200 bones.

A rat’s skeleton is very similar to a mouse’s except for the size (as rats are giant) and some differences between their skulls.

Problems Caused By Baby Rats and Baby Mice

Rats and mice may cause health problems by transferring bacteria or other transferable diseases. They spread ailments either by their excretion or by crawling over the utensils in your kitchen and spoiling food.

Rodents may also bring parasites to your houses, such as fleas, ticks, or mites. These parasites spread various illnesses that are quite serious.

Damage Caused by Baby Rats and Baby Mice

Onc inside your house, both rats and mice, work on building their nests. They do that by collecting things they find in your home. They may use their very sharp teeth to chew the insulation of your wires which may lead to fire hazards,

Compared to rats, mice do not have intense chews, so glass and aluminum are safe. On the other hand, rats can chew their way through several building materials.

Pros and Cons of Having a Pet Baby Mouse

They keep themselves hygienicThe rate of reproduction is fast
Reasonable to buy and petSmall and sometimes hard to handle
Good companionsThe urine of male mice gives off a bad smell

Pros and Cons of Having a Pet Baby Rat

Reasonable to buy and petHave a short lifespan
Intelligent animalHave very sharp teeth and loves to chew around
Affectionate and entertainingPrimarily active at night and makes noise

Frequently Asked Questions

Here are some frequently asked questions about baby mice and rats.

Can you have baby mice and rats at the same time?

Typically, you can’t have both at the same time. They are usually mistaken as the same, but specific characteristics distinguish between the two when looked at from a distance.

Do baby rats look like mice?

Baby rat is larger than a mouse and looks a bit different. Baby rats have larger heads that appear fat and blunt. They also do not have a tail as long and thin as a mouse.

Is a mouse a baby rat?

No, they may appear similar at first glance, but they belong to two different species. Certain features distinguish a mouse and a baby rat. For instance, rats have hairless and scaly tails. Mice have ears large and floppy as compared to rats.

Which is more dangerous; baby rat or mouse?

Rats can cause more significant damage to your house, health, and food. They are larger, more cautious, and difficult to control. Some rats grew up to such a large size that even cats don’t try to chase them.

How do you tell if it’s a baby rat or mouse?

When a rat is pretty young, it looks bigger than a full-grown mouse. The mouse has larger ears and a smaller head. The tail of a mouse is also different than that of a rat in size and appearance.

Does a baby mouse mean an infestation?

One baby mouse signifies that there is a litter, which means that there are mature mice. If you find a baby mouse, it indicates an infestation as a baby mouse is never alone; it will have other babies with it as well.

Can you touch a baby rat?

It’s better to not touch a baby rat. They can defend themselves with their sharp teeth and claws and can give you micro-injuries. Meanwhile, rats and mice are hosts of zoonotic micro-organisms and can transmit different diseases to humans.

Do baby rats have diseases?

Rats can carry diseases like rat-bite fever and leptospirosis etc. They mostly have harmful parasites like ticks, mites, fleas and can also transfer diseases through their feces and urine.

What are the signs of rats in a garden?

Chew marks, burrows, droppings, holes, or smudges in your garden indicate signs of rats in your garden. It is better to call pest control to prevent infestation as they reproduce rapidly.

What attracts rats to your house?

Leftover or pet food, uncovered garbage, holes in the wall of your houses or gardens may attract rodents. They are also in search of shelter, especially when it’s cold. It’s imperative to keep your home clean to keep rats away.

What color is mouse urine when it dries?

It is a yellow liquid that becomes sticky when dried. Also, they may turn to dust after drying, which spreads viruses. It has a strong smell and is usually detected from afar.

What is the most dangerous rodent?

Rats are considered as most dangerous rodents. They are flexible and make their way through very tiny holes. It is hard to trap them as they are cautious when exploring a new place quickly.


While rats and mice may cause quite some damage when your house is infested, they also make pretty good pets as they are inexpensive animals and do not occupy much space. And differentiating between baby mice and baby rat is crucial to meet their housing and nutritional requirements.

Hopefully, this baby mouse vs baby rat guide will help you distinguish one species from the other.

SmallPetsX.Com does not provide veterinary advice. Our aim to help small pet owners understand their pets a little better so that they can provide their pets with the life they deserve. All content is therefore for informational purposes only. If you're concerned about the health of your pet you should seek medical advice from a vet.

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