The main differences between newborn squirrels and rats are the shape of the head, eyes, snouts, and length of their limbs. Newborn squirrels have rounder-shaped heads, larger, round eyes, longer limbs, and weigh more than newborn rats.
How do you know if the small newborn rodent you have found is a newborn squirrel or a rat infant?
In this article we look at physical differences you can look for to tell newborn squirrels apart from rats.
Newborn Squirrel vs. Rat Overview
Newborn squirrels and rats are both rodents that are born blind and hairless. Both are also referred to as ‘kittens, ‘kits’ or ‘pups.’
As newborns, squirrels and rats look similar. But, there are a few physical differences that set these two rodents apart.
| Physical traits | Newborn Eastern Gray Squirrel | Newborn Brown Rat |
| Scientific Name | Sciurus carolinensis | Rattus norvegicus |
| Gestation period | 44–45 days | 22–24 days |
| Size of litter | 2–3 squirrels per litter | 8 rats per litter |
| Body mass | 0.4–0.6 ounces | 0.21–0.28 ounces |
| Head | Broad, rounded head and a short, rounded muzzle. | Newborn rats have an elongated oval-shaped head with a long tapered muzzle. |
| Ears | Newborn squirrels’ ears are small, pointed, and flat against their heads. | Newborn rats’ ears are small and rounded. |
| Eyes | Newborn squirrels’ eyes are closed and eye slits are not visible. Their eyes are round and large. Eyes open at 5 weeks. | Newborn rats’ eyes are small and oval. Their eyes are closed but the eye slits are visible. Eyes open at 2 weeks old. |
| Color | Newborn squirrels are hairless and have pink skin | Newborn rats are hairless and have pink skin |
| Tail | Newborn squirrels have a hairless tail that is about half the size of their bodies. | Newborn rats have a hairless tail that is less than hair the size of their bodies. |
| Limbs | Long limbs | Short limbs |
| Diet | Mother’s milk | Mother’s milk |
| Weaning Age | 7–10 weeks-old | 3–4 weeks-old |
| Age when they leave the nest | 10 weeks-old | 4 weeks-old |
| Daily activity | Dirnual | Nocturnal |
Newborn Eastern Gray Squirrels
Eastern gray squirrels are one of the most common tree squirrels in North America. They are born pink, hairless, and with closed eyes. They are small, weighing about 0.5 ounces.
Eastern gray squirrels are born after 44–45 days in the womb. They are born without fur. The only hair they are born with is their whiskers. Their skin is pink in color.
They are born with closed eyes and are blind for the first few weeks of their lives. Although you can see the shape of their eyes, their eye slits are not visible as their eyes are closed.
The squirrel pups’ ears are folded flat against their heads. Their tails are also without fur.
Infant squirrels open their eyes after 5 weeks. By the time they are 6 weeks old, they look like smaller versions of adult squirrels.
Squirrels feed on their mother’s milk for the first weeks, while they are still considered pups. Weaning begins at 7 weeks and is complete by the time they are 10 weeks old.[1]
Newborn Brown Rats
Also known as Norway rats, brown rats are the most common wild rat species in the world. They are born pink, without fur, and with closed eyes. They have small tails at birth, which grow as they grow.
Brown rates give birth to a litter of 8 rat pups after 22 to 24 days of gestation.
Rat pups are born hairless, pink in color, and blind. The shape of their eyes is visible under their pink, almost translucent skin, and their eye slits are visible.
Their eyes are oval and small compared to their head size. They open their eyes after 2 weeks.
They feed on their mother’s milk. Weaning starts when they are between 3 and 4 weeks old. They leave the nest when they are 4 weeks old.[2]
Newborn Squirrel vs. Rat: Similarities
Both newborn squirrels and rats are rodents, blind, and pink when born. They also both have hairless tails. Both baby rats and squirrels feed on their mother’s milk until weaned.
While squirrels and rats are inherently different, with clear physical and behavioral differences, they do also have some similarities.
These physical similar traits make them difficult to distinguish, which is why many people confuse them for one another.
Here are physical similarities between newborn squirrels and rats
- Hairlessness
- Colour of skin
- Appearance of tails
Newborn Squirrel vs. Rat: Hairlessness
Both squirrels and rats are born without fur. The only hair they have are whiskers.
Squirrel pups are hairless for the first 2 weeks of their lives. Their fur starts to grow when they are about 3 weeks old.
Rat pups’ fur starts to grow from they are 2 weeks old.
Newborn Squirrel vs. Rat: Color of the Skin
Both newborn squirrels and rats are born hairless with bright pink skin.
After a week or two, a squirrel pup’s head and back start to turn darker in color.[3]
Rats remain pink until they have grown fur. They start growing fur at 2 weeks old.
Newborn Squirrel vs. Rat: Tails
The pink hairless tails of newborn rats look similar, but it doesn’t stay this way.
Rats’ tails remain hairless and grow longer as they grow. Squirrels’ tails become fluffy and grow to be as long as their bodies.
Newborn Squirrel vs. Rat: 5 Physical Differences
The main differences between newborn squirrels and newborn rats are the shape of the head, eyes, ears, length of legs, and weight.
During a squirrel and rat’s first week of life, they look so similar that it is understandable if you mistake them. Fortunately, we have found five physical differences you can look out for.
- Head shape
- Eye shape and size
- Ear shape and size
- Length of limbs
- Weight
1. Newborn Squirrel vs. Rat: Head Shape
Newborn squirrels have broad round-shaped heads with rounded, short muzzles, while newborn rats have flatter oval-shaped heads with long, tapered muzzles.
2. Newborn Squirrel vs. Rat: Eye Shape and Size
Even though their eyes are closed, the shape of newborn squirrels’ and rats’ eyes are visible through their skin.
Newborn squirrels’ eyes are closed. Their eye slits are not visible. The eye shape is round and large when compared to their head size.
Newborn rats’ eyes are oval and small compared with their head size. Their eyes are closed and the eye slits are visible.
3. Newborn Squirrel vs. Rat: Ear Shape and Size
Newborn squirrels’ ears are small, pointed, and squashed flat against their heads. Newborn rats’ ears are small, rounded, and flat against their heads.
4. Newborn Squirrel vs. Rat: Limbs
The limbs of newborn squirrels are longer than the limbs of newborn rats.
5. Newborn Squirrel vs Rat: Weight
If you have the opportunity to weigh a newborn tree squirrel and compare it with a newborn rat, you will notice that the squirrel is heavier.
Common rats weigh between 0.21–0.28 ounces at birth. A newborn gray squirrel weighs between 0.4–0.6 ounces.
Differences Between Squirrel and Rat Families
Newborn squirrels and rats are both rodents, but from where and when they sleep to who looks after them, these pups have different life experiences based on their species.
Tree squirrels are diurnal. They are most active during the day and sleep at night. Rats are nocturnal and active at night.
Eastern gray squirrels newborns live in nests, also known as dray, in trees or dens, nests inside tree cavities. They grow up with one or two siblings and are cared for by their mothers.
Brown rats will nest in several spaces in urban areas, from inside people’s homes (in wall cavities, roofs, or under floorboards) to sewer systems. In the wild, they burrow into grassy banks.[4]
Brown rats not only share their nests with their 7 siblings but can share a nest with a few litters of rats. They grow up in a community where mother rats will care for pups even if they are not their own.
