12 Types of Rodents in Pennsylvania! (w/Pics)
Did you find a rodent in Pennsylvania?
First, I hope it was outside and NOT in your house. 🙂
Second, I’m guessing you’re here to try and identify the correct species. Luckily, you’ve come to the right place! I compiled a list of the most common rodents in Pennsylvania, with photos and links to help find the one you’ve found.
As you will see below, I have broken this list into TYPES of rodents instead of individual species. There are DOZENS of different species of rodents in Pennsylvania.
If you need additional information help with rodent identification, check out this field guide!
Here are 12 types of RODENTS found in Pennsylvania!
In Pennsylvania, these rodents live in nearly every environment imaginable.
Some, like pocket mice, are highly adapted to dry, hot deserts, while others live in cooler boreal forests. You can find them in suburban, urban, and rural areas. Chances are, no matter where you are right now, there’s a mouse somewhere nearby!
- RELATED: 28 Types of MAMMALS Found in Pennsylvania! (ID Guide)
Mice are one of the most numerous rodents in Pennsylvania. There are over 70 species living in North America, but one of the most common is the House Mouse (Mus musculus).
House Mice are the most common species in your home because they’re adaptable to human presence. They readily eat food scraps, build their nests in walls or dark attics and basements, and spend most of their time hidden from view. You’ve likely shared your home with a House Mouse at least once over the years. Although most people would prefer not to have them, they aren’t the worst roommates!
You probably know voles as field or meadow mice, but this type of rodent is more closely related to hamsters. Voles use burrows for nesting, shelter, and rest. They create woven grass nests placed in the burrows or under logs.
As their name suggests, they prefer grassland or open forest habitats. Like most rodents in Pennsylvania, voles are dietary generalists, which means they will eat many different types of food. Garden plants, flowers, crops, and grasses are common food sources.
Voles are an important food source for many predators, including birds of prey, snakes, and wild and domesticated cats.
Although they’re easily recognized and well-known, voles are not commonly found in homes. They prefer open space and grasses to eat, so they ignore most populated areas.
Although rats are common rodents in Pennsylvania, the most numerous and well-known species isn’t even native to North America. Instead, the Brown Rat (Rattus norvegicus) is thought to have originated in China and Mongolia. Look for Brown Rats anywhere people are living, particularly in urban environments. They’re best known for living in sewer tunnels and subway systems, scavenging food from the trash.
Although many people find rats off-putting, there are quite a few native species that don’t really have much in common with the Brown Rat. They tend to live away from humans in secluded forests or deserts.
Most rats are opportunistic feeders. They will eat whatever is most plentiful, which means some populations survive on human refuse. However, others eat plant matter like roots, stems, leaves, berries, and seeds.
One of the most interesting things about native rats is the way they use their tails. Like other rodents in Pennsylvania, rats climb trees, walls, and fences to get to food. Their tails aid in balance and act as an additional limb to help hang on to branches!
Many people battle these rodents in Pennsylvania at their bird feeders!
Squirrels eat various foods, but naturally, their favorites are nuts, such as acorns, walnuts, and hazelnuts. As winter approaches, squirrels start hiding food in many locations, which provides them nutrition through the colder months. They hide more food than they will ever find, and some extra seeds will eventually grow into new trees. Who knew that squirrels could play such an important role in seed dispersal?
Squirrels can adapt to many environments throughout Pennsylvania. However, they’re most often found in patches of forests with trees that produce their favorite foods: tree nuts! Look for them everywhere, from rural areas to college campuses to suburban backyards!
Although chipmunks are a subgroup of ground Squirrels, most people refer to them separately, and it’s easy to see why! These tiny rodents live in Pennsylvania and are quite different from other species.
You can recognize chipmunks by their small size, bold stripes, and mischievous nature. They often dart around backyards and decks, looking for food and shelter. At my house, we have a chipmunk so determined to build a home in our garage that we can scarcely open it to get to our cars!
Chipmunks are omnivorous. While they mainly eat seeds, nuts, and fruits, they also enjoy bird eggs, small frogs, and insects. So look for them anywhere a food source is abundant, from open fields and forests to backyards, parks, and populated areas.
#6. Common Muskrat
- Ondatra zibethicus
- Adults range from 16 to 25 inches in total length and weigh 1.5 to 4 pounds.
- Their coloring is blackish-brown on the back, lighter brown with a reddish tinge on the sides, and pale on the underside.
- They have short front legs with small feet, strong hind legs with large, partially-webbed feet, and a laterally flattened, scaly tail.
Muskrats are one of just a few semi-aquatic rodents in Pennsylvania.
They occupy marshes, streams, ponds, rivers, and lakes with fresh and brackish water. This species lives in dens built into riverbanks or lodges they construct from sticks. Muskrats construct homes with underwater tunnels and dry, above-water chambers. Interestingly, they will sometimes move into occupied beaver lodges and cohabitate with them.
Being mostly omnivores, Muskrats typically feed on aquatic plants such as cattails, water lilies, and duckweeds. But when food is scarce, they sometimes eat other animals, including crayfish, snails, frogs, insects, and fish.
Muskrats are an important part of the ecosystem in Pennsylvania, helping keep areas of marshes open and creating essential habitats for waterfowl. Unfortunately, this species was introduced to Europe as fur stock and has become invasive in many countries. They cause issues by burrowing into dikes and levees and causing flooding.
You’ve probably heard the popular myth that lemmings commit mass suicide by diving off cliffs to their death. Although not quite accurate, it is true that these rodents do sometimes jump off cliffs!
Instead of trying to meet an untimely death, they’re following a biological need to disperse or spread out from a population boom. Lemmings can swim, so normally, they’re jumping toward the water. However, they often end up in the Atlantic Ocean or other large bodies of water and ultimately drown.
Interestingly, lemmings have the most erratic populations of any rodents. Their numbers can explode and then drop to near extinction within one to two years. Scientists aren’t sure exactly what causes these population shifts, but they believe it has to do with the populations of the lemmings’ predators, like stoats and snowy owls.
#8. American Beaver
- Castor canadensis
- Adults are 29 to 35 inches long, with a tail length between 7.9 and 13.8 inches, and weigh between 24 and 71 pounds.
- They have a dark brown coat of waterproof fur, webbed feet, and a large, flat, black tail.
- Their large, continuously growing incisors (teeth) are orange due to thick layers of enamel.
The American Beaver is North America’s largest rodent!
These incredible rodents are known as ecosystem engineers, meaning they’re one of just a few species that actively work to alter their habitat. They do so by building dams with trees, branches, and mud. Beavers use the dams for shelter, food storage areas, and dens for raising young.
Ponds created by beaver dams serve as important habitats for many types of wildlife. They also help reduce erosion and slow water movement, promoting moisture in drought-prone areas. Especially in northern climates, the water in the pond needs to be deep enough that it doesn’t freeze solid, allowing the beavers to swim under the ice all winter.
Beavers are excellent swimmers and can stay submerged for up to 15 minutes. They spend as much time as possible in the water, where they are less vulnerable to predators. This species uses its large tail to slap the water to signal danger to other beavers, as well as fat storage.
#9. North American Porcupine
- Erethizon dorsatum
- Adults range from 2 to 3 feet in length and weigh about 20 pounds.
- Their fur ranges in color from brownish-yellow to black, with white highlights on their quills.
- Porcupines are covered in approximately 30,000 hollow quills.
While North American Porcupines generally spend much of their time on the ground, they can also climb trees, using their tail for support. But they aren’t the best climbers; one study found that 30% of the porcupines had healed fractures from falling from trees.
They’re well known for their sharp quills used for defense. When threatened, porcupines draw up the skin of their back, bristling so that the quills face all directions. Then, the porcupine keeps its back to the predator and moves its tail back and forth. But, despite their effective defense, porcupines are still preyed on by fisher cats, coyotes, wolverines, and other predators that have adapted to hunting them.
Contrary to popular belief, porcupines can’t throw quills at their attacker! 🙂
#10. Groundhog (Woodchuck)
- Marmota monax
- Adults measure between 16.3 and 26.6 inches long.
- Their coloring ranges from gray to cinnamon to dark brown, and they have white-tipped guard hairs, which give them a silvery appearance.
- They are stocky, with rounded ears and a bushy tail.
Groundhogs, also called woodchucks or whistle pigs, occupy forests, fields, pastures, and hedgerows. They thrive near humans, and agriculture operations have increased their food access. Groundhogs construct dens; most have a summer den near food sources and a winter den near protective cover.
In the fall, Groundhogs store large amounts of fat for hibernation. They are “true hibernators,” meaning that their body goes dormant for the entire season. During this time, their heart rate and body temperature fall dramatically until they leave hibernation in late winter or early spring.
Unfortunately, these rodents can become a nuisance in Pennsylvania to farmers, gardeners, and homeowners due to their tunneling behavior. Groundhogs are most affected by vehicle collisions, hunting, trapping, and predation from various species, including domestic dogs.
The following two groups of animals – moles and shrews – are technically not rodents at all.
Instead, they’re a separate group of mammals with a few key differences. But, because so many people consider them rodents, I’ve included them here to give you the best information possible.
Almost every single trait of the mole is adapted to its underground lifestyle.
For example, their respiratory systems can process carbon dioxide efficiently, which allows them to breathe underground where there is less oxygen. They also have spade-like front paws perfect for digging and a cylindrical body covered in sleek fur that helps them slide through tunnels easily.
Although many people in Pennsylvania consider these rodents garden pests, they’re very good for soil structure and plant health. They eat grubs, earthworms, and other larvae that feed on plant roots.
Moles have the unique ability to store earthworms alive by paralyzing them with their saliva. They store hundreds of earthworms in underground “larder” burrows built specifically for this purpose. That’s one way to keep your dinner fresh!
Shrews look like long-snouted mice, but they’re much more closely related to moles and hedgehogs! They have sharp, spiky teeth that they use to cut through vegetation.
With an estimated 100 million individual animals worldwide, Shrews are one of the most common rodents in Pennsylvania.
They’re very small and terrestrial, meaning they spend most of their time on the ground. They eat worms, insects, seeds, and vegetation.
Although they don’t hibernate, some species of Shrew enter torpor during winter and undergo other body changes to survive the cold. For example, they can reduce their body weight by up to 40%, which allows them to conserve energy when food is scarce!
Which types of rodents have YOU seen before in Pennsylvania?
Let us know in the comments!