Mammals

Land Mammals

There are many different land animals in the Chesapeake Bay watershed. Listed below are some of the most prominent seen at or around the grounds of Fort McHenry.

Eastern Cottontail

Sylvilagus floridanus

A small rabbit with a red-brown or gray-brown fur pattern with large hind feet, long ears, and a short tail. Lives in fields, farms, woods, and backyards across the area. The Eastern Cottontail eats mainly plants including clovers and grasses. A cool fact about this animals is that it usually hydrates itself by retaining the water from the plants that were consumed.

Eastern Gray Squirrel

Sciurus carolinensis

One of the most common animals, the Eastern Gray Squirrel is small in size with a big gray and brown bushy tail. This animal lives in forests and will very commonly go into the populated areas around the tidal bay region. Squirrels eat nuts and other small plants. Their population is among the highest in the Baltimore Metro area.

Little Brown Bat

Myotis lucifugus

Long glossy fur that can be golden, reddish, olive or dark brown. These bats usually grown up to 3.5 inches with wingspan of 9 to 11 inches. The Little Brown Bat eats mainly aquatic insects such as midges, mayflies, caddisflies and other types of insects. The feeding usually takes places two hours after dark, so chances are you will not be seeing these critters during the daylight.

Opossum in a tree, holding on to a branch — Opossum
NPS

Virginia Opossum

Deidelphis virginiana

A heavyset critter with a white furry coat lives in the swamps, forests, and farm areas around the Chesapeake Bay. The opossum primarily eats insects and animals, with the occasional trip to neighborhood garbage cans. These critters are very susceptive to frost bite which can cause them to lose some extremities during the colder months.

Raccoon

Procyon lotor

The racoon has a long-striped tail with colors on the face resembling a mask. The raccoon lives in forested and grassy areas but are commonly seen in developed areas. They will eat anything that is available; if it is edible, the raccoon will eat it.

Eastern Red Bat

Lasiurus borealis

A medium sized four- to five-inch-long bat with distinctive red fur with males sporting a brick or rusty red. While females sport a more frosted shade of red. They both have tuffs of white fur on their shoulders. Feeds on a wide variety of insects, and are most active at dusk. This bat can fly up to almost 40 miles per hour, far faster than any speed limit at Fort McHenry!

Red Fox

Vulpes vulpes

The rusty fur color with big pointy ears are the indicating features on the Red Fox. Red foxes live in the forests and meadows around the area, which is an optimal spot for them to find their food source of mice, squirrels, and birds. Those pointy ears are quite effective as they can pick up small mammals making noise underground!

Male White Tail Deer standing in tall grass — White Tailed Deer (male)
NPS

White Tailed Deer

Odocoileus virgnianus

A brown and tan medium size species of deer that live in the forested areas all over the east coast. These animals have an omnivorous diet consisting of mainly green plants, and various fruits such as berries, apples, and grapes. White Tail deer are overpopulating the region, causing some food source issues within some herds.

Semi-Aquatic Mammals and Rodents

Semi-aquatic mammals are species that thrive in both aquatic and terrestrial environments, exhibiting unique adaptations that allow them to navigate and survive in both habitats.

Beaver

Castor canadensis

The beaver is a large, brown, semi-aquatic mammal with a distinctive flattened, paddle-like tail. It lives in lakes, streams and forested wetlands throughout the Chesapeake Bay watershed. A beaver builds lodges of sticks and mud on islands, river banks and shorelines. They can chew down a small tree in just a few minutes to eat or to repair their dams and lodges.

Brown Rat

Rattus norvegicus

The brown rat, also known as the common rat, street rat, sewer rat, wharf rat, Hanover rat, Norway rat and Norwegian rat, is a widespread, common species of rat. It is a brown or grey rodent with a body length of up to 28 cm (11 in) long, and a tail slightly shorter than that.

Deer Mouse

Peromyscus maniculatus rubiterre

A medium sized mouse with big black eyes and russet brown on their upper half while their underneath is white. With large-rounded ears, pinkish paws, and a multi brown colored tail. This species of mouse lives in woodlands and meadow areas. The mouse feeds on insects, fruit, nuts. and other forms of vegetation.

Groundhog

Marmota monax

A rodent like creature that prefers solidarity spending their summer and fall seasons napping underground. Their diet consists of various fruits, plants, tree bark, and grasses. Groundhogs in many contexts, are considered to be pests, but offer many different ecological roles at the fort. Some of the vegetation is kept under control by this critters.

House Mouse

Mus musculus

The house mouse is a small mammal of the rodent family Muridae, characteristically having a pointed snout, large rounded ears, and a long and almost hairless tail. House mice usually run, walk, or stand on all fours, but when eating, fighting, or orienting themselves, they rear up on their hind legs with additional support from the tail.

Meadow Vole

Microtus pennsylvanicus

Also known as the field mouse or meadow mouse, the meadow vole has rich, dark brown fur with grayish or pale brown underparts. It has small ears and dark brown feet. They are able to swim well and are the most abundant rodent in the Chesapeake Bay’s marshes.

Muskrat

Ondatra zibethicus

The muskrat is a medium sized, semi-aquatic mammal with brownish fur and a long, rudder-like tail. It is found in marshes and other shallow-water areas throughout the Chesapeake Bay watershed. The muskrat feeds mostly on the roots and rhizomes of marsh plants, but will also eat fish, frogs, insects and shellfish. It will build separate feeding lodges or platforms so it can get out of the water and eat.

River Otter

Lontra canadensis

The river otter has a long, streamlined body with dense brown fur. It has a wide, round head with small ears and long, white whiskers that it uses to detect prey. River otters feed mostly on fish but will also eat frogs, crabs, crayfish, and small mammals. It can be found along lakes, streams, rivers and marshes throughout the Chesapeake Bay watershed.

Last updated: January 21, 2026

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