Credit: Mary Konchar Delmarva Fox Squirrel

Blackwater National Wildlife Refuge is located on the Eastern Shore of Chesapeake Bay in Dorchester County, Maryland, about 12 miles south of Cambridge. Established in 1933, the Refuge consists of approximately 27,000 acres of brackish marsh, freshwater ponds, and brushy and timbered swamps. The wooded areas are predominately loblolly pine and mast producing hardwoods; three-square bulrush is the dominant vegetation in the marsh. Although the mammals of Blackwater are often overlooked in favor of the more abundant and conspicuous bird life, the Refuge hosts a wide variety mammals.

One species worthy of special note is the large, grizzled-gray Delmarva fox squirrel. Currently listed as an endangered species, this squirrel is found at only a few localities on the Eastern Shore, with Blackwater Refuge hosting the largest natural population. Forest management programs at Blackwater are oriented toward perpetuation of this handsome squirrel, and visitors wishing to catch a glimpse of this sometimes elusive mammal are advised to look carefully in the woods bordering the Wildlife Drive.

One unusual resident of the Refuge is the sika deer, which is actually a species of elk that originates in Japan, Taiwan and eastern Asia, and was introduced onto James Island in the Chesapeake Bay about 1916. Sika deer prefer the more secluded areas of the Refuge, but they are quite common in southern Dorchester County. Sika are smaller and darker than the white-tailed deer, often retaining their spots as an adult. Visit the Maryland Department of Natural Resources website to learn more about sika deer in the state.

Nutria is another non-native mammal with ties to Blackwater, but the nutria are no longer found at the Refuge. A nutria is a large aquatic rodent introduced from South America. The mammals were brought into Maryland in the 1940's for use on fur farms but eventually they reached the wild where they adapted to the climate of Blackwater Refuge. The nutria population began to compete with the native muskrat and waterfowl populations for habitat resources, and eventually the nutrias' feeding habits caused such extensive damage to Refuge wetlands that local, state, and federal authorities coordinated their efforts to effectively remove nutria from Blackwater Refuge. Visit the Nutria section of this website for more information about the ongoing efforts to keep nutria off of Refuge property.

Credit: Sid Keiser Sika Deer

The following list of 30 mammal species is based on observations by Refuge personnel and a report prepared by John L. Paradiso of the U.S. Fish and Wildlife Service. Eight additional species are listed as hypothetically existing on the Refuge since it is within their range. Scientific names and order in which they appear follow Miller and Kellog, "List of North American Recent Mammals (U.S. National Museum Bulletin 205)," while common names were taken from Burt and Grossenheider, "A Field Guide to the Mammals." More detailed information on the following species may be obtained from Paradiso, "Mammals of Maryland, North American Fauna, No. 66 (U.S. Fish & Wildlife Service, April 1969)."

Opossum
(Didelphis marupialis)
Common in wooded areas and wood margins. Occasionally seen along roadsides at night. Omnivorous -- eats both plant and animal food.

Masked Shrew
(Sorex cinereus)
Uncommon.

Least Shrew
(Cryptotis parva)
Common in the marsh.

Shorttail Shrew
(Blarina brevicauda)
Common in damp woodland soil habitats.

Starnose Mole
(Condylura cristata)
Common in damp soil.

Eastern Mole
(Scalopus aquaticus)
Common in cultivated fields.

Little Brown Bat
(Myotis lucifugus)
Common. Roosts in hollow trees.

Red Bat
(Lasiurus borealis)
Common in woodlands.

Eastern Cottontail Rabbit
(Sylvilagus floridanus)
Very common in brushy thickets bordering roads and dikes. Frequently seen during spring and summer.

Gray Squirrel
(Sciurus carolinensis)
Common throughout Refuge woodlands. Prefers nut-producing hardwood trees. More arboreal than the Delmarva fox squirrel.

Delmarva Fox Squirrel
(Sciurus niger cinereus)
Common in wooded areas that contain little or no underbrush. Distinguished from gray squirrel by its larger size. The coloration varies but is usually light gray. This squirrel spends more time on the ground than the gray squirrel and often feeds in corn and soybean fields.

Credit: USFWS Southern Flying Squirrel

Southern Flying Squirrel
(Glaucomys volans)
Seldom seen because of its nocturnal habits.

Rice Rat
(Oryzomys palustris)
Common throughout the brackish marshes.

White-footed Mouse
(Peromyscus leucopus)
Abundant in wooded and brushy areas.

Meadow Vole
(Microtus pennsylvanicus)
Abundant in marsh where it will build its nest in muskrat houses.

Pine Vole
(Pitymys pinetorum)
Common on all dry land habitats.

Muskrat
(Ondatra zebethicus)
One of the most abundant mammals at Blackwater. Their large dome-shaped houses may be seen throughout the marsh.

Nutria
(Myocaster coypus)
Larger than a muskrat, it is sometimes mistaken for a beaver. Currently absent from the Blackwater marsh

Black Rat
(Rattus rattus)
Uncommon.

Norway Rat
(Rattus norvegicus)
Common.

House Mouse
(Mus musculus)
Common around Refuge buildings and in wild.

Credit: Bob Quinn Red Fox

Red Fox
(Vulpes fulva)
Common, but seldom seen. Inhabits wooded and brushy areas where it feeds on rabbits, rodents and birds.

Gray Fox
(Urocyon cinereoargenteus)
Uncommon. Prefers the heavily wooded areas.

Raccoon
(Procyon lotor)
Very common in all wooded areas bordering water. Its varied diet includes fish, frogs, rodents, eggs, insects and plants.

Longtail Weasel
(Mustela frenata)
Common in brushland, fields, and marsh.

Mink
(Mustela vison)
Uncommon. May be found in all aquatic habitats.

Striped Skunk
(Mephitis mephitis)
Common in brushy areas of Refuge.

River Otter
(Lutra canadensis)
Uncommon, but occasionally seen along banks of Wildlife Drive.

Sika Deer
(Cervus nippon)
Abundant. Found in the more secluded areas of the Refuge.

White-tailed Deer
(Odocoileus virginianus)
Abundant. May often be seen at dusk in tree-bordered fields.

A Hypothetical Listing of Species Based on Reported Range:

Keen's Bat
(Myotis keenii)

Silver-haired Bat
(Lasionycteris noctivagans)

Eastern Pipistrell
(Pipistrellus subflavus)

Big Brown Bat
(Eptesicus fuscus)

Hoary Bat
(Lasiurus cinereus)

Evening Bat
(Nycticeius humeralis)

Southern Bog Lemming
(Synaptomys cooperi)

Meadow Jumping Mouse
(Zapus hudsonius)