U.S. Fish & Wildlife Service

Blackwater

National Wildlife

Refuge

Wildlife Drive

Blackwater National Wildlife Refuge

2145 Key Wallace Drive

Cambridge, Maryland 21613-9535

410/228 2677

410 228 3261 Fax

e-mail: fw5rw_bwnwr@fws.gov

www.fws.gov/blackwater/

Federal Relay Service 

for the deaf and hard-of-hearing

1 800/ 877 8339

U.S. Fish & Wildlife Service

1 800/344 WILD

http://www.fws.gov/

September 2008

Wildlife Drive

USFWS

MARCH 3, 1849

U S. . DEPARTMENT OF THE INTERIOR
Take a Drive on 

the Wild Side!

Blackwater National Wildlife Refuge 

welcomes you to tour our popular 

Wildlife Drive that can be accessed 

by automobile, bicycle or on foot. 

Walking and biking on the drive is 

permitted, however, visitors must 

remain on the paved road. While on 

the refuge, please obey all signs, and 

do not feed or harass the wildlife. 

The Wildlife Drive is open daily from 

dawn until dusk. 

This guide points out some of 

Blackwater’s wildlife management 

programs. It is keyed to numbered 

observation points along the drive. 

National wildlife refuges provide 

protection, food and cover for 

wildlife through specific land and 

water management programs. 

Although this refuge is managed 

primarily for migratory birds and 

endangered species, many other 

types of wildlife share the wide 

diversity of habitats. The careful 

observer will see a variety of plants 

and animals along the drive. 

Freshwater habitat is scarce on 

Blackwater National Wildlife Refuge 

because of the predominantly 

brackish (mixture of salt and fresh 

water) conditions in the vicinity. The 

dike on which you are riding was 

constructed to create the freshwater 

impoundment to your right, which 

adds to the diversity of habitat for 

wildlife. 

Scan the shallow edges for dabbling 

ducks such as mallards and 

Northern pintails; wading birds 

such as great blue herons and great 

egrets; and shorebirds like yellowlegs 

and dunlins. The impoundments are 

drained in summer to encourage 

the germination of natural moist 

soil vegetation such as wild millet, 

smartweed and redroot cyperus 

which provide food for waterfowl. 

The drained mudflats also provide 

good feeding areas for shorebirds 

and other marsh and water birds. 

In the late summer, the water control 

structures are closed to allow rainfall 

to fill them, making the seeds and 

tubers of these plants and a variety 

of invertebrates, such as snails, 

worms, and larvae, available to the 

migratory waterfowl. 

The water to your left is part of the 

Little Blackwater River. The river is 

named for its dark color from tannic 

acids picked up as it drains through 

peat soil in the marshes. 

At this point, if you would like to visit 

the Observation Point and the Marsh 

Edge Trail, take the road to the left. 

To rejoin the Wildlife Drive, double 

back and continue from this point. A 

self-guiding leaflet for interpreting 

the Marsh Edge Trail is available at 

the trail head. 

On your left is a bluebird nest box. 

These boxes have been erected to 

help improve bluebird reproduction. 

Bluebird nesting sites have 

decreased due to lack of natural 

nesting cavities. Nesting boxes are 

installed in suitable habitat to allow 

the species to nest. Other birds such 

as tree swallows, chickadees, titmice 

and wrens may also use the boxes. 

Bluebirds, as well as other species, 

consume large quantities of insects, 

especially mosquitoes. As many as 

140 bluebirds have fledged in one 

year from the refuge’s boxes. 

2. Bluebird Box

Marsh Edge Trail

1. Moist Soil 

Vegetation
3. Wood Duck 

Box

4. Prothonotary

Warbler Box

5. Delmarva 

Peninsula Fox 

Squirrel

A few duck species use hollow trees 

for nesting. At Blackwater, the only 

cavity nesting duck is the wood 

duck. Timbering and land clearing 

for agriculture and development 

have eliminated many of the mature 

forests that historically provided 

an abundance of trees with natural 

cavities. These nesting boxes are 

used to replace disappearing natural 

sites. When not occupied by wood 

ducks, the boxes may have flickers, 

sparrowhawks and screech owls as 

tenants. Notice the cone shape 

structures below the boxes. 

This is called a “predator 

guard”, which helps keep 

out nest predators such as 

raccoons and snakes. 

Prothonotary warblers are one of the 

two cavity nesting warblers in the 

United States. Most warblers build 

their nests in small trees, shrubs 

or on the ground. The small, yellow 

prothonotary warbler prefers natural 

cavities (decaying snags) located 

over water in swampy lowland 

forest of river bottom woodlands. 

Humans have reduced and altered 

the natural habitats making nesting 

sites increasingly difficult to find. 

Since these warblers do not excavate 

their own holes, they compete with 

other cavity nesters like Downy 

woodpeckers, Carolina chickadee, 

and Carolina wrens for nest sites. 

This woodland is managed to 

provide habitat for the endangered 

Delmarva Peninsula fox squirrel, 

which prefers a mature forest with 

little undergrowth. At one time 

these large squirrels lived in areas 

from southeastern Pennsylvania to 

Virginia, but natural populations are 

now found in only a few locations 

on Maryland’s Eastern Shore. 

They have become endangered 

primarily due to the loss of forests 

to agriculture and development for 

human use. The refuge provides 

habitat and protection to the largest 

remaining natural population of 

Delmarva Peninsula fox squirrels 

in the world. The fox squirrel has 

a light, steel-gray coat and a large 

fluffy silvery tail with black edges. 

The gray squirrel, which also 

inhabits the refuge, is smaller and 

has reddish or brown hair mixed in 

its gray coat. The fox squirrel feeds 

more on the ground than the gray 

squirrel and can be seen venturing 

further into fields to feed on 

agricultural products. 

You will pass a parking lot on your 

right for one of the refuge’s walking 

trails, the Woods Trail. In spring, 

these wet woods are alive with the 

calls of mating tree frogs and toads 

and numerous songbirds. The Woods 

Trail allows you to trek through 

Delmarva Peninsula fox squirrel 

habitat and observe this endangered 

species. If you choose to hike the onehalf mile trail, you may want to apply 

insect repellant as biting insects are 

abundant from mid-April through 

late September.

An important part of the wildlife 

management program at Blackwater 

is to retain diverse agricultural fields. 

More than 500 acres of croplands 

are planted with millet, sorghum 

(milo), corn, buckwheat, clover, 

soybeans or rye grass to provide 

high energy food and cover for many 

species of wintering waterfowl and 

other wildlife. White-tailed deer 

may be seen feeding in these fields, 

especially in the early morning or 

evening. They prefer the “edge” 

6. Deer

Woods Trail
Blackwater

National Wildlife

Refuge

Little Blackwater River

Wildlife Drive

K ey Wallace

Entrance

Visitor

Center

D rive

To Cambridge

Egypt Road

335

B l a c k w a t e r R i v e r

LEGEND

Visitor Center

Auto Drive and

Bike Trail (5 mi.)

Walking Trail

Parking Area

Eagle Resting Sites

Wooded Area

Marsh

Observation Site

Refuge Headquarters

0 .5 1 Mile

0 .5 1 Kilometer

To

Cambridge

Self Service

Pay Station

Woods Trail

(1/2 Mile)

Marsh Edge

Trail 1/3 Mile

Observation

Site

North

Refuge

Headquarters

Wildlife Drive Stops

1

2

3 4

5

6

7 8

9 10

11

5
7. Waterfowl

8. Fresh and 

Brackish Water 

Marshes

habitat where forests, meadows 

and croplands come together. In 

addition to white-tailed deer, smaller, 

white-rumped sika (pronounced 

“see-kuh”) deer, an Asian species 

of elk introduced to James Island 

in 1916, have also been observed at 

Blackwater. Abundant in the marshy 

areas, sika deer are grazers that feed 

on the marsh grasses, while whitetailed deer are primarily browsers 

that feed on the leaves, buds and 

twigs in forested areas. Both species 

use agricultural crops. 

As you drive through the refuge, 

you may notice waterfowl with 

aluminum leg bands, or, more 

rarely, numbered neck collars. 

These bands are tools that help 

biologists obtain information 

about waterfowl movement and 

abundance in different areas. The 

waterfowl are captured in nets or 

wire traps, identified, banded and 

then released. Each bird’s species, 

age, sex, and date and place of 

banding are recorded by the 

refuge staff and forwarded 

to a laboratory in Laurel, 

Maryland. Recovered bands 

are turned in by hunters, or are 

reported by other banding stations 

when these birds are recaptured. 

Information on migration and other 

aspects of their life history are 

valuable in managing for waterfowl. 

Species of waterfowl using 

Blackwater include Canada and snow 

geese, tundra (whistling) swans, and 

more than 20 species of ducks. 

From here you can see typical 

habitat used by waterfowl, marsh 

birds and muskrats. The dike you 

are on separates the freshwater 

impoundments on your right from 

the tidal, brackish marsh and 

Blackwater River on your left. 

The impoundments are drained 

in the summer to allow growth 

of moist soil plants, and in some 

impoundments, the planting of crops 

such as Japanese millet or milo. The 

impoundments are then flooded in 

the fall mainly through rainfall. 

The water levels 

are carefully 

controlled 

so that the 

impoundments 

provide abundant 

high energy and 

protein foods as well 

as resting sites for the 

waterfowl and other 

migratory birds that 

depend on the refuge 

from fall to spring. 

In the late winter, prescribed 

burns are done in the marsh to 

remove dead vegetation. This helps 

to promote new, vigorous spring 

growth of the Olney three-square 

(Scirpus americanus) and other 

marsh vegetation that is eaten by 

waterfowl and muskrats. These 

carefully planned burns also prevent 

the buildup of dried vegetation that 

can cause extremely hazardous and 

volatile conditions that fuel wildfires. 

During the summer, egrets, herons 

and other water birds feed on fish 

and crustaceans of the brackish 

marsh. They also eat frogs and 

snakes found in the fresh waters of 

the impoundments. Turtles are often 

seen sunning themselves on the logs. 

Approximately 45 species of reptiles 

and amphibians are found on the 

refuge. 

9. Muskrat and 

Nutria

Muskrats, sometimes observed 

swimming in the water, not only feed 

on the marsh vegetation, but also 

use it to build dome shaped homes 

called lodges. These can readily be 

seen after prescribed burning of the 

marsh, but are hard to find in the 

summer when the marsh vegetation 

grows higher than the lodges. The 

large rodents reproduce very rapidly. 
Blackwater is one of nearly 550 

refuges in the National Wildlife 

Refuge System administered by 

the U.S. Fish and Wildlife Service. 

The National Wildlife Refuge 

System is a network of lands and 

waters managed specifically for the 

protection of wildlife and wildlife 

habitat and represents the most 

comprehensive wildlife management 

program in the world. Units of the 

system stretch across the United 

States from northern Alaska to 

the Florida Keys and include small 

islands in the Caribbean and South 

Pacific. The character of refuges is 

as diverse as the nation itself. The 

Service also manages National Fish 

Hatcheries and provides Federal 

leadership in habitat protection, 

fish and wildlife research, technical 

assistance and the conservation and 

protection of migratory birds, certain 

marine mammals, and threatened 

and endangered species. 

Illustrations © Alex Briggs 

10. Osprey

11. Bald Eagle

U.S. Fish and 

Wildlife Service

The young are considered adults in 

approximately two months. Trapping 

by permit is used to control the 

muskrat population and prevent 

damage to marsh vegetation from 

overgrazing. 

The nutria, a much larger South 

American rodent, was introduced 

in this area in the 1940s for their 

fur. Nutria burrow into the marsh 

to feed on the roots of marsh plants. 

They reproduce more rapidly than 

the muskrat, do not have any natural 

predators, and there is little demand 

for their fur. Nutria are partially 

responsible for the loss of thousands 

of acres of wetlands over the past 

several decades. An effort to remove 

nutria from the area was started in 

2002, and today they are rarely seen 

on the refuge. 

Ahead on your left you will notice 

sections of marsh outlined with 

stakes and fencing. These are 

experimental marsh restoration 

plots that were planted in 2003 to 

test the feasibility of rebuilding some 

of the marsh that has been lost to the 

nutria. A larger marsh restoration 

project is planned for the future. 

The nesting platform to your right 

helps to compensate for the scarcity 

of suitable tall trees near the water 

on which osprey would normally 

build their nests. The shallow waters 

of the Blackwater River provide 

excellent fishing habitat for this 

“fish hawk.”

Osprey populations declined in the 

mid-1900s as a result of pesticide 

use and increased human activity. 

The pesticide, DDT, which caused 

the eggs that were laid by these 

birds to be too thin and soft to hatch, 

was banned in the United States in 

1972. This legislation and various 

management techniques have helped 

raise the population of the osprey, as 

well as other raptors such as the bald 

eagle and the peregrine falcon.

The dead tree “snags” to your 

left are a favorite resting spot for 

the bald eagle, as well as hawks, 

vultures, herons and egrets. Bald 

eagles prefer the tall loblolly 

pines isolated near the water for 

nesting and roosting. Areas on 

BlackwaterNational Wildlife Refuge 

where eagles nest are protected 

from human disturbance to prevent 

nest abandonment. The area in and 

around the refuge boasts the largest 

concentration of nesting eagles on 

the east coast outside of Florida. The 

eagle population increases during the 

winter when migrant eagles visit the 

area.