Blackwater NWR Wildlife Drive:
TAKE A DRIVE ON THE WILD SIDE!
Blackwater National Wildlife Refuge welcomes you to tour our
popular
Wildlife Drive by automobile, bicycle, or 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 refrain from feeding or
harassing the wildlife.
This guide points out some of Blackwater's wildlife
management programs.
It is keyed to observation points along the drive.
National Wildlife Refuges provide protection, food and cover
for wildlife
through specific land and water management programs. Although
the Refuge is managed primarily for migratory birds, 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.
1) MOIST SOIL VEGETATION
Freshwater habitat is scarce on Blackwater Refuge because of the
predominantly
brackish (mixture of salt and fresh water) conditions in the vicinity.
The
freshwater impoundment to your right (you are riding on the dike) was
constructed to add to the diversity of habitat for wildlife. The small
islands
provide cover and nesting habitat for waterfowl. 
Scan the shallow edges for dabbler ducks, such as mallards
and Northern
pintails; wading birds such as great blue herons and great egrets; and
shorebirds like yellowlegs and dunlins. In the summer the impoundments
are drained to encourage the germination of natural moist soil
vegetation,
such as wild millet, smartweed, and redroot cyprus which provide food
for waterfowl. The drained mudflats also provide good feeding
areas for shorebirds and other marsh and waterbirds.
In the fall, 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 and worms, available to the migratory
waterfowl.
The water to your left is part of the Little Blackwater
River.
The river is named Blackwater because of the dark color from tannin
picked up as it drains through peat soil in the marshes.
* At this point, if you would like to visit Observation Point
and
the Marsh Edge Trail, you may take the road to the left. To then rejoin
the Wildlife Drive, double back and continue from here. A self-guiding
leaflet for
interpreting the Marsh Edge Trail is available at the trail head.
2) BLUEBIRD BOX 
Bluebird nesting sites have decreased due to the use of steel
posts
for fencing instead of wooden posts. Therefore, artificial nesting
boxes are being
installed in open areas to allow the species to nest. If not occupied
by
bluebirds, the boxes are used by tree swallows and pesky house
sparrows. The tree
swallows and bluebirds consume a great deal of insects, especially
mosquitoes.
As many as 140 bluebirds have been fledged in one year from the
Refuge's boxes.
3) PROTHONOTARY WARBLER BOX
Prothonotary warblers are one of the two cavity nesting
warblers in
the United States. Other species of warblers build their nests in the
crotch
of small trees or shrubs, or on the ground. Prothonotarys prefer
natural cavities
(decaying snags) over water in swampy lowland forest or river bottom
woodlands
subject to flooding. They have problems finding suitable nest sites due
to human encroachment decreasing their habitat and the altered
landscape attracting new predators (raccoons, cowbirds, dogs, and
cats).
These warblers do not excavate their own nest sites so they
compete
with other hole nesters like Downy woodpeckers, Carolina chickadees,
and Carolina
wrens.
4) WOOD DUCK BOX
A few duck species use hollow trees for nesting. At
Blackwater,
wood ducks are the only ones found searching for suitable cavities in
the spring.
Timbering and land clearing for agriculture and development have
eliminated many of the mature forests which historically provided an
abundant number of trees with natural cavities. Therefore,
artificial nesting boxes are used effectively to replace diminishing
natural sites. When not occupied by wood ducks, the boxes may have
flickers, sparrow
hawks (kestrels), screech owls, or annoying starlings as tenants. The
Refuge maintains about 200 wood duck boxes which fledge an average of
600 wood ducks
a year.
Notice the cone shape structures below the boxes. This is
called
a "predator guard". The purpose is to keep out predators such as
raccoons
and snakes.
5) DELMARVA FOX SQUIRREL 
This woodland is managed to provide habitat for the
endangered Delmarva
fox squirrel which prefers a mature forest with little undergrowth.
These large squirrels are now unique to the Delmarva peninsula. They
have
become endangered, in part, due to the loss of suitable woodlands to
agriculture
and development for human use. Blackwater Refuge provides habitat
and protection to the largest remaining natural population of Delmarva
fox squirrels
in the country.
The Delmarva fox squirrel has a light, steel-gray coat and a
large fluffy
silvery tail with black edgings. The gray squirrel, which also inhabits
the Refuge, is smaller and has reddish or brown hair mixed in with the
gray coat.
Venturing further into fields to utilize agricultural products, the
Delmarva
fox squirrel feeds more on the ground than the gray squirrel.
* You will pass a parking area for one of the Refuge's
walking trails,
the Woods Trail. If you choose to hike the one-half mile woodland
trail,
you may want to apply insect repellant, as biting insects are abundant
from mid-April
through late September. In spring, these wet woods are alive with the
calls of mating tree frogs and toads, as well as numerous songbirds.
6) DEER
An important part of wildlife management at Blackwater is the
diversity
of the agricultural fields. More than 600 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" habitat where
forests, meadows, and croplands are close together.
A smaller, white-rumped sika (pronounced "see-kuh") deer,
actually an
oriental species of elk introduced to James Island in 1916, can also
been observed
at Blackwater. Abundant in the marshy areas, the sika are grazers
that feed on the marsh grasses, while the white-tailed deer are
browsers that feed on
the leaves, buds and twigs in the forested areas. Both species,
however,
utilize agricultural crops.
7) FRESH AND BRACKISH WATER MARSHES
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.
By carefully controlling water levels in the impoundments, natural
foods
and resting sites are made readily available to the wintering waterfowl
that depend on the Refuge through the winter.
In late winter the old growth in the marsh is burned under
carefully
monitored and prescribed conditions to promote new, vigorous spring
growth of the Olney three-square (Scirpus americanus) marsh vegetation
which is eaten by waterfowl, muskrats, and nutria. Burning also
prevents the
buildup of the dried vegetation which can cause extremely hazardous and
volatile fuel
conditions conducive to wildfires. 
During the summer, egrets, herons, and other water birds feed
on the
fish and crustacean of the brackish marsh. They also eat frogs and
snakes found in the impounded fresh waters. Turtles are
often seen sunning themselves on the logs. Approximately 45 species
of reptiles and amphibians are found on the Refuge.
8) MUSKRAT & 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 be readily seen after prescribed burning on your left, but
are hard
to find in the summer when the marsh vegetation grows higher than the
lodges.
The large rat-like rodents reproduce very rapidly. The young
are
considered adults in approximately two months. Trapping by permit is
utilized
to keep a healthy, controlled population.
The nutria, a much larger South American rodent, was
introduced in this
area in the 1940's for their fur. They eat much the same thing and
reproduce just as quickly as the muskrat. However, they do not have any
predators
except man. As a result, the large population is causing enormous
damage to the marsh.
Nutria trails through the mud may be observed at low tide.
9) OSPREY
The nesting platform to your left helps to compensate for the
scarcity
of suitable tall trees near the water on which osprey would normally
build
their nests. The shallow water surrounding the structure provides
excellent
fishing habitat for this "fish hawk."
The osprey, like the bald eagle and peregrine falcon, is
staging a comeback
after its decline due to pesticides and increased human activity. The
pesticide, DDT, which caused the eggs that were laid by these birds to
be too thin
and too soft to hatch, was banned in the United States in 1972. This
legislation
and other management techniques has helped raise the population levels
of all
three declining species.
10) BALD EAGLE 
The dead tree "snags" to your left are a favorite resting
spot for the
bald eagle as well as for hawks, vultures, herons, and egrets. Bald
eagles
prefer the tall loblolly pines isolated near the water for nesting and
roosting.
Areas on Blackwater Refuge where eagles like to nest are protected from
human encroachment.
The mere presence of people during nesting periods poses an added
threat
to the survival of this threatened symbol of our country. There are
approximately 60 eagles on the Refuge year round, with winter
populations often exceeding
100.
Another troubled species, the peregrine falcon, migrates
through the
Refuge in the fall and spring.
11) WATERFOWL
As you drive through the Refuge, you may notice that many of
the Canada
geese are wearing numbered neck collars. The collars (white on
migratory
geese, yellow on resident geese) are placed on Canada geese to obtain
information
on their movement and abundance in different areas. Many of the
waterfowl also wear numbered aluminum leg bands. 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 the Banding Laboratory in Laurel, Maryland. Bands are turned in by
hunters, or band numbers reported by other banding stations when these
birds are recaptured.
Information on migration and other aspects of their life history are
valuable for proper waterfowl management and determining ecologically
sound
hunting regulations.
Species of waterfowl using Blackwater include tundra
(whistling) swans,
Canada and snow geese, and more than 20 species of ducks.
For more information on Blackwater's Wildlife Drive, stop by
our Visitor
Center or call 410-228-2677. Drive Guide cassette tapes are available
through
the Friends of Blackwater Eagle's Nest Bookstore, which is located in
the Visitor Center.
