U.S. Fish & Wildlife Service

Great Meadows

National Wildlife

Refuge 

Concord Unit Trails

Great Meadows National Wildlife Refuge

73 Weir Hill Road

Sudbury, MA 01776

978/443 4661

978/443 2898 Fax

http://www.fws.gov/northeast/greatmeadows/

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/

July 2008

printed on recycled paper with vegetable based inks

MARCH 3, 1849

U S. . DEPARTMENT OF THE INTERIOR
Welcome to the Great Meadows 

National Wildlife Refuge – 

Concord Unit, which is considered 

one of the best inland birding 

sites in Massachusetts by noted 

ornithologists. This is a "Leave No 

Trace" area. The 2.7 miles of trails 

within the unit, including the Dike, 

Timber, Edge, and Black Duck Creek 

trails go through a variety of habitats 

that harbor various species including 

a variety of migratory waterfowl. 

The Dike Trail is part of the original 

250 acres donated by Samuel Hoar in 

1928 establishing the Great Meadows 

National Wildlife Refuge.

A good place to start your walk is 

from the observation tower beside 

the parking lot. From here you can 

best see the full extent of the upper 

pool to the left and the lower pool to 

the right, separated by the dike trail 

down the middle. We commonly refer 

to these pools as ‘impoundments’, 

indicating that these pools are manmade rather than natural ponds. 

The dike itself is also man-made. It 

runs between the upper and lower 

pools and turns to the east along one 

side of the lower pool separating the 

“meadow” from the river.

While walking along the Dike Trail, 

you can expect to see or hear several 

wildlife species, particularly birds. 

By far the most common and noisiest 

residents of this wetland are the redwinged blackbirds. These birds are 

easy to identify by their glossy black 

plumage and unmistakable vibrant 

orange and yellow shoulder-patches. 

Red-winged blackbirds nest early 

in the spring and summer, but are 

seen perched at the tops of the maple 

saplings and button bush along the 

fringes of the pools throughout the 

summer.

Great blue herons are another 

frequent visitor to the pools. These 

tall blue-grey birds are often seen 

standing in the shallows where they 

hunt fish and frogs, or flying slowly 

and gracefully over the water. 

Northern water snakes, leopard and 

bull frogs, marsh wrens, swallows, 

swifts, muskrats, and various colorful 

species of dragonflies are also very 

common sightings along the dike.

This goose, 

designed by J.N. 

Ding Darling, has 

become the symbol 

of the National 

Wildlife Refuge 

System.

Dike Trail 

(1.7 miles)

Common Sights 

and Sounds

Welcome

Great blue heron

©Julien Beauregard

Red-winged 

blackbird

c
Marsh

River / Pond

Roads

Hiking Trails

Forest

Parking

Observation Tower

Restrooms

Concord River

Upper Pool

Lower Pool

Dike Trail

Black Duck

Creek Trail

(0.15 miles)

Edge Trail

(0.35 miles)

Timber Trail

(0.4 miles)

Dike Trail

(1.7 miles) Boston & Maine R.R. (Abandoned)

now known as Bay Circuit Trail

Route 62

Monsen

Road

NORTH

Great Meadows Legend

National Wildlife 

Refuge

Concord Unit Trails
Every summer the two 

impoundments are systematically 

drained into the Concord River, 

they refill with river water later in 

the season. The resulting mud flats 

provide ideal feeding grounds for 

many species of shore birds and 

waterfowl that migrate in mid to 

late summer. On any given day in 

late July or August, you may see a 

wide range of birds including various 

species of sandpipers, killdeer, lesser 

and greater yellowlegs, and great 

egrets. Large numbers of great blue 

herons, ducks and Canada geese are 

also attracted to these muddy and 

nutrient-rich feeding grounds. 

Native plant species such as cattail, 

pickerelweed, wild iris, arrowhead, 

and American lotus are all emergent 

plants. Their stems are ridged so that 

they can extend beyond the surface of 

the water. 

Water lilies and duckweed are two 

of the many floating plants common 

in the upper and lower pools. Their 

leaves rest on the surface of the 

water to obtain the maximum amount 

of sunlight. These plants are either 

connected to the soil by long weak 

stems or float free on the surface. 

Many animals such as ducks and 

muskrats depend on these plants for 

food, and fish depend on them for 

shade and cover. 

One of the biggest threats to the 

delicate Great Meadows ecosystem is 

the spread of invasive exotic plants, 

primarily water-chestnut (Trapa 

natans L.) and purple loosestrife 

(Lythrum salicaria). These foreign 

‘invaders’ are very aggressive and 

out-compete native plants while 

providing little or no value to wildlife. 

There are numerous methods used 

to control or eliminate invasive 

species, including mechanical and 

manual harvesting, herbicides, 

biological controls, and water-level 

manipulation. For example, here 

at Great Meadows we have been 

controlling purple loosestrife with 

the galerucella beetle, (Galerucella 

pusilla), which is native to the 

plant’s natural European habitat and 

feeds exclusively on it. Therefore 

the purple loosestrife is controlled 

without any adverse effects on the 

rest of the environment. 

Draining the pools leaves the waterchestnut seeds (called caltrops) dry 

and infertile, allowing plants more 

beneficial to wildlife to grow. 

Each of these trails goes through 

woodland dominated in places by 

pines and oaks, and in other places 

by maples. Gray catbirds, eastern 

wood-pewees, cardinals, phoebes, and 

flycatchers are some of the various 

song birds which make woods like 

these their homes. 

We hope you have enjoyed 

the trails here at Great 

Meadows. Please come 

again soon!

Native Plants 

and their Roles Timber Trail 

(0.4 miles), 

Edge Trail 

(0.35 miles), and 

Black Duck Creek 

Trail (0.15 miles)

Migratory Invasive Plants

Waterfowl and 

Water-level 

Management

Greater 

yellowlegs

Purple loosestrife

Cardinal

Cattails