U.S. Fish & Wildlife Service

Great Meadows

National Wildlife

Refuge 

Concord Unit Trails
Great Meadows National Wildlife 

Refuge is one of more than 555 

refuges in the National Wildlife 

Refuge System which is 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 resource 

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 the refuges 

is as diverse as the nation itself.

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 

This goose, 

designed by J.N. 

Ding Darling, has 

become the symbol 

of the National 

Wildlife Refuge 

System.

Dike Trail 

(1.7 miles)

Welcome

Great blue heron

©Julien Beauregard

c
side of the lower pool separating the 

“meadow” from the river. Visitors 

can get an even closer look on our 

observation platform located midway 

on the dike.

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 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 

common sightings along the dike.

Common Sights 

and Sounds

Red-winged 

blackbird
Upper Pool

Black Duck

Creek Trail

(0.15 miles)

Boston & Maine R.R. (Abandoned)

now known as Bay Circuit Trail

Route 62

Monsen

Road

NORTH

Great Meadows 

National Wildlife 

Refuge

Concord Unit Trails
Marsh

River / Pond

Roads

Hiking Trails

Forest

Parking

Observation Tower

Restrooms

Observation Platform

Concord River

Lower Pool

Dike Trail

Edge Trail

(0.35 miles)

Timber Trail

(0.4 miles)

Dike Trail (1.3 miles)

(0.5 miles) 

Legend
Every summer the two 

impoundments are systematically 

drained into the Concord River, and 

then 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, visitors 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. 

Native Plants 

and their roles

Migratory 

Waterfowl and 

Water-level 

Management

Greater 

yellowlegs

Cattails
One of the biggest threats to the 

delicate ecosystem at Great Meadows 

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, biologists 

at Great Meadows have used the 

galerucella beetle (Galerucella 

pusilla), to control the growth of 

purple loosestrife. Native to the 

plant’s European habitat, the beetle 

feeds exclusively on the plant’s 

leaves, flowers, stems and roots. This 

natural method of controlling purple 

loosestrife has no adverse affects on 

the surrounding environment. 

Draining pools where water chestnut 

grows is another example of naturally 

controlling invasive species. The 

drained pools leave the water 

chestnut seeds (called caltrops) dry 

and infertile, allowing more beneficial, 

native plants to grow.

Each of these trails winds 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 these habitats 

their homes. 

We hope you have enjoyed the trails 

here at Great Meadows. Trails are 

open sunrise to sunset. Please come 

again soon!

Timber Trail 

(0.4 miles), 

Edge Trail 

(0.35 miles), and 

Black Duck Creek 

Trail (0.15 miles)

Invasive Plants

Purple loosestrife

Cardinal
Great Meadows National Wildlife Refuge

Mailing address:

73 Weir Hill Road

Sudbury, MA 01776

Physical address:

Monsen Road

Concord, MA 01742

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/

August 2012

printed on recycled paper with vegetable based inks

MARCH 3, 1849

U S. . DEPARTMENT OF THE INTERIOR