At a Glance

Hours: Grounds open sunrise to sunset, all year. Visitor Center open Saturday and Sunday, 10 am-4 pm.

Cost: Free.

Tips: Bring a scope. ■  If planning to hike any of the trails, wear sturdy waterproof hiking boots and consider carrying a hiking stick as there are some steep sections. ■   Restrooms are located in the Visitor Center and there is a portable restroom in the parking area and at the White Oak canoe camp.

Best Seasons: Fall, winter, spring.

Breeding Bird Atlas Blocks: Lower Marlboro NE, Lower Marlboro NW

Local MOS Chapter: Patuxent Bird Club

Merkle Natural Resources Management Area

11704 Fenno Road, Upper Marlboro, MD 20772
(301) 888-1377 (weekends only)
301-888-1410 (weekdays)

Note: As of September 2021, the Visitor Center is closed until further notice.

Merkle Natural Resources Management Area (formerly Merkle Wildlife Sanctuary) is truly one of the birding gems of Prince George’s County. It is located on the Patuxent River in the southern part of the county, adjoining the Jug Bay Natural Area of Patuxent River Park just to the north. See the overview map of Jug Bay area parks at the link at left. Merkle’s 1,670 acres are under the management of the MD Department of Natural Resources, protecting the rich habitats of the Patuxent River marshes.

Merkle provides sweeping views of the Patuxent River, which flows past a landscape composed of agricultural fields and woodlands. The main entrance lane to Merkle, accessed from Fenno Road, passes through mature hardwood forest of beech, yellow poplar, and oak, before making a wide loop around a grassy field in front of the Frank Oslislo Visitor Center. A deck at the Visitor Center provides an overlook for several freshwater ponds that may hold waterfowl, shorebirds, or waders, depending on season and water levels. A bird feeding station and pollinator garden can also be viewed from the deck. There are several picnic tables and benches near the Visitor Center.

In addition to the entrance from Fenno Road, Merkle NRMA can also be accessed from the adjoining Jug Bay Natural Area through the spectacular Chesapeake Bay Critical Area Driving Tour, a 4.3-mile route, mostly one-way, that starts at Selby’s Landing at the end of Croom Airport Road in Patuxent River Park. The Driving Tour heads south, crossing Mattaponi Creek and its extensive freshwater marsh along a specially engineered wooden trestle bridge that allows free flow of the underlying water. One can stop at a wooden observation platform on the bridge, providing an overlook of the Mattaponi Creek and marsh, and then a little further on is a tall metal observation tower that gives wide views of the Patuxent River.

A short dirt side road leads north from the Driving Tour to the White Oak Landing canoe camp and launch area (a stop on the 80-mile-long Patuxent Water Trail) that provides excellent views of the marshes at the junction of the Mattaponi Creek with the Patuxent River; watch for the sign for White Oak Landing on the left as you drive south on the one-way road. White Oak Landing is great place to check for rails and other marsh dwellers. A short distance past the turn for White Oak Landing, a metal gate on the left marks the start of a short trail to a tall metal observation tower that provides an expansive view of the Patuxent River. There is parking for one or two cars on the right, just past the metal gate. During the winter, waterfowl may be spread out on the river as far as the eye can see, so carry your scope with you when you climb the tower.

The Driving Tour continues through fields at Merkle, some planted in crops and some with mowed grass; the mix of crops and grass changes from year to year. Within Merkle, there is a short two-way road near the Visitors Center that allows access to the part of the Driving Tour that loops through Merkle’s fields, without having to start at Selby’s Landing.

The entire Driving Tour (that is, from Selby’s Landing to Merkle) is open to cars only on Sundays from 10 am to 3 pm, year-round. But pedestrians and bikers may use the entire Driving Tour route daily, year-round. In addition, the 2-mile portion of the tour located within Merkle NRMA is open for driving, hiking, biking, and horseback riding daily, year-round, but the part of the tour that starts at Selby’s Landing is only open to cars on Sundays. Thus one must enter Merkle directly from Fenno Road on every day but Sunday.

There are also several hiking trails at Merkle that explore the upland forests, fields, and marshes. These trails are natural surface and are open to hikers only and closed to bikes and horses.

  • The Paw Paw Trail (1.2 miles round trip from Visitor Center; yellow-blazed) is a relatively flat, family-friendly trail that weaves past streams and ponds and through forests and fields. Keep an eye open for paw paw trees with their green,oval shaped fruits that ripen in fall. Paw paws are the largest fruit native to Maryland and are the larval host plant for Zebra Swallowtail butterflies. This trail offers good diversity of habitat, more so than the other trails.
  • The Poplar Springs Trail (2.6 miles round-trip from Visitor Center; red-blazed) is another relatively flat trail that connects the forested areas on either side of the main entrance road of Merkle. Named for the native poplar tree, this trail passes Merkle’s champion yellow poplar which measures 116 feet tall and nearly 17 feet in circumference. This trail goes into mature hardwoods and is a good place to look for Forest Interior Dwelling Species that favor old trees. Pileated Woodpeckers are easily found here.
  • The Mounds Trail (2.2 miles round-trip from Visitor Center; blue-blazed) is a hilly trail that follows the top (and sometimes sides!) of a ravine, offerings views of Lookout Creek. It’s most unique features are the large, man-made mounds of dirt known as “ha-has” that give the trail its name. While their exact purpose is unknown, they are believed to be either early boundary markers or defenses built by soldiers during the War of 1812. The Mounds Trail goes through a mix of old and second-growth woods and has the added benefit of looking out over productive wetlands. It’s a great place to look for flycatchers as well as Red-headed Woodpeckers. Note that the Mounds Trail is accessed as a branch off the Paw Paw Trail.
  • The Lookout Creek Trail (0.9 miles round-trip from the Catfish Pond parking area; white-blazed) is a flat, figure-eight shaped trail that winds through forests and wetlands. Named for Lookout Creek which feeds into the Patuxent River, hikers will get a beautiful view of the water and encounter various species of waterfowl and wetland vegetation. This trail is accessed from the Critical Area Driving Tour near Catfish Pond. Sometimes, much of the trail is under water, so be prepared. There is an opportunity for rails where the trail meets Lookout Creek, and the mature hardwoods along the trail harbor thrushes, warblers, and small woodland birds.
  • The Boardwalk Trail, also accessed from the Critical Area Driving Tour near Catfish Pond, is a short spur (410 feet long) that leads to a long pier that projects into the Patuxent River, a great place to spot Ospreys, Bald Eagles, herons and egrets. The Boardwalk Trail is wheelchair-accessible, although the first part is crushed stone and may be soft after rainy weathrer.
  • The Catfish Pond Trail is another short spur (450 feet long), directly across from the Boardwalk Trail, that leads to an overlook and blind at Catfish Pond, home to orioles, vireos, and Green Herons.

Over 230 species have been reported in total from the five eBird hotspots in Merkle NRMA:

During migration, there can be a good diversity of species along the Driving Tour and entrance road, and rarities do occur. The fields and hedgerows along the Driving Tour can be a good spot for migrating Bobolinks.

In winter, stop along the Critical Area Driving Tour at points where the Patuxent is visible to look for waterfowl on the river. After harvest, the agricultural fields may harbor plovers, sparrows, meadowlarks, American Pipits, and Horned Larks. White-crowned Sparrows are possible near the Visitor Center in winter. The large field in front of the Visitor Center may hold Eastern Meadowlarks.

At the end of the Mounds Trail, there has been a small breeding colony of Red-headed Woodpeckers. Other nesting birds include Wood Duck, Bald Eagle, Osprey, Eastern Screech-Owl, Pileated Woodpecker, Prairie Warbler, Yellow-throated Warbler, Yellow-breasted Chat, Eastern Meadowlark, Summer Tanager, and Blue Grosbeak.

In migration, shorebirds often visit the edges of the ponds visible from the deck of the Visitor Center. Shorebirds also use the mudflats visible at low tide along the shore of the Patuxent. The fields and hedgerows along the Driving Tour can be a good spot for migrating Bobolinks.

At any time of year, check the bird feeding station and native plant garden behind the Visitor Center for feeder birds.

Wheelchair Access:  

Merkle is a great place for those who are mobility impaired. Although the foot-trails are not wheelchair-accessible, there is excellent birding from or near the car on the Critical Area Driving Tour and the main entrance road. The Boardwalk is also rated as handicapped-accessible, although there is a short gravel path leading to the boardwalk.

Pet Policy: 

Pets are allowed on leash; pick up after your pet.

Special Designations:

Parts of Merkle NRMA are contained within the Jug Bay Important Bird Area as designated by National Audubon Society. ■ Merkle NRMA is a part of the Chesapeake Bay Gateways Network of the National Park Service.

Special Features:

Fishing is available in the Merkle ponds from April through September. ■ There are many exhibits in the Visitor Center, most of them kid-friendly, including a live animal exhibit with turtles, snakes, and an Eastern Screech-Owl; there is also a book nook and animal tracks display with a sandbox for kids. There is  a large indoor viewing area, stocked with binoculars, scopes, and field guides, with two-story-tall glass windows looking out over the bird feeding station, garden, and farther off, the wildlife ponds. ■  An outdoor deck at the Visitor Center overlooks the feeder area and ponds. ■ The History Corner at the Visitor Center highlights the War of 1812 on the Patuxent as well as local Native American heritage. ■ Nature hikes and children’s programs are provided by Maryland Conservation Corps members and Maryland Park Service Rangers. Call for program details and schedule.

The Patuxent Riverkeeper is a grass-roots organization dedicated to improving the health of the Patuxent River and connecting local communities to the river. The Riverkeeper organization has a headquarters building on the river at Nottingham, just south of Merkle NRMA. Patuxent Riverkeeper rents canoes and kayaks to members and to the public and hosts public events throughout the year. ■ Merkle NRMA is one of the sites on the Patuxent Water Trail.

Local MOS Chapter:

The local chapter of the Maryland Ornithological Society is the Patuxent Bird Club, which offers field trips and meetings with informative programs, all free and open to the public.


A brief informative video, produced by Maryland Public Television, covers the history of Merkle and some of its features, including beautiful aerial footage of the habitats.


Gravel lot at the Visitor Center and at various designated small lots along the Driving Tour.


From US Route 301 at MD Route 4 near Upper Marlboro: Go south on Route 301 for about 4.0 miles and turn left (southeast) onto MD Route 382/Croom Road. Proceed 4.0 miles to St. Thomas Church Road and turn left (east). In about 2.2 miles, the road makes a sharp right, turning south, and becomes Fenno Road. Continue on Fenno Road for a half-mile, to the entrance road to the Merkle NRMA on the left. Turn here and follow the entrance road through a hardwood forest, then continue as it winds past agricultural fields. Stay straight and go through a metal gate where the entrance road passes a private residence on the right. The entrance road will loop around a wide grassy field to bring you to the Visitor Center parking lot.

To enter Merkle NRMA via the Critical Area Driving Tour at Selby’s Landing: From MD Route 382/Croom Road, turn left (east) onto Croom Airport Road and follow to the end of the road at Selby’s Landing. The start of the Critical Area Driving Tour is adjacent to the boat launch at Selby’s Landing. The Driving Tour from Selby’s Landing is open to cars only on Sundays from 10 am until 3 pm, but can be walked or biked on any day or time.

Nearby Sites:

Prince George’s County: Beltsville Agricultural Research Center (restricted access) ■ Bladensburg Waterfront Park, Colmar Manor Community Park & Anacostia River Trail ■ Cedarville State ForestFort Foote Park ■ Fort Washington (National) Park ■ Fran Uhler Natural Area ■ Governor Bridge Natural Area ■ Greenbelt (National) Park ■  Greenbelt Lake Municipal Park (Buddy Attick Lake Park)Lake Artemesia Natural Area ■ Milltown Landing Natural Resources Management Area ■ Oxon Cove Park & Oxon Hill Farm ■  Patuxent Research Refuge – South Tract (National Wildlife Visitor Center)Patuxent River Park – Jug Bay Natural Area ■ Patuxent River Park – Mount Calvert Historical & Archaeological Park ■ Piscataway MOS Sanctuary ■Piscataway (National) Park: National Colonial Farm, Boardwalk, Wharf Road/Farmington Landing & Marshall Hall ■  Rocky Gorge Reservoir – Supplee Lane Recreation Area & Duckett DamRosaryville State Park ■ Schoolhouse Pond

Anne Arundel County: Davidsonville Park  ■ Jug Bay Wetlands Sanctuary

Charles County:  Cedarville State Forest  ■ Indian Creek Natural Resources Management Area  ■ Maxwell Hall Park


Bottomland DeciduousConifersHedgerowsUpland Deciduous Agricultural Crop Fields or Fallow FieldsHay Meadows, Pasture, Grass FieldOld Fields, Shrubby Meadows Forested SwampFreshwater Marsh or FloodplainFreshwater Pond, Lake, or ReservoirMud Flats (Tidal or Non-Tidal)Rivers & Streams


BeginnersBicycle Trails (Bikes may be prohibited on some trails)Bird Feeding StationBirding By CarBoardwalkBoat or Canoe/Kayak LaunchFishingFree - No Entry Fee at Any TimeHiking/Walking TrailsNative Plant Garden or Meadow/Pollinator PlantsNature Education ProgramsObservation Platform or TowerParkingPets AllowedPicnic AreaRestroomsWater ViewWheelchair Accessible FeaturesYoung People / Families


Chesapeake Bay Gateways NetworkDriving Tour (Roadside Birding)Nature CentersThe Rivers of the Western ShoreWater Trails