At a Glance

Hours: Grounds open sunrise to sunset, all year. Visitor Center open daily 10 am-5 pm from May thr Oct; but only Sat and Sun 10 am-4 pm Nov thr April.

Cost: Free.

Tips: Don’t miss the observation towers along the Driving Tour; walk along the bridge over the Mattaponi.

Best Seasons: Fall, Winter, Spring.

Local MOS Chapters: Patuxent Bird Club

Merkle Natural Resources Management Area

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

Merkle Natural Resources Management Area (NRMA) adjoins the Jug Bay Natural Area of Patuxent River Park just to the north. The NRMA’s 1,670 acres are under the management of the MD Department of Natural Resources. Formerly known as Merkle  Wildlife Sanctuary, the property has been re-classified as an NRMA.

The NRMA provides sweeping views of the Patuxent River, flowing past a landscape composed of agricultural fields and woodlands. The main entrance lane to the NRMA, accessed from Fenno Road, passes through mature hardwood forest before making a wide loop around a grassy field in front of the Frank Oslislo Visitor Center. Several foot trails pass along field edges and through woodland habitat. 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 can also be viewed from the deck.

Merkle NRMA can also be accessed from the adjoining Jug Bay Natural Area through the 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. The Driving Tour crosses 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 side road from the Driving Tour leads to the White Oak Landing canoe camp and launch area that provides excellent views of the river and marshes; watch for the sign for White Oak Landing on the left as you drive south on the one-way road. 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 Visitor’s 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. 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 Wildlife 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.


Over 220 species have been reported on eBird from Merkle Wildlife Sanctuary. 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 feeder area in winter.

At the end of the Mounds Trail, there has been a small 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.

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


Free, at Visitor Center and at various pullovers along the Driving Tour.

Special Features:

The Critical Area Driving Tour is good for those who are mobility-impaired. The Boardwalk is also handicapped-accessible. ◾ Fishing is available in the Sanctuary ponds from April through September. ◾ There are many exhibits in the Visitor Center, many of them kid-friendly, including a live animal exhibit with turtles, snakes, and an Eastern Screech-Owl and a book nook and animal tracks display with a sandbox for kids. There is also a large indoor viewing area, stocked with binoculars, scopes, and field guides, looking out over a bird feeding station. An outdoor deck also overlooks the feeder area. ◾ 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. A very informative video, produced by Maryland Public Television, is posted at; the video covers the history of Merkle and some of its features, including some beautiful aerial footage of the habitats. ◾ Parts of Merkle Wildlife Sanctuary are contained within the Jug Bay Important Bird Area as designated by National Audubon Society. ◾ Merkle Wildlife Sanctuary is one of the sites on the Patuxent Water Trail. ◾ Merkle Wildlife Sanctuary is a part of the Chesapeake Bay Gateways Network of the National Park Service. ◾ 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.


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 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 Rd. 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 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:

Patuxent River Park-Mount Calvert; Patuxent River Park-Jug Bay Natural Area; Milltown Landing WMA; Schoolhouse Pond.


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 FeeHiking/Walking TrailsLake, Pond, Bay, River, OceanNative Plant Garden or Meadow/Pollinator PlantsNature CenterObservation Platform or TowerParkingPets AllowedPicnic AreaRestroomsWheelchair Accessible FeaturesYoung People / Families


Chesapeake Bay Gateways NetworkDriving Tours (Birding By Car)Nature CentersThe Rivers of the Western ShoreWater Trails