At a Glance

Hours: Grounds are open from dawn to dusk, year-round; house open weekends Apr – Oct, Sat: 10:00 AM —  4:00 PM & Sun: 12:00 PM —  4:00 PM; closed weekdays.

Cost: Free.

Tips: If mobility-impaired, you can stay in the car and get good views of the river from a pull-off on the entrance road. Note: no restrooms on site. Nearest restrooms are at Patuxent River Park – Jug Bay Natural Area Visitor Center.

Best Seasons: Year-round.

Local MOS Chapters: Patuxent Bird Club

Patuxent River Park – Mt. Calvert Historical & Archaeological Park

16801 Mount Calvert Road, Upper Marlboro, MD 20772
(301) 627-1286

Mount Calvert Historical and Archaeological Park is part of the Patuxent River Park  and is managed by the Maryland-National Capital Park and Planning Commission. Mount Calvert is worth a visit for the spectacular view of the Patuxent River and its marshes at the north end of Jug Bay.  During most of the year, these marshes are filled with birds.  The marshes hold one of the largest stands of native wild rice on the East Coast; the wild rice is an important food for birds migrating through the area in the fall, and also offers nesting habitat for a number of marsh birds.

The eBird list for Mount Calvert has over 190 species, quite a diversity for a relatively small site – only about 30 acres in the main parcel near the house (not including marshes), plus another 80 acres of woods and marsh near Charles Branch. The compact size of the site means it can be thoroughly birded in an hour or two.

Mount Calvert was an important tobacco plantation in the 18th and 19th centuries, and was the site of the first county seat of Prince George’s County, from 1696 to 1721. The existing brick plantation house was built in 1796, with additional construction in 1809. Today the house is a museum with exhibits concerning the intertwined local history of tobacco growing, slavery, and pre-colonial Native American settlements. The area also had significant activity in the War of 1812, when invading British warships came up the river, and this is documented in outdoor placards near the house. There are active archaeological excavations underway to uncover more of the history of the site.

The house sits on a knoll that provides a panoramic view of the Patuxent River and the head of Jug Bay. A gravel road near the house leads down to the water’s edge, where a wharf formerly provided a loading area for tobacco being shipped out by barge. The wharf area is now a soft launch for canoes and kayaks, and a short floating pier provides a good vantage point for birding.

Near the house, large fields are planted with agricultural crops that vary from year to year. The crop fields provide good habitat for field birds.

Near the entrance gate, a foot trail runs along the bed of the historic railroad that ran from Washington, DC to Chesapeake Beach in Calvert County, 1900 to 1935. One can walk along the trail from the entrance gate north to the Charles Branch of the Patuxent River, a one-way distance of about a half-mile. The trail passes between hedgerows and woods edges that offer excellent habitat for songbirds. The freshwater marsh at the Charles Branch may have waterfowl in winter and shorebirds, particularly snipe and yellowlegs, in migration.


Over 190 species have been reported on eBird from Mt. Calvert. The Patuxent River Park’s official bird checklist for the Jug Bay area of the Patuxent River lists 305 species.

Soras are a specialty during fall migration, when they come in to feed on wild rice in the marshes; walk down to the canoe/kayak launch to listen for them.  Virginia Rail is also possible. Also check here for Marsh Wrens, Least Bitterns, terns, herons and egrets in spring and summer. In winter, stand on the knoll near the house and parking area to scope the waters of the river for waterfowl and gulls.  In late summer, use that vantage point to look for terns. Check the agricultural fields in winter for pipits and sparrows, including Savannah and White-crowned. Grasshopper Sparrows may be present in summer, and Swamp Sparrows use the marshes in winter. American Tree Sparrows use the hedgerows of the rail-trail some winters. All year, walk the trail along the old railway bed to look for songbirds, plus waterfowl and shorebirds in the Charles Branch marsh.


Free parking in grassy area (signed) near the house; also at the start of the rail-trail near the entrance gate. Do not park in crop fields or in the signed “No Mow” area. Do not park in front of the private residences near the entrance gate.

Special Features:

Archaeological excavations open for visits on most Saturdays from April through October. House has exhibits focusing on local history of tobacco plantations, slavery, Native Americans. Outdoor placards detail events of War of 1812. ▪️ Jug Bay is a component of the Chesapeake Bay National Estuarine Research Reserve. ▪️ Patuxent River Park is a site on the Chesapeake Bay Gateways Network, a partnership led by the National Park Service. ▪️ The Jug Bay area has been designated an Important Bird Area by the National Audubon Society. ▪️ Mount Calvert is one of the sites on the Patuxent Water Trail. ◾ 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 on Croom Road for about 2.3 miles; then turn left onto Mount Calvert Spur Road. In 900 feet, at the T-intersection, turn left again (east), onto Mount Calvert Road. The entrance gate to Mount Calvert is straight ahead at the end of the road (about 2.8 miles).

Nearby Sites:

Patuxent River Park – Jug Bay Natural Area; Jug Bay Wetlands Sanctuary (Anne Arundel County); Merkle NRMA; Milltown Landing WMASchoolhouse Pond.


Bottomland DeciduousHedgerowsUpland Deciduous Lawn, Ballfields, Golf Course Agricultural Crop Fields or Fallow FieldsOld Fields, Shrubby Meadows Forested SwampFreshwater Marsh or FloodplainMud Flats (Tidal or Non-Tidal)Rivers & Streams


BeginnersHabitat Restoration ProjectHiking/Walking TrailsHistorical FeaturesLake, Pond, Bay, River, OceanNative Plant Garden or Meadow/Pollinator PlantsObservation Platform or TowerParkingPets AllowedPicnic AreaVisitor Center, Interpretive Displays, Exhibits


Audubon Important Bird AreasChesapeake Bay Gateways NetworkHistorical SitesState Natural Areas & WildlandsThe Rivers of the Western ShoreWater Trails