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. ■   There is a portable restroom in the parking area and at the White Oak canoe camp.

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.

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.

Hours:

Grounds open sunrise to sunset

Frank Oslislo Visitor Center: Closed till Further Notice

As the wintering ground for the largest concentration of Canada geese on the Chesapeake Bay's western shore, Merkle is one of Maryland's most unique Natural Resource Management Area.

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.

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.

Paw Paw Trail

This is a flat, family friendly trail that weaves past streams and ponds and through forests and fields. Look out for paw paw trees along the trail that grow green, oval shaped fruits. Paw paws are the largest fruit native to Maryland and were a favorite dessert of President George Washington. This trail is 1.2 miles long and is rated easy. The trail is blazed yellow.

Poplar Springs Trail

This is a 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. Poplar Springs is 3.0 miles long and is rated easy/moderate. The trail is blazed red.

Mounds Trail

This is a hilly trail that follows along the top of a ravine and offers views of Lookout Creek. Its 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. This trail is 2.3 miles long and rated moderate. The Mounds Trail is blazed blue.

Lookout Creek Trail Named for Lookout Creek which feeds into the Patuxent River​, this flat, figure-eight shaped trail winds through forests and wetlands. Hikers will enjoy a beautiful view of the water and encounter various species of waterfowl and wetland vegetation. This trail is .72 miles and can only be accessed from the Critical Area Driving Tour (CADT). Lookout Creek Trail is blazed white.