Merkle Wildlife Sanctuary is the only wildlife sanctuary operated by the Maryland Department of Natural Resources. It is the wintering ground for several thousand Canada geese, the largest concentration on the western shore of the Chesapeake Bay.
Reminder: The Critical Area Driving Tour is closed to hikers, cyclist, and horse back riders from October 1st until December 31st.
The sanctuary was named after Edgar Merkle (1900-1984), an active conservationist who devoted much of his life to protecting and providing for wildlife. Many knew him as the founder of Merkle Press in Washington, D.C. (1936), and others knew him as the originator of a goose breeding plan to introduce Canada geese to the western shores of Maryland (1932). Starting with a handful of breeding pairs, a great deal of perseverance, and a habitat improvement plan in mind, Mr. Merkle eventually encouraged thousands of geese to visit the 400-acre Merkle farm to feed and rest. In 1970, the Merkles sold their land, including some donated parcles, to the state. With the acquisition of adjoining tracts, the wildlife refuge now encompasses 1,670 acres.
The geese arrive in mid-October and stay until late February or early March. About 100 geese stay year round. During the peak of the season, more than 5,000 geese may be present. Corn, millet and other crops favored by geese are grown for them, adding to the marsh and aquatic plants that flourish in the ponds and along the Patuxent River.
The sanctuary also offers habitats for a variety of birds and mammals. White tail deer are prominent at the sanctuary, especially during the winter. Red fox and skunk make their homes here at the sanctuary as well. In the summer, osprey nest close to the Visitor Center and hummingbirds, finches and purple martins are abundant. In the neighboring ponds, visitors are likely to see a great blue heron stalking its prey or the splash of a large mouth bass chasing after its dinner. You may also see a blue bird scurrying to find grass for its nest or baby wood ducks jumping from their nests for the first time.
Merkle Wildlife Sanctuary Trail Map
A new map of the trails at Merkle Wildlife Sanctuary can be downloaded for free from this website. Please make sure to read the printing instructions and information for how to download the file to cell phones. The map is in a PDF format that requires Adobe Reader. To get the free Adobe Reader go to Adobe.com.
- "Click" here to view the Merkle Wildlife Sanctuary Trail Map
- "Click" here to view the instructions for printing and downloading the Merkle Wildlife Sanctuary Trail Map
Please leave pets at home so that we may provide a restful habitat for wildlife of all kinds.
Horses are welcome at Merkle, but only on roadways and the Critical Area Driving Tour (CADT), from January through September.
There are four hiking trails at Merkle that explore the upland forests and marshes of the Patuxent. Our trails are open to hikers only. Bikes and horses may visit nearby Rosaryville State Park. All trail distances are round-trip, measured from the Visitor Center (except Lookout Creek Trail).
- 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 oval shaped, green 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 Paw Paw trail is blazed yellow.
- Poplar Springs Trail: This is a flat, wide trail that connects the forested areas on either side of Merkle Road. Named for the native poplar tree, this trail passes Merkle Wildlife Sanctuary’s champion Yellow Poplar which measures 154 feet tall and over 15 feet in circumference. Poplar Springs is 3.0 miles long and is rated easy to moderate. This 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. It’s most unique features are the large, manmade 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. Mounds trail is blazed blue.
- Lookout Creek Trail: This flat, figure-eight shaped trail 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 .72 miles and can only be accessed from the Critical Area Driving Tour (CADT). Lookout Creek Trail is blazed white.
The 4.3 mile Chesapeake Bay Critical Area Driving Tour (CADT) is open for self-guided driving tours on Sundays from 10 a.m.-3 p.m. throughout the year. The tour starts at Patuxent River Park. Take Croom Airport Road, off Croom Road (north of Merkle). The CADT travels across the Mattaponi Creek onto Merkle Wildlife Sanctuary. This is a one way drive.
The CADT is open for hiking, biking, and horse back riding daily January 1st – September 30th.
The CADT is closed for hiking, biking, and horse back riding October 1st through December 31st every year to provide a peaceful resting ground for migratory Canada Geese and other waterfowl.
Frank Oslislo Visitors Center
The center is a handsome building set atop a rise overlooking several ponds and many acres of fields and woods sloping down to the Patuxent River. Its two-story wall of windows and circular balconies face a spectacular view.
Inside you will find exhibits about the life history and management of the Canada Goose along with seasonal displays that encompass a variety of different environmental and wildlife topics, many of them kid friendly. Check back annually to see our new displays. Children will also love our live animal exhibit in our discovery room, with turtles, snakes, and toads. A kids coloring table, book nook, and animal tracks sand box are also popular features for kids. For those of you who love bird watching, there is a large bird feeder viewing area, stocked with binoculars and scopes that provide many hours of enjoyment.
Nature Hikes are provided weekly by Maryland Conservation Corps (MCC) members and Maryland Park Service rangers. See the Maryland Department of Natural Resources Calendar of Events for program details.
The Maryland Department of Natural Resources (DNR) has formally dedicated the Frank Oslislo Visitors Center at Merkle Wildlife Sanctuary in honor of the 32-year employee, who was instrumental in developing Management Plans that, to this day, guide the management for many DNR properties. Oslislo, who passed away in October of 2008 from cancer, was the face of DNR before the Board of Public Works (BPW) and the Maryland General Assembly for many years. Read more about Frank Oslislo's dedication to preserving Maryland's natural resources.
The Frank Oslislo Visitor Center is open weekends from 10 a.m. to 4 p.m.
Merkle has five fishing ponds open to the public. Stocked are large mouth bass, blue gill, and various other species. They are prime habitat for wildlife, are great for wildlife observation and photography along with fishing.
Merkle ponds open April 1st of every year and close October 1st of every year. Please obey sanctuary hours.
If you plan to fish, please sign-in at our sign-in box located on the right as you walk up the steps to the visitor center. Please obey special fishing guide lines specified on the sign-in sheet and make sure you have your fishing licenses. All vehicles should be parked at the visitor center. You may then walk to the pond of your choice. Special parking arrangements can be made for those with disabilities who have an Access Maryland pass.
Since Merkle is a wildlife sanctuary, fishing is regulated to help us manage the fish populations in the pond. Be aware that only two fishing lines may be in a pond at a time. If you have two lines, you are the only one allowed to fish. If someone else has a line in, you may only fish with one fishing line.
Upper Marlboro is home to one of the most diverse bird populations in Maryland. Don’t forget to bring your binoculars!
There are several picnic tables located around the sanctuary. Please note we are a trash free park and that all trash you bring to park you take home with you. Grills and open fires are not permitted at the sanctuary.
Hours of Operation
Sanctuary Grounds: Open Sunrise to Sunset
Frank Oslislo Visitor Center: The visitor center hours have changed. Open weekends only from 10 a.m.- 4 p.m. until further notice.
Critical Area Driving Tour: The CADT is open for driving on Sundays from 10 a.m. to 3 p.m. The CADT is open for hiking, biking, and horse back riding daily January – September. The CADT is closed for hiking, biking, and horse back riding October 1st through December 31st every year to provide a peaceful resting ground for migratory Canada Geese and other waterfowl.
Merkle Wildlife Sanctuary is located in Prince George's County.
- From Annapolis: 34.5 miles
Follow Route 50 West to Route 301 South. Continue on Route 301 South to Croom Road (Route 382). Turn left on Croom Road. Continue on Croom Road and turn left on St. Thomas Church Road, which will turn into Fenno Road. Continue until you see Sanctuary signs on your left at Merkle Road.
- From Baltimore: 35.5 miles
Exit Beltway (I-695) at Route 3 South to Route 301 (joins at the junction with Route 50). Continue on Route 301 South to Croom Road (Route 382). Turn left on Croom Road. Continue on Croom Road and turn left on St. Thomas Church Road, which will turn into Fenno Road. Continue until you see sanctuary signs on your left at Merkle Road.
- From Washington, D.C.: 11.7 miles
From Beltway (I-495/95) follow to Exit 11 at Route 4 East (Pennsylvania Avenue) toward Upper Marlboro. Continue on Route 4 to Route 301 South. Continue on Route 301 South to Croom Road (Route 382). Turn left on Croom Road. Continue on Croom Road and turn left on St. Thomas Church Road, which will turn into Fenno Road. Continue until you see sanctuary signs on your left at Merkle Road.
Merkle Wildlife Sanctuary
11704 Fenno Road
Upper Marlboro, MD 20772
Link to Google Maps
Phone: (301) 888-1377 or (301) 888-1410
Hours of Operation
Sunrise to Sunset
Certain activities are permitted outside of the regular park hours (e.g. fishing, boat launch, hunting where permitted). Please check with the park before your visit if you plan to engage in an activity which requires you to be in the park before or after the posted hours.
Contact the Park Service
- Toll Free: 1-800-830-3974
- Reservations: 1-888-432-2267
- Park Watch: 1-800-825-7275
- Email Us