Merkle Wildlife Sanctuary and Visitor's Center

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

Mataponi Creek 


The sanctuary was named after Edgar Merkle (1900-1984), an active conservationist who devoted much of his life to protecting and providing for wildlife. 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 2,000 geese may be present.

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


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 relatively flat 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, 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. 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.

Critical Area Driving Tour

Critical Area Driving TourThe 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. year round. The tour starts at Patuxent River Park and continues into Merkle Wildlife Sanctuary, crossing the Mattaponi Creek. To access the Critical Area Driving Tour: take Croom Airport Road, off Croom Road to Patuxent River Park. 

The 2-mile portion of the CADT located within Merkle Wildlife Sanctuary is open for hiking, biking, driving and horse back riding daily February 1st – September 30th.

The CADT is closed for hiking, biking, driving and horse back riding October 1st through January 31st, except Sundays, every year to provide a peaceful resting ground for migratory Canada Geese and other waterfowl.

Frank Oslislo Visitor Center

The Maryland Department of Natural Resources (DNR) has formally dedicated the Frank Oslislo Visitor 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.

Inside you will find:

  • Interpretive displays about the life history and management of the Canada Goose
  • Seasonal displays that encompass a variety of different environmental and wildlife topics, many of them kid friendly
  • Live animal exhibit in our discovery room with turtles, snakes, and an eastern screech owl
  • Book nook an an animal tracks display with a sandbox for kids
  • A large bird feeder viewing area, stocked with binoculars, scopes, and field I.D. books that proivde many hours of enjoyment
  • A history corner that highlights the War of 1812 on the Patuxent and local American Indian Heritage


The Frank Oslislo Visitor Center is currently open daily from 10 a.m. to 5 p.m. Beginning November 1st through May 1st, it will be open weekends only from 10 a.m. to 4 p.m. 

Nature hikes are provided weekly by Maryland Conservation Corps members and Maryland Park Service Rangers. See the DNR Calendar of Events for program details.


Merkle has five fishing ponds open to the public. Guy fishing in 1 of 5 fishing ponds open to public at Merkle State ParkThey are stocked with largemouth bass, bluegill, and various other species. Along with fishing, visitors can also enjoy wildlife observation and photography as these ponds provide prime habitat for a variety of wildlife. 

Merkle ponds open April 1st of every year and close October 1st of every year. Please obey park hours.

If you plan to fish, please sign-in at our sign-in box located outside of the visitor center. Please obey the special fishing guidelines specified on the sign-in sheet and make sure you have your fishing licenses. All vehicles should be parked at the visitor center. 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.​​

Online Services

Contact the Park Service

  • To Report Violations of Park Rules: 1-800-825-7275 (Park Watch) or 1-410-260-8888 (Communications Center)
  • General Information: 1-800-830-3974 (Annapolis Office)
  • Reservations: 1-888-432-2267
  • Email Us
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