At a Glance

Hours: Daylight hours year-round. The sanctuary is located in a residential area and care should be taken to avoid disturbing the neighbors. The eBird hotspot is labelled as “restricted access,” but this is because of the lack of parking. See parking instructions in main part of the description.

Cost: Free. Donations to the MOS Sanctuary Fund are appreciated.

Tips: Wear sturdy waterproof footwear as the ground will be muddy. ◾ No restrooms. ◾ No on-site parking. See parking instructions in main part of description.

Best Seasons: Spring and fall migration and early summer for breeding birds; mid-winter through early March for waterfowl.

Breeding Bird Atlas Block: Round Bay SW (Click on Atlas Block name for list of breeding birds from 1st and 2nd Atlases). Read about the MD & DC Breeding Bird Atlases.

Local MOS Chapter: Anne Arundel Bird Club

Mandares Creek MOS Sanctuary

North of private residence at 1308 River Road, Crownsville, MD 21032
Contact: MOS Sanctuary Chair

Note:  On April 12, 2023, a brush fire swept through Mandares Creek Sanctuary and wiped out the trees and marsh vegetation in most of the sanctuary. The fire occurred in the afternoon and was brought under control by the county fire department. Thankfully, none of the adjacent homes were damaged and no one was injured. We do not know how the fire started but the entire state has been under a high alert for fire because of dry conditions. In the aftermath of the fire, the MOS Sanctuary Committee is working with volunteers from the Anne Arundel Bird Club to monitor the re-growth of plants and the return of wildlife at the sanctuary. If you visit, please submit an eBird report.


Mandares Creek MOS Sanctuary, at just 8.2 acres, is the smallest property in the MOS sanctuary system. Though small, the sanctuary is located in an environmentally sensitive area of the Severn River Watershed in Anne Arundel County (see Special Designations and Conservation Value below), and represents MOS’s sole example of tidal marsh on the Western Shore of the Chesapeake Bay. The sanctuary lies on Maynadier Creek, which forms a cove off of Round Bay on the Severn River.

Although small, Mandares Creek MOS Sanctuary is part of a larger network of productive bird habitat. Across the road are large forested tracts, privately owned, that hold mixed deciduous and coniferous forest and a bog known as Deep Ditch Bog, part of the Maynadier Creek stream valley. Additionally, to the east and south there are several forested tracts, also privately owned, that are protected by conservation easement. Anne Arundel County owns the nearby Brewers Pond Natural Area, which has frontage on the Severn River. Because of all the protected lands in the area, Mandares Creek attracts more than its fair share of birds.

The property was donated to MOS in 1974 by Lt. Col. William G. Bodenstein and his wife, Otelia Francis Bodenstein. Lt. Col. Bodenstein served a term as the President of MOS from 1976 to 1978, and was greatly devoted to the MOS sanctuary program. The Bodensteins were both professional entomologists who worked at the Beltsville Agricultural Research Center.

Most of the Mandares Creek Sanctuary consists of tidal marsh, once a thriving cattail marsh but now consisting mostly of phragmites. Only a small portion of the sanctuary is walkable, namely a strip of deciduous woods and some understory hollies along River Road and a small wooded area near the north boundary of the sanctuary, adjacent to private residences. There are no established foot-trails, but the small non-marsh portion can be easily walked as it has no significant shrub layer. See the sanctuary map at link at left.

The outer reaches of the sanctuary on Maynadier Creek could productively be explored by kayak, canoe, or johnboat, but there is no put-in at the sanctuary, so launching would have to occur elsewhere. The nearest public launch site is downstream on the Severn at Jonas Green Park near the US Naval Academy. There is another launch site at Tucker Street in Annapolis, but this launch is open only to residents of the City of Annapolis. See the Maryland Department of Natural Resources’ interactive Maryland Public Water Access Map for details.


Over 55 species have been reported on eBird from the Mandares Creek Sanctuary hotspot, but the eBird record is preliminary, consisting of only 17 checklists as of fall 2021. MOS encourages birders to submit eBird checklists for Mandares Creek as often as possible, even if the checklist consists only of drive-by and incidental observations. Note that the eBird hotspot is labelled as “restricted access,” but that is only because of the lack of on-site parking (see parking instructions below).

A smattering of waterfowl occur fall through spring: Canada Geese, Wood Ducks, Lesser Scaup, Bufflehead, and Common Mergansers. Wood Ducks are confirmed breeders in this Atlas block, and so birders should be on the lookout for evidence of breeding at the Sanctuary.

Double-crested Cormorants and Great Blue Herons can be seen from the sanctuary. Among gulls, only Ringed-Bills and Laughing have been reported, but others (Herring, Great Black-backed) are likely, given eBird reports from other hotspots on the Severn River, such as Arlington Echo Outdoor Education Center. Terns might also be expected in the spring or summer. Tree Swallows and Purple Martins can be seen overhead or over the water. Other swallows would also be expected in this area but have not yet been reported from the Sanctuary; see list of expected birds below.

Ospreys are common from spring through fall, and Red-shouldered Hawks are also present. Bald Eagles have not yet been reported but are prevalent in the area, with a known nest nearby on Little Round Bay.

There is a good selection of woodpeckers: Yellow-bellied Sapsucker (winter); the much-prized Red-headed; Red-bellied; Downy; Hairy; and Northern Flicker. Pileated has not yet been reported but is likely to use the extensive forest across the road. Belted Kingfisher has been reported once but is probably regular.

Other species at Mandares Creek Sanctuary include small woodland or wetland birds: Eastern Phoebe, White-eyed Vireo, Yellow-throated Vireo, American Crow, Blue Jay, Carolina Chickadee, Tufted Titmouse, Ruby-crowned Kinglet (winter), White-breasted Nuthatch, Blue-Gray Gnatcatcher, Winter Wren (winter), Carolina Wren, Gray Catbird, Brown Thrasher, Northern Mockingbird, Eastern Bluebird, Hermit Thrush (winter), American Robin, House Finch, American Goldfinch, Fox Sparrow (winter), White-throated Sparrow (winter), Song Sparrow, Swamp Sparrow (fall migration), Eastern Towhee, Red-winged Blackbird, Common Grackle, Common Yellowthroat, Yellow-rumped Warbler (winter), Northern Cardinal, Blue Grosbeak and Indigo Bunting.

Based on eBird reports elsewhere along the Severn River as well as on the list of confirmed breeding birds from the First and Second Breeding Bird Atlases, some expected birds, possibly breeders, include American Black Duck; Yellow-billed Cuckoo; Chimney Swift; Ruby-throated Hummingbird; American Woodcock; Great Horned and Barred Owls; flycatchers including Great Crested, Eastern Kingbird, Eastern Wood-Pewee, and Acadian; Red-eyed Vireo; Fish Crow; Northern Rough-winged, Bank, and Barn Swallows; House Wren; Wood Thrush; Cedar Waxwing; Chipping Sparrow; Brown-headed Cowbird and both orioles (Baltimore and Orchard); locally breeding warblers such as Ovenbird, Worm-eating, Louisiana Waterthrush, Black-and-White, Kentucky, Hooded, American Redstart, Northern Parula, and Pine; both tanagers (Summer and Scarlet). Birders can consider this a target list of birds to watch for at the sanctuary.

Wheelchair Access:

There is no wheelchair access to the sanctuary. There is no safe area to pull over for roadside birding from a car, other than as a drive-by.

Pet Policy:

Pets are allowed on leash; be prepared to pick up after your pet.

Special Designations and Conservation Value:

The sanctuary lies within the Chesapeake Bay Critical Area and as such is protected under state law. You can read about the Chesapeake Bay Critical Area Commission, view an interactive map of the Critical Areas, and learn more through the Chesapeake Bay Foundation’s Citizen’s Guide to the Critical Area Program in Maryland.

The sanctuary is also part of a scenic buffer associated with the State’s designation of the Severn River as a Scenic River.

Mandares Creek MOS Sanctuary is protected in perpetuity by deed restrictions and through a conservation easement held by the Maryland Environmental Trust and the Severn River Land Trust. According to the easement, Mandares Creek Sanctuary “contains a substantial part of one of the largest and least disturbed tidal marshes in the entire Severn River Watershed (source: Gems of the Severn Part I and Gems of the Severn Part II, by the Severn River Commission, 1988). The property is also adjacent to a bog containing several rare bog plants, and the waterfront area has been identified as a Historic Waterfowl Staging and Concentration area by the Maryland Natural Heritage Program.”

The four acres of woodland at Mandares Creek MOS Sanctuary lie within an area classified by the Maryland Department of Natural Resources (DNR) as a Targeted Ecological Area. Targeted Ecological Areas are lands and watersheds identified by the DNR as the most ecologically valuable areas in the State; they are considered the “Best of the Best” and receive priority for conservation by the State. For more information on how DNR prioritizes land for conservation, see the DNR information sheet “GreenPrint Lands Are Important.”

The sanctuary is in an area categorized by DNR as a Green Infrastructure Wildlife Hub. Green Infrastructure identifies the State’s remaining large blocks of forest and wetlands (hubs) and the habitat pathways (corridors) that connect them. For more information on how DNR prioritizes land for conservation, see the DNR information sheet “GreenPrint Lands Are Important.”

Most of the sanctuary lies with an area identified by DNR as important for Forest Interior Dwelling Species. The sanctuary is also in a Sensitive Species Project Review Area, meaning that any planned development or disruption of the habitat undergoes extra scrutiny by the state.

Most of the Mandares Creek Sanctuary is located in an area classified by MD DNR as Tier 2 – Extremely Significant for Biodiversity Conservation under their Bionet – Biological Diversity Conservation Network initiative; while the strip along the northern boundary, abutting the private residences, is classified as Tier 5 – Significant for Biodiversity Conservation.

MD DNR offers a Parcel Evaluation Tool that provides an analysis of conservation benefits for a particular parcel of land.   Using this tool, the Mandares Creek MOS Sanctuary scores

  • 5 stars out of 5 for providing “Habitat Connectivity.”
  • 5 stars out of 5 for providing “Rare Species and Wildlife Habitat.”
  • 2 stars out of 5 for “Support of Aquatic Life.”
  • 3 stars out of 5 for “Forests Important for Water Quality Protection”
  • 3 stars out of 5 for “Coastal Community Resilience”
  • 3 stars out of 5 for “Future Wetland Habitat”
  • 4 stars out of 5 for “Proximity to Other Protected Lands,” presenting conservation opportunities that contribute to landscape scale protection which is key for conserving healthy aquatic and terrestrial ecosystems.

The dollar valuation portion of the parcel evaluation tool shows that the ecosystem services provided by the Mandares Creek MOS Sanctuary are valued at $2,916.35 per acre per year, or $23,914.07 for the entire 8.2 acre tract.

Special Features:

The local chapter of the Maryland Ornithological Society is the Anne Arundel Bird Club, offering field trips and meetings with informative programs, all free and open to the public.


A short YouTube video, created by former MOS Sanctuary Committee Chair Dominic Nucifora, will take you on an armchair tour of Mandares Creek Sanctuary.


There is no on-site parking at the sanctuary, and it is not advisable to try to park on River Road, as it has no paved shoulders and cars tend to travel at an excessive speed. The owners of a sawmill located just north of the sanctuary, on the opposite side of the road, have been very kind in allowing us to park there. Be sure to ask permission at the office before you leave your car there.


Mandares Creek MOS Sanctuary is located on River Road in the Crownsville area of Anne Arundel County, northwest of Parole and Annapolis.

From the Annapolis area (including approaches from the Eastern Shore via the Chesapeake Bay Bridge): From US Route 50 near Annapolis, take Exit 23B for Crownsville, turning left at the traffic signal at the end of the ramp to go west on MD Route 450/West Street. In about 800 feet, Route 450 turns left, but do not turn – stay straight here to continue north on MD Route 178/Generals Highway. In 1.7 miles, bear right to go north on Old Generals Highway. In just 0.4 miles, turn right onto River Road. The Sanctuary will be on your right in 1.5 miles, south of the intersection with Maynadier Lane Stop at the sawmill on the left just past the Sanctuary and request permission to park in their lot during your visit.

From the south: Use US Route 301 northbound or MD Route 2 northbound to reach US Route 50. Then follow directions above from the Annapolis area.

From Baltimore and points north: From the Baltimore Beltway, take Exit 4 for I-97 south. In 12.3 miles, take exit 5 for MD Route 178/Generals Highway, heading east toward Crownsville. In 1.2 miles, turn left to continue east on Herald Harbor Road. In 1.4 miles, turn right to go south on River Road. The sanctuary will be on your left in 0.6 miles, but before you get there, watch for the sawmill on your right and turn in there to request permission to park in their lot during your visit.

From the west: Use I-70 eastbound, US Route 40 eastbound, or other route to reach the Baltimore Beltway. Then follow directions above from Baltimore.

Nearby Sites:


Bottomland Deciduous Forested SwampFreshwater Marsh or FloodplainRivers & Streams

Features and Amenities:

BeginnersFree - No Entry Fee at Any TimePets Allowed


MOS Sanctuaries