Mashomack

Mashomack is open from dawn to dusk, seven days a week. During or following severe weather we may need to close unexpectedly. If the gate is closed, the preserve is closed. Please do not enter the grounds.

Here are some things to keep in mind: 

• Trails open dawn to dusk, seven days a week.
• Visitor Center Bathrooms open 8 a.m. to 4 p.m., seven days a week.
• Visitor Center Exhibits open 10 a.m. to 3 p.m., Thursday thru Saturday.
• Mashomack trails are open weekends only for the month of January.

Birds: Since 1980, more than 200 species of birds, including 79 nesting species, have been recorded at Mashomack Preserve. No matter what season or time of day you decide to visit, you’re sure to witness something amazing.

In the summer, look for towhees in the understory, scarlet tanagers and Baltimore orioles in the canopy, and red-tailed hawks along the edges of open, grassy meadows. In the fall, Mashomack serves as a popular migration stopover point for many birds. Black duck, Canada geese, hooded mergansers and other waterfowl winter in our salt marshes and surrounding bays.

Together with nearby Gardiners Island, Mashomack also supports one of the East Coast's largest concentrations of nesting osprey. The coastal areas and salt marshes are great places to view other birds as well, such as great blue herons, great and snowy egrets, green herons and black-crowned night herons.

Animals: Mashomack’s many habitats harbor a plethora of animal life. Painted turtles basking on a sunny log or spring peepers chirping their amorous intentions may be found in the freshwater wetlands, along with a shy muskrat. A summer’s day is alive with the sights and sounds of insects: monarch and swallowtail butterflies, dazzling dragonflies or buzzing cicadas. The common grey squirrel and cheeky chipmunk are almost always sighted, while occasional reports of a black racer or other harmless snakes also surface.

Salt marshes shelter a multitude of marine species including clams, blue claw crabs and a variety of fishes. The night brings little brown bats and moths, including the beautiful luna and rare imperial. Other nocturnal creatures may leave footprints, scat or rubbings to signal that a fox, raccoon or deer passed by.

Plants: The only natural community of its kind on Long Island, the Pine Swamp Complex is comprised of plants rooted in a floating mat of sphagnum moss. Probes have found organic accumulations 10 feet thick dated to be 3,900 years old. Fringed by water willows and a diverse shrub layer including swamp azalea, highbush blueberry, white alder, winterberry and mountain holly, the swamp also includes a stand of white pines that shelter two state-protected orchids—the whorled pogonia and the pink lady slipper. The Usnea lichen grows on shrubs and trees here, attracting ruby-throated hummingbirds, which use the lichen in their nests.

In accordance with the Department of Justice’s amended regulation implementing Title III of the 1990 Americans with Disabilities Act (ADA) regarding Other Power-Driven Mobility Devices, Mashomack has completed an assessment of our public areas and trails. While some types of OPDMDs can be accommodated, there are necessary restrictions on their use.

• Visitor Center: The Harman Hawkins Visitor Center at Mashomack was updated in 2004 to provide universal access to all public spaces. The main entrance features direct access from the parking area trail to the front porch. The relatively open space floor plan includes ~36” doorways, and displays are built for comfortable viewing from wheelchairs. The two public toilets are both accessible (wide doors, large area for wheelchairs, comfort-height commodes and grab bars). An ADA-compliant ramp leads from the front porch to the patio and trail head area. The Education Building is also accessible via a ramp.
• Picnic Area: As of spring 2021, new ADA-compliant picnic tables are available. Please remember to pack it in and pack it out (don’t leave trash behind).
• Boardwalk: The boardwalk at the entrance of Mashomack is fully compliant with the forest service recommendations and standards for accessibility.
• Joan C. Coles Trail: First opened in 2000, The Joan C. Coles Memorial Trail (roughly 1 mile in-and-out) is a barrier-free trail that provides scenic views of the preserve’s stunning natural features, amenable to wheelchairs and strollers.
• Manor House: Mashomack’s Manor House is a fully restored 19^th century summer estate, now used as a conference facility and for local community gatherings. It is fully accessible with an exterior ramp for entering and exiting, an accessible restroom and an elevator to the second floor to an accessible bedroom and bathroom.
• Clean Water Septic Upgrades: In Suffolk County, where Mashomack is located, nitrogen pollution from more than 370,000 septic systems and cesspools is the primary cause of harmful algal blooms (HABs), including red tides and blue-green algae outbreaks. The septic systems at The Nature Conservancy’s 2,350-acre preserve were part of the problem. Like virtually all of the septic systems on Long Island, Mashomack’s were never designed to treat nitrogen in wastewater. Just like in other places, these cesspools and septic systems were installed long before we understood the impact conventional systems could have on our ecosystems. In fact, the nitrogen pollution and HABs that result are linked to beach closures, shellfish die-offs and the deterioration of estuaries and coastal marshes, which serve as nurseries and habitat for 65% of our recreational and commercial fish species and help buffer increasingly dangerous and more frequent ocean storms. The Nature Conservancy has been a leader in policy solutions to the problem of nitrogen pollution from septic systems. Now, instead of contributing to the problem, Mashomack is modeling the solution, with four new, clean-water septic systems that treat wastewater nitrogen onsite.

Explore the many trails and wonders of Mashomack.

Trail map here.

Mashomack’s Environmental Explorers program, running annually for more than 30 years, is a summer favorite on Shelter Island. Kids ages 8-12 spend four days exploring our changing environment while learning all about nature in a hands-on, fun-filled way through hikes, paddles and adventures galore. Mashomack’s amazing fields, forests and waters also provide inspiration for participants to become environmentally conscientious citizens. 

Check out nature.org/nyevents for more. 

Check out our 2025 Summer Programs here.