Canceled due to rain

This spring, we’re calling for volunteers to help plant over 400 native trees and shrubs. Be a part of a local effort to advance long-term goals for climate resilience and wildlife habitat restoration. This 45-acre forest restoration project in Community Park North is a joint initiative between the Municipality of Princeton and FOPOS, and it is funded in part by a Natural Climate Solutions grant from the NJDEP. From majestic canopy trees like white oak, red maple, and mockernut hickory to beautiful understory species such as redbud, flowering dogwood, and blackhaw viburnum, you’ll be helping rebuild a thriving, resilient ecosystem. No experience needed!

Volunteer with Friends of Princeton Open Space on Saturday, April 25th. There will be two volunteer sessions; the morning session is from 10 a.m. to 12 p.m., and the afternoon session is from 1 p.m. to 3 p.m. Come to one or both. Bring a friend and groups are welcome!

RESERVE YOUR SPOT

Celebrate Arbor Day with Friends of Princeton Open Space (FOPOS) and eco-artist Susan Hoenig on Friday, April 24th at 10 AM for a unique experience that blends art, nature, and conservation. Explore the beauty of American beech trees through a special indoor exhibition, then step outside for a guided nature walk to a beech grove in John Witherspoon Woods.

Along the way, learn how these remarkable trees support entire forest ecosystems and why they are increasingly at risk from Beech Leaf Disease (BLD), a fast-spreading threat that can weaken and kill infected trees. Hear directly from the FOPOS stewardship team about the work underway to protect these vital trees and forest ecosystem.

REGISTER TO VOLUNTEER

This spring, we’re calling for volunteers to help plant over 400 native trees and shrubs. Be a part of a local effort to advance long-term goals for climate resilience and wildlife habitat restoration. This 45-acre forest restoration project in Community Park North is a joint initiative between the Municipality of Princeton and FOPOS, and it is funded in part by a Natural Climate Solutions grant from the NJDEP. From majestic canopy trees like white oak, red maple, and mockernut hickory to beautiful understory species such as redbud, flowering dogwood, and blackhaw viburnum, you’ll be helping rebuild a thriving, resilient ecosystem. No experience needed!

Volunteer with Friends of Princeton Open Space on Tuesday, April 21st, from 1 p.m. to 3 p.m. Come to one or both. Bring a friend and groups are welcome!

RESERVE YOUR SPOT

A community hike to commemorate the induction of Witherspoon Woods and 153-Acre Wood Old-Growth Areas into the Old-Growth Forest Network.

Join us for a celebration of TWO Old-Growth Forests in Princeton. We will celebrate and initiate both forests and head on a hike into Witherspoon Woods to see the oldest and most enduring trees in the region.

We will walk through a portion of the 40-acre Witherspoon Woods, known for its stately red oak, tulip poplar, black cherry, red maple and white oak trees in a mixed hardwood forest. Taking the red trail requires sturdy shoes as the terrain is uneven with frequent rock outcrops along the natural surface path.

REGISTER FOR GARLIC MUSTARD FORAGING

Join the Friends of Princeton Open Space (FOPOS) and local experts Matt and Shannon for a garlic mustard foraging & land stewardship session at the Billy Johnson Mountain Lakes Nature Preserve in Princeton.

During this stewardship session, participants will learn about the origins of garlic mustard and how to identify this plant. We will spend some time removing this tasty, but invasive plant that threatens the biodiversity at the Preserve and crowds out native plants. Folks will be able to take their garlic mustard harvest home, as well as taste some homemade garlic mustard recipes (compliments of Matt and Shannon). Recipes will be shared with participants so that you too can make these unique and delicious recipes at home.

REGISTER TO VOLUNTEER

This spring, we’re calling for volunteers to help plant over 400 native trees and shrubs. Be a part of a local effort to advance long-term goals for climate resilience and wildlife habitat restoration. This 45-acre forest restoration project in Community Park North is a joint initiative between the Municipality of Princeton and FOPOS, and it is funded in part by a Natural Climate Solutions grant from the NJDEP. From majestic canopy trees like white oak, red maple, and mockernut hickory to beautiful understory species such as redbud, flowering dogwood, and blackhaw viburnum, you’ll be helping rebuild a thriving, resilient ecosystem. No experience needed!

Volunteer with Friends of Princeton Open Space on Saturday, April 18th. There will be two volunteer sessions; the morning session is from 10 a.m. to 12 p.m., and the afternoon session is from 1 p.m. to 3 p.m. Come to one or both. Bring a friend and groups are welcome!

REGISTER FOR NATURE JOURNALING MEETUP

We'll meet at Mountain Lakes House to draw from nature in a playful and non-judgmental setting. This meetup is FREE, although registration is required. The program is designed for adults and older teens. Younger participants (under 16) are welcome to join if accompanied by an adult.

What is a meetup and how is it different from a class? While a class is a structured learning environment with a defined curriculum, schedule, projects, and goals, a meetup is a gathering of people with shared interests who get together, often with a facilitator (in this case Eleni Litt).

Meetup Location: Mountain Lakes House

REGISTER FOR GARLIC MUSTARD FORAGING

Join the Friends of Princeton Open Space (FOPOS) and local experts Matt and Shannon for a garlic mustard foraging & land stewardship session at the Billy Johnson Mountain Lakes Nature Preserve in Princeton.

During this stewardship session, participants will learn about the origins of garlic mustard and how to identify this plant. We will spend some time removing this tasty, but invasive plant that threatens the biodiversity at the Preserve and crowds out native plants. Folks will be able to take their garlic mustard harvest home, as well as taste some homemade garlic mustard recipes (compliments of Matt and Shannon). Recipes will be shared with participants so that you too can make these unique and delicious recipes at home.

RESERVE YOUR SPOT

Join the Friends of Princeton Open Space (FOPOS) and expert birder Winnie Hughes Spar for a guided bird walk through the Billy Johnson Mountain Lakes Nature Preserve in Princeton, NJ. Together, we will observe Princeton's birds and learn about their fascinating habits!

Space is limited to 20 participants; be sure to sign up in advance. Please note that this event is geared towards adults.

REGISTER TO VOLUNTEER

Celebrate Earth Day all month long. Volunteer with Friends of Princeton Open Space at the Billy Johnson Mountain Lakes Nature Preserve. Join us as we work in our forest or riparian restoration project areas for critical tasks such as invasive species removal, spring planting, or installing cages around native plants to protect them from deer & beaver browse.

Volunteer with Friends of Princeton Open Space on Saturday, April 4th. There will be two volunteer sessions; the morning session is from 10 a.m. to 12 p.m., and the afternoon session is from 1 p.m. to 3 p.m. Come to one or both. Bring a friend and groups are welcome!

Join us at Mountain Lakes House to discuss "Walden" by Henry David Thoreau. The discussion will include an indoor study of plant pressings, with the opportunity to create one.

This series is presented in partnership with the Princeton Public Library and the Princeton Environmental Film Festival, and is dedicated to readings about conservation, stewardship, and our relationship with nature.

Sign up for this session via Princeton Public Library. You do not need to be a library cardholder to register.

RESERVE YOUR TICKET

Join the Friends of Princeton Open Space (FOPOS) and South Jersey Wildlife Tours for a guided Eastern Screech Owl Walk at dusk on Saturday, March 21st at 7:30pm.

Did you know that Eastern Screech Owls are one of the most common owl species in North America? Odds are you have one of these nocturnal neighbors mere miles (or less!) from your doorstep. During this experience, we will walk the trails at the Billy Johnson Mountain Lakes Nature Preserve in Princeton and listen and look for Eastern Screech Owls, learning much more about them along the way.

Space is limited to 20 participants; be sure to sign up in advance. Please note that this event is geared towards adults as it begins at 7:30 PM.

Please note that Screech Owl sightings are not guaranteed. We do have high owl activity at the preserve but you never know how the night will go.

REGISTER TO VOLUNTEER

Join FOPOS for a land stewardship volunteer session at the Billy Johnson Mountain Lakes Nature Preserve in Princeton on Saturday, March 21st. Volunteers will work under the guidance of the FOPOS stewardship staff to perform ecological restoration work and invasive plant removal.

We have two volunteer sessions: 10AM-12PM and 1PM-3PM. You are welcome to attend one or both sessions. Groups welcome!

REGISTER FOR THE MARCH NATURE WALK

Join us for our March Nature Walk through the trails of the Billy Johnson Mountain Lakes Nature Preserve. This guided walk offers a chance to explore the Preserve as spring emerges and the land wakes from its winter rest.

Meetup Location: Mountain Lakes House parking lot

REGISTER TO VOLUNTEER

Join FOPOS for a land stewardship volunteer session at the Billy Johnson Mountain Lakes Nature Preserve in Princeton on Wednesday, March 18th from 10AM-12PM. Volunteers will work under the guidance of the FOPOS stewardship staff to perform ecological restoration work and invasive plant removal.

REGISTER FOR NATURE JOURNALING MEETUP

We'll meet at Mountain Lakes House to draw from nature in a playful and non-judgmental setting. This meetup is FREE, although registration is required. The program is designed for adults and older teens. Younger participants (under 16) are welcome to join if accompanied by an adult.

What is a meetup and how is it different from a class? While a class is a structured learning environment with a defined curriculum, schedule, projects, and goals, a meetup is a gathering of people with shared interests who get together, often with a facilitator (in this case Eleni Litt).

Meetup Location: Mountain Lakes House

REGISTER TO VOLUNTEER

Join FOPOS for a land stewardship volunteer session at the Billy Johnson Mountain Lakes Nature Preserve in Princeton on Saturday, March 7th. Volunteers will work under the guidance of the FOPOS stewardship staff to perform ecological restoration work and invasive plant removal.

We have two volunteer sessions: 10AM-12PM and 1PM-3PM. You are welcome to attend one or both sessions. Groups welcome!

CANCELED due to poor site conditions.

Join the FOPOS Tree Tenders this winter for stewardship training that prepares volunteers to work independently at the Preserve. Attend a Tree Tenders training session on Saturday, February 28th, from 11 am to 1 pm, and get oriented to the work this season.

As a volunteer Tree Tender, you'll support the health of the Preserve’s native trees and shrubs by gently caring for young plantings, conducting invasive plant removal, clearing invasive vines from protective cages, and keeping an eye on our newest restoration areas. Tree Tenders will also help monitor trails and deer exclusion fences. Volunteers in these roles will walk the trails, patch small fence issues, and report any significant damage to staff. Ideally, monitoring would happen weekly (or biweekly) to help us meet our stewardship goals this season. Adults may work independently as a Tree Tender, while minors must work under the supervision of a parent or guardian. At our training sessions, the FOPOS Director of Nature Resources and Stewardship will orient you to the tasks. You can attend one or multiple training sessions until you feel comfortable working independently.

REGISTER FOR TREE TENDER VOLUNTEER TRAINING

CANCELED due to poor site conditions.

Show your LOVE for the Billy Johnson Mountain Lakes Nature Preserve! Join the Friends of Princeton Open Space (FOPOS) for a volunteer stewardship session on Saturday, February 28th, 2026.

Volunteers will work under the guidance of the FOPOS stewardship staff to perform ecosystem restoration and invasive species removal in the Billy Johnson Mountain Lakes Nature Preserve. If you have tools and can bring them along, please do!

We have two volunteer sessions: 10AM-12PM and 1PM-3PM. Please pick the time slot that works best for you! You are also welcome to attend both sessions. Groups welcome!

REGISTER FOR THE GREAT BACKYARD BIRD COUNT

Join the Friends of Princeton Open Space (FOPOS) and South Jersey Wildlife Tours on Monday, February 16th at 10 a.m. We’ll walk the trails at the Billy Johnson Mountain Lakes Nature Preserve to observe and count bird species as part of the Great Backyard Bird Count, a worldwide community science project that helps researchers better understand bird populations. Along the way, learn tips for attracting wildlife to your own backyard and hear how FOPOS is working to protect and restore your backyard—our local open spaces. Perfect for birders of all experience levels. Space is limited to 20 participants; be sure to sign up in advance.

Cost: FREE. This free community event is sponsored by Friends of Princeton Open Space. Consider making a donation to FOPOS and show your love for our local environment! All donations support our year-round work.

This event has been relocated to the Princeton Public Library due to icy parking conditions at the Preserve.

Join us at Mountain Lakes House to discuss "A Bird Came Down the Walk: Select Bird Poems" by Emily Dickinson. After the discussion will venture out for a short guided bird walk with expert birder Winnie Hughes Spar.

This series is presented in partnership with the Princeton Public Library and the Princeton Environmental Film Festival, and is dedicated to readings about conservation, stewardship, and our relationship with nature. Led by Diana Newby, FOPOS board member and associate director of writing at Princeton University, each meeting includes a discussion of the book and an accompanying activity. This meeting's activity will be led by FOPOS trustee Winnie Hughes Spar. Registration is requested.

Sign up for this session via Princeton Public Library. You do not need to be a library cardholder to register.

POSTPONED TO SATURDAY, JANUARY 31st at 4 pm due to snowy, icy conditions.

Join the Friends of Princeton Open Space (FOPOS) and South Jersey Wildlife Tours for a guided Waterfowl Walk . We will explore the trails around the lake at the Billy Johnson Mountain Lakes Nature Preserve in search of the fascinating waterfowl wintering in Princeton.

Space is limited to 20 participants; be sure to sign up in advance.

Cost: FREE. This free community event is sponsored by Friends of Princeton Open Space. Consider making a donation to FOPOS and show your love for our local environment! All donations support our year-round work.

REGISTER FOR THE WATERFOWL WALK

Join the Friends of Princeton Open Space (FOPOS) this winter as a volunteer Tree Tender!

Looking to lend a hand this winter? Join the FOPOS Tree Tenders and nurture the forest through its peaceful winter season. Attend a Tree Tenders training session on Saturday, January 24th, from 11 am to 1 pm, and get oriented to the work this season.

As a Tree Tender, you'll support the health of the Preserve’s native trees and shrubs by gently caring for young plantings, conducting invasive plant removal, using hand pruners to clear invasive vines from protective cages, and keeping an eye on our newest restoration areas. Tree Tenders will also help with regular trail and deer exclusion-fence monitoring. Volunteers in these roles will walk and monitor trails, patch small fence issues, and report any significant damage to staff. Ideally, monitoring would happen weekly (or biweekly) to help us meet our stewardship goals this season. Adults may work independently, while minors will be paired with a partner and check in with FOPOS staff before and after their volunteer shift.

REGISTER FOR TREE TENDER VOLUNTEER TRAINING

POSTPONED to Saturday, January 24th from Monday, January 19th, 2026 due to weather conditions

Join the Friends of Princeton Open Space (FOPOS) on MLK Day for a volunteer land stewardship session on Saturday, January 24th, 2026, and honor Dr. King's dedication to service and community.

Volunteers will work under the guidance of the FOPOS stewardship staff to perform ecosystem restoration and invasive species removal in the Billy Johnson Mountain Lakes Nature Preserve.

We have two volunteer sessions: 10AM-12PM and 1PM-3PM. Please pick the time slot that works best for you! You are also welcome to attend both sessions. Groups welcome!

REGISTER TO VOLUNTEER

Join the Friends of Princeton Open Space (FOPOS) this winter as a volunteer Tree Tender!

Looking to lend a hand this winter? Join the FOPOS Tree Tenders and nurture the forest through its peaceful winter season. Attend a Tree Tenders training session on Tuesday, January 6th, from 11 am to 1 pm, and get oriented to the work this season.

As a Tree Tender, you'll support the health of the Preserve’s native trees and shrubs by gently caring for young plantings, conducting invasive plant removal, using hand pruners to clear invasive vines from protective cages, and keeping an eye on our newest restoration areas. Tree Tenders will also help with regular trail and deer exclusion-fence monitoring. Volunteers in these roles will walk and monitor trails, patch small fence issues, and report any significant damage to staff. Ideally, monitoring would happen weekly (or biweekly) to help us meet our stewardship goals this season. Adults may work independently, while minors will be paired with a partner and check in with FOPOS staff before and after their volunteer shift.

REGISTER FOR TREE TENDER VOLUNTEER TRAINING

Join the Friends of Princeton Open Space (FOPOS) this winter as a volunteer Tree Tender!

Looking to lend a hand this winter? Join the FOPOS Tree Tenders and nurture the forest through its peaceful winter season. Attend a Tree Tenders training session on Tuesday, December 16th, from 11 am to 1 pm, and get oriented to the work this season.

As a Tree Tender, you'll support the health of the Preserve’s native trees and shrubs by gently caring for young plantings, conducting invasive plant removal, using hand pruners to clear invasive vines from protective cages, and keeping an eye on our newest restoration areas. Tree Tenders will also help with regular trail and deer exclusion-fence monitoring. Volunteers in these roles will walk and monitor trails, patch small fence issues, and report any significant damage to staff. Ideally, monitoring would happen weekly (or biweekly) to help us meet our stewardship goals this season. Adults may work independently, while minors will be paired with a partner and check in with FOPOS staff before and after their volunteer shift.

Register for this volunteer session.

We'll meet at Mountain Lakes House to draw from Nature in a playful and non-judgmental setting. This meetup is FREE, although registration is required. The program is designed for adults and older teens. Younger participants (under 16) are welcome to join if accompanied by an adult.

What is a meetup and how is it different from a class? While a class is a structured learning environment with a defined curriculum, schedule, projects, and goals, a meetup is a gathering of people with shared interests who get together, often with a facilitator (in this case Eleni Litt).

Meetup Location: Mountain Lakes House

Register for this Nature Journaling Meetup

Stop in any time at our Holiday Open House. Enjoy a warm drink, holiday treats, and our Perspectives on Preservation photography exhibition. Learn more about the Friends of Princeton Open Space and while you're here, take a stroll outside to see our beautifully decorated Christmas tree and gather with community members to celebrate the season.

Free and open to all. We kindly ask for your RSVP.

Stop in any time at our Holiday Open House. Enjoy a warm drink, holiday treats, and our Perspectives on Preservation photography exhibition. Learn more about the Friends of Princeton Open Space and while you're here, take a stroll outside to see our beautifully decorated Christmas tree and gather with community members to celebrate the season.

Free and open to all. We kindly ask for your RSVP.

Please join Friends of Princeton Open Space at the Mountain Lakes House for the opening reception of our annual Perspectives on Preservation Photography Exhibition, featuring selected photographs from our 2025 photo contest, as well as photographs of the Mountain Lakes Open Space Area by Frank Sauer.

Free and open to all. We kindly ask for your RSVP.