Events & Programs
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 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
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!
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.
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.
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 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 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 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
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 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!
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 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!
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
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.
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.
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.
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.
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!
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.
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.
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
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.
Join us at Mountain Lakes House to discuss "Finding the Mother Tree" by Suzanne Simard. The discussion will include an activity focused on fungal networks and their role in tree communications.
Presented in partnership with the Princeton Public Library and the Princeton Environmental Film Festival, this series 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 intern Sari Pehnke. Registration is requested.
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
Join the Friends of Princeton Open Space (FOPOS) for a volunteer land stewardship session on Saturday, November 8th. There will be two sessions: 10 a.m. - 12 p.m. and 1 p.m. - 3 p.m.
Volunteers will work under the guidance of the FOPOS stewardship staff to perform ecological restoration work, which may include native planting and invasive species removal in the Billy Johnson Mountain Lakes Nature Preserve.
Meetup Location: Mountain Lakes House Parking Lot within the Billy Johnson Mountain Lakes Nature Preserve
Looking to register for multiple volunteer sessions this fall? Register HERE.
POSTPONED TO MONDAY, NOVEMBER 3RD DUE TO WEATHER
Celebrate the beauty of autumn with a guided nature walk through the vibrant trails of the Billy Johnson Mountain Lakes Nature Preserve. We'll begin at the scenic Mountain Lakes House and set out into the preserve to witness the stunning fall foliage.
Along the way, we’ll pause to appreciate the natural beauty of the season and collect native seeds from select species. These seeds will support our Native Seed Propagation Program, which helps restore and sustain healthy native plant communities in the preserve and beyond. As a bonus, participants are welcome to take home a small packet of extra native seeds to plant in their own gardens and continue supporting local biodiversity.
This event is suitable for all ages and is a wonderful way to enjoy the crisp fall air, connect with nature, and contribute to conservation efforts
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
Join FOPOS for a FALL Planting Session! Volunteers will work under the guidance of the FOPOS stewardship team to plant native trees and shrubs, supporting forest regeneration and remediating the damage done over the decades by severe storms, invasive species, and heavy deer browsing.
Volunteer Sessions Date & Time: Saturday, October 25th | 10 a.m. to 12 p.m. & 1 p.m. to 3 p.m.
Bring shovels, pick axes, buckets, and work/garden gloves
Meetup Location: Mountain Lakes House Parking Lot within the Billy Johnson Mountain Lakes Nature Preserve
Looking to register for multiple volunteer sessions this fall? Register HERE.
Join FOPOS for a FALL Planting Session! Volunteers will work under the guidance of the FOPOS stewardship team to plant native trees and shrubs, supporting forest regeneration and remediating the damage done over the decades by severe storms, invasive species, and heavy deer browsing.
Volunteer Sessions Date & Time: Sunday, October 19th | 10 a.m. to 12 p.m. & 1 p.m. to 3 p.m.
Bring shovels, pick axes, buckets, and work/garden gloves
Meetup Location: Mountain Lakes House Parking Lot within the Billy Johnson Mountain Lakes Nature Preserve
Looking to register for multiple volunteer sessions this fall? Register HERE.
Book Walk & Talk with Ecological Artist Susan Hoenig
Hosted by Friends of Princeton Open Space (FOPOS)
Join FOPOS and renowned ecological artist Susan Hoenig for a guided Book Walk & Talk through the Billy Johnson Mountain Lakes Nature Preserve. Explore her White Oak and American Chestnut Leaf Sculptures while hearing insights from her new book, Birds and Berries: The Lives of Trees (July 2025).
Birds and Berries: The Lives of Trees (July 2025) can be purchased through Blurb.com
Discover how climate change is reshaping the delicate relationship between birds and berry-producing plants, vital for pollination, seed dispersal, and migratory survival. This is a unique opportunity to connect art, ecology, and climate awareness in the natural world.
This event is free and space is limited!
Meeting Location: Mountain Lakes House | 57 Mountain Ave | Princeton
Join FOPOS for a FALL Planting Session! Volunteers will work under the guidance of the FOPOS stewardship team to plant native trees and shrubs, supporting forest regeneration and remediating the damage done over the decades by severe storms, invasive species, and heavy deer browsing.
Volunteer Sessions Date & Time: Saturday, October 18th | 10 a.m. to 12 p.m. & 1 p.m. to 3 p.m.
Bring shovels, pick axes, buckets, and work/garden gloves
Meetup Location: Mountain Lakes House Parking Lot within the Billy Johnson Mountain Lakes Nature Preserve
Looking to register for multiple volunteer sessions this fall? Register HERE.
Join FOPOS for a FALL Planting Session in Community Park North! This fall, volunteers will work under the guidance of the FOPOS stewardship team to plant more than 500 native trees and shrubs to support forest regeneration and remediate the damage done over the decades by severe storms, invasive species, and heavy deer browsing. These plantings will boost long-term carbon sequestration, provide essential habitat for wildlife, and create a healthier, more resilient environment for the entire community.
Bring shovels, pick axes, buckets, and work/garden gloves
Volunteer Sessions Date & Time: Saturday, October 11th | 10 a.m. to 12 p.m. & 1 p.m. to 3 p.m.
Meetup Location: Main Parking Lot for the Billy Johnson Mountain Lakes Nature Preserve
Looking to register for multiple volunteer sessions this fall? Register HERE.
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!
BYO: Bring binoculars and water. Wear comfortable hiking shoes or sneakers; the trails can get muddy, especially around the lake.
Join FOPOS for a FALL Planting Session in Community Park North! This fall, volunteers will work under the guidance of the FOPOS stewardship team to plant more than 500 native trees and shrubs to support forest regeneration and remediate the damage done over the decades by severe storms, invasive species, and heavy deer browsing. These plantings will boost long-term carbon sequestration, provide essential habitat for wildlife, and create a healthier, more resilient environment for the entire community.
Bring shovels, pick axes, buckets, and work/garden gloves
Volunteer Session Date & Time: Wednesday, October 8th | 1 p.m. to 3 p.m.
Meetup Location: Main Parking Lot for the Billy Johnson Mountain Lakes Nature Preserve
Looking to register for multiple volunteer sessions this fall? Register HERE.
Join FOPOS for a FALL Planting Session in Community Park North! This fall, volunteers will work under the guidance of the FOPOS stewardship team to plant more than 500 native trees and shrubs to support forest regeneration and remediate the damage done over the decades by severe storms, invasive species, and heavy deer browsing. These plantings will boost long-term carbon sequestration, provide essential habitat for wildlife, and create a healthier, more resilient environment for the entire community.
Bring shovels, pick axes, buckets, and work/garden gloves
Volunteer Sessions Date & Time: Saturday, October 4th | 10 a.m. to 12 p.m. & 1 p.m. to 3 p.m.
Meetup Location: Main Parking Lot for the Billy Johnson Mountain Lakes Nature Preserve
Looking to register for multiple volunteer sessions this fall? RegisterHERE.
Join FOPOS for a FALL Planting Session in Community Park North! This fall, volunteers will work under the guidance of the FOPOS stewardship team to plant more than 500 native trees and shrubs to support forest regeneration and remediate the damage done over the decades by severe storms, invasive species, and heavy deer browsing. These plantings will boost long-term carbon sequestration, provide essential habitat for wildlife, and create a healthier, more resilient environment for the entire community.
Bring shovels, pick axes, buckets, and work/garden gloves
Volunteer Session Date & Time: Wednesday, October 1st | 10 a.m. to 12 p.m.
Meetup Location: Main Parking Lot for the Billy Johnson Mountain Lakes Nature Preserve
Looking to register for multiple volunteer sessions this fall? RegisterHERE.
Join Friends of Princeton Open Space on Sunday, September 28th for our annual Fall Fest fundraiser at the Mountain Lakes House, overlooking the beautiful lake at the Billy Johnson Mountain Lakes Nature Preserve in Princeton, New Jersey.
🎶 Live Music
🌱 Delicious Plant-Based Fall Foods
🍻 Craft Beverages
🌻 Nature-Themed Fun
Early Bird: $60 per person — ended 9/21
Children 12 and under: Free, but registration is required
White Oak Champion – $2,500 (Includes 10 tickets)
Red Maple Guardian – $1,000 (Includes 4 tickets)
Pawpaw Tree Protector – $500 (Includes 2 tickets)
Serviceberry Supporter – $250 (Includes 1 ticket)
