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.

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

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

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.

Register for this volunteer session.

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

Sign up for this session via Eventbrite.

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

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.

Register for this volunteer session.

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.

Register for this volunteer session.

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

Register for this Book Walk and Talk

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.

Register for this volunteer session.

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.

Register for this volunteer session.

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.

Register for the Fall Bird Walk

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.

Register for this volunteer session.

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.

Register for this volunteer session.

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.

Register for this volunteer session.

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

• General Admission: $70 per person — starting September 22

Children 12 and under: Free, but registration is required

Become a Fall Fest Sponsor

• 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)

Help FOPOS kick off planting in Community Park North, where we’ll plant over 500 trees this fall!.

Join thousands of volunteers nationwide on September 27 for National Public Lands Day. Help protect, preserve, and celebrate “Our Home Outdoors.” From local parks to national forests, our public lands are where memories are made and communities come together.

Friends of Princeton Open Space (FOPOS) is hosting land stewardship volunteer sessions on Saturday, September 27th, in celebration of National Public Lands Day. There will be two volunteer sessions: 10 a.m. to 12 p.m. and from 1 p.m. - 3 p.m. Come to one or both!

Sign up for this session via Eventbrite.

Join Friends of Princeton Open Space (FOPOS) at the Mountain Lakes House for a book club dedicated to readings about conservation, stewardship, and our relationship with nature. New book club members welcome! Led by Diana Newby, FOPOS board member and Associate Director of Writing at Princeton University, we'll spend our fourth meeting discussing Richard Powers's book The Overstory. Winner of the 2019 Pulitzer Prize for Fiction, The Overstory gives a sprawling and ambitious account of the interconnectedness of living things, with a particular focus on the complex relationship between humans and trees over multiple generations of American history.

Sign up for this session via Eventbrite.

Join the Friends of Princeton Open Space (FOPOS) for a weekday volunteer land stewardship session on Wednesday, September 24th, from 1 p.m. - 3 p.m.

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

Sign up for this session via Eventbrite.

Join the Friends of Princeton Open Space (FOPOS) for a volunteer land stewardship session on Saturday, September 20th. 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 and invasive species removal in the Billy Johnson Mountain Lakes Nature Preserve.

Sign up for this session via Eventbrite.

Join the Friends of Princeton Open Space (FOPOS) for a weekday volunteer land stewardship session on Wednesday, September 17th, from 9 a.m. - 11 a.m.

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

Sign up for this session via Eventbrite.

Join FOPOS and Eleni Litt for a 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 to expect: Meetups with Eleni start off with welcoming everyone, and sharing brief introductions. Eleni will provide suggestions for themes and approaches along with some initial prompts so you won’t be looking at the blank page for long! You’ll be encouraged to notice what grabs your attention the most and to follow your own curiosity, mindful that using the suggested themes and/or prompts is entirely optional! Participants then set out on their own for 45-50 minutes or so to draw, paint, and/or collage on the grounds of the Mountain Lakes House, after which we meet back for an informal conversation to share the results, noting that sharing is always optional! In this setting, learning is embraced as an experience and a process rather than an explicit destination. These meetups are for artists and non-artists alike, and prior drawing or Nature Journaling experience is neither required nor necessary!

Sign up for this session via Eventbrite.

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!

Did you know that New Jersey is one of the best states in the country for birdwatching? Our diverse habitats and our location in the Atlantic Flyway, a migratory route along the Eastern Seaboard, positions the garden state as a leader in birdwatching.

Sign up for this session via Eventbrite.

Join the Friends of Princeton Open Space (FOPOS) for a trail crew volunteer session on Thursday, September 4th, from 1 p.m. - 3 p.m.

Volunteers will work under the guidance of the FOPOS stewardship staff to help maintain the trails at the Billy Johnson Mountain Lakes Nature Preserve. Are you comfortable using a hammer? Help us install new trail markers along the nearly nine miles of trails at the Preserve.

Sign up for this session via Eventbrite.

Join the Friends of Princeton Open Space (FOPOS) for a trail crew volunteer session on Tuesday, August 28th, from 1 p.m. - 3 p.m.

Volunteers will work under the guidance of the FOPOS stewardship staff to help maintain the trails at the Billy Johnson Mountain Lakes Nature Preserve. Are you comfortable using a hammer? Help us install new trail markers along the nearly nine miles of trails at the Preserve.

Sign up for this session via Eventbrite.

Join us for a nature walk around the lake at the Billy Johnson Mountain Lakes Nature Preserve. We'll observe the great diversity of life at the Preserve with possible sightings of eastern painted turtles, great blue herons, beavers, salamanders, crayfish, and macroinvertebrates. Learn about various plant species and habitat restoration projects aimed at preserving native organisms. After our walk, we’ll head back to the Mountain Lakes House to delve into the world of lake life collected during our walk. Using field microscopes, we'll explore the diversity of plants & waterbugs and discover their role as indicators of ecosystem health.

This walk will be moderately challenging along trails with uneven terrain and a rocky stream crossing. All ages are welcome!

Sign up for this session via Eventbrite.

Join the Friends of Princeton Open Space (FOPOS) for a weekday volunteer land stewardship session on Wednesday, August 27th, from 9 a.m. - 11 a.m.

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

Sign up for this session via Eventbrite.

Join the Friends of Princeton Open Space (FOPOS) for a trail crew volunteer session on Tuesday, August 26th, from 1 p.m. - 3 p.m.

Volunteers will work under the guidance of the FOPOS stewardship staff to help maintain the trails at the Billy Johnson Mountain Lakes Nature Preserve. Are you comfortable using a hammer? Help us install new trail markers along the nearly nine miles of trails at the Preserve.

Sign up for this session via Eventbrite.