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.

Join us for an adventurous hike along the White Trail at the Billy Johnson Mountain Lakes Nature Preserve! We'll begin at the Mountain Lakes House, then make our way into John Witherspoon Woods, the oldest forest in the Preserve. This walk features rocky, uneven terrain and is best suited for those seeking a moderate challenge.

Along the way, we'll pass through a stunning grove of beech trees, follow along the winding rocky tributary of Mountain Brook, and venture into the boulder fields of the Princeton Ridge, where we’ll visit Devil’s Cave. This is more than just a walk; it's an immersive journey through the wild beauty of what many call Princeton’s “Central Park.”

Come prepared for adventure, wear sturdy shoes, and experience Princeton's natural and rugged beauty.

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 20th, 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.

Would you be interested in registering for multiple volunteer sessions this season? Register HERE.

Join the Friends of Princeton Open Space (FOPOS) for a volunteer land stewardship session on Saturday, August 16th. There will be two volunteer sessions; the morning session is from 9 a.m. - 11 a.m and the afternoon session is from 1 p.m. to 3 p.m. Come to one or both. Bring a friend!

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.

Would you be interested in registering for multiple volunteer sessions this season? Register HERE.

Join the Friends of Princeton Open Space (FOPOS) for a trail crew volunteer session on Thursday, August 14th, from 9 a.m. - 11 a.m.

Volunteers will work under the guidance of the FOPOS stewardship staff to help monitor and maintain the trails at the Billy Johnson Mountain Lakes Nature Preserve. Volunteers will assist with trail maintenance tasks, such as clearing overgrown vegetation, monitoring for fallen trees, and picking up litter. No prior experience is necessary... just a willingness to get your hands dirty and make a positive impact!

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 13th, 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.

Would you be interested in registering for multiple volunteer sessions this season? Register HERE.

Join the Friends of Princeton Open Space (FOPOS) for a volunteer land stewardship session on Saturday, August 9th, 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.

Would you be interested in registering for multiple volunteer sessions this season? Register HERE.

Join Friends of Princeton Open Space for a fun and interactive scavenger hunt through the Billy Johnson Mountain Lakes Nature Preserve, Princeton’s “Central Park.” Led by FOPOS's summer interns, this guided adventure will take participants through some of the Preserve’s most fascinating natural and restored habitats. From the mysterious Devil’s Cave nestled in a boulder field to the thriving pollinator garden, you’ll discover the ecological diversity and hidden beauty that make this area so special.

Whether you're a longtime visitor or new to the Preserve, this scavenger hunt offers a fresh way to engage with the land, learn about local ecology, and have fun outdoors. All ages are welcome!

Sign up for this session via Eventbrite.

Join Friends of Princeton Open Space for a fun and interactive scavenger hunt through the Billy Johnson Mountain Lakes Nature Preserve, Princeton’s “Central Park.” Led by FOPOS's summer interns, this guided adventure will take participants through some of the Preserve’s most fascinating natural and restored habitats. From the mysterious Devil’s Cave nestled in a boulder field to the thriving pollinator garden, you’ll discover the ecological diversity and hidden beauty that make this area so special.

Whether you're a longtime visitor or new to the Preserve, this scavenger hunt offers a fresh way to engage with the land, learn about local ecology, and have fun outdoors. All ages are welcome!

Sign up for this session via Eventbrite.

Join the Friends of Princeton Open Space (FOPOS) for a volunteer land stewardship session on Saturday, August 2nd, from 8 a.m. - 10 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.

Would you be interested in registering for multiple volunteer sessions this season? Register HERE.

Join Friends of Princeton Open Space for a BioBlitz on Saturday, August 2nd from 11 AM - 1 PM at the Billy Johnson Mountain Lakes Nature Preserve!

A BioBlitz is a community science event where volunteers work together to find and identify as many species as possible in a specific area over a short time. Participants will learn about some of the apps they can use to identify plants and animals (iNaturalist and Merlin Bird Id). Then we'll split into teams to explore different parts of the Preserve. Observations will be added to a dedicated iNaturalist project or recorded manually to help build an inventory of the living species that our stewardship team will use in the future to inform restoration efforts.

This community-powered biological inventory helps build a snapshot of local biodiversity -- plants, animals, fungi, and more. Unlike traditional scientific surveys, a BioBlitz brings together people of all backgrounds to learn, observe, and contribute directly to ecological monitoring. The data collected supports habitat restoration and conservation efforts while helping participants build knowledge and a deeper connection to nature right in their own backyard.

Sign up for this session via Eventbrite.

Join the Friends of Princeton Open Space (FOPOS) for a trail crew volunteer session on Thursday, July 31st, from 9 AM - 11 AM.

Volunteers will work under the guidance of the FOPOS stewardship staff to help monitor and maintain the trails at the Billy Johnson Mountain Lakes Nature Preserve. Volunteers will assist with trail maintenance tasks, such as clearing overgrown vegetation, monitoring for fallen trees, and picking up litter. No prior experience is necessary... just a willingness to get your hands dirty and make a positive impact!

Sign up for this session via Eventbrite.

Join the Friends of Princeton Open Space (FOPOS) for a weekday volunteer land stewardship session on Wednesday, July 30th from 9 AM - 11 AM.

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.

Would you be interested in registering for multiple volunteer sessions this season? Register HERE.

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-judgemental setting.

This Meet Up 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.

This meetup is for artists and non-artists alike, and prior drawing or painting experience is neither required or necessary!

Eleni Zatz Litt (EZL Studio) is a teaching artist, anthropologist, and lifelong learner, with a keen interest in the intersection between art and science. Eleni teaches at the West Windsor Arts Center and the Princeton Adult School; she is a frequent presenter and participant in John Muir Laws’ Nature Journaling Educators Forum.

Sign up for our Nature Journaling Meet Up on Eventbrite

Join the Friends of Princeton Open Space (FOPOS) for a volunteer land stewardship session on Saturday, July 26th. There will be two sessions. The morning session will be held from 9 AM to 11 AM, and the afternoon session will be from 1 PM to 3 PM.

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.

Looking to register for multiple volunteer sessions this season? Register HERE.

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.

Led by Diana Newby, FOPOS volunteer and faculty member in Princeton University's Writing Program, we'll spend our time together discussing Barbara Kingsolver's novel Animal, Vegetable, Miracle.

Sign up for our FOPOS Book Club on Eventbrite

Join the Friends of Princeton Open Space (FOPOS) for a weekday volunteer land stewardship session on Wednesday, July 23rd from 1 PM - 3 PM.

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.

Would you be interested in registering for multiple volunteer sessions this season? Register HERE.

Join FOPOS's stewardship team for an evening moth survey at the Billy Johnson Mountain Lakes Nature Preserve. Moths are fascinating creatures and contribute vital ecosystem services as pollinators and as prey, especially so for baby birds, which primarily rely on caterpillars and other insects for food.

During this session, participants will observe, identify, and learn more about these mysterious night creatures. The program will begin with an educational presentation about moths, led by Patrick Natale, Assistant Professor of Biology at Mercer County Community College, followed by a hands-on activity where participants will log biodiversity data at the Preserve.

Sign up for this session via Eventbrite.

Wineberries are one of New Jersey's most abundant summer brambleberries, but they are also very invasive and outcompete native plants. Fortunately, they are delicious and YOU can help us curb their spread by eating them!

Join local experts Matt and Shannon for a wineberry forage walk at the Billy Johnson Mountain Lakes Nature Preserve in Princeton. During this volunteer stewardship session, participants will learn about the origins of wineberry and how to identify this invasive plant--and then we will get picking! Folks will get the chance to take their wineberry harvest home. A recipe card will be included so that you can make wineberry jam at home!

Sign up for this session via Eventbrite.

Join our summer interns on a guided Tree Identification Nature Walk as we explore the beautiful Green Trail at the Billy Johnson Mountain Lakes Nature Preserve. Come connect with the forest. Learn simple identification tricks, fun facts, and the ecological roles these trees play in our local ecosystem.

Whether you're a budding naturalist or just curious about the woods you wander through, this event is a great way to deepen your relationship with nature.

Sign up for this session via Eventbrite.

Join the Friends of Princeton Open Space (FOPOS) for a weekday volunteer land stewardship session on Wednesday, July 16th from 1 PM - 3 PM.

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.

Would you be interested in registering for multiple volunteer sessions this season? Register HERE.

Join our summer interns on a guided Tree Identification Nature Walk as we explore the beautiful Green Trail at the Billy Johnson Mountain Lakes Nature Preserve. Come connect with the forest. Learn simple identification tricks, fun facts, and the ecological roles these trees play in our local ecosystem.

Whether you're a budding naturalist or just curious about the woods you wander through, this event is a great way to deepen your relationship with nature.

Sign up for this session via Eventbrite.

Join the Friends of Princeton Open Space (FOPOS) for a volunteer land stewardship session on Saturday, July 12th from 1 PM - 3 PM.

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.

Looking to register for multiple volunteer sessions this summer? Register HERE.

Led by Kirstin Ohrt, creator of Footpathing.com, community members of all ages are welcome to join us at Mountain Lakes House to learn how to view the world around you with a photographer's eye in order to capture the beauty of nature. Attendees will learn to consider shape, proportion, angles and depth to create compelling compositions.

Presented in partnership: Princeton Public Library & Friends of Princeton Open Space. 

Register HERE through the Princeton Public Library

Wineberries are one of New Jersey's most abundant summer brambleberries, but they are also very invasive and outcompete native plants. Fortunately, they are delicious and YOU can help us curb their spread by eating them!

Join local experts Matt and Shannon for a wineberry forage walk at the Billy Johnson Mountain Lakes Nature Preserve in Princeton. During this volunteer stewardship session, participants will learn about the origins of wineberry and how to identify this invasive plant--and then we will get picking! Folks will get the chance to take their wineberry harvest home. A recipe card will be included so that you can make wineberry jam at home!

Sign up for this session via Eventbrite.

Join the Friends of Princeton Open Space (FOPOS) for a weekday volunteer land stewardship session on Wednesday, July 9th from 1 PM - 3 PM.

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.

Looking to register for multiple volunteer sessions this season? Register HERE.

Join our summer stewardship interns on a guided nature walk as we celebrate National Pollinator Month! As we wander the trails, we’ll uncover the hidden world of native pollinators, from buzzing bees and fluttering butterflies to surprising pollinators you might not expect.

Sign up for our June Nature Walk on Eventbrite