Using the buddy system, Inge Regan helps an amphibian cross Herrontown Road while Lisa Boulanger lights her path, looks out for cars, and tallies the numbers  Credit: Carolyn Jones

This story was produced in collaboration with CivicStory as part of the Ecology Civics Reporting Project.

A Princeton volunteer brigade helps frogs and salamanders survive their perilous spring migration — but keeping humans safe is proving just as hard.

Princeton, NJ — It was 9 pm and Inge Regan was standing in the middle of Herrontown Road. Rain poured off the brim of her hood as she swept back and forth across the asphalt with her headlamp. “Peeper!,” she exclaimed, bending down to get a closer look. “Ah, too bad. Dead on road.” 

Regan peeled the spring peeper off the tar, flicked it into the bushes, and made a note on her phone. Then she moved on. 

This wasn’t the first squished frog she had seen that March night. She would also find salamanders crushed by passing cars. Each fatality was a gut punch. But even though Regan was there to help amphibians cross this busy Princeton road, she still had to count the ones that hadn’t made it.

Regan leads the volunteer team that helps frogs and salamanders reach vernal pools. She works alongside scientists, naturalists, and a handful of high schoolers. Wearing fluorescent vests and rain-gear, the group pairs up to man a section of road the creatures must cross. The frogs and salamanders are heading toward the vernal pools in which they spawned. By instinct, it is to these pools they must return to breed.

Unfortunately for the amphibians, Herrontown Road transects their spring migration route. This patch of Princeton was once a dirt road wending between woodlands, but is now a busy thruway. Unless a human hand carries the salamanders across this perilous part of their journey — or else someone hustles a hopping frog — the amphibians’ chance of making it to their breeding pools is halved. 

For salamanders, a species in decline, drivers pose an existential risk. That’s why this band of volunteers formed the Princeton Salamander Crossing Brigade, whose job is to speed the animals across 38 feet of tar. Over two migration seasons, the group has achieved remarkable success. Their efforts have generated excitement in the community and on one banner night, the brigade achieved zero deaths. 

Amphibian safety is why the brigade goes out at night in the pouring rain. But an ironbound rule is that human safety is paramount, too. Yet in Princeton, despite the urgency of the cause and pervasive goodwill, assuring the well-being of both amphibians and people is trickier than anyone thought. 

Change starts with … a group chat

There are several salamander crossing brigades in the U.S., including at least six in New Jersey. But despite having one of the highest concentrations of spotted salamanders in the state, Princeton didn’t have a brigade until Inge Regan got an idea.  

Regan first became interested in salamanders in 2022 when she learned that the Herrontown Woods Preserve, on whose board she serves, was even more special than she thought. It contains several vernal pools used by breeding amphibians. Among the seasonal migrants are spring peepers, wood frogs and green frogs, and most alluringly, the spotted salamander — a lizard-like animal covered in yellow dots.  Significant populations live in the upland forests on the Princeton Ridge, and as USGS research shows, salamanders are indicators of ecosystem health. When they are under threat, the entire ecosystem is destabilized, too. Regan learned that on the first few rainy 40+ degree nights in spring, these elusive and ecologically-critical creatures emerge from the mud and march (slowly) toward vernal pools to breed.

Regan, a physician by day, is unfailingly optimistic about humans’ potential to do good. She also sees her volunteer efforts in the Herrontown Woods as an extension of her healing role. So when she kept bumping into naturalists who worried about these salamanders, she knew there was work to be done. 

Regan learned from Steve Hiltner, a botanist and fellow board member, that salamanders were a keystone species with an outsized ecological role. They regulate food webs, connect habitats, and enrich the soil, while being a food source themselves for birds, snakes, mammals, and other amphibians.

Fairfax Hutter, a Princeton-born naturalist who serves on an amphibian crossing brigade in Hopewell Township, flagged the significance of the Princeton salamander population. Increasing traffic on Herrontown Road was becoming a major risk, and she noted that shortly, the New Jersey Department of Environmental Protection would list the spotted salamander as a Species of Special Concern.

Mark Manning, a high school science teacher in Hopewell, and Mark Eastburn, a science teacher at Princeton High School, exposed the scientific wonder of these elusive creatures. One of Eastburn’s students, Bhavya Yaddanapudi, presented a research project on vernal pools at a Herrontown Woods event, helping spark public enthusiasm.

And Lisa Boulanger, a Princeton University neuroscientist, who was tracking salamanders on her own property, provided the final link. Boulanger lives just a few feet from the salamanders’ migration route on Herrontown Road. Her deep knowledge of the species as well as her firsthand accounts of the roadkill she saw each spring inspired Regan to learn more herself. After taking a training course with the Sourland Conservancy — the experts in amphibian crossings in central New Jersey — Regan was inspired to bring all the naturalists’ skills together.

Like so many change agents before her, Regan set up a group chat. 

Safety first

In February 2023, the advisors came together on a WhatsApp group to share their collective knowledge. Over the next few months, they exchanged information about everything from science to traffic patterns. In text bursts, they discussed biology, geology, and public policy; they shared information about other groups safeguarding amphibian crossing routes; they discussed Princeton’s unique history, and the ways local officials could help. The tone was unfailingly collaborative. Whether discussing the way a salamander walks (it’s called undulatory locomotion, apparently) or why brigade members should remove the dead-on-roads (to avoid double-counting), the group moved rapidly toward a shared goal: zero roadkill on major amphibian crossings, known as Big Nights.

By February 2024, the group had a plan. Following advice from the Princeton municipality, and under the auspices of the Sourland Conservancy, they received training on safe crossings. They learned how to handle creatures with delicate skin, as well as the importance of tallying numbers, so scientists could measure progress. Central to their training was human safety. Alongside reflective gear, members learned one strict rule when on the road at night — the moment headlights appear from either side of the curve, someone yells “car!”, and the brigade gets off the road. Even if a driver is speeding toward a salamander, the humans must let the car pass. 

By March 2024, the brigade was ready for action. As winter thawed, they put up roadside signs made by Boy Scout Troop 43 urging drivers to slow down ahead of the Herrontown Road curve. As the temperatures rose, they monitored the weather. When rain was forecast, they turned to tracking radar. Once a brigade member made the call, the team took their positions. Over several nights, they put their training into action, and of the 270 amphibians they counted on the spring 2024 crossing, the brigade protected more than half.

Higher ambitions

The group was proud, but agreed the survival rate wasn’t high enough. As Boulanger noted in a detailed report written for the Princeton town council, even a 25 percent annual mortality could doom the population. 

By February 2025, the brigade pitched a new idea — to close Herrontown Road on Big Nights. It worked elsewhere on the East Coast, so why not in Princeton? Trained volunteers would still be present to monitor the numbers, but with cars removed, both human and amphibian safety would improve. Officials agreed to a pilot.

On March 20, with help from the Princeton police, Herrontown Road was closed. Eight cars still slipped around the barrier, but overall, it was a major success. All 119 amphibians made it across. There were no deaths. Fairfax Hutter, who had been counting numbers in other towns, flagged that this had been a major migration. The group chat exploded with gratitude to local officials for facilitating this victory. 

But then came the twist.

When help becomes a hazard

As the Princeton Salamander Crossing Brigade knew from personal experience, interest in the well-being of the amphibians was contagious. As the town communicated the brigade’s efforts to the community — and asked drivers to avoid Herrontown Road on Big Nights — an increasing number of volunteers pitched in to help. The brigade was happy to share the enchantment of these spring migrations, but they were also clear. All volunteers must be trained.

The Princeton Police Department and town officials erected illuminated signs warning drivers to slow down on Herrontown Road during amphibian crossing nights Credit: Lisa Boulanger

Yet on the single night the police department fully closed that portion of Herrontown Road, an untrained person tried to stop cars that passed the barriers.

The next day, the brigade received bad news. The police department, which had supported the groups’ mission but whose main concern is public safety, could not again close Herrontown Road without also posting officers on site. But because non-emergency road closures count as public events, the event organizers — in this case, the Princeton Salamander Crossing Brigade — must fund the extra police shifts. 

The brigade ran the numbers. It would cost $1,000 a night. 

The group was dismayed. They were a grassroots organization and had neither money, nor a mechanism to raise it. However, as Lisa Boulanger pointed out, safety has always been central to their mission. The group soon realized that the rogue volunteer had highlighted a vulnerability. If one well-meaning citizen could turn up and put themselves at risk, then others might do so, too. The brigade had to find a way to safeguard both humans and amphibians, and to do it in partnership with town officials and an enthusiastic community. The group accordingly set up an online fundraising drive. Fortunately, there were no more major crossings in the 2025 season, which meant the team did not need to tap into the fund. But they would need it next year. Yet with only $500 in the pot, it was not enough to cover the policing costs for even one Big Night.

‘Progress is progress’

Despite the setback, by the close of the 2025 migration season, the Princeton Salamander Crossing Brigade still had a lot to be thankful for. The collaboration with the police department and town officials, the goodwill of everyone involved, and the success of the crossings, showed that their efforts were making a difference.

Bhavya Yaddanapudi, Carina He, Fairfax Hutter, Lisa Boulanger and Inge Regan spoke to the Princeton Town Council about the mission and outcomes of their work.  Credit: Carolyn Jones

On April 14, the brigade was invited to present to the Princeton Town Council. High schoolers Bhavya Yaddanapudi and Carina He recapped the group’s efforts and highlighted the 100 percent success rate of the road closure pilot. As Boulanger and Regan fielded questions, Yaddanapudi and He presented council members with a stack of letters. Written by elementary school children who had heard of the brigade’s work, the letters thanked the police department and local officials for making the magic happen. 

The elected officials were enthusiastic in their response. 

Council president Mia Sacks expressed delight that the council’s efforts to preserve open land had protected the vernal pools. Sacks said that she too would like to train as a volunteer the next year. 

“I know salamanders are great, but so are the people,” added councilperson Leighton Newlin.

Afterwards, brigade members gathered in the twilight outside the municipal building. They posed for photos, and congratulated Yaddanapudi, who had won a prize at a Princeton University science fair for her presentation about Princeton’s salamanders. 

The group also discussed the conundrum of the 2026 season — how to consolidate all this goodwill while assuring the safety of everyone involved? But Regan, ever the optimist, was not deterred.

“Progress is progress,” she said. “There are always things you stumble over, which means you slow down, take a look, and figure it out — just like with a patient.”

As the sky darkened, Regan, Boulanger and Fairfax set off across the municipal parking lot, deep in conversation. They had time — and a team — to once again figure out how to get Princeton’s amphibians safely across the road.  

This story was produced in collaboration with CivicStory as part of the Ecology Civics Reporting Project. 

Co-published with TAPinto Princeton. 

Carolyn Jones is a 2025 Ecology-Civics fellow and a freelance reporter based in Princeton.