Have you ever wondered why some spectacular open spaces don’t have trails for recreation? While assessing properties for public access, trail planners have long prioritized endangered species, safety and trail stability. But, increasingly, there’s a push to preserve much-needed space for wildlife too. These measures are crucial for protecting our region’s unique biodiversity.

Understanding how outdoor recreation impacts local wildlife is more and more essential for the Bay Area’s conservation community. After all, as the human population grows and the demand for outdoor recreation increases, habitats and corridors available to wildlife could shrink. 

How can we create new trail systems that better balance the needs of both creatures and people in our region? That’s what we hope to learn from an ongoing study that’s underway in San Vicente Redwoods.

Here are some of the animals we’ve spotted so far! [Photo credit: Sue Townsend & Pathways for Wildlife]


It’s becoming more recognized in the scientific literature that the presence of people can affect how wildlife use a landscape. Take mountain lions — also known as pumas, panthers or cougars — for example. Notoriously sensitive to humans, they tend to steer clear of areas that we frequent. (Safety note: While human encounters with mountain lions are rare, it’s important to take precautions when you’re out on the trail. Here are some helpful tips.) Meanwhile, for better or worse, species like crows and Steller’s jays have adapted to rely on us for food and other resources. 

When POST and our partners acquired San Vicente Redwoods in 2011, we knew it would be a prime destination for hikers, bikers and equestrians. That’s when POST, Sempervirens Fund and Save the Redwoods League partnered with the Land Trust of Santa Cruz County (LTSCC), who manage public access at San Vicente Redwoods, to devise a plan. Our joint goal was to create ecologically friendly trails with the neighboring flora and fauna in mind.


Though trails are a new addition to San Vicente Redwoods, the area is no stranger to human activity. Local indigenous tribes have cared for the landscape for millennia. After European settlers arrived, the region was logged in its entirety. Train tracks and power lines stretched across it. The property became home to a quarry, and the landscape once supported a cement plant in nearby Davenport. There was even a town in the redwoods where workers then lived.


In 2019, POST and our partners installed 43 cameras and audio recorders throughout San Vicente Redwoods. In addition to along trails and roads, we placed devices in remote locations that we hoped public access would minimally impact. An interesting side note: as far as we know, ours is the first study of its kind to pair acoustic monitors with cameras to capture both mammals and birds!

By analyzing these devices’ data, we can see which animals spend time on the property and how they move. We can also get a clearer picture of their behavior when humans are nearby and when they’re not. 

At first, the study design seemed pretty straightforward. We’d collect data at two distinct intervals: before the trails opened and after the hikers arrived. The ecosystem had been relatively stable for a while, which set the stage for a simple before/after analysis. 

In December 2022, 7.3 miles of new trails welcomed first-time visitors.

But nature has a way of disrupting the best-laid plans. In August 2020, the CZU Fire hit the Santa Cruz Mountains. The blaze destroyed all of our cameras and, with them, a portion of our data. And because the fires significantly changed the conditions at San Vicente Redwoods, our analysis has become more complicated. 

Our initial research taught us a lot about how these rapid changes in environmental conditions affected both wildlife and the landscape. And now that the first phase of trails is open to the public, we are monitoring the impacts humans are having. 


In addition to our study at San Vicente Redwoods, we’ve been working with the Santa Cruz Puma Project. As part of a partnership between UC Santa Cruz and the California Department of Fish and Wildlife, these researchers study how human development affects local mountain lions.

In the clip below from a POST webinar, Dr. Chris Wilmers of the Puma Project explains how mountain lions respond to two distinct sounds: frogs and people talking.

A few years ago, researchers at the Puma Project made an exciting discovery. While collaring local mountain lions and tracking their movements, they found these creatures were raising their young — aka “denning” — on parts of San Vicente Redwoods.

Mountain lions need vast ranges for territory, hunting and breeding. Because San Vicente Redwoods is adjacent to 10,000 acres of undeveloped lands, it adds to a rich contiguous wildlife habitat. 

Thanks to the Puma Project’s research, we knew to consider these feline families while designing the trail network. We worked with LTSCC to avoid running trails through their denning areas. Instead, we set aside parts of the property to use as core habitat. Recreation was limited to pre-existing human structures such as Empire Grade Road or housing in Boony Doon. The new trails have a considerable buffer of 600 meters. 

Making adjustments like these is part of a framework called “adaptive management,” and it’s just what it sounds like. First, we monitor circumstances — wildlife behavior, effects of wildfire and more — and consider them when managing the land. Then, we shift our approach as needed.


Surprisingly, studies like this one are not standard practice when new trails open.  There’s been a long-term assumption that the effects of public access on wildlife are minor, and similar studies have been few and far between. 

At San Vicente Redwoods, we wanted to test this assumption to better understand how the ecosystem responds to human interference. We did our best to design the trails at San Vicente Redwoods to have minimal impact on wildlife.  Measuring the actual results of bringing hikers, bikers and equestrians onto the landscape will let us know if we were successful. When construction for the next phase of trails at San Vicente Redwoods begins, we can use our findings to mitigate any negative impacts.  

So, now if you spot a device along a trail at San Vicente Redwoods, you’ll know a little more about what we’re tracking and why. And remember: where biodiversity thrives, the land and species of all types — including humans — benefit!

About Post

Peninsula Open Space Trust (POST) protects open space on the Peninsula and in the South Bay for the benefit of all. Since its founding in 1977, POST has been responsible for saving more than 87,000 acres as permanently protected land in San Mateo, Santa Clara and Santa Cruz counties. Learn more

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