Where the Wildlife Move: Takeaways from Our Study

As you may know, we’ve been monitoring local wildlife to learn about where they are moving well across the landscape, and where they aren’t. Remember our beloved coyote and badger video? We captured the candid footage of this playful pair as part of our study — in partnership with Pathways for Wildlife — to better understand how animals make their way between local mountain ranges. These unlikely companions sparked our imaginations and warmed our hearts. We know that their presence here is key to our regional biodiversity.

CONNECTING CRITICAL HABITAT

The Santa Cruz Mountains, Gabilan Range and Diablo Range each provide critical habitat for local plants and animals. When wildlife can move freely between the ranges, they thrive. However, traveling throughout our populous region is no easy feat.

All across California, roads, vehicles and human development make safe passage between habitats a life-threatening challenge for animals looking for new territory, food and mates. If they become isolated, we face the possibility that some species might become locally extinct. This would have a profound impact, not only for individual creatures, but entire ecosystems. So, connecting and restoring fragmented habitats is a top priority.

ABOUT THE STUDY

For three years, POST has worked with Pathways for Wildlife — a research organization specializing in animal tracking and movement — to assess connectivity between the mountain ranges in Santa Clara, San Benito, Santa Cruz and Monterey Counties. 

Our research focused on the major roads of this region. We paid special attention to the Aromas Hills and Upper Pajaro Valley, where the four counties and three mountain ranges converge. The goals: to understand where wildlife can currently travel safely via culverts (undercrossings beneath roads) and bridge underpasses, and to identify hotspots where animal and vehicle collisions happen most frequently. Our findings are already informing work by us and our partners to improve transportation infrastructure, buy land in key locations, restore habitat and more. Here are just a few things we discovered.

Data collected by Pathways for Wildlife for POST for this study. Clockwise: deer, bobcat, raccoon, heron, coyote, squirrel.

KEY FINDINGS

• At the 42 camera monitoring sites in the study area, a variety of species used existing undercrossings to cross beneath highways. At the most frequented culvert, we saw 594 crossings by animals native to our region over the course the study!
  
• Most sites within the study area (90%) allowed medium-sized mammals to travel through existing undercrossings, including American badgers, bobcats, coyotes, gray foxes, raccoons and striped skunks.
• Only a quarter of existing undercrossings in the study area (26%) encouraged movement by larger mammals, such as black-tail deer. Though mountain lions were generally camera shy, we found their tracks beneath one bridge.
• Nearly all of the sites with high rates of animal passage are in the Upper Pajaro Valley. And this region was the only place where our cameras detected local badgers!
• Of the ten sites with the fewest images of animals using crossings captured on camera, eight were
  in the Aromas Hills. This area also had a relatively high concentration of wildlife-vehicle collisions,
  including three involving mountain lions. It’s clear that better crossing structures are needed in this area, along US 101.
• The study area is fragmented by roads, highways, rural residential development, agriculture and other forms of human development, making it difficult for mountain lions overall. The Aromas Hills region includes more suitable habitat for mountain lions than the Upper Pajaro Valley.
• Creeks (particularly those with large undercrossings) are vital thoroughfares for several species, especially deer and bobcats, through the Upper Pajaro Valley. 

STUDY RECOMMENDATIONS

The study found that 19 locations offer the most promising opportunities to reduce wildlife-vehicle collisions and improve wildlife movement throughout the region.

These opportunities include protecting and restoring habitat, maintaining or improving existing culverts and bridge underpasses, and constructing new crossing structures in key locations where possible. These ambitious recommendations will take years — and decades — to put in place, and we can’t do it alone. We’ll work with local partners to implement the study recommendations.

SOUTHWARD BOUND

For more than 45 years, POST has focused our efforts on the Peninsula and the South Bay. Our keen understanding is that our projects will have impacts beyond our working area. This study confirmed our hunch that it’s important for us to expand our wildlife connectivity work even further south where the mountain ranges come together to connect northern California to the Central Coast, and east to the interior mountain ranges. Unless we take action, the Santa Cruz Mountains are at risk of becoming isolated — their stunning biodiversity is an asset we can’t afford to put on the line. We’re excited to explore the opportunities presented in the study and to build a more interconnected region so close to home.

Follow POST on Instagram to see more photos and videos of local wildlife caught on camera!

Instagram.com/POSTLandTrust