BOBCATS OF SILICON VALLEY and santa cruz, CALIFORNIA

 
 
Tiburon, also known as B06M, was monitored for 8 months in Silicon Valley as part of the ladscape connectivity study.

Tiburon, also known as B06M, was monitored for 8 months in Silicon Valley as part of the ladscape connectivity study.

ABOUT THE PROJECT

The overarching goal of this project was to evaluate ecological connectivity and prioritize parcel acquisition in one of the most populous regions of the United States where imminent urbanization threatens to completely isolate the Santa Cruz Mountains and it’s faunal populations from other neighboring ranges. The Santa Cruz Mountains are located in a global biodiversity hotspot and are home to numerous faunal species of conservation concern in California, including charismatic pumas. Yet sprawling urbanization radiating from the cities of San Francisco, San Jose, and Santa Cruz threaten to completely isolate the Santa Cruz Mountains from neighboring Diablo and Gabilan mountain ranges, thereby also isolating the animal populations that inhabit the Santa Cruz Mountains, which could have profound consequences for the persistence of wildlife in the Santa Cruz Mountains. There are only two narrow pockets of landscape that were thought to retain some connectivity between the Santa Cruz Mountains and other mountain ranges, but data were needed to determine whether connectivity exists and can be improved, or whether connectivity needed to be restored and then maintained.

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To evaluate ecological connectivity, we needed to view the landscape through the eyes of the animals residing the landscape, and so that’s where the bobcats come in to the picture! To get the bobcat’s perspective, we captured and GPS-collared 36 bobcats over an 15-month period. The collars collected extremely fine-scale 5-minute movement data, and we ultimately collected nearly 700,000 GPS points over an 18-month period.

With these 5-minute movement data, we monitored how, where, and when bobcat crossed roads so we could determine what facilitates and deters bobcats from crossing roads. We also evaluated what natural (trees, shrubs, grass, water, etc.) and anthropogenic (housing development, roads, crops, orchards, and eucalyptus) influence bobcat movement across the landscape. We also monitored the mortality of collared bobcats, and collected information about bobcat mortalities opportunistically found (ie., that were uncollared) during the study.

Cool findings!

Using 5-minute movement data, it is evident that bobcats select to move from tree to tree or bush to bush in this landscape.

After collecting 672,000 5-minute movement GPS-locations, the bobcats really had a lot to teach about how they navigate the landscape of Central Coast California. Some of the highlights are:

  • When moving across a landscape of mixed grass, shrubs, and trees, bobcats prefer to from tree to tree or shrub to shrub

  • Bobcats do not like agriculture! They avoided moving through areas with low-lying crops and orchards. They also do not like eucalyptus, and in fact, they prefer orchards over eucalyptus groves!

  • Bobcats cross roads a lot. We observed 3,333 road crossings across seven arterial roads of interest, including Highway 101. But even though Highway 101 is one of the busiest travel corridors in the entire United States, so long as there were culverts or bridges with natural vegetation on either side, bobcats regularly crossed (under) the busy 8-10-lane freeway!

  • Bobcats mostly died from being hit by cars or from notoedric mange, trends observed in other human-impacted landscapes in California. 94% of the bobcats we tested were exposed to common anticoagulant rat poisons. This type of poison exposure has been linked with immune dysfunction in bobcats, and likely contributed to the cases of mange deaths we observed.

A photo of a $93 million dollar parcel acquired in Coyote Valley in Silicon Valley, California. To make the habitat suitable for wildlife, natural vegetation will have to be restored.

A photo of a $93 million dollar parcel acquired in Coyote Valley in Silicon Valley, California. To make the habitat suitable for wildlife, natural vegetation will have to be restored.

Conservation OUTCOMES

Our first conservation-related objective was to prepare a report describing our research findings and recommendations for land acquisition and restoration. We submitted our report in July 2019, and within 5 months, we received news of a historic $93 million dollar deal reached to preserve San Jose’s Coyote Valley. This land deal is one of many that will occur in the Coyote Valley (found wiin Silicon Valley) and will ensure ecological connectivity between the Santa Cruz Mountains and the Diablo Range. More land acquisition will follow, and much of the land to be acquired is heavily impacted by intense agriculture. To ensure ecological connectivity, local land management agencies will have to restore natural vegetation to the parcels. We have also made recommendations for facilitating safe-road crossings and reducing rat poison use in the areas.

Project Partners

This project was a collaboration between the Chris Wilmers lab at University of California, Santa Cruz, Peninsula Open Space Trust, Santa Clara Open Space Authority, and Land Trust of Santa Cruz.