Studying Wildlife Movement in a Southern California Nature Preserve

In the last year, my research has focused on studying the response of wildlife in San Diego, CA to recreation in a nature preserve. My partners for this project was the City of San Diego, Open Space, the United States Geological Survey (USGS) and the San Diego Association of Governments (SANDAG).

A little background about the preserve: This research was conducted in the Del Mar Mesa nature preserve, a small preserve within the limits of the City of San Diego. The trails in this area were illegally created by immigrant camps, but are now primarily used by bikers and hikers. Since 2008, all trails except for one main fire road through the preserve have been closed awaiting approval by a Natural Resource Management Plan for the area. Very high levels of illegal mountain biking and hiking persist despite closure.

Why this study is important: This nature preserve is the home for multiple threatened, endangered, and/or endemic plant and animal species such as San Diego fairy shrimp, San Diego horned lizards, and San Diego Button Celery. Also, the preserve has had known sightings of mountain lions, bobcats, coyotes, and deer, which were the focus of the study. Because of increasing urbanization, habitats that are suitable for these large mammals are severely reduced, limiting connectivity and wildlife corridors between open space areas in Southern California. As human recreation and development creeps closer to wildlife habitats, it is vitally important to study how we interact with these animals, influence their movement, and how they respond to our activities in changing numbers.

Our study: We split up the study in three parts:

(1) Pre-Enforcement: observe wildlife movement and human activity with only minimal enforcement by rangers in the area.

(2) Enforcement: introduce a targeted enforcement regime aimed to reduce human recreation. See how wildlife responds to a park with decreased/eliminated recreation.
(Conducted by California Fish & Wildlife wardens, funded by SANDAG.)

(3) Post-Enforcement: see if the changes caused by enforcement "stick", how long it takes for wildlife movement and human recreation numbers to decrease.

Results: 
We found that when human recreation was sharply decreased, animals responded relatively quickly by altering their temporal movement patterns. Previously, animals were only captured on camera at times like 2-4am. I found that when human numbers were decreased, many animals responded by using the trails more readily, and many of the cameras captured animals around 7am, then again at 5pm. Previously, these were heavy use mountain biking times (before work and after work).

Further data analysis will be conducted with the help of USGS, and presented in mid-April.