Smile, Lion, You’re on Candid Camera!

by Eric Ettlinger

MMWD biologists like to keep track of things on the Mt. Tamalpais Watershed. We know how many fish are in the creeks (more or less), when rare plants are blooming, where owls are nesting, and we are always trying to understand how the water district’s operations might affect these species. Our most recent effort to catalog the abundance of life on the watershed involves a few carefully placed cameras that “catch” wildlife walking by.

Remote cameras—also called game cameras, trail cameras or camera traps—have become increasingly important for wildlife conservation in the last couple of decades. They’re being used to monitor rare species around the world, and occasionally discover new or long-lost species, such as the recent discovery of a Persian leopard in Afghanistan. MMWD’s camera trapping effort began with an attempt to find another such long-lost species that we suspect may have returned: the Pacific fisher. This large member of the weasel family was last seen in Marin County in 1913, and the closest current population is in Mendocino County. In 2010, Andrea Williams, MMWD’s Vegetation Ecologist, saw an animal on Mt. Tamalpais that fit the description of a fisher. The animal was larger than a raccoon, dark, low to the ground, and had a bushy tail. With the help of a local wildlife researcher, Virginia Fifield, we deployed remote cameras near the observation site and in suitable habitat elsewhere on the mountain. Despite nearly a year of looking, we never captured a photograph of the mystery animal.

The effort was not wasted, however, because the cameras captured an abundance of other wildlife using the roads and trails of the Mt. Tamalpais Watershed. We decided to shift our research towards investigating how these species move across the landscape, which we hypothesized was not simply random. Natural and manmade features such as ridgelines and reservoirs funnel wide-ranging species into “wildlife corridors,” where they would be more likely to encounter our cameras. We therefore strategically placed our cameras in a few of these potential corridors to see what species were traversing the watershed through them.

The videos are already telling us which corridors are wildlife freeways and which are only backroads. A camera on a ridgeline has captured a parade of deer and coyotes, as well as a mountain lion and a bobcat. Wildlife traffic along a nearby valley road has been much lighter. We plan to move the cameras to other potential corridors and over time try to develop a picture of what species are moving across the landscape and where they’re all going.

Check out these videos:

Mountain lion
Coyote pair with large pups
Bobcat

Note: This study has been authorized by MMWD. Placing personal cameras on water district property is prohibited.