Posted on Sat, Sep. 04, 2010

Anticipation hangs over a small group of biologists as wildlife photographer Chris Wemmer removes a small point-and-shoot digital camera from its plastic housing.

Everyone gathers round as Wemmer begins scrolling through the images on the camera’s memory card. Cries of delight go up as the camera’s small viewing screen shows a silhouetted image of a sleek gray fox standing atop a sandstone outcropping. Other shots in the sequence reveal a pair of Western screech owls using the rock as a perch to scan for prey.

“It’s like a whole new world opens up to you,” Wemmer said.

These photographs will join a growing inventory of thousands of images of wildlife found on the Carrizo Plain Ecological Reserve, also commonly known as the Chimineas Ranch. Researchers are using wildlife camera traps as part of an unusually detailed biological inventory of the 30,000-acre wildlife refuge sandwiched between Los Padres National Forest and the Carrizo Plain National Monument in eastern San Luis Obispo County.

The biological inventory of the reserve is in the second of two years. It is being conducted with the help of Wemmer and other camera trap experts by the state Department of Fish and Game, which owns the reserve. The survey focuses on smaller carnivores, such as foxes, raccoons and weasels.

“The integrity of an ecosystem is reflected in the health of its carnivore communities,” said Craig Fiehler, the state wildlife biologist in charge of the study.

Wemmer and Fiehler recently changed out six camera stations in the reserve and downloaded their photographs. All yielded usable photos, but the ones of the sandstone rock turned out particularly well.

“I took one look at that rock and knew it would be the perfect lookout for a carnivore,” Wemmer said.

The outcropping is located in a thick stand of chamise, amid rolling, arid hills of blue oak. The camera trap had been set up a month previously, focused on the outcropping.

Programmed to be active at night, the camera station photographed any animal that visited the rock. Its shutter and flash clicked anytime an infrared sensor detected the moving heat field of an animal’s body.

The Chimineas Ranch has been part of the state’s network of wildlife refuges for less than a decade. Fish and Game recently came under criticism by numerous environmental groups for allowing too much grazing on the reserve. Overgrazing reduces the suitability of the land as wildlife habitat and damages sensitive areas such as streams.

The agency is set to publish a management plan for the reserve by the end of the year. Fiehler’s wildlife inventory will help the agency develop ongoing management strategies, and its findings will eventually be published in scientific journals.

Surveying the site

Fiehler divided the ranch into a grid pattern of 150 separate squares. The goal is to monitor each square at least once with a camera trap baited with punctured cans of cat food or mackerel. Between 10 and 15 camera traps are deployed in the field at any one time.

The cameras are placed in areas that have the best chance of being visited by an animal, such as game trails, rock outcroppings and stream banks. They have recorded more than a dozen carnivore species as well as just about everything else that moves in the reserve, including bears, coyotes, gray foxes, deer, badgers, bats, wood rats, kangaroo rats, jackrabbits, roadrunners, burrowing owls and many other birds, and a single mountain lion.

Memorable sequences recorded include a fox napping in a sandstone cave, pocket mice wrestling, and Townsend’s big-eared bats swooping low over a stock pond.

The study is also remarkable for what it has not found.

Four carnivores that biologists have every reason to think live in the reserve have not yet showed up in a single picture. These include the ringtail, a raccoon-like animal with huge eyes and an extremely long, banded tail; the long-tailed weasel; and striped and spotted skunks.

The lack of skunks, particularly the ubiquitous striped skunk, is especially surprising. But Wemmer has his heart set on finding a ringtail.

“I’ve become like Ahab in search of Moby Dick in my quest to photograph a ringtail,” he said.

Photos as research tool

The Carrizo Plain study is part of the growing use of camera traps in wildlife conservation. They have several distinct advantages as a research tool, Fiehler explained.

They are cheap ($200 for a starter model), are easy to use, yield lots of data, operate continuously for long periods and don’t involve capture and other invasive activities that can harm wildlife. Among the other local uses of camera traps, Cal Poly and Caltrans have a study under way to examine migration patterns of bears and other animals that cross Highway 101 at the top of the Cuesta Grade.

Wemmer, who refers to himself as a camera trap codger, is a retired Smithsonian scientist who has amassed a decade of camera-trapping experience and gives seminars on their use. He has 34 camera traps, most of which he built.

He visits the Chimineas every six weeks. He agreed to get involved in the research project because he was struck by the research potential of the reserve. The sprawling ranch has multiple habitats and varied wildlife, along with a large ranch house that is ideal as a research headquarters.

“It’s like a little piece of historical California,” he said.