On the Prowl

In the warm, still morning, a male bobcat is on the move in the Santa Monica Mountains.

No one can see him. Just a few hundred feet away in one of the parking lots of the national park, oblivious day hikers are coating on sunscreen and picking out trailheads.

The tall grass doesn’t even stir as the bobcat slinks through it, hunting for breakfast.

But wildlife biologist Eric York knows where the bobcat is.

He adjusts the frequency on the radio receiver hanging over his shoulder and hoists the wooden handle of a three-pronged antenna aloft. As he swivels it in the air, the receiver clicks and clucks at him, making soft, steady little noises.

Somewhere out there in the golden fields of Cheeseboro Canyon, a radio collar around the neck of a 20-pound bobcat is doing its job, sending signals back so York can locate his target.

But he is no big-game hunter. Since March, York and a team of national park biologists and student volunteers have been tagging and tailing bobcats and coyotes around the Santa Monica Mountains National Recreation Area, using radio telemetry to study the movements and habits of the animals.

It’s always been a guessing game in the past, figuring out how many animals roam the great expanse of the mountain range that stretches from Ventura County to Los Angeles County.

But through radio telemetry and photographic tracking, biologists hope to finally determine the population of various carnivores, particularly bobcats and coyotes.

More importantly, they believe this study--a collaborative effort of the National Park Service, UCLA, the University of Massachusetts and the Santa Monica Mountains National Recreation Area--will show what the effects of encroaching development are on the species.

“This research program has been a top priority for the parks because we know if we’re going to lose animals in the Santa Monicas, it is going to be the large carnivores,” said project manager Ray Sauvajot.

As York sets off through the fields, drawn up a hillside by the hum of the receiver, he explains that this cat tends to range in lower Cheeseboro Canyon. The cat doesn’t venture farther west than the Calabasas landfill or south of the park’s boundaries. He hunts in the mornings and the evenings and now, just after 9 a.m., it is almost time for him to curl up under a bush and take a lengthy nap.

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But before the cat settles down to sleep, York wants a glimpse of him.

With the antenna held out like a magic wand, the biologist crests a hill and spots his quarry.

“There he is,” he says, pointing to a pair of ears popping out from behind the sagebrush. The cat takes off, turning occasionally to stare at the man chasing him. He ambles down to a creek bed, stops again and whisks his stumpy little tail a few times, annoyed by the disturbance. Then he disappears into the scrubby sage and a few crows wheel into the air to complain about his presence.

Most days, York rises well before dawn and accompanies the animals on their hunts. He usually follows them by truck, noting their bearings on a map. The three coyotes he has collared--two females, one male--specialize in suburban snacks.

“They go from garbage can to garbage can, from house cat to house cat,” York said.

The coyotes are social, hanging out in packs. Sometimes when York tracks them into developments, he can simultaneously hear the radio signal and the collared coyote yelping at a companion. York watches as the coyotes pick a bush--sometimes right next to a house--to sleep in after the sun comes up. Coyotes are unfazed by roadways, and he often sees them trotting down sidewalks at dawn, he said.

But bobcats are loners.

“Typically they kind of avoid each other,” York said.

York and his team have five of the cats collared, three males and two females. In March, one of the males and one of the females spent a day together. York thought they might have been mating, but the female showed no signs of being pregnant.

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Unlike the coyotes--whom they compete with for small prey--the bobcats are not interested in plundering dumpsters and garbage cans. While it is still too early in the study to draw conclusions, project manager Sauvajot said bobcats seem to be staying away from developed areas. If that’s the case, it suggests that the bobcat population size will shrink along with open space.

“Some animals will be pushed out of what is left,” Sauvajot said. “We want to find out what it is about a bobcat that creates that sensitivity to development and what do we need to maintain habitat for them?”

By January, the team hopes to have 15 of both species collared. Using foot-traps that don’t harm the animals, they tranquilize them, weigh them, measure them and attach the collar. In about an hour, the animal shakes off the drug and goes on its way.

Until some of the cubs and pups now being raised get a little bigger, the team will hold off on trapping more animals.

“This fall trapping should be easier because the younger animals are dumber,” York said with a grin. “The adults figured me out pretty quickly.”

Sauvajot said the team would also like to study mountain lions, which are more scarce than bobcats but also live in the Santa Monicas. Hikers and bikers often mistake the smaller, short-tailed bobcats for the tawny mountain lions, which can be 4 feet long. An excited biker called Sauvajot a few weeks ago to report a “mountain lion cub” in Cheeseboro Canyon. More likely what the biker saw was one of the collared bobcats, Sauvajot said.

The study is concentrated now in two Ventura County canyons, Cheeseboro and Palo Comado and in smaller Liberty Canyon just over the Los Angeles County line. But eventually the study will encompass parklands on the southern side of the freeway. One question that intrigues the biologists is if and how the animals cross the Ventura Freeway, which teems with cars at almost any hour of the day.

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Radio telemetry is only half of the program the team has devised. The second component, keeping a photographic record of the animals’ activities, involves more than 50 automatic cameras--donated by Canon, which also put $55,000 into the project--yards of telephone cords, plastic sandwich boxes and jars of the stinkiest, nastiest hunting bait around.

“I’m not sure I’m ready to patent it yet,” York said, holding up one of the makeshift creations. The device, designed to get the animals to photograph themselves by stepping on a pressure plate, is similar to ones York used while studying animals in the Massachusetts woods during graduate school.

The plastic box, a little bit bigger than the camera, is attached to the end of a wooden stack. Inside the box, the camera is wired into a telephone connection, which in turn is wired into a pressure plate a few feet away.

The pressure plate, mostly covered with dirt, conceals a jar of hunting lure, a revolting mix of skunk smell and glandular goop from animals. Its odor most closely resembles something dead. The animals love this, York explains.

“It’s that rank smell,” he said. “Anyone who has ever had a dog knows they love to roll in dead things.”

In its first round of experimentation, the team has already collected many rolls of film. One of the highlights is a series of a gray fox pulling up the pressure plate and rolling ecstatically in the bait, like a cat with catnip.

“He used up the whole roll of film,” Sauvajot said ruefully. “I guess the flash didn’t bother him.”

So far, the only bobcat the cameras have caught is one of the animals swaggering away from the bait. But coyotes, foxes and deer have already proven frequent visitors. Calibrating the pressure plate has been difficult; the first rolls of film included a lot of shots of birds landing on the plate.

Having made some adjustments in the design, the team spent most of the past week reinstalling the cameras. They are set in remote spots up and down the canyons, in areas where animals tend to travel.

As he finished rigging up one of the cameras along a high ridgeline overlooking the Ventura Freeway, York explained how he knows his quarry frequent the hilltop.

“This is Bobcat Litter Box Hill,” York said. “They are just like a cat. They like to use the same area again and again.”

He smiled. A biologist who knows his bobcats.

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Tracking Wildlife

Animals have become unwitting participants in a research project in the Santa MonicaMountains National Recreation Area. Scientists have created a photographic device- designed to get animals to photograph themselves. More than 50 cameras have been installed in remote areas of Cheeseboro and Palo Comado canyons, as well as in Liberty Canyon in L.A. County.

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* Camera: Sits a few feet off the ground in a protective box, camouflaged in mountain vegetation.

* Target animals: Coyotes and bobcats.

* Pressure plate: Connected to the camera with a cord, the weight of the animal lured to the plate by bait, scent lure or both releases the camera’s shutter.

* Source: Santa Monica Mountains National Recreation Area