Cougars’ Worst Foe Is Found to Be Cars : Wildlife: Biologists who tracked 32 cats in Santa Ana Mountains for five years found only seven survived. Roads and development are threatening their habitat.

For the past five years, the deaths of cougars have been tracked by wildlife biologists in the Santa Ana Mountains, where the cats once roamed freely in vast expanses of wilderness.

This unprecedented study of the cougar population over an 800-square-mile range has discovered that its greatest threat is not gunshot wounds, disease or even cannibalism--all of which do occur.

What kills more cougars than anything else is traffic.

Encounters with vehicles have increased with the number of homes and roads built in the mountains, according to the $700,000 study funded by Orange County and the state Department of Fish and Game.

“The cougar population in the Santa Ana Mountain range is clearly in jeopardy of becoming extinct due to habitat loss and fragmentation,” said wildlife biologist Paul Beier, a researcher in the study.

However, the study offers few recommendations. Besides installing chain-link fences along well-traveled mountain roadways and slowing the growth of residential and commercial development, Beier said, “there is not much you can do.”

The study report does show--often in graphic detail--how cougars have succumbed to the effects of increased development.

Of the 32 cougars fitted with electronic tracking collars and studied, only seven survive, researchers said. A third of those that died were hit by cars.

One cat, known to researchers as M-10, suffered two encounters with traffic. Attempting a nighttime crossing of the Riverside Freeway at Coal Canyon, the cougar suffered a broken leg but managed to escape police.

More than a year later, the cougar, fully recovered from the first accident, darted into traffic on Santiago Canyon Road, where it was hit and died of internal injuries.

Researchers found that road deaths were not a factor in the demise of cougars anywhere else in the western states. In most previous studies, it was found that hunting and “predator-control activities” caused the most deaths.

The study estimated that the local cougar population consists of 10 to 14 adult females, as many as five adult males and 10 to 20 cubs. About 800 square miles of habitat exist to support them, but Beier said the most important consideration is to keep pathways or “wildlife corridors” open so the animals can move freely.

The study showed that cougars will travel several miles during nighttime hunting sessions and need passageways that provide a link to other mountain areas.

The corridors also provide key breeding links between cougars in the Santa Ana Mountains and larger numbers in the Palomar range near Temecula. The most critical of those passageways is known as the Penchanga Corridor.

The corridor, named for Penchanga Creek, which runs between the two areas, has become increasingly threatened by the presence of Interstate 15 and development south of Temecula. During the study period, researchers reported, four cougars were killed while attempting to cross Interstate 15.

One option for promoting safer passage, the study stated, is constructing a fence along Interstate 15 to divert cougars to an underpass that would allow access for cats traveling west into the Santa Ana range.

“Although I-15 is the biggest hurdle today, within a few short years, urbanization--if not controlled--will present an even more impenetrable barrier,” the study stated.

“All regional parks, except (Ronald W.) Caspers Wilderness Park (near San Juan Capistrano), will become unusable by cougars if urbanization isolates them,” the study found.

The study’s focus on the threatened habitat clearly overshadowed its conclusions about cougar encounters with humans.

Although the study was initiated after mountain lions mauled two children in separate attacks in Caspers Regional Park in 1986, Beier’s research found that in the past 100 years only 10 deaths can be attributed to cougars in the United States and Canada.

Furthermore, the local study found that “cougars entered urban areas with astonishing rarity and were generally unseen by the thousands of potential observers in their midst.”

“The cougars in our study were remarkably adept at avoiding contact with humans,” the report said, “and it is difficult to imagine that their behavior could have been more reclusive.”

Beier said: “I think most would agree with me that cougars are no more dangerous to humans than breathing the Southern California air.”

Few may be in a better position to offer such an assessment than Beier, who has spent years tracking the animals and recording their habits.

“Probably more than any other animal, the cougar symbolizes the wilderness,” Beier said. “This is an animal with quite a bit of presence. They are the epitome of strength and stealth.

“But when you come across a (cougar’s) fresh kill, like a deer, something so much larger than a cat, you get a deep respect for its strength. The ecosystem would be a much sadder place without it.”