An unusually high number of mountain lions have been seen roaming the Sunol hills and the researcher who discovered them is trying to figure out whether the remote parkland is a one-of-a-kind cougar gathering spot or a random crossroad for peripatetic pumas.

At least nine pumas have been photographed within 4 miles of one another in the Sunol and Ohlone Regional Wilderness areas, a huge stretch of rolling hills and grasslands south of Livermore. That's nine predators crowded in an area smaller than the size of a single male cougar's territory.

Steven Bobzien, an ecologist and the resident mountain lion expert for the East Bay Regional Park District, said that many pumas would not normally congregate on territory 10 times that size.

“The mountain lion densities are really extraordinarily high,” Bobzien said as he climbed out of his truck on a brilliant sunny day recently to check his remote cameras for signs of more cougars. “It's pretty phenomenal.”

Mountain lions are hard to spot in the flesh, so Bobzien relies on remote cameras to do the lion’s share of his work.

The six cameras he attached to trees two years ago have caught the big cats 29 separate times, resulting in 396 photographs. There were several other unidentified cats, he said, but the footage wasn’t clear enough to judge whether they were among the nine he knew.

IDing the cougars

Bobzien and his colleagues combed through the images and identified two males, four females and three sub-adult cougars. Even more startling, Bobzien said, is the fact that all nine pumas were photographed between May and September of last year within a 4.2-square-mile area stretching from the ridge line around Rose Peak to the wooded riparian valley next to Alameda Creek where he placed his cameras. That’s a lot of pumas in a small space in an extraordinarily small time frame, he said.

“I always suspected there were good densities of mountain lions in Sunol-Ohlone, but the number these cameras captured is really remarkable and pretty exciting,” said Bobzien, whose studies mark the first time anyone has attempted to document cougars on East Bay Regional Park land. “It’s nice to know we have these beautiful, majestic predators out there.”

The problem is that there is no way to know at this point the reason for the feline throng. Puma populations can fluctuate depending on how much prey there is, availability of water, how many dispersing juvenile males there are or whether there is a dominant male in the area.

Bobzien said he doubts the mountain lion densities extend throughout the region. Instead, he suspects that he happened to put his cameras at a crossroads where several mountain lion home ranges overlap.

“There is something going on, but we don't have any radio collars on the cats” to help determine whether the cat crush is a fluke or a cunning adaptation to changing conditions, he said.

Which is why Bobzien wants to expand his study and put up cameras in the Oakland hills and in the Mount Diablo range, areas where puma populations have been isolated by highways and development. He is looking for a partner to help pay for radio telemetry collars for the cougars so that he can study their movements, predation habits, and mating and cub-rearing behavior.

Mountain lions, which are also called cougars, pumas and catamounts, were thought to be extinct throughout much of Northern California only a few decades ago. There are now an estimated 3,000 to 5,000 of them in the state, and they are protected under the 1990 California Wildlife Protection Act.

The number of pumas in the state has grown dramatically in recent years judging by the number of reported sightings. The California Department of Fish and Wildlife expects to see future increases in puma encounters due primarily to human encroachment and habitat destruction.

Joining forces

A coalition of conservation groups and wildlife organizations, including the Bay Area Puma Project, the Mountain Lion Foundation and the California Department of Fish and Wildlife, have joined forces in an effort to protect the animals and educate the public about them.

Wildlife biologists in the Bay Area recently stepped up their studies of the muscular felines and their movements. A study using radio and GPS collars is being conducted by UC Santa Cruz researchers in the Santa Cruz Mountains, but nobody has done a comprehensive study of pumas in the East Bay.

Bobzien said the Sunol Regional Wilderness and adjacent Ohlone Regional Wilderness are ideal for having collared mountain lions because there is continuous puma habitat from Del Valle Regional Park to Mission Peak Regional Preserve in Fremont. The ridges and valleys are often teeming with deer, wild pigs, hares and the occasional tule elk wandering up from San Antonio Reservoir, he said.

“This area is so biologically diverse, it’s amazing,” Bobzien said. “It’s kind of a blend of Northern and Southern California species. We’ve got roadrunners, magpies and one of the highest nesting densities of golden eagles in the world.”

Even without collars to confirm his theories, Bobzien has been able to calculate puma movements based on the number of images taken at the various camera stations. The mountain lions, for instance, were photographed most frequently in and around Alameda Creek in June, July, August and September, he said. The creek dried up in October the past two years and that is when the pumas stopped being seen in the area, he said.

“It shows how critical water is in the movements and dispersal of these carnivores, and it probably indicates the movements and dispersal of prey,” he said. “They are a really important predator that has a ripple effect on the ecological functionality of a particular region.”

Video of a bobcat

No images of mountain lions were found when Bobzien checked the camera stations that recent sunny day, but there was video of a bobcat seemingly charging and pouncing on the camera. There were also images of cows, squirrels, a raccoon, several mice, a great horned owl and a farmer’s passing truck.

The discouraged ecologist was about to call it a day when something big, furry and feline leaped out from behind a nearby tree, prompting a moment of exhilaration. Was it one of the nine cougars?

“It’s a bobcat!” Bobzien said to his companions before hightailing it around a thicket in an attempt to head off the smaller, but no less fearsome, predator. It was not his lucky day. The animal got away unphotographed and, judging by the feathers scattered about, it had carried away the remains of a band-tailed pigeon.

Peter Fimrite is a San Francisco Chronicle staff writer. E-mail: pfimrite@sfchronicle.com. Twitter: @pfimrite.

Five facts

about pumas

1 As many as 5,000 pumas live in

California.

2 Thousands of the big cats were killed between 1907 and 1963, when bounties were offered for shooting them.

3 Cougar hunting was banned in California in 1990 when the animals were given special protected status under the California Wildlife Protection Act.

4 There have been 17 verified mountain lion attacks on humans in California since 1890, including six deaths.

5 An average of about 112 cougars are killed in the state each year primarily by trappers or ranchers with depredation permits.





If you encounter a puma

Do not try to run away. Instead, stand tall, face the animal and back away slowly. If it approaches, stand your ground, yell menacingly and hold up a stick or weapon.