Wildlife sleuths use DNA to understand deadly pet attacks in Santa Cruz Mountains
Genetic research can reveal the killing patterns of mountain lions and coyotes, protecting domestic animals.
At dawn, silent and unseen, a mountain lion climbed over a tall iron gate and crept down the driveway of Ron Aldana’s Los Gatos ranch, pouncing on his pet goat Chupita and killing her instantly.
But the deadly attack left behind an important clue: saliva.
A sample, quickly swabbed from the wounds of the dead goat, is part of a small but growing collection of DNA from wild predators collected for the new Bay Area Carnivore-Livestock Interactions Project (BACLIP).
Like crime-scene DNA collected by police, a trace amount of genetic material can reveal the identity of the mountain lions or coyotes that hunt on the edges of our communities, sometimes killing pets and livestock.
Developed after extensive conversations with local livestock producers, BACLIP is a partnership between the nonprofit Panthera and the Midpeninsula Regional Open Space District, UC Cooperative Extension, UC Santa Cruz and CSU Fort Collins, among others.
The five-year project, which started in 2022, focuses on deaths caused by mountain lions and coyotes in three counties: Santa Clara, Santa Cruz and San Mateo. It could reveal if the same animals are responsible for repeated attacks on domestic animals — and suggest solutions, said wildlife biologist Veronica Yovovich of Panthera, which leads the project.
“We’re trying to figure out how we can minimize losses due to carnivores,” she said. With enough data, “we can say something meaningful about predation and ‘problem animals.'”
For instance, if the same patterns of DNA show up in samples from different incidents, it suggests that a single predator is a repeat offender, with an acquired taste for pets and livestock.
If the DNA pattern is unique, the predator may have just grabbed an animal that had the misfortune of crossing its path. The killing was opportunistic, not strategic.
In human crimes, DNA has been used to prove that suspects were involved in crimes and to free people who were wrongly convicted. It has been integral to several high-profile criminal cases, like the Golden State Killer.
BACLIP’s wildlife project is a research effort, not a management tool. So while it won’t quickly reveal a specific “problem animal,” its general findings will guide livestock and wildlife policies, as well as help create tools to prevent attack.
“It will help find the best ways to prevent mountain lions and coyotes from interacting with livestock and pets, so we can coexist,” said Leigh Ann Gessner of the Midpeninsula Regional Open Space District, which manages 70,000 acres of the Santa Cruz Mountains, connecting the San Francisco Peninsula to the San Mateo County coast and the South Bay.
Based on patterns of blood hemorrhages, the BACLIP research team can determine whether the domestic animal was killed by a carnivore or just scavenged after a natural death.
The DNA, retrieved with a cotton swab, can reveal whether the predator’s DNA belongs to a mountain lion, coyote, domestic dog or some other animal. It can even identify an individual.
So far, BACLIP has sent an estimated 10 samples to the California Department of Fish and Wildlife’s Genetics Research Lab for analysis. It is still awaiting results.
Meanwhile, the team is testing various techniques to deter predators. Possible strategies include the use of audio, visual and physical stimuli to frighten them away. “Turbo fladry,” a low current electric line of fencing with red flagging, is proven to help protect livestock from wolves in the Great Lakes and Northern Rockies regions. Panthera is now testing the fencing to see if it fends off the Bay Area’s mountain lions.
“There are wide-reaching benefits for this research,” said Gessner. “It will provide information that can help public land managers like Midpen, and also private homeowners.”
In recent years, a growing number of horror stories have echoed in community conversations and internet message boards, recounting tales of bold predators that attack pets and livestock alike.
Wild carnivores pose an increased threat because their numbers have escalated — and a swelling number of Californians are living on the edge of wilderness.
Historically, both mountain lions and coyotes were heavily hunted in California. They grew fearful of humans, and their numbers dwindled.
In 1990, the passage of Proposition 117 — commonly known as the “mountain lion initiative” — placed a permanent ban on the sport hunting of lions in California. An estimated 3,200 to 4,500 mountain lions now roam the state. The Santa Cruz Mountains comprise the largest contiguous mountain lion habitat in the greater Bay Area, with a population estimate of 50 individuals, according to UC Santa Cruz professor Chris Willmers of the Santa Cruz Puma Project.
Coyotes are even more ubiquitous. The California Department of Fish and Wildlife estimates that there are 250,000 to 750,000 coyotes statewide. Postmortem studies of their stomachs show a smorgasbord of samplings: rabbits, birds, bugs, fruit — and an occasional cat or dog.
As more land is developed for human use, wild spaces are fragmented, so it’s harder for wild animals to find shelter, water and open range. Mountain lions may traverse yards and pastures. Coyotes adjust to the clatter and commotion of urban life.
Ron Aldana built an imposing eight-foot-tall fence to protect his small ranch, located on Summit Road in the Santa Cruz Mountains.
At daybreak on June 11, Aldana released Chupita from her nighttime stall in a barn. Then he went inside to cook breakfast. He heard his dogs bark but dismissed it.
An hour later, he joined his dogs on a quick stroll down the driveway — and discovered, to his shock, Chupita. The goat had been killed by a bite on her neck, and was missing part of her thigh.
He discovered large paw prints on both of the freshly painted stucco columns that support his wrought iron gate. At six feet, the gate was slightly lower, and easier for a cat to climb, than the fence.
“We were devastated,” said Aldana, who called the California Department of Fish and Wildlife for help. A wildlife official promptly responded and swabbed the wound for DNA. “It happened so quickly. The mountain lion must have been nearby, waiting.”
Worried for the safety of his dogs, he keeps them inside at night. At dawn and dusk, he waits with them.
He’s discovered the nearby skeletons of two deer, and has heard reports of another mountain lion attack in the neighborhood earlier this year.
“The research is a great idea,” he said. “If it’s proven that one animal is doing this all, that would be good to know. Especially if it’s a crazy one.”
If you believe your pet or livestock was killed by a carnivore, contact:
California Department of Fish and Wildlife at (707) 428-2002.