Community, Diversity, Sustainability and other Overused Words

Rat Poison Found in Mountain Lion P-41's Body found in the Verdugo Mountains

National Park Service biologists began tracking P-41 in May of 2015

12/19: Lab tests were unable to determine a cause of death for P-41, a mountain lion whose movements in the Verdugo Mountains were captured in beautiful photographs by citizen scientists, National Park Service officials said.

But the lab results from the state Animal Health and Food Safety Laboratory did show the cougar suffered from a common issue among big cats in California's wildlife-urban interface: poisoning.

"The lab found both first- and second-generation anticoagulants in his liver," Seth Riley, a wildlife ecologist for the Santa Monica Mountains, said in a statement. "We continue to see indications that these poisons are working their way up the food chain through what we believe is unintentional poisoning."

Residents found the male puma in October near Shadow Hills, officials said. The cat had been dead for several days and was noticeably thin. The body was too decomposed to pinpoint a cause of death, according to the park service said.

The compounds found in P-41's system were brodifacoum, bromadiolone, chlorophacinone, difethialone, diphacinone, and difenacoum.

"Exposure to anticoagulant rodenticides is common among the mountain lions we necropsy, from all over the state" said Deana Clifford, senior wildlife veterinarian for the California Department of Fish and Wildlife. "Sadly, we were not able to determine the cause of death and to tell the full story of this animal, but we do know he was thin at the time of his death."

Although it's not known exactly how P-41 ingested the poisons, researchers believe mountain lions are exposed through secondary or tertiary poisoning, meaning that they consume an animal that ate the bait, such as a ground squirrel, or an animal that ate an animal that consumed the bait, such as a coyote. See infographic on how rodenticide can work its way up the food chain.

National Park Service researchers have documented the presence of the anticoagulant rodenticide compounds in 14 out of 15 local mountain lions that they have tested, including in a three-month-old kitten.

National Park Service biologists began tracking P-41 in May of 2015 and found that, with the exception of the Griffith Park mountain lion known as P-22, he had the smallest home range of any adult male mountain lion in the study.

The GPS function on P-41's collar failed earlier this summer, so biologists were unable to track how, if at all, the La Tuna Fire affected his movements. He was approximately 10 years old at the time of his death.

Since 2002, the National Park Service has been studying mountain lions in and around the Santa Monica Mountains to determine how they survive in an increasingly fragmented and urbanized environment.

The California Department of Fish and Wildlife is responsible for overseeing the management and conservation of mountain lions in the state.

Santa Monica Mountains National Recreation Area (SMMNRA) is the largest urban national park in the country, encompassing more than 150,000 acres of mountains and coastline in Ventura and Los Angeles counties. A unit of the National Park Service, it comprises a seamless network of local, state, and federal parks interwoven with private lands and communities. As one of only five Mediterranean ecosystems in the world, SMMNRA preserves the rich biological diversity of more than 450 animal species and 26 distinct plant communities. For more information, visit


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