Rat Poison is Killing Endangered Mountain Lions in California

December 21, 2017 at 11:12 pm

13 out of 14 Los Angeles-area mountain lions tested positive for rat poison, at least three have died

Mountain lion P-41 when he was first captured in May of 2015. Photo Credit: National Park Service.

A mountain lion that managed to cross a Southern California freeway and make its home in the mountains north of Los Angeles was found dead in October.

The animal was being studied, along with about 50 other mountain lions in the Santa Monica Mountains, by the National Park Service to determine how they survive in an increasingly urbanized area.

Because his death occurred a few weeks after after wildfires burned a good chunk of his home range in the Verdugo Mountains, researchers thought the fires might’ve contributed to his death. But lab work performed by the California Animal Health and Food Safety Laboratory found six different anticoagulant rodenticide compounds in his liver.

National Park Service researchers found rodenticide in 13 out of 14 other mountain lions they tested recently, and have attributed at least three mountain lion deaths to the the poison.

Researchers believe mountain lions are exposed to rat poison indirectly, by consuming animals that ate the bait, such as mice or squirrels, or animals that ate other animals that ate the bait, such as coyotes:

“We continue to see indications that these poisons are working their way up the food chain through what we believe is unintentional poisoning,” said Dr. Seth Riley, wildlife ecologist for the Santa Monica Mountains National Recreation Area.

“The long-term survival of mountain lions in this region is threatened by a number of factors, none more significant than the loss and fragmentation of habitat by roads and development,” the National Park Service says on its website.

This leads to deaths not only from vehicle collisions, but from lack of genetic diversity due to inbreeding, because the animals are “basically trapped on an island of habitat, surrounded by freeways and the Pacific Ocean.”

Mountain lions — also known as cougars, panthers and pumas — used to flourish all over North and South America.

They are now nearly extinct in the Eastern part of the United States, and are a protected species in California. The Sierra Nevada mountains are one of their few remaining habitats.

The mountain lion is regulated under the Convention on International Trade in Endangered Species of Wild Fauna and Flora.