When two mountain lion kittens were discovered in a remote den in the Santa Monica Mountains three years ago, there were concerns about their ability to survive in this challenging environment.

Although a wildlife corridor across the busy 101 Freeway is in the planning stages, I wondered back in January 2016 if it would it be built in time to save these two kittens.

Sadly, the answer is no. One of those kittens, three-year-old P-47, was found dead last month by the National Park Service after his GPS collar sent out a mortality signal.

It wasn’t another mountain lion or a vehicle that killed him. Like too many other mountain lions in this area, it was rat poison.

A liver test found that P-47 had been exposed to six different anticoagulant compounds that are commonly found in second-generation rodenticides: brodifacoum, bromadiolone, chlorophacinone, difethialone, diphacinone, and difenacoum. A necropsy determined poor P-47 had suffered internal hemorrhaging in his head and lungs.

“It’s unfortunate to see an otherwise healthy mountain lion lost from what appears to be human causes,” Seth Riley, wildlife ecologist for Santa Monica Mountains National Recreation Area (SMMNRA), said in a news release.

Of the 22 mountain lions in this area that the National Park Service tested, 21 had ingested rat poison, including a three-month-old kitten. P-64survived the devastating Woolsey wildfire but was found dead a few weeks later. Like P-47, P-64 been exposed to a shocking six different anticoagulant compounds.

Mountain lions usually ingest rodenticides when they eat an animal that ate the poison, such as a gopher, or when they eat an animal that ate an animal that consumed the poison, such as a coyote that ate a squirrel.

What’s especially tragic about P-47′s death is that he could have helped increase the genetic diversity of the L.A. mountain lion population, if only he had lived long enough to mate. His father, P-45, had traveled from territory north of Los Angeles.

Along with rodenticide poisoning and vehicle strikes, another major threat to L.A. mountain lions is inbreeding, due to their limited habitat. These lions have the lowest genetic diversity ever recorded of any mountain lion population besides the Florida panther that went nearly extinct, Jeff Sikich, an SMMNRA biologist, said in 2016.

A recent study warned that Southern California’s mountain lions could also become extinct in just 50 years. To help prevent this from happening, deadly anticoagulant rodenticides should be banned and a wildlife corridor over the 101 Freeway needs to be built ASAP.

“Like their mom, the kittens are now wearing tracking devices. Here’s hoping the NPS discovers them crossing that wildlife bridge five years from now,” I wrote three years ago. How heartbreaking that P-47 will never get that chance.

Take Action

Please join over 130,000 people who have signed this Care2 petition urging the California Department of Transportation to start constructing the wildlife bridge over the 101 Freeway.

To help save wildlife statewide, please sign and share this petition telling the California Department of Pesticide Regulation to outlaw deadly second-generation anticoagulant rodenticides.

Don’t use rat poison, and tell everyone you know not to use it, either. You can find better alternatives on the Safe Rodent Control website.

This article was first published by Care2.com on 03 May 2019.