SUNLAND (CBSLA) – Researchers said Tuesday they were unable to determine the cause of death for a roughly 10-year-old male mountain lion known as P-41 whose remains were found near the Verdugo Mountains, but they said the animal had multiple rat poisons in its system.

P-41 was found dead by a resident Oct. 4 near the Shadow Hills neighborhood south of the 210 Freeway.

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National Park Service officials said in October they suspected the 7,000-acre La Tuna Fire may have contributed to P-41’s death, but a necropsy determined that the animal’s remains were too decomposed to pinpoint a cause of death.

The presence of six types of rat poison in P-41’s system, however, point to a growing threat to the region’s mountain lion population, officials said.

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

NPS officials said anticoagulant rodenticide compounds have been found in 14 of 15 lions tested for the substance. Researchers believe the lions are not ingesting the poison directly, but get it in their systems by eating rodents such as squirrels that had already ingested it. The poison can also move up the food chain, first by being ingested by a rodent, then infecting a coyote that eats the rodent, then moving into a lion that eats the coyote.

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“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 state 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.”

Also in October, the remains of P-27 were found in the Santa Monica Mountains. Described as the dominant male in the area, P-27 is believed to have been dead for at least one month when his remains were discovered.

The region’s freeway network has served to isolate the mountain lion population in the Santa Monica Mountains, biologists say. In April, biologists confirmed that a 4-week-old female mountain lion recently discovered in the Santa Monica Mountains was likely the product of inbreeding.

Caltrans has proposed building a wildlife bridge across the 101 Freeway in Agoura Hills that would allow animals to travel between the Santa Monica Mountains and Simi Hills.

The NPS has been studying mountain lion movements in the region since 2002 using GPS collars.

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