8 min read

People Are Accidentally Poisoning These Famous Mountain Lions

There's an easy way to save their lives — but most people don't know about it.

When biologists noticed a sickly mountain lion on their trail cameras in 2014, it was hard to believe that he was once the stunning big cat who rose to stardom on the front cover of National Geographic.

Just the year before, he was vibrant, strong and prowling near the Hollywood sign in Los Angeles. He had even crossed two of California’s busiest freeways seamlessly to get there. But now, he looked to be on the brink of death — and rat poison was to blame.

mountain lion california rat poison
P-22 suffering from mange in 2014 | National Park Service

“He was suffering from mange and we found that he had been exposed to rodenticides,” Seth Riley, a biologist for the National Park Service who studies mountain lions in the Santa Monica Mountains, told The Dodo. “He was in really rough shape.”

Luckily, the mountain lion, known as P-22, was captured and treated for the mange and made a full recovery. But his case pointed to an issue biologists had been seeing for years in bobcats, coyotes and, now, in mountain lions: Rat poison is making its way up the food chain, putting California’s largest urban predators at risk.

mountain lion california rat poison
P-34, a female mountain lion who died from rat poison in September 2015 | National Park Service

Since 2002, all but one of the 13 mountain lions tested by the National Park Service have had one or more rat poison compound in their systems — which is causing biologists to pin responsibility for a number of illnesses and deaths on unintentional poisoning.

“Various pest control companies argue that the products they use are safe and that there’s not going to be any secondary poisoning,” Riley said. “But there is. We have seen a huge amount of exposure in bobcats, coyotes and mountain lions.”

The type of poisons that have continuously been found, Riley said, are called anticoagulants. Once ingested by a rodent, these substances remove the blood’s clotting ability, and, slowly, the rat or squirrel will bleed to death internally. In some cases, the poisoned rodent can live up to 10 days after initially being exposed to the poison — leaving time for larger predators, like raccoons or foxes, to become poisoned themselves from hunting the rodents.

mountain lion california rat poisoning
An unidentified female spotted in the Verdugo Mountains | National Park Service

Eventually, the poison reaches the animals at the top of the food chain, like mountain lions or hawks, and cause imminent illness or death. The illness most frequently associated with exposure to the poison is mange — which comes about once the animal’s immune system becomes weakened from the poison.

“Our best guess is that the mountain lions are originally getting the poison in their system from hunting poisoned coyotes,” Riley said. “When they first kill something, they’ll go straight for the organs — especially the liver, which is where the largest concentration of poison is, since the animal’s liver is trying to filter out the contaminant.”

california mountain lion rat poison
A female, known as P-39, ready to eat a meal | National Park Service

This is believed to be the case for P-41, the most recent mountain lion to be found dead with rat poison in his system. While his cause of death was undetermined, as he had been deceased for days by the time he was found in October, Riley believes the poisons certainly weren’t helping the big cat.

“He had six different compounds in his system,” Riley added. “That’s the most compounds we’ve ever found.”

While the state of California has outlawed second-generation anticoagulants for regular use and they’re not sold at hardware stores, professional pest control companies are still authorized to use them. Additionally, residents can legally purchase first-generation anticoagulants, which have also been found in the systems of mountain lions and countless other predatory species including hawks, owls, coyotes and bobcats.

bobcat rat poison california
A bobcat with mange receiving medical treatment in July 2016 | National Park Service

Regardless of which type of poisons people use, biologists suggest using other methods of pest control. Laurel Serieys, wildlife biologist and manager of research website Urban Carnivores, believes the simplest way to stop the unintended exposure of wildlife to poison is to stop using the poisons altogether.

“If your pest problem feels beyond your control, consider finding a pest control company that uses sustainable practices to assist you,” Serieys advises. “Companies that practice Integrated Pest Management [an ecosystem-based strategy that focuses on long-term prevention of pests] should use poisons only as a very last resort.”

california mountain lion rat poison
P-41, a male who was found dead in October 2017 | National Park Service

Serieys also suggests installing nesting boxes in trees around your home to encourage predatory birds to settle nearby, who will naturally help control rodent populations. Owls are especially drawn to these boxes since they don’t build their own nests.

“The truth is, the only reason people have been using poisons for a long time is that it’s quick, easy and cheap,” Riley added. “There are a ton of ways to solve pest problems without using poison — and various folks have been working hard on every level to ask people to stop using them and for stores to stop selling them. As long as these animals continue to be exposed, it will clearly continue to be an issue.”

california rat poison mountain lion
Riley with a mountain lion kitten for examination | National Park Service
For more information about how to prevent wildlife poisoning, check out this guide from WildCare. You can also research how to build nesting boxes for birds of prey near your home.
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