In 2014, biologists noticed a sickly mountain lion on one of their trail cameras. The irony is that he was once the stunning big cat who rose to stardom on the front cover of National Geographic.
He was vibrant, strong and prowling near the Hollywood sign in Los Angeles years before. He even crossed two of California’s busiest freeways seamlessly to get there, but he now looked like he was on the brink of death. The reason: rat poison.
“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 said. “He was in really rough shape.”
The mountain lion, known as P-22, was captured and treated for the mange and has made a full recovery. Biologists had been seeing this issue 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.
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 since 2002. This is causing biologists to pin responsibility for a number of illnesses and deaths from 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.”
Riley said the type of poisons that have been found are called anticoagulants. When ingested by a rodent, these substances remove the blood’s clotting ability, and, slowly, the animal will bleed to death internally. The poisoned rodent can live up to 10 days after initially being exposed to the poison. This leaves time for larger predators, like racoons or foxes, to become poisoned themselves from hunting the rodents.
The poison eventually 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 the poison is mange. The animals develop it once their 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.”
The most recent mountain lion, P-41, was found dead with rat poison in his system. His cause of death was undetermined because he had been deceased for days by the time he was found, Riley believes the poisons 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.”
The state of California has outlawed second-generation anticoagulants for regular use. Despite them not being sold at hardware stores, professional pest control companies are still authorized to use them. Residents can legally purchase first-generation anticoagulants, which have been found in the systems of mountain lions and countless other predatory species including hawks, owls, coyotes, and bobcats.
Biologists suggest using other methods of pest control. Laurel Serieys, a wildlife biologist, and manager of research website Urban Carnivores believes the best way to stop the unintended exposure of wildlife, 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.”
Serieys suggested installing nesting boxes in trees around your home to encourage predatory birds to settle nearby. The birds will help control rodent populations. Owls are especially drawn to these boxes because 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.”
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