People who grow marijuana illegally in the backwoods of California are poisoning wild animals, including rare ones. They use rat bait and other toxic chemicals to protect their plants. NPR's Elizabeth Shogren visited the Hoopa Reservation in Northern California, where tribal members and biologists are worried about the problem.

ELIZABETH SHOGREN, BYLINE: We scramble through snow-covered brush on a remote hillside.

MARK HIGLEY: Here's a marijuana plant that kept growing after it was cut.

SHOGREN: The tribe's biologist, Mark Higley, holds up a rotten pot plant. It's left over from a bust last summer. A law enforcement team found 8,000 marijuana plants here, three to six-feet tall. They also found lots of rat poisons and empty containers left over after growers used the toxic chemicals. Here's what happens. The growers irrigate their plants. Rats chew on the plants to get moisture and that kills the plants. So the growers try to kill the rats.

HIGLEY: The problem is we have wild rodents out here that eat the rat poisons, and then they become little time bombs. They don't die for seven to 10 days, maybe two weeks, and they stagger around and then they become easy prey for northern spotted owl, fisher, foxes, bobcats.

SHOGREN: And then when predators eat the poisoned rodents, they get poisoned and sometimes die. Higley says this has become a common scene in forests throughout Northern California. That same week in a bust in a national forest nearby, sheriff's deputies found a dead fisher. It's a rare relative of the weasel, about the size of a cat. Higley was there. He says the marijuana growers had laced hotdogs with a toxic insecticide and hung them up on large fishhooks.

HIGLEY: And then that fisher had hotdog in its esophagus and in its stomach and died of acute poisoning.

SHOGREN: Higley and other biologists study fishers closely because the federal government is considering putting them on the endangered species list. They know what kills them because they tracked them with radio collars. When an animal stops moving, researchers race into the forest to find the body before predators do.

In fact, the dead fisher first clued in scientists for the widespread use of these poisons by illegal pot growers. Then researchers went back and looked at tissue samples from fishers that had died in previous years. Nearly all the animals had been exposed to rat poisons. Higley says these poisons cause nearly a third of the deaths of male fishers on the Hoopa Reservation over recent years.

HIGLEY: It was just devastating, I mean, to know that such a high percentage of the fisher population across the entire range in California was exposed to these rat poisons and knowing that it's not just fishers, but all the other carnivores got to be exposed to it. It just seems absolutely criminal.

SHOGREN: Particularly on the reservation. The Hoopa tribe banned all toxic chemicals decades ago to protect its natural resources. Aaron Pole is a wildlife technician and a member of the tribe.

AARON POLE: I'm enraged. Why won't they go somewhere else and grow?

SHOGREN: Pole has come across illegal marijuana farms when tracking fishers and rare northern spotted owls. And he's been part of teams cleaning up sites after busts. A big pile of trash is still left over from a clean up here a couple of months ago. It includes empty fertilizer bags and lots of irrigation hose that growers used to bring water from a stream.

POLE: It's pretty selfish. You know, it's like they come in and they're reaping the benefit of, you know, some quick cash. All the environmental damage is happening here and we have to deal with it.

SHOGREN: The fishers are a special concern because the tribe uses their skins for arrow quivers in a traditional healing dance. The tribe also worries about poisons getting into fish and game and the rivers where children play. Wildlife ecologist Mourad Gabriel is tracking the problem all over the northern half of California. In his lab in a logging town near the coast, he opens a locked freezer and pulls out a corpse of a furry animal.

MOURAD GABRIEL: So you can see here, it's still a little frosty but this is a beautiful, beautiful male fisher.

SHOGREN: It was found dead near Yosemite National Park hundreds of miles away. Gabriel plans to take it to the University of California, Davis for an examination to determine the cause of death. But these days, whenever a fisher turns up, he suspects rat poisons. He goes in with law enforcement during busts of illegal pot farms, sometimes getting lowered from a helicopter. Afterwards, he hikes back into the spots. He hauls out whatever rat poisons he finds and he sets up motion-sensing cameras.

GABRIEL: Just to see what kind of wildlife actually visits these sites.

SHOGREN: He shows me pictures of fishers, mountain lions, gray fox, deer and a bear.

GABRIEL: This bear is actually walking in and investigating bottles of insecticides and fertilizer.

SHOGREN: Gabriel recently got the results from the exam of that frozen fisher from Yosemite. It did die from rat poisons. And then earlier this month, Gabriel suffered a very personal blow. His pet dog was poisoned with the same kind of rat bait and died. He thinks it was malicious. The local sheriff is investigating. Elizabeth Shogren, NPR News.


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