Fishers used to range across wide stretches of the West Coast. Even in reduced territories, these cat-sized members of the weasel family play a crucial role in the forests of the Pacific Northwest and Sierra Nevada mountains. Although not adept at fishing, fishers are excellent hunters: they keep forest rodent populations in check and bravely take on porcupines.

But lately, those western woods they call home have been less than hospitable. A group of conservationists that includes WCS scientists recently revealed that toxic rodenticides lurk beneath the canopy, as more and more illegal growers of marijuana seek to keep rodents at bay. Fishers may be unintended victims of these poisonings, but they’re directly impacted: a recent study showed that 79 percent of deceased fishers were exposed to one or more rodenticides.

Fishers may not be the only victims of these poisonings. Study co-author and WCS Scientist Sean Matthews and his colleagues believes the toxins could harm other rare carnivores that inhabit the region as well, such as the Sierra Nevada red fox, wolverine, and California spotted owls.

To learn more about fisher poisonings on the West Coast, read our press release.