Rodenticides Threating California’s Carnivores – a Firsthand Account

I haven’t seen a Bobcat in my neighborhood in over four years, and not for lack of effort. I often take walks, and every time I travel along the roads near our house, I keep an eye out for anything animal shaped: in fact, in the past few months, I’ve seen six coyotes, lots of deer, several Jackrabbits, Brush Rabbits, Wild Turkey, and even a Dusky-footed Woodrat. But why no Bobcats – an animal that I used to observe as often as many of these other species? I’ve  wondered about this matter for a long time, and while hiking a few years ago at Rancho San Antonio, my local county park, I often observed signs indicating sick Bobcats and urging visitors to report sightings of any Bobcats they observe. However, at that time, I felt that it must have simply been a transient disease epidemic that was due to end sometime soon…

A few weeks ago however, we received a notice that stated otherwise: dozens of Bobcats were reported sick or dead in my local area and many rangers even described watching fur-less, emaciated bobcats die in meadows where I’ve seen healthy Bobcats before. I soon realized that many of the first Bobcats I observed years ago were now deceased, and population of these wonderful wildcats I once enjoyed was now seriously depleted, if not gone for the foreseeable future. The reason? Anticoagulant rodenticides. Local use of these toxins by contractors and landscapers causes rodents to not die immediately, but move about hindered and stunned. Predators such as Bobcats, seeking easy prey, eat these poisoned rodents, and then become ill themselves, soon dying a painful death. The Midpeninsula Regional Open Space District has now taken a powerful stance against these terrible poisons, and many are advocating for the toxins to be banned altogether throughout California.

This problem of Anticoagulant Rodenticides, particularly Second Generation Anticoagulant Rodenticides (abbr. SGARS), is not limited to the SF Bay area. Bobcats have been reported sick and dead in the suburbs of Orange County, as well as in San Diego County too. Moreover, these toxins don’t only affect Bobcats. Biologists are concerned of the welfare of populations of the Federally Endangered San Joaquin Kit Fox in the Bakersfield area too, as well as in small carnivores in the Southern Sierra Nevada. On my recent trip to Northwestern California’s Klamath Mountains in Humboldt County (trip report coming soon), I learned of several new species the SGARS were affecting too in that region. While SGARS are primarily used by landscapers and contractors in the metropolitan areas of the Bay Area and Southern California, a very different and more sinister cast of characters use these in the Northwest: illegal pot growers. Speaking to local naturalist and bird expert Rob Fowler, I realized these toxins, used to protect marijuana plants in Humboldt, Trinity, and Mendocino Counties, were having similar effects on local predator populations in that region too.

The Pacific Fisher, a large cat-sized member of the weasel family, once occurred commonly in moist forest habitats of Idaho, Montana, Oregon, Washington, and Northern California. Due to immense pressure from the fur trapping industry, this species is now only present in localized pockets of the Northwestern Montana, Extreme Northeast Idaho, the Olympic Peninsula, Sierra Nevada, and Klamath Mountains. And the Klamath Mountains of Northwestern California and Southwestern Oregon, with a Pacific Fisher population numbering in the low thousands, are thought to hold the largest and most significant population of these rare forest carnivores. However, even in their present stronghold, this elusive animal is under threat. The Hoopa Valley Indian Reservation, a rugged region of moist Douglas-fir and Tanoak Forests previously contained the healthiest and most important Fisher population in California. However, recent surveys have indicated that since the late 1990s, there has been a >70% drop in Fisher numbers on the Hoopa lands. Biologists, puzzled at this sudden population decline, researched potential causes: disease, increased predation, and more, but still couldn’t connect the pieces of the puzzle. However, several sad discoveries in remote regions of the reservation finally connected the clues: dead and dying fishers, with little to no external trauma were found and examined. Once dissected, biologists noticed large amounts of bleeding in the animals’ bodies, discovering that SGARS used at illegal marijuana farms were at fault. Alarmed, they began testing other dead fishers found previously for SGAR presence: they found the toxins present in the bloodstream of over 80% of deceased fishers. Further testing on other predators in the region, such as Bobcats, Mountain Lions, Minks, Foxes, Bears, and rare Spotted Owls confirmed the biologists’ worst fears: the toxins had cascaded through the ecosystem in Hoopa, just as they had in many other areas of California. As biologists researched the matter further, the evidence against SGARS mounted: cans of poison were found throughout the landscape, some even near creeks; one grow site even had poisoned hot dogs hanging from fisher hooks – not doubt used to poison the unlucky bear or other carnivore curious enough to taste. Amounts of poison enough to kill over 20 bears, hundreds of woodrats, and dozens of Fishers and Spotted Owls! This behavior is just disgusting and should not be condoned on any level.

However, there is hope. Starting May 20, 2014, California banned the use of household anticoagulant rodenticides, particularly the most potent SGARS – a good step in the right direction. However, these products are still available to licensed operators. Too many loopholes still exist for criminals such as pot growers to gain access to these poisons and the only solution to this problem is to block access completely. The problem isn’t just a wildlife issue, it’s estimated that over 10000 children are exposed to Anticoagulant Rodenticides every year. Let’s support a cleaner, healthier environment and remove these poisons from California.

Thanks for reading,


Please read more about the problem:

Here for Bobcats in the Bay Area:

And here for Fishers in NW California:

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