Since 2006, WildCare has been working to combat the use of rat poisons (rodenticides) to control rodents. Why are we against rat poisons? Because rat poisons don’t just kill rodents. They also kill the animals that eat rats and mice, like hawks, owls, foxes, raccoons and skunks.
Shockingly, analysis of the WildCare rodenticide testing data shows 76% of tested animals have a positive result for rodenticide in their blood! Scroll down to learn more.
WildCare wants to spread the word about the dangers of rodenticides to hawks, owls and other animals, and to give people everywhere humane and effective options for controlling rodents.
Poster by Yard Smart Marin
How to Control Rodents Humanely
The best method of rodent control is prevention. Rodents tend to set up camp in our homes when food and space are made available to them.
Remove potential rodent homes like yard debris, trash, construction waste, etc. Remove ivy from on and near structures. Consider removing dense ground-covering plants too. Rats and mice are prey animals, and they much prefer to cross open spaces with the protection of covering vegetation. Removing hiding places deters rodents or makes them more visible to their natural predators.
Eliminate food sources. Keep your garbage completely sealed with lids closed and secured. Keep bulk food, seed, and dry pet food in metal cans with secure lids. Pick up fallen fruit. Take birdfeeders inside at night. A significant percentage of nuisance rodent calls to WildCare’s Living with Wildlife Hotline (415-456-SAVE) relate back to the presence of spilled seed from bird feeders. Place a tray to capture seed under your feeder and empty it nightly, and/or sweep up spilled seed every evening.
Exclude rodents from your home. Seal openings 1/2 inch or larger around the outside of your house with metal, concrete, or Stuf-fit Copper Mesh Wool, which can be found online or at hardware stores.
Include natural rodent predators in your solution. A family of five owls can consume up to 3000 rodents in breeding season. Placing a nest box to encourage a family of owls to make your property home can be a great alternative to commercial pest control methods. Please DO NOT erect an owl box if you or any of your neighbors are using rat poisons! Please visit hungryowls.org for more information.
Use catch-and-release traps as a safe, sanitary, and humane solution. Catch-and-release traps will allow you to remove rodents from inside your home, but you must prevent their return by sealing entrance and exit holes and removing attractants (see above). Remember it is illegal in the state of California and cruel to relocate animals (click to learn why), so trapped rodents should be deposited outside once entry points have been sealed.
If you exhaust all the above efforts and decide to employ lethal methods, please consider purchasing a rat zapper or snap traps. Be careful about where you place lethal snap traps. These traps should only be used indoors, out of reach of children or pets.
If you find it necessary to use snap traps outdoors, to protect nontarget animals including federally protected birds, traps should be placed in locked tamper-resistant boxes. Never use glue boards, they are not humane and cause extreme suffering to any animal that gets caught in them, including federally protected migratory birds. Learn more about why glue traps should NEVER be used here.
Keep in mind that lethal methods will only work if all the other steps outlined above are taken and maintained.
WildCare’s Rodenticide Testing Program
WildCare's Rodenticide Diagnostics and Advocacy Program is a major research initiative in partnership with the Environmental Protection Agency, the Humane Society of the United States, the California Department of Pesticide Regulation, and the UC Davis California Animal Health and Food Safety Laboratory.
Together, we are working to eliminate dangerous rat poisons that affect wildlife, pets and people.
When an animal is admitted to WildCare's Wildlife Hospital, poisoning is not usually the obvious reason for admission. The majority of our patients are hit by cars, caught by cats, otherwise injured, or found without the tell-tale symptoms of rodenticide poisoning such as bleeding from the mouth or other orifices and conspicuous anemia.
But even without symptoms of anti-coagulant rodenticide poisoning, WildCare's data reveals that the majority of rodent-eating patients like hawks, owls, raccoons and foxes are carrying these toxins in their bodies.
And the impact is far-reaching. The various toxins stay in body tissues for a surprisingly long amount of time. Brodifacoum and bromadiolone, two of the most prevalent and toxic second-generation anti-coagulant rodenticides remain in body tissues for 217 days and 248 days respectively, which is one of the reasons so many WildCare patients test positive. These animals are simply unable to rid their bodies of the poisons.
Various studies have found these poisons in the fetuses of pregnant animals, and an increasing number of studies including this one on Notoedric Mange in Bobcats and Mountain Lions show clear links between rodenticide exposure and increased mortality from non-poison-specific causes.
So what do WildCare's data reveal?
From July 2013 - June 2014, 95 samples from WildCare patients were submitted to the CAHFS lab at UC Davis, and 86% of those samples were positive for rodenticide exposure. For 5% of the tested subjects, rodenticide exposure was the actual cause of death. Over the entire duration of WildCare's Rodenticide Testing Program, we tested over 400 animals. Shockingly, 76.8% of tested samples were positive for rodenticide exposure.
A few animals tested had one type of rat poison in their systems, but most had two, three or even four of these deadly formulations in their blood. It is staggering to contemplate that nearly 77% of the rodent-eating wild animals you see running around your neighborhood, or encounter on hiking trails probably have multiple anticoagulant compounds in their bodies. Sometimes at levels high enough to kill!
WildCare's partnership with the California Department of Pesticide Regulation has provided the California government with irrefutable evidence that rat poisons don't just kill the rodents they target.
The map above charts the location where many of the WildCare patients that tested positive for rodenticide exposure have been found.
Because the majority of our patients do come from Marin County, the concentration of poisoned patients is centered in Marin, but the correlation is obvious. These poisons are being used everywhere and wild animals are paying the price.
The shockingly high percentage of animals that test positive for exposure (76.8%) is the first, and most notable result of WildCare's study in partnership with DPR, but several other interesting correlations have come through as well.
For instance, the vast majority of tested patients had not just one, but two, three or even four of the most common rodenticide compounds in their systems. This indicates that these animals are dining on poisoned rodents frequently; that poisoning is not a rare occurrence.
Brodifacoum is without a doubt the most commonly seen compound in our patients, with all but one of the tested subjects testing positive for it. Brodifacoum is the compound in the majority of the most readily-accessible rat poisons for consumers.
The July 2014 ruling by the California Department of Pesticide Regulation making rat poisons using the four most common anticoagulants unavailable to regular consumers as of did have an impact on this overwhelming prevalence of brodifacoum in our patients.
The following numbers reflect species totals for WildCare patient rodenticide exposure in 2013:
|Great Horned Owl
|Northern Spotted Owl
|Western Screech Owl
As the above chart indicates, Barn Owls, Northern Raccoons and Gray Foxes are the animals most affected according to WildCare's data.
As our data from previous years have also indicated, Barn Owls, Northern Raccoons and Gray Foxes are the animals most likely to have rat poison in their systems, although all rodent predators are susceptible.
Ironically, these three species are particularly adept at eating rodents and thus provide some of nature's best free rodent control. If you have raccoons and foxes moving through your yard, you likely do not have problems with rats and mice.
By allowing these predators to be poisoned, we are destroying the best chance we have at maintaining a natural balance of rodent populations.
The vast majority of tested animals must have received their rodenticide load through secondary poisoning, whereby an animal eating a rat dying of poisoning gets poisoned himself. Due to the nature of so-called "second generation" anticoagulant rodenticides, a rodent may take several days to die of dehydration and internal bleeding, during which time he may return to a bait box again and again.
These rodenticides are advertised to "kill in a single feeding" and, while no doubt the first feeding is what eventually kills the rodent, the time lapse between initial feeding and death means a dramatically higher toxic load builds up in the rodent's body tissues. By the time a Great Horned Owl eats that rodent, it has many times the lethal level of poison in its system.
Other animals in our 2013 testing data including the opossum and the crows probably encountered the poisoned bait itself and consumed enough to poison themselves. Domestic pets may also be poisoned the same way, and data from Poison Control Centers nationwide demonstrate that children can be poisoned too. (Click to read more about risks to children and pets.)
The data WildCare has been collecting on rodenticide prevalence since 2010 provide unequivocal proof that predatory wildlife is being poisoned from eating poisoned rodents. But more information was needed to complete the picture.
Data from WildCare’s testing protocols has been a critical contribution to the field and will help biologists and conservationists around the country to inform consumers about the far-reaching environmental havoc from these incredibly toxic poisons.
Update December 2020 AB 1788
On September 29, CA Governor Gavin Newsom signed AB 1788 in a huge win for wildlife.
The bill puts a moratorium on dangerous second generation anticoagulants until the California Dept. of Pesticide Regulation finishes its reevaluation process.
Too often WildCare sees the damage done to wildlife by these poisons. This is a great win for wildlife and for everyone who supports eliminating these poisons from our environment!
Here is the text of a letter WildCare sent to the Governor, thanking him for his action:
RE: signing of AB 1788
Dear Governor Newsom,
We are writing to express our appreciation for your signing of AB1788, limiting the use of second-generation anticoagulant rodenticides. As you noted in your signing announcement, these rodenticides are deadly for precious wildlife across the state.
As you know, WildCare is based in Marin County and operates a wildlife hospital along with numerous other resources and nature education programs. In 2006 WildCare began an initiative to test raptors, foxes, bobcats and other predatory animals for base-line blood coagulation levels and potential rodenticide poisoning. Shockingly, analysis of the data shows 76% of tested animals receive a positive result for rodenticide in the blood over the course of our study.
Based on our work in our wildlife hospital over the past decade and a half, we remain very concerned about the prevalence of these poisons in our environment and the future health of beneficial (rodent-eating) predators. There rodenticides are a threat not only to mountain lions and wildlife in rural areas, but also in suburban communities like Marin and throughout the San Francisco Bay Area.
With gratitude and sincere thanks for your support.
Kate Van Gytenbeek, President Ellyn Weisel, Executive Director
WildCare Board of Directors WildCare
We also want to thank our friends at Raptors Are The Solution for putting together an excellent call to action on this issue. Here is the press release they issued when the bill was signed (will open as a PDF).
Information on Rodenticides and WildCare's Work to Combat Them
In WildCare's Wildlife Hospital, animals showing obvious symptoms of rodenticide poisoning, like bleeding from the eyes and nose, lethargy and anemia, are treated aggressively with Vitamin K injections and other anti-rodenticide protocols.
But sometimes patients don't show obvious symptoms, and the "norms" for blood-coagulation levels (a prime indicator of anti-coagulant poisoning) are not yet standardized in wildlife medicine.
In 2010 WildCare began an initiative to test raptors, foxes, bobcats and other predatory animals for base-line blood coagulation levels and potential rodenticide poisoning. Shockingly, analysis of the data from those initial years of testing showed that 68.1% of tested animals shows a positive result for rodenticide in the blood. Cumulative data over the entire testing period (over 400 animals tested) brought that total to an even more shocking 76.8%.
Most of these patients were admitted to WildCare's Wildlife Hospital for reasons other than symptoms of poisoning (being hit by cars or showing other injuries are the most common), but these test results show that the majority of local predators are functionally living with anticoagulant toxins in their blood. What does this say about the prevalence of these poisons in our environment and the future health of these beneficial (rodent-eating) predators?
Rodenticide poisoning unintentionally kills the very animals nature has provided to keep rodent populations in check. WildCare is working to raise public awareness and bring legislative influence to bear against the use of these toxins.
In August 2013, WildCare began a year-long research study in partnership with the California Department of Pesticide Regulation (DPR) on the effects of anticoagulant rodenticides on wildlife. Read the results of that study on the Rodenticide Testing Program tab.
Update March 2014:
A victory for wildlife! The California Department of Pesticide Regulation has adopted a regulation that makes the most dangerous second generation anticoagulant rodenticides, rat poisons, California restricted materials. This means in effect that the products will no longer be sold on retail store shelves and they will be out of reach to the general consumer as of July 2014.
The regulation affects all pesticide products containing the active ingredients brodifacoum, bromadiolone, difenacoum, or difethialone. Brand names for these products include d-Con and Generation.
WildCare applauds this new regulation as it will benefit untold numbers of wild animals that today carry heavy loads of anticoagulant poison in their bodies due to eating poisoned rodents.
“This is a practical sensible regulation that goes a long way to protecting our wildlife,” said Brian Leahy, DPR Director. “Second generation anticoagulant rodenticides can contain some pretty powerful chemistry. Restricting the use of SGARs to only certified applicators will significantly reduce unintended exposures to non- target wildlife.”
WildCare’s Director of Wildlife Solutions and Advocacy, Kelle Kacmarcik agrees.
“WildCare has been working with DPR, US EPA and California Department of Fish and Wildlife on this issue for many years,” she says. “We are thrilled to share this announcement and we congratulate DPR for taking this important step toward the health of our wildlife.”
76.8% of tested patients had positive results for exposure to anticoagulant rat poisons in 2013.
In June of 2014, the EPA announced that they are starting the process to ban the most deadly second generation rodenticides from the consumer market.
While WildCare applauds the spirit of this decision, we are concerned about weaknesses in this recent ruling.
The California Department of Fish & Game (DFG) is concerned too. In a recent letter to the California Department of Pesticide Regulation, John McCamman, Director of DFG writes:
"These second-generation anticoagulant rodenticides have a long, well-documented history of impacting non-target wildlfie, and thus, the Department of Fish and Game recommends revising California regulations to make these materials restricted."
The term "non-target wildlife" refers to animals like hawks, owls and foxes that eat rodents poisoned with anti-coagulant rodenticides (rat poisons), and end up poisoned themselves.
In their letter, the DFG cites studies in which 92% of raptors collected in San Diego County and 79% of federally endangered San Joaquin Kit Foxes in the Bakersfield area showed residues of anticoagulant rodenticides in their blood. Of 104 Mountain Lions tested since 2005, 82 had rodenticides in their blood! The rat poison may not have killed the animals, but its presence in their bloodstreams is a disturbing indicator of the prevalence of these poisons in our environment.
WildCare's numbers show the same alarming trend-- 76.8% of the animals tested in our Wildlife Hospital show positive results for rodenticides, even if suspected poisoning isn't the reason the animal came to WildCare.
Why California Needs Stricter Regulations
While the EPA decision to ban the most deadly of the "second generation" anti-coagulant rodenticides from the consumer market is very important, the biggest flaw in the decision is the fact that venues in rural locations, like farm and feed stores could still sell these deadly products in large quantities! This loophole will still allow these products to be sold and put wildlife, including animals like foxes, bobcats and Mountain Lions at risk for secondary poisoning.
On July 11, 2011 The CA Dept of Fish & Game requested in a letter to CA Department of Pesticide Regulation that stricter controls (beyond what the recent EPA action called for) be put in place. Accompanying this letter was documentation of 240 cases of secondary poisoning in California across a variety of species and rodenticides. This data is extremely compelling as it is proof that every rodenticide (even the ones listed as alternatives by the EPA) does kill wildlife.
Eliminating rodenticides completely will be a long battle. Every step taken to reduce these toxins in our environment is a step in the right direction.
WildCare fully supported the recommendation of the California Department of Fish and Game and wanted the California Department of Pesticide Regulation (DPR) to further restrict the rodenticides that are proving to be deadly to wildlife. To this end we started a petition that garnered 2,272 signatures.
Gray Fox Tests Positive for Rodenticide Poisoning
On January 29, 2011 WildCare admitted Patient number #0070, an adult Gray Fox showing the symptoms of rat poison toxicity, including lethargy and anemia.
This poor animal died, and his liver was sent to UC Davis for testing to determine the cause of death.
Results from the submitted liver sample came back positive for three anticoagulant rodenticides: Brodifacoum, Bromadiolone and Difethialone. All of these are second-generation, long-acting anticoagulant rodenticides that interfere with normal blood clotting and cause depression, anorexia, anemia, bloody feces, ataxia (lack of coordination), weakness and subcutaneous hemorrhages among other symptoms.
This fox had obviously consumed rodents that had eaten rat poison, and the cumulative toxic load killed him.
This information will help us stop the use of these dreadful poisons!
Meet five orphaned Gray Foxes and learn more about WildCare's work in our video "The World of WildCare".
Success in 2007 - San Francisco Bans the Use of Anticoagulant Rodenticides in City Parks
After months of deliberation the EPA has made a decision to remove 2nd-generation rodenticides from the consumer market! Further, professional pest control operators using these poisons will now be required to use them only inside if exposure to children, pets and non-target animals is possible. This means target rodents will die away from areas where wildlife hunt.
Thank you to everyone who wrote to the EPA and spoke out on this issue!
Read more about WildCare's efforts to combat the poisoning of non-target wildlife (like hawks, owls and coyotes) below:
WildCare members from spring of 2007 will be familiar with the case of Red-shouldered Hawk #0061, brought to WildCare suffering from anti-coagulant rodenticide poisoning that occurred in Golden Gate Park. This beautiful bird was released back to the park’s botanical garden after intensive treatment for poisoning while TV cameras brought the issue of rodenticide poisoning to public attention.
Several other hawks brought to WildCare had not been so lucky; they died within days of rodenticide poison being used in the area. Red-shoulder #0061 became the ambassador for a policy change by the San Francisco Department of the Environment, which now prohibits the use of certain rodent poisons outdoors to protect the park’s wildlife.
Anti-coagulant poisons, known as “second-generation” or “singlefeed” rodenticides, are sold under various product names, and contain the active ingredients brodifacoum, bromadiolone and difethialone among others. They are strong enough to kill a rodent “after a single feeding.” A rodent consumes the poison at a bait station, and then slowly dies of internal hemorrhage. What makes these poisons so dangerous to wildlife is that, although a single feeding of poison will eventually kill, it takes four to seven days for the rodent to die. During this time rodents can consume more bait, raising the level of toxins in their bodies to a dose lethal to the larger animals that eat rodents and carrion, such as hawks, owls, foxes, raccoons, opossums, skunks and coyotes.
San Francisco Ban; EPA Assessment
Patient #0061’s situation caused an uproar in San Francisco and led the city’s Department of the Environment to enact an immediate temporary ban on the use of “second-generation” anti-coagulant rodenticides in outdoor areas like Golden Gate Park. In May of 2007 the San Francisco Commission on the Environment voted to make this ban permanent, adding these rodent poisons to the city’s Restricted Poison list.
In the face of evidence that a wide variety of species including threatened and endangered species are dying from eating poisoned rodents, the United States Environmental Protection Agency (EPA) also started considering limiting the use of these poisons throughout the country. WildCare supporters and others sent hundreds of letters to the EPA in favor of this ban.
The final EPA Risk Mitigation Decision for Ten Rodenticides report from May 28, 2008 is here. This document outlines the measures taken by the EPA in 2008. Specifically, those measures included two major components. First, To minimize children’s exposure to rodenticide products used in homes, EPA is requiring that all rodenticide bait products marketed to general and residential consumers be sold only with bait stations, with loose bait (e.g., pellets and meal) as a prohibited bait form. Second, to reduce wildlife exposures and ecological risks, the Agency will require sale and distribution limits intended to prevent general consumers from purchasing residential use bait products containing four of the ten rodenticides that pose the greatest risk to wildlife (the second generation anticoagulants – brodifacoum, bromadiolone, difenacoum, and difethialone). Moreover, bait stations will be required for all outdoor, above-ground uses of these second generation anticoagulants.
When is Poison Appropriate
To those of us who work with wildlife, the answer is obvious: never. Poisoning alone never eliminates a pest animal problem, and the collateral damage outweighs all quick-fix fantasies. Poison used with other nuisance wildlife management techniques may seem effective, but if you use the other techniques, you won’t need the poisons anyway.
Our houses, gardens, vineyards and farms are a great source of free food for hungry animals. The gardeners in Golden Gate Park believe that rodent populations are increased by park visitors who feed ducks and squirrels.
The only real way to eliminate pest animals is to remove what attracts them. Wildlife population size is determined by the amount of food and habitat available. Bird feeders provide gourmet dining for rodents. To prevent rodents from feasting at the feeder at night, place the feeder on a pole and clean up any seed that falls to the ground.
To exclude rodents from buildings, seal entrance locations. Keep a lid on trash pails and compost containers. The EPA agrees, noting in its Proposed Risk Mitigation Decision for Nine Rodenticides that “without habitat modification to make areas less attractive to commensal rodents, even eradication will not prevent new populations from recolonizing the habitat.”
In Golden Gate Park, part of the problem was solved by volunteers who made wire baskets to cover the plants the rodents were eating. Another solution the park plans to adopt is to add a trash pick-up on Saturdays, so that cans aren’t full when Sunday park visitors arrive.
Nature’s Best Rodent Control
Rodents play an important role in nature. Removing rodent food sources and habitat, while encouraging natural predators, is the only permanent solution. WildCare encourages natural forms of rodent control through exclusion and predator support. One family of hungry barn owls can consume more than 3,000 rodents in a nesting season. Placing a Hungry Owl Project nest box on your property can help control rodent populations throughout your neighborhood and beyond, while maintaining the naturally balanced food chain. Learn more at hungryowls.org.