California Department of Fish and Wildlife

Rodenticides can harm wildlife; please use carefully

Throughout California, the use of poison baits to control rodents has injured and killed numerous wild animals and pets. This is because predatory and scavenging birds and mammals like owls, hawks, raccoons, bobcats, mountain lions, foxes, skunks and coyotes that eat dead or dying rodents that have consumed these baits will also be poisoned. Pets will also eat dead or dying rodents and unprotected bait.

The best way to control rodents and protect wildlife and pets is to use non-chemical means of rodent control, such as exclusion and sanitation when possible. If rodenticides are used, it is important to protect both pets and wildlife by reading – and following – the label directions of any rodent baits you purchase, and only purchasing those that are legal for the pest you are trying to control. Because of documented hazards to wildlife, pets, and children, the U.S. Environmental Protection Agency is in the process of canceling products that do not comply with safety requirements. The California Department of Pesticide Regulation is also taking action to restrict public access to these materials in California. In the interim, please do your part by avoiding use of rodenticide products containing the active ingredients brodifacoum, bromadiolone, difethialone, and difenacoum.

CDFW has also seen an increase in the number of strychnine-related wildlife losses in recent years. Strychnine is only legally used to control pocket gophers and must be placed underground in gopher burrows. Strychnine should not be used to control mice, rats, or ground squirrels. Any above-ground use of strychnine may lead to unintentional poisoning of wildlife and pets, and may lead to enforcement action by CDFW, the appropriate County Agricultural Commissioner, or both.

Protect your wild neighbors, pets, and children from accidental poisoning. Choose non-chemical pest control methods. If you must use pesticides, do so very carefully and follow all label directions.

Rodenticide Baits: Frequently-Asked Questions

Q. How do rodent baits harm wildlife and pets?
A. It's possible for wildlife and pets to consume the poison directly. However, it's more common for some animals to receive a secondary exposure. A secondary exposure occurs when wildlife or pets consume dead or dying rodents that have eaten the rodent bait. Wildlife that can be affected by secondary poisoning include owls, hawks, eagles and mammals such as raccoons, foxes, bobcats, mountain lions and coyotes.
Q. How can I protect wildlife and pets, but still control rodent pests?
A. The most effective and safest ways to address rodent issues are through exclusion and sanitation. For example, seal off any rodent entrances to your home, remove debris from your yard, and make pet food inaccessible to rodents. Traps can also be effective in removing rodent pests. If you use rodent bait, it is important to follow label directions carefully and immediately dispose of any rodent carcasses that result. Rodent baits with the active ingredients brodifacoum, bromadiolone, difethialone, and difenacoum are very toxic and persistent and have been found widely in non-target wildlife. Please avoid using them.
Q. What kind of rodenticide is legal to use for field rodents?
A. It is legal to use diphacinone, chlorophacinone, and warfarin (first-generation anticoagulants) for control of field rodents. Cholecalciferol is an acute rodenticide that poses less risk of secondary exposure and is legal to use to control field rodents. It is illegal to use products that contain the active ingredients brodifacoum, bromadiolone, difenacoum or difethialone to control field rodents – away from buildings.
Q. Why are brodifacoum products so dangerous for wildlife and pets?
A. Brodifacoum, bromodialone, difenacoum and difethialone are toxic to rodents in a single feeding. However, the rodent will not die until several days after feeding and may continue to ingest more poison. The poison is then available to a predator or scavenger that eats the rodent. If the exposed rodent does not die, the poison can persist in its body for several months, and any animal that eats the rodent will ingest the poison.
Q. How do these rodent baits work?
A.. Brodifacoum, bromodialone, difenacoum and difethialone are second-generation anticoagulants. Warfarin, chlorophacinone, and diphacinone are first generation anticoagulant rodenticides. Both kinds of anticoagulant rodenticides work by preventing blood clotting. Animals that ingest them die from internal hemorrhaging (bleeding) several days after ingesting the material. While the mechanism of all anticoagulants is similar, second-generation products (brodifacoum, bromadiolone, difenacoum and difethialone) are much more toxic and persistent, so they pose a much greater threat to non-target wildlife. Cholecalciferol is an acute rodenticide that causes kidney failure.
Q. How do you know rodent baits are poisoning wildlife?
A. Since 1994, CDFW's Wildlife Investigation Laboratory has confirmed at least 300 cases of wildlife poisoning from anticoagulant rodent baits. Brodifacoum was the poison most frequently detected. Animals harmed include coyote, gray fox, red fox, San Joaquin kit fox, fisher, raccoon, fox squirrel, bobcat, mountain lion, black bear, Hermann's kangaroo rat, bald eagle, golden eagle, Canada goose, great-horned owl, barn owl, red-shouldered hawk, red-tailed hawk, Cooper's hawk, turkey vulture and wild turkey.

Since animals typically retreat to their dens, burrows or other hiding places in the final stages of anticoagulant poisoning, the number of non-target wildlife killed by these compounds is likely be much greater than we know. Field monitoring of wild populations of bobcats, mountain lions, coyotes, San Joaquin kit foxes, fishers, and raptors confirm widespread exposure to predatory and scavenging wildlife.
Q. Can I control rodent pests without using poison baits?
A. Yes. The most effective rodent control program uses exclusion techniques (such as sealing rodent entrances to your home) and sanitation (removing rodent habitat such as ivy or wood piles); animal removal is used only when necessary. More information on controlling mice, rats, and field rodents is provided on the University of California Integrated Pest Management Website.
Q. I found a dead raccoon (or other small wild animal) in my yard. What should I do?
A. First, do NOT touch it bare-handed. Wildlife can carry diseases and parasites, so always wear protective clothing – especially gloves – before handling dead or dying animals of any kind. If you're in an urban or suburban area, you can call your city or county animal control office with detailed information about the animal's appearance and condition. Even if they don't have the staff to come retrieve it, they may like to know about it, as the one you found may not be the only one.
Q. If I think my pet has been poisoned, what should I do?
A. If your pet is having seizures, is unconscious or losing consciousness, or is having difficulty breathing, phone ahead and take your pet immediately to your local veterinarian or emergency veterinary clinic. If you know of any rodenticide that your pet has had access to, bring this information with you – especially the name of the product and active ingredient(s) – as it will help the veterinarian effectively treat your pet.

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Updated 4/22/2014