Information on Rat Poisons (Rodenticides) and WildCare’s Work to Combat Them

Red-tailed Hawk poisoned by rat poison. Photo by Alison Hermance
This Red-tailed Hawk died of internal bleeding after eating a rodent poisoned by anticoagulant rat poison. Photo by Alison Hermance

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.

The rat poisons currently available throughout most of the United States and the world build up to extremely toxic levels in the bodies of the rodents that consume them. As the rodent dies, it becomes a tempting meal to a hungry predator. Once eaten, that toxic load of poison transfers, and the anticoagulant effect of the rodenticide causes internal bleeding and often death in the body of the predator.

Even if the dose of poison isn’t enough to kill the predator animal, it is still a highly toxic substance with significant adverse health indications. Many animals carry a “sub-lethal”  amount of poison in their blood that may make them more susceptible to injury and illness.

In WildCare’s Wildlife Hospital, animals showing obvious symptoms of rat poison (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 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.

Most of these patients were admitted 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. Please donate today to help our efforts!

How to Control Rodents Humanely

Barn Owls. Photo by Alex Godbe

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 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.

Keep in mind that lethal methods will only work if all the other steps outlined above are taken and maintained.