Rodenticide Poisoning in Wildlife

Rodenticides don't just harm the rodents they target. Thousands of wild animals are killed by these poisons every year.

An up-close view of a Great Horned Owl. He has very yellow eyes.Rodenticides are a type of poison commonly used by homeowners and pest control companies to get rid of unwanted rodents. These poisons work by preventing a rodent's blood from clotting, causing them to bleed internally. However, they don't just work on the rodents they target. Rodenticides are just as lethal for any animal that consumes the poison. Each year, thousands of non-target wildlife species are killed when they directly or indirectly consume rodenticides.

The Wildlife Center has admitted many patients with rodenticide poisoning, though it can be difficult to diagnose. There is no reliable blood test for rodenticides in most wildlife species, nor is there a standardized clotting factor for veterinarians to reference. 

Prevention is the key to solving this issue. By choosing to use alternatives to rodenticides to handle rodent problems, you can help stop this toxin from killing wildlife. 

 

Why are Wild Animals Eating Rodenticides?

Rodenticide poisons are designed to smell and taste good to rodents to entice them to eat them, but they can be just as appealing to wild mammals, including squirrels, opossums, skunks, raccoons, and foxes. Even if rodenticides are kept out of a wild animal’s reach, mice and rats will often carry the poison out with them, sometimes leaving it in places where wild animals can find it. Once consumed, these poisons will have the same anti-coagulation effect on wild animals as they do on rodents, causing internal bleeding, cardiovascular shock, and eventually death.

Passing the Poison Through the Food Web

Most cases of rodenticide poisoning in wildlife don't happen because an animal directly consumes the poison; it occurs secondarily when raptors or other predators consume a poisoned rodent. When a mouse or rat consumes rodenticides, they generally do not die right away. Many of them make their way out into the environment before succumbing to the poison. These poisoned rodents are weaker and less coordinated than their healthy counterparts, making them easy prey and more likely to pass the poison throughout the food web. Once a predator consumes a poisoned rodent, the rodenticides bioaccumulate, or build up, in their bodies and inhibit their blood’s ability to clot, causing them to suffer a slow and painful death.

Rodenticides kill more than just rodents. An infographic showing the food web.

How Widespread is this Issue?

Though the effects of rodenticides are well studied, the extent of their impact on wildlife is still being discovered.  One study found that all of the 43 Red-tailed Hawks admitted to a wildlife clinic in Massachusetts had anticoagulant rodenticides present in their liver tissues. Another review of rodenticide poisoning showed that this issue is wide-ranging and isn't exclusive to certain types of animals; birds, mammals, reptiles, and invertebrates are all being exposed to these poisons. 

Danger to Pets and Children

In addition to the threat to wildlife, rodenticides also pose a significant risk to pets and children. The bright colors of rodenticide poisons often attract attention, and the ingredients that make them tasty for mice and rats also make them seem like a nice treat to pets and kids. Even if rodenticides are kept in a secure location, rodents will often carry the poisons out with them, leaving them in places that pets and children have access to. Each year, rodenticides are one of the most common poisons that cats, dogs, and other household pets ingest, and more than 10,000 children are exposed to rodenticides in the United States.

If you suspect your child or pet may have ingested or come into contact with rodenticides, call these poison control numbers, or call your veterinarian for your pets and 911 for your children. Poison Control: 1-800-222-1222; ASPCA Poison Control: (888)-426-4435. 

Alternatives to Rodenticides

The following are some safe, environmentally friendly ways to solve rodent problems around your home or business.

  • Seal entry points into your home. These could be around cabinets, attics, basements, crawl spaces, etc. You can use one-way door exclusion devices to make sure no rodents are trapped inside before sealing up the entry points.                                                                        
  • Secure food resources such as birdseed, pet food, trash, and compost piles that may attract rodents to your yard.                                         
  • Make sure shredded paper or fabric is not easily available. Rodents often use these materials to make a nest for their young.                     
  • Attract raptors to your yard by putting up nest boxes, planting trees, and leaving dead trees up. A single owl can consume thousands of mice and rats every year.                                       
  • Place botanical rodent repellents, such as Fresh Cab, in areas where you suspect rodents are residing. These plant-based products can be very effective at repelling mice and rats without causing harm to non-target wildlife.                                                                                          
  • Never use glue traps to manage rodent issues. These types of traps are indiscriminate and inhumane.

Additional Resources