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Is rat poison a problem in YOUR neighborhood?

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Is rat poison a problem in YOUR area?

WildCare's data indicates that the answer is probably yes.

WildCare tests our predatory animal patients— animals that eat rats and mice— for exposure to rat poisons. Our laboratory data document conclusively that a predator animal that eats a poisoned rodent ends up poisoned himself.

Of the 138 samples sent to the California Animal Health and Food Safety Laboratory (CAHFS) at UC Davis in 2012, an astonishing 75.6% of tested patients show some exposure to these toxic poisons. The perce

This map charts the location where WildCare patients that tested positive for rodenticide exposure were found. The map includes all rodenticide-positive patients since WildCare began testing comprehensively in 2010.

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.

Northern Spotted Owl in the hospital. Photo by Alison Hermance  
Three adult Northern Spotted Owls like this one tested positive for rodenticides in their blood in 2012.  Photo by JoLynn Taylor
Great Horned Owl. Photo by Melanie Piazza  
Whooo's poisoning me? Great Horned Owls are disproportionately represented in WildCare's data of positive rodenticide results. Photo by Melanie Piazza  
Gray Fox kit being examined. Photo by Melanie Piazza  
Gray Foxes like this young orphaned patient represent the highest percentage of positive results. These little animals are fantastic rodent control, so their poisoning is extremely disturbing. Photo by Melanie Piazza  
Family of Gray Foxes. Photo by Susan Mark  
A healthy family of Gray Foxes in your yard are not only thrilling to observe, they provide free rodent control! Photo by Linda Campbell  
Raccoons at WildCare. Photo by Christine Margle
Raccoons eat lots of rodents and will keep your property free of rodent infestations, unless they are poisoned. Photo by Christine Margle
Red-tailed Hawk poisoned by rodenticides. Photo by A Hermanc  
A Red-tailed Hawk poisoned by rodenticide shows the tell-tale bleeding from eyes and nares that indicate anticoagulant exposure. Photo by Alison Hermance  
Great Horned Owl babies  
Great Horned Owlets like these can easily be poisoned when their parents bring them a poisoned rodent. Help WildCare halt the use of these deadly poisons!  

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 horrible 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 admittance. 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?

The following numbers reflect species totals for WildCare patient rodenticide exposure in 2012:

Species Number of
positive tests
Percentage of
total animals
Barn Owl 9 8%
Cooper's Hawk 2 2%
Great Horned Owl 15 14%
Red-shouldered Hawk 1 <1%
Red-tailed Hawk 6 6%
Screech Owl 5 5%
Spotted Owl 3 3%
Turkey Vulture 4 4%
       Raptors (etc.)        45        43%
Crow 4 4%
Raven 1 <1%
       Songbirds       5
Gray Fox 20 19%
Opossum 9 8%
Raccoon 16 15%
Striped Skunk 9 8%
Coyote 1 <1%
Western Gray Squirrel 1 <1%
     Mammals      56      52%
  Total: 106  

As the above chart indicates, Great Horned Owls, raccoons and Gray Foxes are the animals most affected according to WildCare's data.

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 2012 testing data including the opossums, the Western Gray Squirrel 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 collects on rodenticide prevalence provides unequivocal proof that predatory wildlife is being poisoned from eating poisoned rodents. But more information is needed to complete the picture.

WildCare is seeking funding that will enable us to perform necropsy exams to determine the cause of death of wild animals that tested positive for rodenticide.

At this time the necropsy exam is the missing link in the data collection efforts as the exam can confirm whether or not rodenticide poisoning was the actual cause of the animal's death. The data gleaned from the necropsy exams will advance both our own research in this area as well as that of our partner agencies in this project.

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. Keep garbage lids closed and sealed.

Eliminate food sources. Keep bulk food, seed, and dry pet food in metal cans with secure lids.  Pick up fallen fruit. Take birdfeeders inside at night.

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 www.hungryowl.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).

If you exhaust all the above efforts and as a last resort decide to kill the rodents, please consider purchasing a rat zapper or snap traps. Keep in mind that lethal methods will only work if all the other steps outlined above are taken and maintained.

We need your support! Please click here to donate toward our Rodenticide Diagnostics and Advocacy Program!

WildCare's data is available for research projects

Are you working on a project for which WildCare's rodenticide exposure data would provide valuable support?

Please email Kelle Kacmarcik, WildCare's Wildlife Solutions Manager at kelle@wildcarebayarea.org to request.


2013 Updated Rodenticide Testing Data

WildCare continues to test our predatory patients for exposure to toxic rat poisons, and the results continue to shock. A disturbing number of carnivorous animals, those animals that provide natural rodent control, are carrying these dangerous poisons in their bodies.

Even if poisoning isn't what brought an animal to WildCare, our testing data shows that the majority of our rodent-eating patients have been exposed to these anticoagulant substances. No one knows the long-term effects of this exposure.

In the first quarter of 2013, we tested 28 animals. Of the 28, 22 tested positive for rat poison in their blood. That's 78.6%.

Victims include several Barn Owls, a couple of Great Horned Owls and Red-shouldered and Red-tailed Hawks. Mammals such as skunks, raccoons and foxes also show high rates of exposure. In fact, combined data for the past two and a quarter years show that Gray Foxes and Great Horned Owls are the most commonly exposed.

Since WildCare started our Rodenticide Diagnostics and Advocacy Program (RDAP), we have tested 246 animals, of which 169 tested positive for some level of exposure, for a cumulative total of 68.7%.

These poisons are killing the very animals nature provides to control rodent populations. Long term, the use of rat poison will mean fewer predators and exponentially more rats. Please do not use rodenticides!

Read more below and click to read about these toxins' potential hazards to children and domestic pets. Click here to read about alternative approaches to rodent control. 
spacer2.gif Barn Owl. Photo by Mary Pounder
A Barn Owl patient at WildCare. Barn Owls are very likely to have rodenticide in their blood because they consume so many rodents. Photo by Mary Pounder

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