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Rat poisons killing hawks, owls and others

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Is rat poison a problem in YOUR area?

WildCare's data indicate 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 like this owl that eats a poisoned rodent ends up poisoned herself.

Of the 138 samples sent to the California Animal Health and Food Safety Laboratory (CAHFS) at UC Davis in 2013, an astonishing 76.8% of tested patients show some exposure to these toxic poisons.

The map above charts the location where 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.

 Breaking News:

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.”

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!  
Rat at birdfeeder. Photo by Laura Lind  
Rat at a bird feeder. Photo by Laura Lind
Bring bird feeders inside at night and sweep up all spilled seed to prevent rodent visitors.
Barn Owls and owl box. Photo by David Goodman
A family of Barn Owls can eat 3,000 rodents in a breeding season. An owl box can attract them to your property. Photo by David Goodman  

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 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 2013:

Species Number of
positive tests
Number of
individuals tested
Barn Owl 9 11
Cooper's Hawk 2 3
Great Horned Owl 4 4
Northern Spotted Owl 1 1
Red-shouldered Hawk 9 10
Red-tailed Hawk 12 17
Saw-whet Owl 1  1
Sharp-shinned Hawk 1 1
Turkey Vulture 1 2
Western Screech Owl 3 3
White-tailed Kite 2 4
Crow 2 7
Raven 1 1
Gray Fox 13 14
Opossum 1 1
Raccoon 30 34
Striped Skunk 13 16

As the above chart indicates, Barn Owls, Northern 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 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.

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. This study will help researchers understand the ways in which rodenticides contribute to, or cause these animals' deaths. With DPR's support, we are now requesting necropsies of deceased patients to determine not only if the animal has rodenticides in his system, but also if the toxic load was the actual cause of the animal's death, or just a contributing factor.

The second component of the study will be to determine exposure levels of rodenticides in domestic animals.

Data from WildCare’s testing protocols is a critical contribution to the field and will help biologists and conservationists around the country to inform consumers that the evidence of far-reaching environmental havoc from these incredibly toxic poisons is mounting.

How to Control Rodents Humanely

Rodents are an integral part of the environment, and they are the primary food source for most of the predatory animals in our area. It is not possible, nor is it desirable, to eradicate rodents outside.

However, most people do not want rodents inside their homes or damaging their property. The following information will help you effectively eliminate rodent problems without resorting to the use of rat poisons.

The best method of rodent control is prevention. Rodents tend to set up camp in our homes and businesses 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.

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.

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 3,000 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. DO NOT erect an owl box if you or anyone in your neighborhood is using poison, however. 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). 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.

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, Director of Wildlife Solutions at kelle@wildcarebayarea.org to request.

What would YOU do if you found a poisoned owl?

You'd call WildCare's 24-hour Living with Wildlife Hotline 415-456-SAVE, of course!

Where else can you get expert advice, in real time, at the moment you need it most?

WildCare's Hotline answers thousands of calls every year from people just like you! But it receives no external funding to provide this invaluable service.

Click to donate now to help us raise $8,000 by April 8, 2014 to support our 24-hour Living with Wildlife Hotline today!

Donate now!

Baby Barn Owl with leg in a cast
This baby Barn Owl broke his leg in the fall from his nest and received help at WildCare. Our Hotline operators may have helped this baby's rescuers bring him in. Photo by Melanie Piazza