Photograph by Curtis Cartier
Smells A Rat: Rebecca Dmytryk of WildRescue says rodenticides found in devices like this can accumulate in the systems of raptors. She'd rather see owls introduced to control rodents.
Throughout Santa Cruz and other towns, poisoned rodents are becoming deadly meals for wildlife.
By Curtis Cartier
WALK IN any direction in Santa Cruz and chances are you'll come across a box of rat poison before long. The small, plastic cartons look like overgrown Roach Motels and are usually found near trash cans and alleyways, pressed flush against a wall. Inside are any of a number of toxic concoctions. The worst contain anticoagulant chemicals that, once ingested by a rodent, cause internal bleeding and eventual death. What's less known about these deadly rodenticides is that they are potentially lethal to other animals, especially birds of prey, for which rats and mice are a steady meal.
Nearly a dozen rodenticides have been named by the Environmental Protection Agency as posing "significant risks to wildlife, including birds, such as hawks and owls, and mammals, including raccoons, squirrels, skunks, deer, coyotes, foxes, mountain lions, and bobcats." The poisons are also a danger to pets like house cats, which can eat infected mice and become sick, and dogs, which often eat the poison itself.
Yet few regulations exist that protect "nontarget" animals against ingesting the poisons. And even though, after June 4, new EPA restrictions will be handed down that limit the purchasing of anticoagulant rodenticides to authorized "bait shops" and their use to "agricultural areas," many conservationists worry the efforts will be too little, too late.
"These poisons are killing owls and hawks and pets, and no one is talking about it," says Rebecca Dmytryk, founder of WildRescue, a nonprofit animal emergency service based in Moss Landing. "Once an predator like an owl eats a rodent that is poisoned, it can stay in the owl for four to six weeks, and it builds up. The problem is that the birds can appear to be behaving normally until it's too late."
Last week Dmytryk and her husband, Duane Titus, relocated a family of barn owls discovered nesting in a business owner's sign in downtown Santa Cruz to a hand-built box in the same area. These birds, she says, will scarf down about a dozen mice, rats and other small rodents each evening, and in turn will absorb anything the creatures have in their bellies. And since a rodent poisoned by rodenticide is often disoriented, it becomes easy prey for the birds--in fact, poisoned prey can make up a significant part of the birds' diet. Dmytryk is hoping to turn the tables on chemical rodenticide and has pledged to help people build "owl boxes" on their property to attract the small raptors.
"The birds themselves do a much better job killing mice and rats than these terrible poisons," she says. "We're putting these harmful chemicals out there with no regard for how they affect the food chain."
Flo Tseng, director of the wildlife clinic at Tufts University in Massachusetts, agrees. She has led a team of researchers who, over the last year, have collected autopsy data for hundreds of dead birds that died in the clinic or were found in the wild. She says 87 percent of the birds that were tested showed signs of rodenticide consumption.
"If these kinds of poisonings are as prevalent everywhere as what we're seeing in our study, then it's a serious problem," she says. "I think we need to be aware of what these substances can do."
Tseng's research dovetails with the EPA's own statistics, which show that up to 81 percent of 265 great horned owls analyzed by the agency showed exposure to anticoagulant rodenticides. In California, another EPA study showed that of 106 bobcats, mountain lions and San Joaquin kit foxes, 84 percent had also been exposed to rodenticide. According to EPA spokesman Dale Kemery, "The EPA suspects that the results are representative of nontarget wildlife exposures nationwide."
It's not just birds and wildlife that are threatened by these toxins. Dr. Jay Vick of the VCA Animal Hospital in Santa Cruz says he treats three to five dogs per year that have eaten rodent poison.
"Relay toxicosis, as it's called when an animal is poisoned from eating another poisoned animal, is usually only dangerous for elderly or sick cats," he says. "But for dogs, they often eat the poisons directly. When they come in they'll be weak and there is often hemorrhaging in the brain and the joints. It's very discomforting for the dogs. It usually takes four to six weeks to get them back to health."
In agricultural areas, rodenticides are used on a massive scale. Santa Cruz County Agricultural Commissioner Ken Corbishley says rodents do very little damage to crops, but crop buyers almost always require the farmers to use rodenticides as part of a contractual agreement. He says the idea of changing these practices rarely comes up when he talks with farmers.
"I've never heard farmers talking about getting rid of [chemical rodenticides]," he says. "It's just not something that's really talked about."
Dmytryk, meanwhile, says she hopes to get people thinking about it.
"If people realize that our beautiful birds and mammals are in danger from something as easily fixed as rodenticide, I think they'll wake up," she says. "We can't ignore it anymore."
For information about building an owl box, email Rebecca Dmytryk at [email protected] or visit www.wildrescue.org. For a list of dangerous rodenticides identified by the EPA visit www.epa.gov/opp00001/reregistration/rodenticides/.
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