poison-food-chain_oc-mj2014

8 MAY—JUNE 2014

POISON

The use of second-generation anticoagulants, com-monly found in rodenticides, faces new restrictions on how and who can administer its usage. The change in who can use such toxic chemicals comes as a result of collateral deaths to wildlife. Since ro-dents are a staple of their diets, raptors, foxes and bobcats are the most frequent victims of second-ary poisoning. Here, a trio of Norway rats (Rattus norvegicus) emerging from hole in a suburban yard at night. The Norway rat occur in the Central Valley, urban coastal areas and the Lake Tahoe area.

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Earlier this year, state regulators at the California Depart-ment of Pesticide Regulation made a monumental deci-sion to change the way people use certain toxic chemicals to kill rodents. Ultimately, that decision will have lasting ramifications for wild animals that will no longer suf-fer a miserable death because of the thoughtless labeling

practices and careless applications of second-generation anticoagulants (SGARs) that are used in rodenticides.

In March, DPR regulators reclassified four SGARs and ordered them labeled as restricted materials by July 1. That decision prohibits anyone except professional exterminators from using the chemicals. For de-cades, these anticoagulants have been in rodenticides that are available to anyone.

The abuse of rodenticides has left countless animals—wildlife and household pets—suffering a miserable and grotesque death. The end is slow and allows the victim time to become easy prey for some preda-tor higher on the food chain. The poison is passed on to the predator, making it a new victim.

DPR set a July deadline to remove the chemicals from shelves ex-cept by the use of professional, certified applicators (exterminators).

Environmental scientists at the California Department of Fish and

Dispersal of Chemicals That Kill Rodents Prove Often to be the Last Supper for Wildlife too

Story By Dana Michaels

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Wildlife applauded DPR’s decision. For decades, CDFW’s environmental scientists have witnessed the suffering and death from SGARs when non-target animals and birds eat poisoned rodents.

Not everyone has seen the decision as beneficial and some voice concern over being overrun with what they fearfully describe as disease-ridden vermin. But the notion is unrealistic. There remain numer-ous ways to deal with rodents without harming non-targeted animals. (See sidebar, Non-Toxic Rodent Controls are Available)

DPR’s decision restricts only four chemicals that are most likely to cause the secondary poisoning of animals other than rodents. The chemicals include the SGARs brodifacoum, bromadiolone, difena-coum and difethialone. Scientists have de-termined these are more toxic and longer-lasting than older rodenticide compounds.

The popular rodent baits made with SGARs promised to kill rodents with only one feeding. What most inexperienced users failed to understand was that the poi-son worked slowly with terrible collateral results. In the several days that it takes for the SGARs to work, the rodents continue to eat the bait, which concentrates toxins in their bodies before they die. Meanwhile, their natural predators still see them as a tasty meal, and while weakened, they’re easy to catch.

When predatory and scavenging birds and mammals eat the dead or dying ro-dents that have consumed these baits, the predators can become poisoned. Common victims include all types of wildlife: owls, hawks, raccoons, bobcats, mountain lions, foxes and coyotes. In two cases, tertiary poisoning occurred when mountain lions ate coyotes that had eaten rodents that had eaten anticoagulant rodenticide bait. This is how toxins work their way up the food chain.

The chain does not limit itself only to wild animals. House pets that are allowed to roam will also eat dead or dying rodents that have eaten the bait, or in some cases have eaten unprotected bait themselves, with the same results. Veterinarians have treated dogs and cats that have ingested just enough poison to make them sick, but not kill them. According to the Marin Humane Society says dogs are especially

susceptible to these toxins, and d-CON has been used to intentionally poison pets.

Poison control centers report approxi-mately 10,000 U.S. children are exposed to rodenticides every year. The U.S. Environ-mental Protection Agency cited that figure when, in 2011, it required all rodenticides intended for above-ground residential use be placed in bait boxes.

CDFW Research Made the Connection

CDFW scientists have been study-ing dead wildlife for decades with par-ticular interest in evidence of poisoning by legal pesticides since at least 1994. By 1998, CDFW scientists thought there was enough evidence of widespread rodenti-

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National Park Service biologists Joanne Moriarty and Jeff Sikich, top image, measure a captured mountain lion’s incisors in late March. The big cat was treated for mange, bottom image, a parasitic disease of the hair and skin. Blood tests later showed exposure to anti-coagulant rodenticides, commonly known as rat poison.

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cide poisoning in non-target wildlife to ask the DPR to restrict the use of brodifacoum, one of the four culprits, to certified profes-sional users. DPR estimates that 98 percent of brodifacoum is used by unlicensed peo-ple such as homeowners and maintenance workers. The perception might be that people whose livelihood requires a profes-sional license are more likely to be trained and use toxic products only as directed to ensure an acceptable level of safety.

“When SGARs, which are lethal with one feeding, became available for home-owner use, the department started receiv-ing more reports of poisoned non-target wildlife,” said Bob Hosea, a CDFW envi-ronmental scientist who did research on rodenticide-poisoned wildlife from 1994 to 2006. Since rodents are a staple of their di-ets, raptors, foxes and bobcats are the most frequent victims of secondary poisoning.

As investigations proceeded, CDFW received carcasses of dead animals from wildlife care facilities. Researchers discov-ered that in a large radio telemetry study along the Coast Range in the San Francisco Bay area, golden eagles were found to have been exposed to SGARs. Mountain lions and bobcats from the Thousand Oaks area had been exposed as well. A dead moun-tain lion that had been exposed was found in Palm Springs. In each case, the question became how could animals like mountain lions and golden eagles be exposed to these pesticides if they were only to be used inside and adjacent to buildings?

Most disturbing was the discovery that 73 percent of San Joaquin kit foxes—a protected species under both state and federal law—that were recovered from the unique urban population in Bakersfield, had been exposed to these compounds.

Environmental scientist Stella McMil-lin has directed anticoagulant research for CDFW since 2006. “When animals die of anticoagulant poisoning, it is often obvi-ous,” she said. “Sometimes you can see the bruising even before you open the carcass. There’s a lot of blood inside the bodies from the internal hemorrhaging antico-agulants cause.”

Other external signs may include blood oozing from the legs and mouth of birds and mammals, from the nose in mammals and red bruises from blood run-

Like most animals, rodents go where food is available and they feel safe. So the easiest way to discourage them is to remove or modify any-

thing that could make them comfortable. Sanitation is the first step to controlling rodents. Without sanitation, all your other efforts will be wasted and rats will return.

Food

Norway rats eat a wide variety of foods but seem to prefer cereal grains,

meats, fish, nuts and some fruits. Roof rats will eat those things, but they prefer fruits, nuts, berries, slugs and snails. They are especially fond of avocados and citrus. Both species will eat your pets’ food—an easy meal.• Pick up fruit that has fallen from trees

as soon as possible.• If you have any kind of dry pet food,

bulk food (i.e., rice) or seeds, keep it in metal containers with tight lids, especially if you store it in a garage or shed. Rodents can chew through almost anything else.

• Never leave any food out (human or pet), especially outside or in the garage.

• If you have a bird feeder, put it on a slick metal pole and take it indoors at night.

• Secure your garbage in a tightly sealed can.

• Seal water leaks and remove standing water that can attract unwelcome animals (and waste water.)

Remove “Guests”

Seal all the entries to your home, but first, make sure there are no rodents

that could be trapped inside. Dead animals inside a wall or attic will stink! Trap and remove any rodents that are already there. Set traps in secluded areas where they’ve been seen or are likely to travel, such as close to walls, behind objects, in dark cor-ners, on ledges, shelves, fences, pipes and

garage rafters. In areas where children, pets or birds might go, put the trap inside a box or use some kind of barrier to keep them away from it.

Check traps daily and wear disposable gloves when removing rodents from traps; place them in a sealed plastic bag then into your garbage bin for weekly collection. Wash your hands after handling traps or rodents, even when using gloves.

Exclusion

Seal all openings where cables, wires and pipes enter buildings, and any cracks

or holes in foundation, walls and roofs with hardware mesh and concrete, plaster or metal whenever possible. Rodents can squeeze into holes that are as narrow as a half-inch in diameter. At the very least, stuff stainless steel or copper pot scrub-bers or Stuf-fit copper mesh wool into the spaces. All are sold online and at hardware and discount stores. Norway and roof rats can chew through polyurethane spray foam fillers, wood, sheet rock, caulking and plas-tic sheeting.• Repair or replace any damaged ventila-

tion screens under eaves or around the foundation of your home.

• On windows that can be opened, keep screens in good condition; repair holes.

• Cover rooftop plumbing vent pipes and attic vents with screens.

• Whatever method you use, check your work periodically, so you can repair it if it weakens or gets damaged.

Support Nature to Support You

Protect rodents’ natural predators—birds of prey. Providing tall trees that owls

and other raptors favor will encourage them to hang around your yard and remove rodents for you.• During breeding season, a family of

five owls can eat as many as 3,000

Non-Toxic Rodent Controls are Available

Non-Toxic ControlsContinues on Page 19

12 MAY—JUNE 2014

ning freely under the skin on all animals. The animals’ bodies are checked for

evidence of trauma that would indicate another cause of death. But even animals killed in other ways often have antico-agulants in their systems. Sick or dying animals are more vulnerable than healthy ones to injuries and death by other means.

“Back in the 1990s, it was easier for our findings to be discounted,” McMillin said. “But now multiple studies by different researchers have shown the same thing. Whether it’s mountain lions and bobcats, fishers, raptors or kit foxes, our wild preda-tors and scavengers are being exposed to SGARs at very high rates.”

Rat poison in old-growth forests?

A 2012 study entitled Anticoagulant Rodenticides on our Public and Community Lands: Spatial Distribution of Exposure and Poisoning of a Rare Forest Carnivore revealed significant impact on fishers (Martes pen-nanti). The fisher once lived throughout the West Coast of North America but is now a candidate for listing under the fed-eral Endangered Species Act. The conclu-sion drawn was that the rodenticide that’s killing them is almost certainly being used by people illegally growing marijuana on public and private lands.

When CDFW’s Chief of Enforcement Mike Carion took the helm as the state’s top wildlife officer and the leader of California’s warden force, he inherited a problem that had been around for a long time, but was taking on a new high-profile status. “Illicit marijuana grows are wreak-ing havoc on our wildlife and the habitat they need to survive,” he said. “Illegal marijuana grows have huge impacts on the environment, not only through illegal stream dewatering and habitat destruc-tion, but also by the use of pesticides like d-CON to protect the crops. Many of the pesticides are not even legal for use in the United States. It’s devastating for wildlife.”

There may also be a connection between non-lethal rodenticide poisoning and mange in some species. National Park Service wildlife ecologist Dr. Seth Riley led a study to determine whether there is a correlation between anticoagulant expo-sure and notoedric mange in bobcats and mountain lions in Southern California.

The animals in Santa Monica Moun-tains National Recreation Area were studied between 1996 and 2006. Blood and liver tests indicated that 90 percent of the mountain lions and 92 percent of the bobcats had been exposed to roden-ticide—often more than one type. If the poison doesn’t kill them outright, it tends to lower their resistance to disease, which can result in a form of mange that causes dehydration and a slow, painful death.

“They have a crusty face and head, and become emaciated,” Riley said. A significant number of mortali-ties and declines in population have been noted in bob-cats in the Malibu

area because of rat poison. All the cats with mange also had anticoagulants in their systems.

Two collared mountain lions—part of 31 lions involved in the Riley study—were killed by rat poison, researchers have learned. Both lions had killed and eaten coyotes in the previous month. Necropsies indicated the lions were poisoned by the coyotes they ate, and that the coyotes carried high levels of rodenticide toxins

“Some people do read the labels but think if they use twice as much as directed, it will be twice as effective. That is absolutely wrong!”

Bob HoseaCDFW Environmental Scientist

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from the rodents they ate. A target pest can continue to consume bait before it dies, causing super-lethal SGAR concentrations to accumulate in its body. Predators and scavengers that consume such rodents are then exposed to very high doses of these toxic compounds.

The first-ever cases of mange in San Joaquin kit foxes occurred in Bakersfield last year. It is unknown wheth-er there is a connection between mange and SGAR exposure. What is known is that last year at least three of the endangered foxes died from SGAR poisoning and an additional five died from mange. All of the foxes that died of mange had been exposed to SGARs. Evidence shows that most of the animals were exposed to more than one kind of SGAR. Scientists at the CDFW Wildlife Investigations Laboratory and California State University-Stanislaus Endangered Species Recovery Program studied kit fox habitat use to try and deter-mine potential sources for anticoagulant exposure. The foxes that tested positive for SGARs were more likely to be found near golf courses and undeveloped areas—de-spite the fact that SGARs are labeled only for use in and within 100 feet of build-ings. These results support the theory that people are using the SGARs in the wrong settings, in violation of the instructions on the products’ packaging. (The study is online at http://digitalcommons.lmu.edu/cgi/viewcontent.cgi?article=1144&context=cate.)

“Some people do read the labels but think if they use twice as much as directed, it will be twice as effective,” Hosea said. “That is absolutely wrong!”

New Restrictions Can Save Wildlife

Because of hazards documented by the late 1990s, the U.S. Environmental Protection Agency (EPA) was considering restrictions on such products at the same time as DPR. The chemical industry lob-bied against new state regulations and con-vinced DPR to wait for the federal agency’s decision.

“Rodenticide manufacturers were

asked in June 2008 to adopt the safety measures – bait stations and formulation changes,” the EPA said. “They were given three years—until June 2011—to make the changes, and most manufacturers met that deadline. Reckitt Benckiser, the manufac-turer of d-CON, is the only rodenticide manufacturer that is currently producing and selling products that do not meet the current safety standards.”

The current standards for products that contain SGARs and are marketed to residential consumers throughout the U.S. are: • Bait stations must be protective and

tamper resistant. Only bait forms that can be secured in bait stations, like blocks or pastes, may be used in these products.

• Products may contain no more than 1 pound of rodenticide bait.

• Active ingredients may not contain the second generation anticoagulants brodifacoum, bromadiolone, difena-coum or difethialone.

The EPA has been moving to ban household sales of products containing brodifacoum by canceling the legal reg-istration of products that do not comply with these safety requirements (www.epa.gov/pesticides/mice-and-rats/). Without legal registration, such dangerous products cannot be sold to unlicensed consumers in the U.S.

Twelve d-CON mouse and rat poisons will be affected by this, so the manufactur-er, Reckit Benckiser, has stopped fighting and negotiated an agreement with the EPA. According to their news release, the company “will voluntarily discontinue production of d-CON baits containing

second generation antico-agulant rodenticides. Those rodent control products will be replaced with a new line of rodenticide baits in 2015, which have been registered with the U.S. EPA and are approved for con-sumer use in every state, including California.”

California won’t wait another six months to get

the most dangerous rat poisons off store shelves. DPR’s new restrictions take effect in July.

The California Office of Administra-tive Law approved DPR’s new regulations in March, making all SGARs restricted materials. The following week, Reckitt Benckiser sued DPR for restricting d-CON’s active ingredients to certified pest control professionals and sought to delay imple-mentation of the new rules. A California Superior Court denied that request on May 9.

As stated in DPR’s Initial Statement of Reasons, restricting the use of all SGARs to only certified pest control profession-als will significantly reduce unintended exposures to non-target wildlife. Certi-fied applicators will ensure that SGARs are properly used, placed and monitored, and that poisoned rodents are disposed of properly.

It’s believed that certified applicators generally perform qualitative site assess-ments to determine how to effectively control the target species. SGARs are only one of several tools certified applicators may use for effective rodent control. In contrast to general consumers, certified ap-plicators are more likely to implement in-tegrated pest management (IPM) strategies and use non-pesticide measures—especially preventive strategies—before resorting to pesticides. Licensees and permit holders have more requirements related to such strategies than non-certified applicators. For example, IPM strategies are covered in the certification examination process and continuing education courses attended by certificate holders and licensees.

The DPR and EPA are not acting rashly. Six years have passed since the EPA

Rat PoisonContinues on Page 19

We’ve asked for tighter regulation of brodifacoum״for nearly 20 years because of evidence that wildlife was being poisoned. In that time, Reckitt Benckiser could have employed scientists to develop safer alternatives, but instead chose to employ lawyers to stall the process.״

Stella McMillinCDFW Environmental Scientist

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Rat PoisonContinued from Page 13

imposed the new safety requirements. Every rodenticide manufacturer com-plied except Reckitt Benckiser. Now these agencies must take action for the safety of non-target animals and people.

“We’ve asked for tighter regulation of brodifacoum for nearly 20 years be-cause of evidence that wildlife was being poisoned,” McMillin said. “In that time, Reckitt Benckiser could have employed scientists to develop safer alternatives, but instead chose to employ lawyers to stall the process.”

Safe, Effective Rodent Control

There’s more than one way to keep rodents away, and some are safer than others. CDFW urges residents to employ non-chemical means of rodent control in order to protect the state’s wildlife.

“The best way to keep rodents out of your home is by eliminating access points that rats and mice might use to enter,” McMillin said. “It can be as easy as stuffing stainless steel or copper pot scrubbers, or Stuf-fit copper mesh into small holes.”

More information on protecting wild-life and pets from rodenticide baits is on CDFW’s website at www.dfg.ca.gov/educa-tion/rodenticide.

Dana Michaels is a marketing specialist with the California Department of Fish and Wildlife. Her stories have appeared before in Outdoor California.

rodents. You can encourage them by hanging a nest box on your property. Be cautious, however, and don’t do this if you or any of your neighbors are using any kind of rat poison. Remember that poisoned rodents can poison the predators, scavengers and pets that eat them.

No Rat Habitat

Keep your home and yard neat and clean. Don’t give rats places to

hide.Remove things rodents can hide

under, such as wood piles, debris, con-struction waste, dense vegetation and ground-covering vines, like ivy.

Resources for More InformationTo learn more about owl nest boxes, visit www.hungryowl.org Raptors Are The Solution (RATS): www.raptorsarethesolution.org/ University of California Integrated Pest Management: www.ipm.ucdavis.edu/PMG/PESTNOTES/pn74106.html#MANAGEMENT Find your county’s UC Cooperative Ex-tension office for local advice at http://ucanr.edu/County_Offices/ For safer, legal rodent bait station prod-ucts visit: www.epa.gov/pesticides/mice-and-rats/rodent-bait-station.html

Non-Toxic Controls Continued from Page 13

Researchers removed only 93 ticks from one reptile, one bird and seven mam-mals, a number substantially less than what would be expected had animals been found in rural instead of urban areas. Ticks included three infamous human-biters and disease carriers: the western black-legged tick, the Pacific Coast tick and the American dog tick. These ticks have broad feeding habits—the western blacklegged tick alone dines on 108 species of lizards, birds or mammals. It is the primary carrier of two bacteria that cause human diseases in the far western United States: Lyme dis-ease and the rarely acquired granulocytic anaplasmosis.

Gray fox was the most heavily para-sitized animal as six of only 29 animals yielded more than half of all ticks enumer-ated. Nearly 100 wild turkeys were deemed tick-free, but previous research revealed that rural turkeys are an important host of nymph western-blacklegged ticks in Sonoma County.

Researchers rejoiced over some discov-eries in the study. Two canines, a coyote from Livermore of Alameda County and a gray fox from Lafayette of Contra Costa County, exhibited signs of tick paralysis. Tick paralysis is a serious, crippling and sometimes fatal disease affecting pets, livestock, wildlife and occasionally people. The paralysis is caused by a toxin secreted in the saliva of certain female ticks while feeding. The disease in wild canines resem-bles that in dogs. It begins with incoordi-nation and an ascending, flabby paralysis in the rear legs. In more severe cases, the paralysis progresses to the front legs. The treatment is simple—find and remove any attached ticks before their toxin may claim the animal’s life. After tick removal, the victim usually makes an uneventful recovery within two days. The partially paralyzed coyote and gray fox recovered fully and were released.

This is the first published report in the United States of tick paralysis in a natural-ly infested coyote, and only the third case recorded in a gray fox. Ticks from the coy-ote were not saved because that animal’s disease onset predated the current survey. Ticks removed from the fox were adult American dog ticks, an aggressive human-biter commonly causing tick paralysis in dogs in the Sierra Nevada foothills. Akin to dogs, coyotes and foxes are preferred hosts of adult American dog ticks. Since many afflicted animals escape detection,

tick paralysis may have a more deleteri-ous impact upon wild-canine populations than realized.

Molecular testing likewise produced some intriguing results. Eight ticks found attached to mammals contained Lyme disease bacteria or a relapsing fever bac-terium that can infect humans. The ticks were removed from the paralyzed gray fox from Lafayette, another gray fox from Orinda and a brush rabbit from Martinez, all of Contra Costa County, and a rac-coon from Tracy in San Joaquin County. These telltale discoveries inform wildlife rehabilitators, health-care providers and veterinarians that wildlife, people or their pets can be exposed occasionally to tick-transmitted zoonotic bacteria in metro-politan areas of the greater San Francisco Bay region.

As Heckly opined, “many opportuni-ties exist for the research community to use animals brought to wildlife rehabili-tators.” The yearlong survey of ticks on urban wildlife exemplified that approach, and opened new doors between research-ers and facilities like the Lindsay Wildlife Museum. It also produced some compel-ling findings of wildlife-medical or public health significance. And, it was made possible by the diligent efforts of the staff at the Lindsay Wildlife Museum.

Robert S. Lane is a Professor Emeritus of Medi-cal Entomology at the University of California, Berkeley. He studies the biology of ticks and the ecology and epidemiology of tick-borne diseases. His stories have appeared before in Outdoor California.