Supertoxic rat poisons threaten owls, other wildlife

VANCOUVER, B.C. — With the spooky glow of his headlamp illuminating an antenna in his hand, Paul Levesque stalks one of Canada's last remaining barn owls.

"Are you getting anything?" research-team leader Sofi Hindmarch asks over a walkie-talkie.

"I got it!" Levesque responds. Then a few seconds later, dejected, he radios back: "No. I lost the signal."

Working in darkness, with the quarter-moon obscured by clouds, these two scientists are trying to figure out what an elusive, radio-collared owl is eating along this country road just beyond the suburbs that ring Vancouver. Their mission is to determine whether the decline of Canada's barn owl is tied, in part, to supertoxic rat poisons.

Scientists know at least some owls are dying under gruesome circumstances, bleeding to death from stomach hemorrhages in an agonizing and days-long decline. The culprit: an extra-potent class of rodenticides that has flooded the market, designed to more effectively kill rats, a food source for the owls.

Six of 164 dead barn owls, barred owls and great horned owls in a western Canada study had pesticide levels high enough to kill them outright, causing the fatal hemorrhages. Pesticide readings in 15 to 30 percent of the others appeared toxic and seemed likely to handicap owls in a variety of ways, scientists say.

The Canada study is the latest evidence amassed by researchers that poses an unsettling question: Are we willing to poison owls and a variety of other wild animals in order to fight rats? That's what this new generation of rat poisons does.

Into the food chain

"We're finding this stuff all over the place," said John Elliott, an Environment Canada scientist who co-authored the owl study published last year. "There's a lot more rodenticide in the food chain than we would have ever thought."

Studies in Canada, the United States and Europe show the new generation of rat poisons is killing a variety of wild animals, including mountain lions, bobcats, coyotes, foxes, deer, raccoons and bald eagles. Hundreds of wildlife-poisoning deaths have been documented.

After a years-long process, the U.S. Environmental Protection Agency (EPA) will begin enforcing new rules in June to better control the rat poisons, although the restrictions don't go as far as desired by some wildlife advocates, including the U.S. Fish and Wildlife Service.

The chemicals in question are anticoagulants: They prevent an animal's blood from clotting or coagulating. The first of these, synthesized in the 1940s, is known as warfarin — the same chemical sold to humans as Coumadin, a prescription blood thinner.

The new rat poisons came along in the 1970s. With the old ones, rats had to feed on the pesticide for several days. With the new versions, only a single dose is needed. Brand names include Havoc, Talon, Contrac, Maki, Ratimus and d-CON Mouse Pruf II.

The hunt for owls

On a balmy but cloudy night, Hindmarch is trying to capture a barn owl, one of three owl species that ingested the rat poisons in last year's study. The barn owls in and around Vancouver are among the last of those birds remaining in Canada. Two weeks ago, they were declared a "threatened" species. A smaller population, classified as "endangered," lives in eastern Canada.

The hunt this night is in a gritty industrial outpost in Vancouver, where rats scamper boldly between a defunct lumberyard where they live and a bustling grain terminal where they sneak their meals.

Hindmarch, of Simon Fraser University, and Levesque fiddle with their owl traps, preparing for their 9-5 shift — 9 p.m. to 5 a.m., that is.

"Can you grab one of the girls?" Hindmarch asks Levesque, referring to the mice they hope will lure an owl to their traps.

The scientists carefully put the mice inside cages that will protect them when an owl swoops down.

"It's 'working time,' " Hindmarch says as she grabs the first mouse and scoots it through the open door of a small cage. "You'll get crackers soon."

Levesque, a freelance contract scientist, puts the cage down in tall grass. He slips in some crackers and steals back to wait inside his truck to see an owl arrive. The noisy snacking attracts barn owls, which then are caught in the trap.

Hindmarch's objective is twofold: to collect the owls' blood to test for rat poisons; and to fit the owls with radio transmitters so she can figure out where they are feeding. She wants to know whether urban owls are eating more poisoned rats than their country cousins.

A toxic load

Her work follows up on a study analyzing owls found dead in British Columbia and the Yukon Territory, which showed that nearly three-quarters had rodenticides in their livers. Earlier studies in Europe, New Zealand, New York and elsewhere documented the poisons spreading to wild animals.

Taken together, the research suggests the improved rat-killers are imposing a toxic load on the environment that no one bargained for. Owls and other wild animals are eating some rats that have ingested extraordinarily high doses of poison, researchers say.

"The rats are really little toxic packages running around before they die," said Michael Fry, a wildlife toxicologist and pesticides expert with the American Bird Conservancy. "If the rat is carrying 10 or 15 times a lethal dose, the animal that consumes it is at a much higher risk of consuming a lethal dose."

Once an animal eats a poisoned rat, the pesticides stay in the predator's system for a long time. It takes six months or longer for just half the dose to be eliminated from some animals' bodies.

"If you're just getting one dose on top of another, you get this constant exposure," said Nancy Golden, a U.S. Fish and Wildlife Service toxicologist. "It's one thing to have enough to kill you outright. But what about the ones that are just carrying this body burden? What effect does that have on their fitness? That's what worries me."

New sales limits

Pushed by environmentalists who successfully sued, the EPA in 2008 issued rules for these rat poisons that largely take them out of the consumer market next year.

Pesticide manufacturers say the EPA action was overkill but should eliminate any doubts about the products' safety for wildlife.

"There was not strong evidence to compel (EPA) to put into place the (new rules). However, they did so," said Karen Reardon of Responsible Industry for a Sound Environment, which represents pesticide manufacturers. "We have now even further added protections for secondary wildlife exposure."

In June, the sale of loose rat baits will be banned in "big-box" stores like Home Depot as well as other retail outlets. However, consumers can purchase up to 1 pound in bait "stations" designed to keep out kids and dogs. Professional exterminators may continue to use the loose baits under some circumstances.

Golden predicted the poisoning of wild animals will continue under the new rules.

"I wouldn't use anticoagulants in my backyard," said Golden. "These things are pervasive and are turning up in places we did not expect. ... They're certainly not contained where we think they are."

Robert McClure is from InvestigateWest, a nonprofit journalism studio in Seattle. www.invw.org