Outside Palm Desert, Calif., a young bobcat dies mysteriously at a nature preserve. South of Nevada City, a farmer finds an owl dead near his decoy shed. In San Rafael, a red-shouldered hawk bleeds heavily from its mouth and nose before succumbing at an animal care center.

Each of those incidents shares a link to a widely used toxin that is turning up at dangerous levels in wildlife across the nation: rat poison.

Over the years, rat poison has spared people untold filth and disease. But a new generation of highly toxic, long-lasting poisons is killing not only rats, mice and ground squirrels, but whatever feeds on them, too.

As a result, toxins are rippling outward from warehouses to woodlands, from golf courses and housing complexes to marshes and nature sanctuaries. In California, the victims include bobcats, barn owls, red-tailed hawks, coyotes, kit foxes, kestrels and scores of other predators and scavengers.

“Rodenticides are the new DDT,” said Maggie Sergio, director of advocacy at WildCare, a San Francisco Bay Area wildlife rehabilitation center that has responded to dozens of poisoning cases. “It is an emergency, an environmental disaster. We are killing nature’s own rodent control.”

Researchers say the federal government has been slow to respond to the problem, which has been building for more than a decade. This June, after years of study, regulations take effect nationwide banning the most toxic, long-lasting rat poisons from hardware stores, big box home improvement centers and other consumer outlets.

“We’ve been collecting data forever,” said Stella McMillin, an environmental scientist with the pesticide investigations unit of the California Department of Fish and Game. “They took 10 years after we knew it was a problem. It was absolutely too long.”

Research by McMillin and others shows that exposure to rat poison is widespread, especially in and near urban areas where pests, people and poison mix. Around Bakersfield, 79 percent of endangered San Joaquin kit foxes tested have turned up positive for rodenticide. Near Los Angeles, 90 percent of bobcats sampled had rat poison in their blood. “Basically, when we look for it, we find it,” McMillin said.

The same is true all over. Seventy percent of owls sampled in western Canada had rat poison in their livers. In New York, half of 265 birds of prey tested were positive for poison. In Great Britain, one of every two barn owls tested was contaminated.

“The truth is, it’s not just across the state but across the country and across the world,” said Seth Riley, a wildlife ecologist with the National Park Service whose research has linked exposure to rat poison to a rare, often fatal form of mange in bobcats in Southern California.

The poison is turning up in wilder parts of California, too, alarming scientists. One such place is the central and southern Sierra Nevada, including Yosemite National Park, where it has been discovered in the livers of a member of the weasel family, the Pacific fisher.

Scientists worry that exposure might impair reproduction in some species – as it did with DDT – or trigger other kinds of harm. But such research is costly and often takes years to yield results.

All pesticides are potentially dangerous, of course, but rat poison is especially so because rats that eat it take days to sicken and die, making them ideal targets for predators.

“They become basically little poison pills,” said Robert Hosea, an environmental scientist with the Fish and Game Department.

And once they die, their remains are toxic until they decompose. “Whatever eats them, gets it,” Hosea said.

Two tongue-twisting toxins turn up most often in wildlife: brodifacoum and bromadio-lone. On store shelves, they go by such names as D-Con, Havoc, Talon, Tomcat Ultra and Just One Bite.

Companies make the compounds super-lethal because many rats and mice have grown resistant to older poisons, such as warfarin. The new products are so toxic their use is forbidden in farm fields and restricted in and around homes, warehouses and other confined locations.

But these safeguards haven’t prevented them from turning up in exceedingly wild locations, including the Sierra National Forest and Yosemite National Park, where 19 of 21 fishers sampled showed traces of rat poison. One died from it.

The newer-generation poisons will become scarcer in June, when sales of small packets and blocks are banned. But larger bait blocks will still be available at farm stores. And licensed commercial pesticide applicators will still be able to use the stuff. “Our hope is this will shrink the amount that is available,” McMillin said. “But there is a big loophole. The homeowner who knows that the new products work a lot better can still get the products that are a problem.”

Distributed by Scripps Howard News Service.