Good article describing how we are killing nature's rodent control by using rat poisons.

Rat poisons infiltrate wild food chains

By Tom Knudson / The Sacramento Bee

Outside Palm Desert, 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 California: rat poison.
Over the years, rat poison has spared state residents 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 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."
Full article