New Rat Poisons Killing Rodents (and Everything Else)

poisoned rat photo
Photo: Katie Tegtmeyer / cc

Rodents have plenty of natural predators, like foxes, coyotes, owls, hawks, and bobcats -- but thanks to a powerful new rat poison, there's less of them all. Conservationists say that California wildlife is in a state of emergency due to the widespread use of a potent rodenticide that has, unsurprisingly, found its way up the food-chain, poisoning countless species that would otherwise help keep the rat and mice population in check, naturally. Instead, they're dying too.Across California, rat poison has proven to be an effective way of tackling the surmounting rodent problem in urban and rural areas -- but substances used for pest-control clearly aren't so well controlled or confined to pests. In addition to rats and mice, squirrels and other small wildlife have fallen victim to the toxins, though it doesn't end there.

After eating the poison, rodents are not killed immediately, but are rather weakened initially, becoming an easy target for larger predators. Those animals then are either killed too as a result, or forced to live with the effects of the toxins.

"Rodenticides are the new DDT. It is an emergency, an environmental disaster. We are killing nature's own rodent control," says Maggie Sergio, who runs a center that has cared for wildlife exposed to the rat poison, to the Sacramento Bee.

The poison has spread up the food-chain so much, in fact, that in some parts of California, more predators have rat poison in their systems than not -- and it's not discriminating. According to the Bee, 79 percent of endangered San Joaquin kit foxes tested were found to be harboring the toxin, as were 90 percent of bobcats tested near Los Angeles.

"Even if it doesn't kill animals outright, it could predispose them to predation, accidents and all kinds of things," Reg Barrett, professor of wildlife management at the University of California, Berkeley, told the Bee. "If you're running around half-gassed from poison like this, you're probably not functioning 100 percent."

For researchers and those treating injured wildlife, the problem has been evident for nearly a decade, but action on a federal level has been slow. But beginning this summer, a ban on the most potent, long-lasting rat poisons will be enacted -- though some warn that it may not be strict enough as it only limits its sale in some stores.

From the Sacramento Bee:

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."

Experts say that while rat poison may be effective at killing rodents (and just about everything else), it might not even the best method of pest control. By limiting the amount of food available for the scavengers, and working to reduce the sorts places that rats and mice can hide, the problem could be greatly reduced.

Then, of course, there's protecting and conserving the rodents' predators to curb the infestation in the most natural way -- and making sure they aren't poisoned to death because of it.

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