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Rat poisons take care of rodent problems, but also kill wildlife and pets

Lester Graham
Michigan Radio
Reserachers find most Great Horned Owls have rat poison in their systems. This is a captive owl at the Howell Nature Center.

Wildlife are being poisoned and much of the time people using the poisons are not even aware of the danger. One Michigan resident is on a crusade to make people understand what’s at risk when they use rat poison.

David Collins became interested in rat poison after a pair of Great Horned Owls nested in a park in Ann Arbor. He learned owls are often poisoned because they go after slower-moving rats that have been poisoned. He started noticing rat poison bait traps around his town.

“I'm walking my dog. I'd walk by them repeatedly and not really think that there was anything I could do about it. It's, you know, city properties and businesses. And it wasn't until this year that I finally decided, hey, maybe I can talk to somebody and see if I can get them to change their mind,” Collins said. 

Credit Lester Graham / Michigan Radio
Michigan Radio
David Collins stands next to the Ann Arbor City Hall. Rat poison bait traps line the outside wall around the building.

He talked with some of the businesses about the risks of poisoning wildlife. They removed the traps.

Then he noticed Washtenaw County buildings had a lot of the bait traps. He called his county commissioner. In days the county removed them.

“Yeah. It was it was deceptively quick because not everyone is quite so cooperative. But it did help me realize that maybe there is a chance to to get rid of a few of them in town, if nothing else,” Collins said.

Collins learned about the link between rat poison and wildlife because of the Howell Nature Center’s website.

Dana DeBenham is the recently-retired wildlife director at the center. They take in thousands of injured wild animals each year and try to treat them so they can be released again. She showed a captive bald eagle and other raptors that cannot be released into the wild because their injuries are too severe.

We then visit a barn owl they’ve named Gilly. Fittingly, the owl lives in a barn.

Credit Lester Graham / Michigan Radio
Michigan Radio
Recently retired Wildlife Director of the Howell Nature Center Dana DeBenham is the center's expert on wildlife and rat poisons.

"A pair of barn owls or a family of barn owls in your barn can eat two to 4000 mice and rats a year. That's fantastic natural rodent control,” DeBenham noted.

Barn owls have been wiped out in Michigan because of loss of habitat and because of rat poison. DeBenham says all kinds of wildlife are exposed to rat poison.

"Studies show, for instance at Tufts University in Massachusetts, that 86% of the raptors coming in test positive for rodenticides,” she said.

Birds of prey are not the only ones being poisoned.

“It's affecting all kinds of wildlife, not just raptors. Foxes, coyotes, bobcats,” she said.

Pets are also being poisoned.

Kerry McKinney is an emergency care veterinarian at the Ann Arbor Animal Hospital.

"I think it's a concern that the pets have access to the rodenticide themselves. I think the secondary exposure with pets eating poisoned rodents is probably a little bit less likely, but certainly possible," McKinney said.

She added that rat poison is one of the top ways pets are poisoned.

“Nationwide, according to Pet Poison Help Line, that's one of the top 10 poisoning cases that they see typically over the last several years," McKinney said.

Credit Lester Graham / Michigan Radio
Michigan Radio
The opening to a rat poison bait trap.

Not all rat poisons work the same. The "first generation" poisons are anticoagulants which work slower over a few doses. Newer "second generation" anticoagulants kill rats much faster and build up in wildlife much faster. And then there are neurotoxicants; it’s much more difficult to save an animal exposed to them. (See this information with a list of rodenticides and information about the chemicals.)

There are rat poisons which don’t kill wildlife or pets. They’re often called “eco-friendly” rat poisons.

However, when someone has a rat problem, they usually want the fastest, most lethal poison to get rid of the vermin as quickly as possible.

David Collins, the guy trying to get rat poison bait traps removed in his town, understands that a rat infestation is a horrible problem for a restaurant, or school, or home.

Credit Lester Graham / Michigan Radio
Michigan Radio
A barn owl at Howell Nature Center sits under a heat lamp on a cold winter day. Barn owls are excellent rodent hunters, but the birds have been wiped out in Michigan because of habitat loss and rat poisons.

“I'm not entirely against rodenticides in all cases, but I want to make sure that if people do choose to use them, if they've exhausted every other possibility and their rodent problem is so severe, that they openly acknowledge the reality that they'll be taking many other animals and possibly even pets along with them,” Collins explained. 

The experts say before poison, first, don’t attract rats. Don’t leave pet food outside. Clean up under your bird feeder. Keep tight lids on trash cans and pick up pet waste. Then, if you feel you must put out rat poison bait traps, use an eco-friendly one that won’t kill wildlife or pets.

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Lester Graham reports for The Environment Report. He has reported on public policy, politics, and issues regarding race and gender inequity. He was previously with The Environment Report at Michigan Public from 1998-2010.
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