if you consider using a pest control company:
- Request the names of the products used for rodent control. Don’t hire anyone who won’t tell you.
- Seek companies with poison-free solutions (such as barriers, traps, cleaning up habitat).
- Demand alternatives to rodenticides. Pest control companies won’t use rodenticides if they are not profitable.
Rodenticides
Rat poison, or rodenticide, is widely used to kill rodents such as rats, mice, and voles. But rat poison has harrowing consequences to the rest of us. Rodents aren’t the only animals to sicken or die from rat poison: so do other wildlife, pets, even children. And rodents rapidly develop resistance to each new rodenticide, leading to ever-more-toxic poisons that linger long in the environment. Rodenticides have now made their way into the food chain in harmful ways that are only beginning to be realized.
Raptors in human environments are highly vulnerable to rodenticides. They prey heavily on rodents, as well as on small birds, which may feed on rodenticide-laden insects. Secondary poisoning in raptors and other non-target wildlife is well documented. Wherever rodenticides have been studied in wildlife, the prevalence is high and the effects are devastating.
What Rodenticides Do
Second-Generation Anticoagulants
There are a lot of rodenticides. The most common are anticoagulants, which cause animals to bleed to death internally. The most potent are second-generation anticoagulant rodenticides (SGARs). Only one dose is enough to be lethal.
SGARs have very long half-lives, accumulating in an animal’s liver—and remaining in the environment—for months. Although only one dose is fatal to a rat, SGAR-poisoned rodents die slowly, making them easy prey for raptors and other predators.
SGARs were partially banned by the EPA in 2015, but only after an uphill battle with manufacturers such as Reckitt-Benheiser, maker of d-Con. Yet they are still widely used (e.g., Neogen Havoc, d-CON).
Ever notice those ubiquitous black boxes around commercial buildings, in alleys, and even at residences? They contain rat poison and are installed by pest control companies. Some are mechanical traps, but most contain rat poison. Common SGARS are Brodifacoum, Bromadiolone, and Diphethialone. Look closely at the bait boxes; they list the type of poison inside.
Other Rodenticides
As rodents adapt to anticoagulant rodenticides, other types of rodenticides are now also in use. These include:
Bromethalin, a nerve poison (Tomcat, Motomco)
Cholecalciferol, a fatal concentration of vitamin D3 that causes kidney failure (d-CON recently replaced the anticoagulant brodifacoum with cholecalciferol).
Zinc phosphide, a liver, kidney, and nervous system poison (Tomcat, RatX, Wilco Zinc Homeowner Bait, Havoc)
These newer rodenticides are more difficult than anticoagulants to identify in dead and dying animals in time to treat them, and their secondary effects on other animals are not well studied.
Three Certainties About Rats and Rodenticides
1. We will never get rid of rats.
2. No method of rodent control is permanent. If rat poison worked, we wouldn’t have to keep using it.
3. The harm caused by rodenticides far exceeds their limited benefits. There is no such thing as a “good” rat poison.
The Good News
Most rodent invasions can be controlled without rat poison. Really! Rodent problems usually arise because people unintentionally create desirable rodent habitats. Before you consider poisoning, take stock. The first line of defense against rodents is integrated pest management: Exclude, Clean Up, Modify Habitat.
For more information
Poisons used to kill rodents have safer alternatives. Audubon, January-February 2013.
Raptors and rat poison. Living Bird, Summer 2015.
Raptors are the Solution (RATS).
Rodenticides and Raptors Project. Urban Raptor Conservancy.
1. Exclude: defend your fortress
- Identify where rodents can enter a home or building (e.g., crawl spaces, eaves, and ventilation pipes). Rats can enter very small spaces!
- Exclude access with material that rats can’t easily chew (hardware cloth, steel wool).
2. Clean up: eliminate sources of food, shelter, and water
Clear Up Trash
- Get rid of food scraps and pet waste
- Tightly secure garbage bags
- Close waste bins tightly. Don’t overfill.
Secure Compost Bins
- Tightly close compost bins. They make cozy homes for nesting rodents.
- Don’t use compost bins in cold weather, when food decomposes slowly
- Never add meat or fat
Eliminate Open Food Sources
- Bird feeders are also rat feeders!
– Use seed blocks or cakes, which leave less food on the ground
– Remove excess seed daily (rake it up or put a dropcloth below feeders)
– Take in feeders overnight - Clean up unharvested fruit and vegetables
- Never leave pet food outside
- Secure backyard chicken and duck coops (this is hard)
– Close or remove feeders overnight
– Install rat-proof flooring
3. Modify Habitat
- Remove ivy and other dense undergrowth. Ivy is perfect rat habitat.
- Clear vegetation 3-6′ away from buildings. Rats hate to move in the open.
- Eliminate water sources
Make A Difference
In their book, Urban Raptors, Dykstra & Boal pointed out that cities are the planet’s only expanding ecosystem, while nonhuman ecosystems are shrinking. Even as urban raptors and other wildlife increasingly make their homes in urban environments, bait boxes—black boxes of powerful rodenticides—appear as the norm, right next to wildlife habitats such as parks and other open spaces. Each of us who is a steward of wildlife can do something to reduce their exposure to rodenticides. What benefits wildlife benefits us all.