Crafting effective messaging in anti-rodenticide advocacy

What kinds of arguments are most effective at convincing people to stop using rodenticides?

Author: William McAuliffe

Rodenticides—poisons used to kill rodents—might cause days of suffering to billions of rodents every year.¹ In a recent piece for The Animals Issue of Current Affairs, I lament the fact that, while there is much activism against the use of rodenticides, little of the messaging addresses the suffering rodents endure when they are poisoned. After all, they are poisoned at much higher rates than humans, pets, or wildlife. Rodents don’t suffer any less just because they are a disease vector in the contexts where we poison them. If we can control their populations more humanely and at a relatively low cost to ourselves, we have a strong moral reason to do so.

Of course, people do not often grant nonhuman animals much consideration, especially “pest” populations. It might not be persuasive to ask people to stop using rodenticides for the benefit of rats. If there are other arguments that do a better job of convincing the public, anti-rodenticide activists should probably use them instead, even if they are personally motivated by helping rodents.

Indeed, in partnership with Che Green, we confirmed that there are almost certainly better ways of framing the issue. He conducted focus groups and individual interviews with a diverse sample of American adults. We intentionally recruited several respondents who had dealt with a rodent infestation in recent years. Several of them had used rodenticide, among a wide variety of other methods.

Che began by explaining what rodenticides are and why pest managers use them. Then, he presented six different arguments (as shown below) against rodenticide, based on common arguments that anti-rodenticide activists use in billboards, pamphlets, and petitions.²

Argument 1: Effects on non-target wildlife

Text Interviewees Read: Rodents often consume more poison than is necessary to kill them, leading to “bioaccumulation,” whereby the poison remains toxic in the rodent’s body long after its death. As a result, natural predators of rodents, including owls, hawks, and mountain lions, can be poisoned by rodents after consuming rodents that have eaten rodenticides. They will also sometimes exhibit abnormal behaviors, causing them to die in other ways, such as getting hit by cars. Rodent populations will bounce back quickly from predation, but the poisoned predators of rodents have smaller populations that recover more slowly.

Argument 2: Effects on pets and children

Rodenticides pose a danger to those we want most to protect: Our children and pets. Each year, thousands of children mistake rodenticides for an edible treat, sending them to the hospital. Pet dogs and cats risk hospitalization and even death from eating dead rodents or the rodenticide baits themselves. Some of the common rodenticides have antidotes, but other common ones do not.

Argument 3: Poison = Profit

Rather than taking preventative steps like sealing entryways, pest control companies are motivated to use rodenticides because they hook customers indefinitely. Rodenticide bait boxes will attract rodents to your home because they have tasty food inside like peanut butter. Pest managers charge a monthly fee to put out new bait boxes because the rodent problem never goes away. Pest companies also like rodenticide baits more than traps because they do not have to keep checking them for trapped rodents.

Argument 4: Effect on rodents

Rodenticides are thought to cause rodents 2-3 days of intense pain before eventually causing death. For example, some types of rodenticides cause symptoms of internal bleeding in rodents: dizziness, abdominal pain, diarrhea, hypothermia, rapid heartbeat, and difficulty breathing. Poisoned rodents often act in ways suggesting that they are in pain, including discontinuing eating, standing in a hunched posture, and wandering into open spaces where they are vulnerable to predators.

Argument 5: Long-term ineffectiveness

Customers often believe that rodenticides will eliminate every rodent in or near their home or business. But rodenticides have not and never will kill an entire rodent population. Without continued retreatment, the population will quickly rebound, as a single female rodent can birth hundreds of offspring in a year. Although rodenticides can provide short-term relief from rodents, you will never permanently solve a rodent problem using them.

Argument 6: Innovative humane solutions

New, more humane technologies have made rodenticides obsolete. For instance, there is a liquid birth control bait that takes longer than rodenticides to have an impact, but it does not cause pain. For outdoor infestations, pest managers can use carbon monoxide or carbon dioxide in rodent burrows, which kill rodents much faster than rodenticides. For indoor infestations, snap traps with sensors can reduce the labor costs of monitoring traps for dead rodents.

Note: Interviewees did not see the visualizations, which I produced using Imagen on Gemini.

At the end of the interview, Che asked respondents to indicate which argument was the most persuasive and which was the weakest. The results are shown below.

Based on their responses, here are my takeaways:

1. A clear majority of interviewees were most concerned about their children or pets accidentally consuming rodenticide.³ Anti-rodenticide activists should consider centering this messaging around this risk, especially in contexts where it is particularly salient.⁴

2. Not a single interviewee thought rodent-centered messaging was the most persuasive message. Since several interviewees thought it was the least persuasive message, it seems prudent to avoid the harms of rodenticide to rodents themselves. Of course, there will be exceptions, like when communicating about the issue to other animal advocates.

3. Many respondents don’t seem bothered by the fact that rodenticides are not an adequate long-term solution. Advocates must keep in mind that people favor poison primarily because it can address an existing infestation. Humane solutions like rodent fertility control won’t be perceived as an adequate substitute on their own because preventing future births does nothing to address the problem they may have now. Still, advocates can point out to people that rodenticides are frequently used to slow down a rebound in the rat population, not just to knock down a population that is out of control.

We should also acknowledge the strengths and weaknesses of focus groups and interviews. We had 90 minutes to understand the context behind the respondents’ views, and they had ample opportunity to request clarification and adjust their positions accordingly. We only asked them which messages they preferred after they had had the opportunity to discuss all of them. Although we were only able to speak with 21 people, we gained a good understanding of their views. Had we conducted a questionnaire-based survey, we would have had little insight into why people preferred the arguments they did; survey respondents might have failed to understand the questions as we worded them, or may have provided their gut reactions rather than their more considered views.

Still, there is no way around it: 21 is a very small sample. While the “Effects on pets and children” message performed above chance, variability in all of the other responses is consistent with sampling error. We would gain more confidence in our findings if we could replicate them in a questionnaire-based survey, where it would be feasible to recruit a much larger sample.

We have also conducted polls on rodenticides, using thousands of samples (for a summary, see our piece on US rodenticide policy). They paint a broadly similar picture. Most American adults dislike rodenticides and would be open to safer alternatives if they were comparably effective. Yet, they view rodenticides as necessary and don’t want them banned. They’re open to common-sense reforms, but they’re not primarily motivated by sympathy for rats.

Due to resource constraints, we never took full advantage of the main benefit of focus groups: coding the actual transcripts for themes that were common across different interviews. If you’re a researcher or advocate interested in taking a closer look at the data, feel free to reach out to me at william@rethinkpriorities.org.

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Acknowledgements

Thank you to Urszula Zarosa for feedback, to Shane Coburn for copyediting, and to Elisa Autric for publishing.

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1. To be clear, there are no direct estimates of how many rodents are poisoned each year. I feel comfortable saying “billions” because there are about five billion hectares of farmland + built-up land, so you’d only need to assume one poisoned rodent per every five hectares per year to reach billions. It seems unlikely that we’ll get a better estimate anytime soon, as it’s hard enough simply to count rodents alone. For more details, see our piece Abundance Estimates of Three Wild Populations.

2. For example, the Defend Them All Foundation uses five of these arguments in their introduction to the issue.

3. Using a two-tailed alpha of .05, this effect was statistically significant (even after we accounted for the fact that people in the same focus group may have influenced each other).

4. For example, when campaigning against the availability of rodenticides on websites like Amazon.com, the use of rodenticides by homeowners’ associations, etc.