What Trade-Offs Will The Public Accept In Predator Control Debates?

Invasive animal species can present a dilemma for animal advocates. Their continued presence can cause great harm to native animals by preying on them directly or by competing with them for resources. But reducing invasive animal populations may require killing large numbers of them. Often, the most effective methods for eradicating an invasive population cause significant pain and suffering.

This is just one of multiple trade-offs inherent in managing invasive animal populations. These trade-offs are commonly considered by officials and intellectuals, but few surveys or studies have directly questioned the public on their preferences.

That’s just what this study set out to do. Researchers focused on New Zealand’s Predator Free 2050 program. Its goal is to “eradicate the most harmful introduced predators from the whole country,” including rats, possums, weasels, stoats, and ferrets. The program is somewhat controversial because of the use of 1080, with concerns about this aerial toxin’s humaneness and impacts on non-target species and the environment. However, it also has an animal welfare argument in its favor: unlike suppression methods, which control predator populations, eradication has a distinct endpoint. This means that if it’s successful, it will prevent the ongoing killing of predators (and the ongoing killing of native species by those predators).

Rather than simply ask New Zealanders what factors they think are more or less important, the researchers used a choice modeling procedure that revealed people’s preferences through their choices. Participants were given pairs of options for predator control methods that varied on several factors: predator pain and suffering, financial cost, environmental contamination, and risk to non-target animals. Some pairs asked about methods meant to completely eradicate predators, while others asked about suppression methods meant to keep their populations under control. Participants chose which option they preferred (or selected “no preference” or “neither option is acceptable under any circumstances”).

A total of 4,058 New Zealanders made 10 choices like these, five on eradication and five on suppression, selected at random from a larger set in an online survey.

These were the main findings:

• On average, people were more concerned about suppression methods than eradication methods. This means that, if given a choice between the two, people tend to prefer eradication.
• Generally speaking, people were more concerned about environmental costs, like contamination and risks to other species, than pain. But severe pain did outrank environmental costs for suppression methods, suggesting that people are less accepting of animal suffering when killing is an ongoing effort. Severe pain also mattered for eradication methods, but less than risks to other species. Having a clear endpoint seems to ease people’s animal welfare concerns but not all of their environmental ones.
• On average, people were more concerned about financial costs for suppression methods than for eradication methods. However, as the survey only talked about costs in relative terms (e.g., “cheapest”), this factor may become more important when people are presented with real-world numbers.

Some other notable findings included:

• Between 4% and 25% of people (depending on the question) said that neither option was acceptable, indicating some public opposition to lethal predator control altogether.
• On average, women were more concerned about humaneness, while men were more concerned about cost.
• On average, urban residents were more concerned about humaneness than rural residents, as were non-hunters compared to hunters.
• Among people who said they were opposed to using the aerial toxin, there was higher concern for humaneness and lower concern for cost, on average.

The researchers conclude that New Zealanders prioritize environmental over animal welfare costs when it comes to invasive species management, though they prioritize animal welfare when the harms to invasive species are perceived as especially severe and ongoing, as in the case of suppression. For advocates, this may mean that emphasizing environmental impacts or the severity of animal harms may help your message resonate more with the public. However, this study only surveyed New Zealanders and was based on the Predator Free 2050 program specifically, so its conclusions may not generalize to other groups or approaches to managing invasive animal populations. Ultimately, the findings demonstrate that public opinion around trade-offs is nuanced, underscoring the importance of digging into the details when polling the public on controversial topics.