Invasive species

Is it ethical to use wild animals to clean up our ecological mess?

A racoon dog in a forest

In Sweden captured and sterilized Racoon dogs are released into the wild with a tracker to find fellow Racoon dogs. Upon location, these animals are killed and the tracked individual is retrieved and re-release for another mission elsewhere. Every mate the "Judas-animal" meets, dies shortly after. Similar methods are used to combat donkeys in Australia and goats on the Galapagos. Photo by Canva.

A new study raises serious questions about the moral implications of using animals in roles such as “assassins”, “snitches” and “moles” in the fight against invasive species, including their own.

Vineyards that use trained falcons to protect their grapes from invasive birds is one example of how animals can help us control invasive species. The World Organisation for Animal Health points to using animals as biosensors and early warning systems for diseases or invasive species in the wild.

However, what are the ethical considerations when we enlist wild animals to perform such tasks? Should we begin asking similar questions about their welfare as we do for domestic and industrial animals, such as dogs, cows, and chickens?

Explores the moral responsibilities

Centre researcher Erica von Essen, alongside colleagues from the University of Pittsburgh and Stockholm University's Department of Social Anthropology, has delved into these questions. Their study explores the moral responsibilities we take on when “recruiting” animals into these roles and draws comparisons to labor contracts with human workers.

“We have to ask ourselves whether it is acceptable, from a moral point of view, that non-human workers – wittingly or unwittingly – are deployed to do our dirty work to eliminate invasive species,” says Erica von Essen.

The study examines several different types of roles or “careers” for non-human laborers and argues that their contributions are often overlooked. This tends to happen because either their actions are seen as just “natural behavior,” or the animals themselves are regarded as property or tools rather than as workers. In total, the researchers identified five roles non-human laborers can have in the fight against invasives:

1. Acting as sensors to monitor the environment (biosensors).
2. Hunting other species, like pests or invasive animals (predators).
3. Taking up space to block other species from settling in the area (placeholders).
4. Tracking or finding remaining populations of a species (Judas animals).
5. Infiltrating invasive species and undermining them from within (moles).

A practice with problematic history

This approach helped the researchers to explore the political and ethical implications of using certain species to control others (“biocontrol”) – a practice with a long and often problematic history of unintended consequences and collateral damage.

For example, when Indian mongooses were introduced in Hawai’i in the late 1800s to control rat populations in sugar cane fields, the day-active mongooses largely ignored the night-active rats and instead decimated native bird populations. Similarly, cane toads from South America introduced in Australia in the 1930s to combat cane beetles quickly spread and became an invasive species requiring control themselves.

“Despite these ill-fated interventions, nonhuman labor is increasingly deployed to control invasive species at various scales”, they write. Today it is being sold to decision-makers and to publics as a ‘nature-based solution’, or even cost-effective, despite the human interventions that such initiatives usually entail. Trying to get sharks to eat the invasive lionfish in the Mediterranean, for example, seems to require divers spoonfeeding them to get them to acquire the taste. More hands-on initiatives are planned still, including potentially genetically engineering and releasing superwasp armies that hatch eggs in or parasite on invasive pests like the stink bug.

The Judas model

Hence, even though it remains less common than chemical (e.g., pesticides and herbicides) and mechanical (e.g., hunting or weeding) control methods, the increasing use of wild animals to manage invasives warrants more caution. The problem is that for non-human laborers, this is done without consent, and they are generally denied benefits, while the advantages of such an arrangement for human managers are clear: there is no obligation to this labor force, and few interventions may be needed to direct or extract labor if it is occurring in the wild. But it is in this extraction that things can go wrong. Even when things go well, and the animals perform their task as ‘good co-workers’, there are some clear harms.

“The Judas model of using one captured animal to locate invasive or feral species like racoon dogs, donkeys, camels and goats for eradication, for example, can technically enlist a lone animal to become part of its own species destruction: every mate it meets, dies shortly after,” says Erica von Essen.

Consider reciprocal obligations

The researchers do not claim it is always wrong to use this “wild workforce” to manage invasive species. But as such projects become more common, it would not be unreasonable to regard animals as co-laborers and to consider which reciprocal obligations humans might have to them. Exactly what a contract with these non-human laborers should include is now a serious question to consider, at least in animal equivalent terms.

The researchers discuss things like rights to refuse to work, care to workers, and retirement. One example of the latter is how goats tasked to graze on invasive plants in Pittsburgh have received “goat pensions” – housing and food even after they are no longer able to labor. Often, they get to stay with their caretakers, who have come to know and value them as individuals.

Such efforts could even foster greater “interspecies solidarity” with benefits for both humans and animals. One example of such interlinkages, as the researchers note, is that prior studies suggest that better conditions for human workers often correlate with improved treatment of animals.

Published: 2025-01-31

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