Changing Planet

Why Doubt Invasive Species Impacts?

Invasive alien species are now found on every corner of the planet and rank higher than climate change as a current threat to endangered species. So then why, despite all the scientific evidence of negative impacts from invasive species, would people be resistant to taking action against them? In two scientific papers released this week myself and colleagues have tried to understand why invasive species have such a low public profile compared to climate change, and furthermore why some elements of society would even try to deny that there is even a problem.

A white-tailed tropic bird killed by a feral cat on its nest at Fernando de Noronha
A white-tailed tropic bird killed by a feral cat on its nest at Fernando de Noronha (Photo by James Russell)

Professor Tim Blackburn and myself undertook some research on science denialism, and found that some of the articles that have been written in the past year, e.g. in New Scientist, The New York Times and The Economist, indeed appeared to conform to a special case of science denialism – invasive species denialism. Much like with climate change denial (or tobacco, or immunisation), some people try to manufacture scientific uncertainty where there is none, as a mask for differences in values, or perhaps other motivations for wanting to obstruct policy action on invasive species. This is concerning, as of all global biodiversity threats, invasive species are the one which requires the most immediate action to prevent new invasions establishing, or where solutions such as complete eradication are achievable.

Difficulties and proposed solutions for advancing invasion biology (Source: TREE)

But invasive species denialism is not the only issue invasion biology faces today. With Dr Franck Courchamp and other colleagues we identified a total of 24 specific problems faced by invasion biology as a discipline, and propose solutions to help move the field forward and achieve better action on responding to the global threat of invasive species. Some of these problems include a lack of clarity on the nature of the threat, reluctance to kill animals, constraining people’s liberties, and a lack of robust legal frameworks. One of the major problems, we believe, is that scientists have tended to focus on communicating only the facts. If scientists better recognised the role that values and motivations play in invasive species management and policy, they could engage in a stronger consensus dialogue model.

Deficit and dialogue models of science communication
Deficit and dialogue models of science communication (Source: TREE)

For reprints of either article please e-mail me

Read All Posts by James Russell

Conservation biologist Dr. James Russell works throughout the world on remote islands and other sites to provide conservation solutions by applying a combination of scientific methods. Follow James on National Geographic voices for regular updates on his own work or other exciting developments in island conservation.
  • Sandilyan

    Am workings as a Fellow on Invasive Alien Species for National Biodiversity authority of India. the article was very nice and i wish to read your two articles and please send me the pdf version to my above mentioned mail id

  • Mike

    It’s saddens me that this echoes the conclusions of a Student Pugwash conference I attended 30 years ago. Back then research was published in the journals with few stories making it to the general public. Now it seems trapped by our information bubbles, and anti-science backlash.

  • Ian A W Macdonald

    Please will you send me PDFs of both your articles. I have been fighting “alien-invasion denialism” here in South Africa for years. I think one of the factors involved is that people are surrounded by aliens in their homes, in their gardens and in their farms and they are intrinsically biased against accepting that “alien” organisms can ever genuinely pose a threat! Ian

  • Matt Chew

    Populations of species that become established anywhere, for any reason, inevitably alter local ecological relationships and processes. Some more so, some less. Different people will bring different experiences and knowledge to evaluating those changes. There is no objective ecological right or wrong criterion to base such comparisons on. Despite the protestations of some, diversity, productivity, tradition (nostalgia) and efficiency are all subjective criteria. There are many good reasons to doubt the pronouncements of invasion biologists, especially their grossest over-generalizations of a complex array of phenomena. There is no good ecological or evolutionary reason to throw every population resulting from human transportation into a single, negatively charged ‘alien’ category. Furthermore, the term of art ‘invasive species’ is itself a non-sequitur. No standard biological definition of ‘species’ describes anything capable of collectively conceiving, organizing or carrying out an ‘invasion’, much less of being constitutionally ‘invasive’. Flinging thousands of species into that hopelessly flawed category is self-evidently bad science. Even humans, whose cultures actually do organize and carry out invasions (including agricultural ones) don’t do anything of the kind ‘as a species.’ If newly established populations of plants or animals increase and spread, the process is much more akin to diffusion than invasion. That is much harder to spin as a public or existential emergency. Mischaracterizing such processes as ‘invasions’ and all their effects as ‘impacts’ carries potential political and economic advantages for those making that case, much as it does for generals playing up an enemy’s threat level to leverage appropriations for advanced weapons. (It’s their metaphor, not mine, so don’t blame me if it undermines their cause). The ‘invasion’ metaphor is misconceived. It does not, and cannot advance ecological science. Certain scientific methods are employed by advocates of the ‘invasion’ metaphor, but one important characteristic stands out in all of their published work: the concept of invasion, born of fear-and-loathing, is a premise front-loaded into every analysis. Findings of invading, invasion and invasiveness are never independent of that premise, because it is impossible (by simple definition, above) to demonstrate. The whole program rests on conservation biology’s founding presumption of ongoing crisis, and is meant to promote and benefit from it. Shoveling all that under the rug, and calling those who choose to examine and describe its shortcomings “denialists” is an ignorant, cynical shot at people who have far less to gain from questioning than we would from simply playing along. By the way, if you really want to keep new populations from popping up, the most important potential inflection point is re-engineering transportation technologies to exclude un-manifested biota, and requiring people and institutions who benefit most from such technologies to bear the burden of making them ‘safer’ in that regard. If that sounds prohibitively difficult, you’ve just understood why it is more popular to blame the organisms, which are abducted and then marooned with no possible responsibility for or knowledge of what happened to them. They wield no economic power and have no political constituency. Nations and organizations can (and likely will) concentrate their meager, ineffective but highly touted efforts at eradicating the organisms being victimized by our commercial sloppiness instead of keeping them from being transported in the first place. It’s just easier to sustain. That strategy allows well-established transnational businesses to socialize part of their operating costs, and new businesses with ways to profit from carrying out the endless slaughter of the (literal) innocents being promoted by the most vitriolic invasion biologists and their allies. Whatever their original motivations, their only tactical option is to kill, and continue killing, and imagine themselves saviors of nature and society.

  • Matt Chew

    As an internationally recognized critic of invasion biology’s philosophical constitution, and author of the seminal history of the field and its ideas, I have never found it necessary to deny that traditional environmentalists find many effects of recent ‘recombinant ecology’ undesirable. Denying their value system or point of view exists would be absurd. I was taught those values and shared them until I found their caustic expression increasingly incoherent and decided to re-examine them systematically. What I found was that from its modern inception, invasion biology has been consistently overzealous and overreaching.

    I can (and have) demonstrated that nativeness can be neither an evolutionary trait nor an ecological characteristic of species — rather, it is a historical fact of varying consequence, case by case and place by place.

    Furthermore, ‘species’, by any common biological definition, can’t possibly undertake an ‘invasion’ by any traditional definition, so ‘species’ cannot be (and aren’t) ‘invasive’. Invasion biologists understand this, and have repeatedly attempted to redefine their way out of that conceptual cul-de-sac. But they have never succeeded, because most are unwilling to abandon the (mere) rhetorical appeal of their eponymous invasion metaphor.

    The biotic composition of ecological units (communities, ecosystems, etc.) has always been dynamic. Historical biogeography is replete with odd juxtapositions produced by as-yet unexplained, long distance dispersal or migrations. Invasion biologists find recent rates of ecological recombination attending modern commerce, and some of their outcomes, distressing. Fair enough; but a shared emotional response, not a scientific finding.

    Invasion biologists and their allies mistakenly indict ‘species’, which obviously did not instigate the changes. They claim that certain species are becoming too widespread and numerous because their association with humans somehow gave them unfair, unnatural advantages. But should the distress of ideologues who want to regulate and adjudicate biogeographical happenstance become the basis of turning the planet even further into a wholesale killing field? I think not.

    The Anthropocene, by any name, is a real phenomenon. Any and every species must persist (or not) under or despite human influences. As always, the survivors of this era will be the founders of life in the next. Suppressing the fittest for nostalgia’s sake is certainly a debatable tactic, and one without any clear scientific rationale. But to paraphrase Abraham Maslow, when the only tool you have is lethal force, perhaps you tend to see every problem as a life to be ended.

  • Dana Bush

    I am working with a scientist who vehemently denies that invasive species are a problem. I need to read some current literature to balance out the articles he loans me. Please send me your two articles.

  • MB Whitcomb

    Matt Chew, you can ramble on and try to deconstruct language to your heart’s content…I waded through what you wrote. I am a simple person, and I hate people like you who want to muddy the water…you may as well scream “fake news”! I see my landscape disappearing under Rosa multiflora thickets in an area with no government support and a population too small to fight back manually. This land provided a great many sources of wild food and has been relatively lightly used by people due to the Northern climate. I don’t need a scientist to tell me that we are in trouble, and I sure can’t live off that one plant. I come home torn and bleeding and you sit there philosophizing. Whatever your motive is, your arguments border on the absurd. I am guessing you grew up in a city and never bothered to understand the delicate relationships in YES our NATIVE landscape. Or maybe you spent a day in the Rosa and decided you were against hard work. These relationships are so sophisticated that they took eons to evolve. We stir them up by bringing in pretty plants by the score, and now we have thorns everywhere in the space of my lifetime instead of mossy, benign forests. The loss of place and my inability to stop people’s ignorance and people like you is deeply depressing, because I understand that we were supposed to be a part of it, and function for good somehow. So yes, it is an emotional issue because it is integrally important to us. Look at the suicide rate among Native Americans, and some of the research being done on “loss of place.” I believe, to some degree, we were meant to be agents of change…but slow change. Not by way of planes, and nurseries, etc. etc. I believe you are the agent of mass extinction with no concept of the harm you are doing. We invasion biologists ARE yelling…because of people like you who think the world evolves on words.

  • MB Whitcomb

    On reflection, I am guessing you are against all use of herbicides and pesticides, but hon? I can’t kill a knotweed by hand…I wish I had back the years I spent trying. Yours is an attempt to politicize a survival issue.

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