Are All Invasive Species Really So Bad?

We humans sure do like to organize things into categories. One of those category partitions is “belongs” and “doesn’t belong”.

More often than not, the things we point at and say belong are the familiar things, and the ones we like. Something that’s new or different, that comes from the other shore or the other side… we feel differently about those things. Sometimes we call them “exotic” — things we like the look of and want around, at least a little, with some controls put in place.

If “exotic” is the nice term we use for things that don’t belong, then “alien” is the word we use when our hackles are up. If something is considered “alien” that’s a pretty good indication we want it gone, or at least want to fence it up so it doesn’t spread out any farther.

When we’re talking about biology and ecosystems, the word we usually use is “invasive”. As in, an “alien” species is “invasive”. It’s a loaded word, and immediately makes us think of associated military terms and tactics of war, so perhaps it’s no wonder invasive species get such a bad rap.

Where Do Camels Belong by Ken Thompson - cover

Ken Thompson’s book “Where Do Camels Belong? Why Invasive Species Aren’t All Bad” is an interesting read on the topic of what makes a species invasive, and reflects a lot of changing ideas about ecosystem biodiversity. He argues that, most of the time, our war against invasive species is misplaced, unnecessary and, often, futile battles that can do as much environmental damage to the so-called native species as the invaders.

There are some species that really have wreaked havoc in some places. The brown tree snake’s arrival in Guam devastated the bird population. We did a show way back with Will Stolzenburg about the truly epic efforts humans have launched around the world to protect fragile island ecosystems from arriving rat populations. But we’re not very good at differentiating genuinely problematic invasive species from the species that are merely migrants. And even when we can definitively point at a species and say “YOU, you’re a problem for sure”, there often isn’t a lot we can do to unscrew that pooch.

Change is hard, especially with a guilty conscience. Knowing it was human arrival that triggered some of these seeming ecological catastrophes makes it hard to turn away and let the ecosystem sort itself out. Often, visible invasive species can be a symptom of human impact and how we’ve changed the environment: if a new species can adapt better to the way we’ve changed the world around us, then it will probably flourish as we flourish.

Ken Thompson’s book reminds us to look beyond our assumptions for actual evidence of harm, to remember that plants and animals have always migrated to new ranges and territories, and to consider that ecologies and environmental systems often work on a much longer timescale than our individual human lives. Sometimes things get thrown out of whack for a while when a new species shows up and makes a splash. But, he argues, the ecosystem will often balance itself again after a time, and things settle down into a new normal.

There may be a cost to invasive species, but there’s also a very real cost to trying to eradicate them. There’s also a risk of stamping out assisted migration strategies that could save endangered species before we’ve had a chance to see if they’re worthwhile. And if we’re going to talk rhetoric about invasive species, we should remember that a lot of the plants and animals we take for granted as being “native”, or just nice to have around, also come from somewhere else. If we’re going to cherry pick which species to wage war against, and which to invite into our gardens, we should at least be aware we’re doing it.

More reading about invasive species and whether or not they’re as bad as we think they are:

Featured photo of purple loosestrife in Ottawa by Jamie McCaffrey.

Rachelle Saunders

Rachelle is the producer and one of the hosts of "Science for the People", a syndicated radio show and podcast that broadcasts weekly across North America. It explores the connections between science, pop culture, history, and politics. By day she slings code as a web developer and listens to an astonishing number of podcasts.

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    1. I’d be happy to look at anything you think I should read, if you want to throw some links my way. Based on my research, it seems there are a lot of researchers shifting opinions on what species should be counted as invasive and, if they are, whether or not it’s possible/a good idea to try and combat them.

    2. Snort.. There is a difference between “all invasive species are bad”, and, “some, and or those introduced by humans without comprehending the impact, generally are.” But, then one thing humans are worse at that seeing their own impact is well.. comprehending nuance when it comes to things they want to be cut and dry.

      Good example – Red Wolves. This one is causing all sorts of issues. First off – there is no known case *ever* of a Red Wolf attacking a human, but people are so freaked out about them near their homes that they get shot at all the time, despite being on the endangered list (and given that their territory now consists of a tiny stretch of land in one state, instead of like 10+ states…) But, then things get even more complicated, because back when they where put on the list it was morphology that was chosen to decide what “is” a Red Wolf. See.. they knew that coyotes where sometimes breeding with them, so they picked out like 14 animals they “thought” looked more like wolves. Genetic testing since though indicated that Red Wolfs are a hybred, and always have been. I.e., they can’t dilute themselves much with coyotes, because they “are” a more or less 50-50 mix of coyote and wolf in the first place. This is leading to some calling for their removal from any lists, on the grounds they are not a “real species”, and calls, on the other hand, to set aside land, where we just bloody leave things alone, and stop mucking with hybridization. The latter argument being, “It happens more than we thought, and we are idiots for not leaving things alone.” In fact, a few species have gone extinct “precisely” because we tried to maintain “purity” of a species, when you could have cross bread, to save them.

      In short, the ones that just figure we should let everything die are using the excuse, “Well, if their are not clear species, then we can hardly claim we are causing extinction, right?”, while the people trying to preserve species are stuck in the old model of, “The morphology of this species looks different than all the others, so we assume its a real species, and not a hybred, and its numbers are so small we need to protect them.”

      As usual, reality is some place between these extremes. So.. tell me, given the range that Red Wolves once had, which was the “invasive” species – the coyotes, or the Grey Wolves, both of which are needed to produce a Red Wolf? And, why the F does it even matter, if its decided that we shouldn’t let the result die off from another invasive species encroaching, and a damn stupid, arrogant, and murderous one, when it comes to predators, even those with no known threat to, ironically, the invasive one (i.e. humans)?

    3. In the Americas, honeybees are an evasive species yet the same people who are so against non native animals are having conniptions over the death of the honeybee.

      Species utility seems to play quite a large role in what gets deemed as unwanted.

  1. The conclusion that invasive control methods have failed in Australia due to the greater number of end species post-control doesn’t follow.

    Say you have X number of invasive species, and after control event Y have Z number of invasive species, where Z > X. You can’t say anything about the effectiveness of the end outcome, because Z may have been an even greater number without control measures. As an extreme example, if you have 7 invasive species before, and 8 invasive species after control, you can’t conclude that control measures were a failure if non-control efforts would have lead to 1,000 invasive species.

    I understand what he’s trying to accomplish, but that blurb in particular felt incredibly dishonest.

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