There is no doubt that human activities have moved organisms from where they evolved into novel environments. Here in the US, we have many ecosystems that are greatly impacted by invasive species, from the Great Lakes to where I live in south Florida. It is since moving to south Florida that I have realized that people get weird about non-native species. In fact, you may have noticed that I am using the term “non-native” rather than invasive. I am choosing to do this because the term invasive should be applied to non-native species that are harmful, and we do not have evidence that many non-native species are harmful.
What do I mean by saying that people are weird about non-native species? I mean that when I meet people and mention or discuss non-native species, I encounter several common attitudes. First, many seem to have an negative or even angry response to non-native species and treat individuals of non-native species as enemies. Second, some people assume negative impacts of non-natives in the absence of evidence. Finally, there seems to be a general reluctance to realistically evaluate whether non-native or even invasive species can be eradicated.
As an example of thinking of non-native species as enemies, I have a friend from Texas who would monitor non-native European starling nests, and kill any offspring just before fledging in order to cause the birds to waste their energy raising offspring that never fledge. This has always struck me as unhinged. As another example, I am aware of a case in Florida where the homeowner would kill all non-native lizards on their property (which is likely all lizards in south Florida). The ire towards non-native species seems quite silly to me, as the organisms themselves are not volitional- they simply ended up here. And in most cases, non-native species are often quite entrenched by the time we are aware of them, such that individual action is unlikely to influence their population sizes.
The second issue is that it is commonly assumed that non-native species are actually invasive, or harmful in some way. While we certainly know that invasive species can initiate ecological disasters (e.g., Burmese pythons in South Florida or brown tree snakes in Guam), in many cases, either there is no evidence or only mixed evidence of negative impacts. For example, here in south Florida, many non-native species are only found in heavily disturbed urban environments. In that case, the non-native species are likely not impacting any native species, and might even boost biodiversity in urban environments.
Finally, even if non-native species are actually invasive or harmful in some way, both individual reactions and policy seem geared towards eradication, rather than understanding how to mitigate negative impacts of invasive species. It is worth noting that complete eradication of an invasive species has basically never happened, except on small and isolated islands. Think cane toads in Australia (still a problem), brown tree snakes in Guam (still a problem), feral hogs in the US (still a problem), and I could go on and on. Probably the most abundant terrestrial vertebrate in Florida is the brown anole, which is native to the Bahamas and Cuba and has been in Florida for nearly a century. I don’t think brown anoles will ever be eradicated, so any policy around this species should focus on understanding any negative impacts and learning how to mitigate them.
How we think of non-native species, and particularly binary thinking about eradication, has ramifications for policy. For example, Florida has some strict laws about capturing and releasing non-native species to avoid the spread of potentially harmful species. This is probably logical for unestablished non-native species, but can lead to farcical outcomes for established non-native species. For example, it might be hard to understand how abundant and widespread brown anoles are if you have not spent much time in south Florida (and don’t spend your time looking for lizards), but I can probably find a brown anole within a meter or two of me anywhere outside in Florida, and I have measured densities of more than one individual per square meter. Because these lizards are so common, many of my students grew up catching them in their backyards or parks, and play games like fashioning lizard earrings (this pugnacious lizard will open its mouth as a warning when captured, and will happily chomp down on an earlobe if presented the opportunity). Of course, the lizards are usually released after capture and a brief stint as earrings. According to current Florida statutes, all of those children are guilty of releasing an invasive species into the wild, which is against the law. This is farcical because there is no way that brown anoles will ever be eradicated, and the release of a lizard ten minutes after capture has zero impact on their population dynamics. So Florida has created a law, based upon the binary response to invasive species (bad=eradicate) that has created millions of unknowing wildlife law violators. It is not too hard to imagine how this could lead to future problems.
Of course, it is clear that some non-native species become invasive, and when they do so, I think we should work to eradicate invasive species and/or minimize the negative impact of invasive species. I think that the most ethical action, when possible, is to eradicate harmful invasive species. I also think it makes sense to avoid introductions of non-native species based upon the precautionary principle. So I am not advocating for a laissez-faire attitude towards invasive species. But I am suggesting that a paradigm shift away from binary thinking about non-native species and towards more nuanced thinking.
Beyond the academic and applied thoughts about non-native species, as a nature-lover, I don’t think it is a beneficial way to view ecosystems as having good species and bad species. I happen to live in a place with lots of non-native species, but I think biodiversity is increasingly homogenized across the globe, and this is only likely to accelerate with a growing human population, global-scale human travel, and global climate change. Where I live, most of the biodiversity of reptiles and amphibians is non-native, at least in urban and suburban environs. I think it is actually dangerous for conservation to teach the broader public that some of the nature around them is bad, or not really nature, somehow. And for many people in heavily urbanized environments, much of the nature that they get to experience may well be non-native species (e.g., house sparrows, rock doves, starlings). I think it is far better to interact with nature in a positive, non-adversarial nature, and to avoid conflating the potential negative impacts of invasive species with our response to individual non-native organisms.
What do I mean by saying that people are weird about non-native species? I mean that when I meet people and mention or discuss non-native species, I encounter several common attitudes. First, many seem to have an negative or even angry response to non-native species and treat individuals of non-native species as enemies. Second, some people assume negative impacts of non-natives in the absence of evidence. Finally, there seems to be a general reluctance to realistically evaluate whether non-native or even invasive species can be eradicated.
As an example of thinking of non-native species as enemies, I have a friend from Texas who would monitor non-native European starling nests, and kill any offspring just before fledging in order to cause the birds to waste their energy raising offspring that never fledge. This has always struck me as unhinged. As another example, I am aware of a case in Florida where the homeowner would kill all non-native lizards on their property (which is likely all lizards in south Florida). The ire towards non-native species seems quite silly to me, as the organisms themselves are not volitional- they simply ended up here. And in most cases, non-native species are often quite entrenched by the time we are aware of them, such that individual action is unlikely to influence their population sizes.
The second issue is that it is commonly assumed that non-native species are actually invasive, or harmful in some way. While we certainly know that invasive species can initiate ecological disasters (e.g., Burmese pythons in South Florida or brown tree snakes in Guam), in many cases, either there is no evidence or only mixed evidence of negative impacts. For example, here in south Florida, many non-native species are only found in heavily disturbed urban environments. In that case, the non-native species are likely not impacting any native species, and might even boost biodiversity in urban environments.
Finally, even if non-native species are actually invasive or harmful in some way, both individual reactions and policy seem geared towards eradication, rather than understanding how to mitigate negative impacts of invasive species. It is worth noting that complete eradication of an invasive species has basically never happened, except on small and isolated islands. Think cane toads in Australia (still a problem), brown tree snakes in Guam (still a problem), feral hogs in the US (still a problem), and I could go on and on. Probably the most abundant terrestrial vertebrate in Florida is the brown anole, which is native to the Bahamas and Cuba and has been in Florida for nearly a century. I don’t think brown anoles will ever be eradicated, so any policy around this species should focus on understanding any negative impacts and learning how to mitigate them.
How we think of non-native species, and particularly binary thinking about eradication, has ramifications for policy. For example, Florida has some strict laws about capturing and releasing non-native species to avoid the spread of potentially harmful species. This is probably logical for unestablished non-native species, but can lead to farcical outcomes for established non-native species. For example, it might be hard to understand how abundant and widespread brown anoles are if you have not spent much time in south Florida (and don’t spend your time looking for lizards), but I can probably find a brown anole within a meter or two of me anywhere outside in Florida, and I have measured densities of more than one individual per square meter. Because these lizards are so common, many of my students grew up catching them in their backyards or parks, and play games like fashioning lizard earrings (this pugnacious lizard will open its mouth as a warning when captured, and will happily chomp down on an earlobe if presented the opportunity). Of course, the lizards are usually released after capture and a brief stint as earrings. According to current Florida statutes, all of those children are guilty of releasing an invasive species into the wild, which is against the law. This is farcical because there is no way that brown anoles will ever be eradicated, and the release of a lizard ten minutes after capture has zero impact on their population dynamics. So Florida has created a law, based upon the binary response to invasive species (bad=eradicate) that has created millions of unknowing wildlife law violators. It is not too hard to imagine how this could lead to future problems.
Of course, it is clear that some non-native species become invasive, and when they do so, I think we should work to eradicate invasive species and/or minimize the negative impact of invasive species. I think that the most ethical action, when possible, is to eradicate harmful invasive species. I also think it makes sense to avoid introductions of non-native species based upon the precautionary principle. So I am not advocating for a laissez-faire attitude towards invasive species. But I am suggesting that a paradigm shift away from binary thinking about non-native species and towards more nuanced thinking.
Beyond the academic and applied thoughts about non-native species, as a nature-lover, I don’t think it is a beneficial way to view ecosystems as having good species and bad species. I happen to live in a place with lots of non-native species, but I think biodiversity is increasingly homogenized across the globe, and this is only likely to accelerate with a growing human population, global-scale human travel, and global climate change. Where I live, most of the biodiversity of reptiles and amphibians is non-native, at least in urban and suburban environs. I think it is actually dangerous for conservation to teach the broader public that some of the nature around them is bad, or not really nature, somehow. And for many people in heavily urbanized environments, much of the nature that they get to experience may well be non-native species (e.g., house sparrows, rock doves, starlings). I think it is far better to interact with nature in a positive, non-adversarial nature, and to avoid conflating the potential negative impacts of invasive species with our response to individual non-native organisms.
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