Invasive Species Bias

I am becoming increasingly aware of an apparent invasive species bias in iNaturalist observations, particular those by new(er) users. Though I realize that iNaturalist isn’t a great tool for mapping the abundance of species, I can’t help but notice a number of places where there are more observations of common and well-documented introduced species than of native species that are actually more abundant. An example would be Dutchess County in New York, which has more observations of garlic mustard, Japanese barberry and multiflora rose than of any native plants, and while these are common species, they aren’t nearly as abundant as native species such as sugar maples, red oaks, shrub willows, jewelweed, goldenrod, etc., though these are poorly represented in comparison. Again, I realize that iNaturalist isn’t intended to map the abundance of species, but I find this somewhat concerning, as it perhaps suggests a trend that people are taking more notice to common invasive species than slightly less familiar natives. We have plenty of data on where these invasive species occur in the area, yet we are seeing constant additions to observations of these species, far outpacing new observations of most native species. What are the implications of this? Will we not accurately document the presence of uncommon natives that are likely to decline in the future - such as red spruce, tamarack, ginseng and lady-slipper orchids where I live - if we continue to focus on well-documented invasive species?

The point of this is to ask how we can help foster knowledge of, and love for, our native species that many commonly seem to gloss over? It isn’t hatred of invasive species, but love of native species, that our degraded ecosystems need most right now.

I’m curious to know others’ thoughts on this matter, and if anyone else has noticed a similar trend?


Well for one, I don’t think its bad that there are observations made on invasive species. For one it is useful in showing their temporal and geographical distribution, and plus they all count as valid iNat observations.

But I have my own two cents about this. I’m not sure if Lantana camara count as invasive (but I’ll use that as a case study), but certainly they pretty much grow everywhere outside their native range, and especially in Hong Kong, they appear in random roadside soil pots to villages, parks and country trails. Furthermore, the top 3 most observed Angiosperms in Hong Kong (including L. camara) are introduced species, and speaking from experience these plants literally grow everywhere. So the fact that they are so abundant (adding on to the fact that their flowers are quite eyecatching) makes it more likely for people to spot them and make an observation. So I suppose statistically that makes sense.

But of course iNat is a great way for one to start learning about the flora and fauna of their region. Heading to the libraries to look for books on native wildlife may also help.


I expect this is simply a result of invasive plants being the most readily available organisms to take a photo of. Most people on iNat live in cities, and go looking for things to photograph that they see along the street or in a park. These urban habitats are not native habitats, and have a greater presence of invasives than natural areas. I would think most people would be much more interested in taking photos off in a forest than looking at weeds in a boring lawn-infested urban park, but those places are harder to get to.

I think changing this would mean overhauling a huge chunk of society. More land would need to be set aside for natural areas near where people live, and not just boring grass lawn parks. A lot more cheap public transportation to natural areas would need to be added. And people would need more time off work so they can have more time to explore away from the concrete jungle. It’s not something I think can be changed much by tweaking iNat, except perhaps finding something to do about bioblitzes or class projects which encourage people to upload 20 observations of the same weed from different angles.


In the top 100 invasive species list!


One of the reasons might be that recording invasive species might be popular projects in schools, etc. It is a fashionable trend now. Just check in the Project area, how many of them have Invasive in their title (in all available languages).


Invasive species can also be easier to identify for locals. I don’t know many plants, but I can spot (yet another) Rosebay Willowherb, or Red Valerian, or Ivy-Leaved Toadflax without being hit by doubt that it could be a close relative I am unfamiliar with.


To clarify, I don’t think having this data on invasive species is bad at all, I’m just concerned that it reflects a greater trend of people overlooking native species. Though we need education on invasive species, I am worried that there isn’t sufficient public outreach/education regarding native species in many areas, or that public interest has shifted away from them for some reason. I’ve also noticed that, at least in New York and New England, that poorly-known invasive species are rarely observed on iNaturalist, an example would be elongate hemlock scale, an abundant and more widespread pest of hemlocks in the region than HWA, and that certainly does not have any lesser impacts to the trees.

I’m actually finding that many of the invasive species observations in Dutchess County and the surrounding area are not limited to cities/large towns, as I had initially suspected, but are actually in more suburban and rural areas, and that they are observed at a similar frequency to common native species in the most developed areas, which I think is interesting as it doesn’t suggest that people can’t get to somewhere these plants are not so abundant, and that they are indeed more focused on invasives when they are in natural areas. I see this beyond iNaturalist, many of my neighbors are well aware of invasive plants and can readily identify them (though they rarely attempt to manage them), but don’t know even some of the most common native trees or wildflowers.

Even more concerning is the proportion of observations of cultivated plants. I did a rough calculation for all of the vascular plant observations in Toronto, Canada and 20% of all observations are of cultivated plants in gardens, parks, etc. (for comparison, if you do the same calculation for the entire province of Ontario, only 5% of vascular plant observations are of cultivated plants). I imagine this is true for most other major cities. The reality is that urban residents lack access to natural spaces and many of them lack an understanding of how natural vegetation communities differ from gardens. Call it nature deficit disorder or whatever you want.


As mentioned above, I suspect the ready availability of invasive species makes them easy observations for people starting out. It would be interesting to follow observations through time to see if they change.
I would also like to suggest that this may be related to plants. Extremely few of the moths I see are non-native. Similarly with birds. For a new person who is looking to observe things, tracking down a bird and getting a decent picture is hard. Much easier to take photos of plants which don’t move and often have flowers. I just hope that these initial efforts move away from the common to the less common.

This is not something I’d ever realised before using iNaturalist, but yeah, a lot of people don’t really understand that e.g. all the trees they see along suburban streets were planted there.


To be honest, it can sometimes be pretty hard to tell if a really “established” plant, especially tree, was planted there on purpose or not if there are no signs. Even if there are signs, those signs could still just be labels on a wild tree, and if there are no signs, the tree could still be planted there. This happened to me actually, I nearly forgot one of the trees in front of my house was planted by us, over 10 years ago.

I’ve never actually heard of people unaware that trees on the sides of roads were planted there on purpose… aren’t they almost always arranged in some way (like, each tree is in a line with roughly the same spacing between them)?

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I find that so many people have absolutely no idea what a plant is, let alone if it is invasive or native. That is what is so great about iNaturalist - the learning opportunities!


When I started on iNaturalist (a whole month ago) I mostly ignored non-native plants until I realized I was doing that. My biases as an old ecological restoration guy were showing. Still haven’t added in most of the exotics but in the interests of completeness I will.


I personally don’t think its a bias. Non-natives are the prevalent species, at least in my area. No one would pass over taking a photo of a lady’s slipper orchid to photograph Garlic Mustard. It’s just what you encounter.

If you look at my observations, most are invasive. I take a walk most days and document species as I walk. It’s a 20 minute walk during lunch break - I can’t get to a pristine woods or rural meadow (although in my experience the woods and meadows are not nearly as pristine as people expect them to be). When you look at the strips of wildlife that exist between our developments, invasives dominate. It’s only logical that they will dominate on iNaturalist as well.


Is this only a problem with plants? Has anyone noticed an invasive species bias with animals? I mostly record animal observations and just from experience, I’ve seen hundreds of the invasive Eastern Gray Squirrel and I have one observation of the native American red squirrel. With other creatures like arthropods, unless their common name mentions a place that isn’t the one I’m in, I usually don’t know if what I’m looking at is native or not. The exclamation point saying a species was introduced by anthropogenic means still doesn’t tell me how long ago that was, whether the species has become naturalized within the ecosystem, etc.

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There are a few issues that may drive the high number of invasive non-native observations.

  • They really are everywhere. My main evidence for quality of a natural area is the lack of non-natives.
  • They’re often showy. Many were brought in for just that reason.
  • They are alien. The “What’s that?” factor.
  • They’re a known problem. People want to help document their extent. I do this but tend to focus new or particularly damaging species. Microstegium is all over NC, I don’t need to document that one. Spotted Lanternfly is something to record but I hope not to.

my $0.02


Agreed, where I live we really don’t need more observations of garlic mustard and multiflora rose from where there already are numerous observations, but we do need observations of new invasive species; and even of common ones from new localities, but I see a lot of repeated observations of the same common species from the same area. Amur corktree is an example of a new invasive species here, and an one that I’m particularly worried about, though not many people seem to be aware of it.

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It is natural that many people new to iNat start by observing plants in their yards and neighborhoods many of which are cultivated or invasive or both. Sometimes natives won’t grow well right near buildings and driveways.
I live in the Piedmont region of South Carolina, but I can’t grow mountain laurel on my back patio or in my front yard. Given all the nearby asphalt that is hardly surprising. Heat island! I compromise by growing ornamentals that behave themselves. Better a healthy ornamental than a dead or diseased native. Be kind to your plants—know your micro-clime. Ideally I’d like to turn the nearby turfgrass back into wildflowers, but getting 100 neighbors to agree probably won’t happen.
This is why arboretums, native bogs, and preserves are so important they show natives at their best and inspire us to want them to survive and multiply.


This also related to what @zookanthos mentioned in his post above about users making observations in more urbanised areas. I would expect its more likely for teachers to bring students to a nearby urban park than to a far away, less accessible forest, for both safety and logistics sake.

Although, for the case of Hong Kong, the country parks are readily accessible even from the urban areas.


Bit of a tangent- I was curious about where Eastern Gray Squirrel would be invasive and also have Red Squirrels. I notice that your observations are New England and Quebec. That’s in the native range of both species.