Marking "hitchhikers" ("traveling" species) - which is the best way?

I apologize if this issue has been discussed before - unfortunately, I could not find an existing topic or solution.

When identifying the bugs, I occasionally see observations of “hitchhikers” - specimens clearly transferred with goods or transport to other regions or even continents (where their populations do not exist). E.g.:

Most often these are not pests, but simply species that are common in their region and have unwittingly embarked on a long trip. So, I would prefer to avoid the negative word “invaders”, using the more neutral “hitchhikers” or “travelers”. Especially since their establishing in the location of observation is often unlikely to be possible. I doubt that the species not known in the wild north of Texas, Arizona and California could live in Canada.

It seems to me that it would be useful to find some way to highlight such observations. They allow us to better understand the ability of organisms to spread. This ability is probably still underestimated in today’s world, which has become small. And most “travelers” simply go unnoticed.

But I’m not sure what is the best way to “mark” such observations. Projects may not be quite suitable, based on the definition:

Projects are designed to automatically include all of the observations that fit the places, taxa, users, quality, and dates that you define.

It would likely be difficult to limit the project for “travelers” to any of these parameters.

I am not even sure that such organisms can be considered wild in the exact meaning of the word. But at the same time, it would be incorrect to confuse them with captives, that is, consciously taken from nature to be kept. They are outside the wild but have found themselves in a place of observation by accidental circumstances. In addition, if such observations were to have a “Casual” rather than “Verifiable” status - they could lose the attention of both users and the scientific community. IMO, this is also undesirable.

Or is the best way to use observation fields? But among the existing fields, I don’t see a suitable one. The ones related to introduction are hardly appropriate for “travelers”. Introduction in the biological sense implies more or less sustainable habitat, not entry per se (IMO). Maybe a “hitchhiker” field with yes/no values should be created?

I would appreciate all opinions.


Not sure what the best answer is, but you might check with the folks who run this project as it’s exactly about those types of observaitons

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Thanks, that’s interesting! But this project is about a different biological phenomenon - parasitoids infesting insects. I mean free organisms accidentally moved by humans to another region / country / continent. This can happen with plant products as well as with any other thing. After all, it is impossible to talk about the observation of a “bug-infested car,” isn’t it?

So for the observations I listed as an example, this project clearly does not fit. But perhaps there are more appropriate ones. I would not want to create a project or field if they would duplicate existing ones. So, I would like to ask the community’s opinion first.


Here’s the most recent thread I know of that addresses this, but there are others:

I agree that these observation can be very useful for many reasons. In general, if humans didn’t intentionally move individual organisms like these, the observations shouldn’t be marked as “not wild”.

In terms of collecting them for viewing, I would guess an observation field is the best way. You can definitely make a new observation field that meets your interest. I would do some searching to see if there are any that already overlap (I searched quickly for “hitchhiker” :✓&q=hitchhiker&commit=Search) and didn’t see much in use.

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I would definetly keep them wild. After all, they aren’t where humans intended them to be, so they technically qualify, and researches would never be able to find them if they were captive.


Thank you! Yes, I meant to write a message in the topic about observation in stores / markets, but I thought my question referred to other cases.

Unfortunately, of the fields related to hitchhikers, one implies a taxon (although it’s not clear to me how it could refer to a taxon in general), the other contains a question about hermit crab and probably can’t apply to all animals or arthropods. And both fields are not used in any observation.

This is one reason why I am cautious. I would not want to create something that would be abandoned and remain one of those “ancient artifacts” like much of the observation fields. Or a project with 5 - 6 observations. My field of identification is quite limited. Although, it seems useful to accumulate such observations in a broader taxonomic context.

But so far, I really don’t see a more reasonable way other than to create another observation field. Unless there are better ideas, I’ll do it after some time.

I usually use an observation field called “Range anomaly” for this because you can then explain why - was it imported in goods, found in a car after a trip, and so on.

It’s not that widely used but it seems to be the one (or probably one of several) that’d do the trick here.


There’re similar threads, search e.g. for ticks.

If you don’t want to create a new observation field, you could also add a tag (like “human-mediated long-distance dispersal” or whatever) that should let you – and I think other iNat users – search for observations based on those terms. You could also set up a traditional project to collect sightings like that and encourage people to tag their observations and add them to the project so they were more easily searchable.

Use a traditional project! That way, you can simply select observations you want to include.

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I’ve been wondering the same thing. Many years ago during the dead of a Canadian winter I bought two large houseplants from a big box store. It was only after I got home that I realized there was a anole of some sort hiding in the leaves of the plants. Clearly it wouldn’t have been invasive and it wasn’t captive given that no one knew it was there. However it would be very useful to track these types of incidents.

Thank you very much! Although this is not exactly the case I am referring to, it is a very useful field that could have much more frequent use. It is often difficult to tell what the unusual observation location is due to - entry, introduction, natural range expansion, insufficient study of the species, or even just a coordinate error. I think this is a good way to highlight all such cases.

I realize that some randomness in the use of the tool (observation fields) is the reverse and inevitable side of its flexibility. Unfortunately, everything has its price. But sometimes it is very difficult to navigate through thousands of fields, many of which are very useful. IMO, often users don’t specify fields just because they don’t know about them.

Thank you! This is probably one of the possible solutions. But I think I need to read more project management manuals.

I agree, it seems like a traditional project would be well suited for this sort of thing (there are similar projects for vagrant birds and mammals, but none for arthropods).

I find projects easier to search and browse than observation fields, but an optional observation field (either an existing one like “range anomaly” or a new one) could be added to the project to provide more information about the context of the individual hitchhiking specimens. So it doesn’t have to be either/or – the two functions complement each other nicely.

Please post here if you do create a project. I think I have an observation or two I could add.


Thank you! I agree and have decided to use both methods.

Observation field “hitchhikers” - I limited it to arthropods, though I’m not sure that’s correct. Maybe “invertebrates” would be more correct? It’s changed - see below.

The “Invisible travelers - arthropod hitchhikers” project - Unfortunately, I don’t have any good ideas for the logo and cover of the project. Like most researchers, I have always paid little attention to such organisms, and I don’t have any suitable photos of my own. And I can’t draw :frowning:. All the free-license images I could find are pest-related. But I wouldn’t want the project to be explicitly associated with biosecurity. I think it’s important to note that not all hitchhikers are harmful or dangerous. Often, they are just little aliens unwittingly stranded far from home.

I would be cordially grateful to anyone who would help add more observations to the project. This is my first experience of creating a project. And I apologize if I am doing something wrong.

Thank you all for the discussion and good ideas!


Could the project be expanded to non-arthropods? Reptile and amphibian hitchhikers are fairly common too, and it would be nice to have a place to put them.

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I agree. I expanded the context of the project and the observation field to “animals”. If there are no oppositions, it is probably better to leave it that way. Although I am not sure that the term can refer, for example, to protozoa. And the non-taxonomic term “invertebrates” seems too unclear to me. After all, if any observations seem inappropriate for the project, they can be reasonably excluded.

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I’m glad this project exists now, I’ve been looking for and adding observations to it. I even found observations of a bird that hitchhiked underneath a trailer!


I think this question is semi-relevant and at least this thread is still open.

A few years ago, I brought a rock home from a construction site I was working on. (It would have been bulldozed or buried, so no harm in relocating it in my opinion.) Today, I decided to upload a couple lichens growing on the rock. I believe they were present when I took the rock, so in a sense they are hitchhikers? Anyways, what’s your opinion on whether they are captive or not?

I don’t think the concept of a hitchhiker applies to plants or fungi (including lichens). Perhaps only in the case of seeds. But a rock is the habitat of a lichen. So, I would refer it more to the introduction. When there is already an established population of the organism in a new place. Although I find it difficult to define, what is a population of organisms that can multiply simply by dividing into parts.

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