A way to check a species northern expansion?

I’ve been keeping an informal eye on some species as they expand into northern zones, due to climate changes. Is there a web resource that tracks reported movements specifically rather than flipping through filtered map views in iNat?

(Please, please don’t say it’s easy to do with simple coding stuff. I lost my secret decoder ring many, many years ago.)


I’m not aware of anything like this, but it sounds cool.

You might find some of the tips in this tutorial posted by @jwidness helpful: https://forum.inaturalist.org/t/how-to-find-out-of-range-observations-wiki/4271

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Speaking for North America, specifically, I think it would be very difficult to track this. It’s hard to see through the “noise” of other variables that can make a species appear to expand its range northward.

I’ve been working on a manuscript looking at the northward range expansion of an orchid species in Canada. It’s more complicated than it sounds. “Northward expansion due to climate change” seems to make sense at first, until you start digging into it. You basically have to test three hypotheses:

  1. The species has colonized a new region due to climate change
  2. The species has always occurred in the “new” region, but has been overlooked.
  3. The species historically occurred in the “new” region, and is recolonizing new habitats within its historical range.

Even when you examine hypothesis 1, you have to somehow filter out other possible environmental changes or vectors of spread. E.g., you somehow have to prove that the species could not have survived in the new regions under historical climate regimes (as opposed to it could have survived, but was limited by other factors, such as dispersal ability).


I think your second point is correlated to a lot of other factors, not the least being its size. I’ve already discovered that many of my tiniest, well-hidden observations are ‘firsts on iNat’ in my area simply because they’re under-observed.


I have a colleague who gets really annoyed when someone proposes that they’ve discovered a range expansion when it might actually be a range extension. A range expansion implies that the species is actually new to that location, whereas a range extension is documentation of a species in a new extralimital location where it might’ve occurred for a long time but was simply overlooked (or it has moved back into a previously occupied area due to improved environmental conditions). One implies an actual change in the species’ range and the other indicates a change in our understanding of the species’ range.


I suspect data on new locations beyond known ranges is much better for vertebrates and a few conspicuous insects than most other animals. If the species is a volant insect, the opportunity for a researcher to discover new locations beyond the known range is probably rather great. Any species that is highly mobile can show up in surprising locations and their range limits are probably rather “fuzzy” with individuals wandering far from where you’d expect. We’ve certainly seen that with birds, some large mammals, and odonates.


I suspect that with the expansion of iNat users is in a big way due to two major things: the re-discovery of nature, by many who never spent as much time outdoors until the pandemic arrived; the dramatic increased technical accessibility created by more powerful, more affordable, less technical camera technology either as smartphone cams, or others.

I also suspect that your colleague is going to be experiencing a lot more annoyance due to the expansion/extension confusion in the years ahead!

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Not exactly what you’re asking for, but this may interest you! It highlights the absolute northern-most and southern-most RG observations of plant species on iNat. You can find your location on the map and see species around you that are at their outer limits of observation, or look up the observed limits of species you are interested in. I’m not sure how regularly it gets updated, but it seems like a cool tool to find species near you at the edge of their range-- and potentially gives you some targets to look to expand the range map for in your area.

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