The typical history chart for a (non-rare) species on iNat will show a steep climb between about 2015 and 2020 and then a gradual rise between 2020 and 2024, mainly reflecting the rise in popularity of iNaturalist.
I’m wondering if anyone has noticed any (non-rare) species or taxa that have actually had a downward observation trend in iNat. The only one I know of is the Monarch butterfly, which peaked in 2021 at 54,659 observations, and has declined (albeit slightly) since then. (The trend is most apparent in the “relative proportions” version of the History chart.) Does anyone know of any other examples? (Obviously the numbers can go all over the place for lesser-known species, so I would limit this question to taxa with at least 5,000 observations.)
Does the “relative proportions” chart mean proportion of that species relative to all other species on iNaturalist? If so, couldn’t that just as well be a sign that other species have been increasingly observed, which would decrease the “relative proportion” regardless of whether the total count of a given species is static, declining, or even increasing?
Not that this is the case in this specific instance, since it seems there’s a somewhat downward trend in overall Monarch observations too (though it’s hard to tell with the years 1958-2014 included in the chart, which makes the past decade nearly illegible). But when looking for other examples, I’d think we should be cautious of using “relative proportions” as a proxy for overall numbers, even if it seems more readable.
Side note: it would be great to be able to limit the temporal range of those charts.
I feel like it’d be hard to find an example of a non-rare species that fits that criteria- most rare species have upward trends regardless because people seek them out more often!
An example I know of it the gopher tortoise, which has shown a slight decline each year, with 2024 being the exception.
Edit: I think it’d be nice to be able to filter a range of years on the history chart so we can get past those individual observaitons from 50+ years ago that make reading them more difficult
Yes, you are correct. In fact most American species will probably show a slight downward trend in the “relative proportions” chart reflecting iNat’s increasing use outside the U.S. So I wouldn’t rely on that chart to reliably indicate a downward trend in observations. I just mentioned it for the Monarch butterfly since you can see the downward trend more clearly in that chart, where it looks (perhaps misleadingly) severe. Unfortunately, neither of the charts are especially useful for showing this sort of year-over-year decline clearly.
Thanks for sharing that! Glad to hear the gopher tortoise population might be stabilizing, although I imagine it’s too soon to tell yet. The last time I saw one was in 2021.
Sometimes there may be regional projects to monitor or increase awareness about a particular taxon, which can lead to a temporary increase in observations that drops off again once the project has ended. This can also create a false impression about population trends.
A particularly dramatic example that comes to mind here is Vespa velutina. In Europe it is an invasive species and a source of some concern for beekeepers in particular. A couple of years ago, a reporting/eradication scheme in Belgium set up an account on iNat to be used by members of the public to submit sightings, which resulted in a veritable flood of hundreds of observations per week. I believe it was eventually decided that this was a violation of iNat’s terms of use and the initiative moved reporting to its own platform, but the observations are still on iNat, making it appear at first glance that there was a huge population surge in 2022, followed by a die-off to previous levels.
More generally, I wonder how much of a role wider public discourses play in shaping observation trends at a particular time. If environmental narratives focus on certain organisms as being particularly threatened, or as being a threat themselves – say, spotted lanternflies in North America – people may make an extra effort to record them whenever they see them. But over time, as an invasive species becomes established or public attention turns to the next organism of concern, it may no longer feel as important to document every individual. So in some cases observation numbers declining or plateauing may not represent population developments as much as declining interest in that organism.
I’m not a statistician, but it seems like these are factors that would be very hard to control for when analyzing data.
Monarchs have also just had really erratic population due to various impacts and there may have been less of them to observe. I observe them when i see them, but only saw 1 this year and none the year before, despite being out a lot, so it may reflect real trends as well
I honestly wouldn’t doubt that trend. I saw and decline in all pollinators in my yard this year. Saw way less butterflies in general in comparison to last year. Saw a flurry of bees in the spring but then we had a really unseasonably hot few days and after that pollinator activity was slow to pick up and sparse in comparison to last year. Now with this drought in PA and unseasonable warm fall I wonder what next year will look like.
The California monarch population took a huge dive from 2018-2020. Since California contributes so many observations to iNat, I think this would have a big impact on overall monarch observations on the platform.
Once observer numbers really starts to plateau and these observers have seen most of the species they can in their areas I think we will see declines in observations per species. This is because a lot of people will make a few observations of each species and then no more.
Also out of curiosity I looked at histograms of the ten most commonly reported dragonflies in Ontario (but using global observations for each species for the histograms). Six out of ten of these species showed slight declines in the last couple of years, especially 2023. 2023 might have been a bad year for dragonflies…
The east has had massive population declines, too. I don’t know of any hard numbers or research on it, but I remember they used to be a common species even five years ago. These days I rarely see them and everyone I talk to agrees.