corvusmonedula OP t1_je4b9t3 wrote on March 29, 2023 at 9:27 AM

Mammals make the largest group recorded, but probably not the largest group run over - mammals are simply easier to spot as they are large, and are probably likelier to motivate people to record their presence.
Records of invertebrates were largely uploaded by people moving on foot.
Reptiles probably make a large group of roadkill, because they are relatively slow moving, utilise road surfaces to warm up, are harder to see while driving, and may even intentionally be killed.

E: Data taken from Roadkill UK project on iNaturalist, data for other regions can be exported from Global Roadkill Observations, and the data were plotted using SankeyMATIC, though I would like to plot this in R to save time.

xopranaut t1_je4gx81 wrote on March 29, 2023 at 10:45 AM

> Reptiles probably make a large group of roadkill, because they are r

The reptiles got to OP just in time to stop their big secret being revealed.

corvusmonedula OP t1_je4r5jv wrote on March 29, 2023 at 12:29 PM

Edited from the grave xD

kompootor t1_je5cqqv wrote on March 29, 2023 at 3:08 PM

I can see this is preliminary for now, so my strong recommendation as you're putting together future versions is to show detailed source and biblio information on the image itself. It's essential to making a professional, usable visualization.

Regarding what you have so far, you obviously will have to find some way to indicate or adjust for the obvious skew people will have toward reporting larger mammals. As a basic adjustment to the data (or rather, to the size of colored blocks in your visualization -- keep the numbers the same) you could divide each species by their average body weight. This may actually have to be a power of the weight, or even the log. if you plot for yourself and then fit the reported deaths versus weight, you'll get an idea of what function to try for the adjustment. For anything like insects in which the entire category has only one report, you might consider omitting that block entirely, noting "insufficient data".

This would seem to me to be the most beneficial adjustment to make, but there might be more adjustments or indications to consider in future, such as for nocturnal species. (They would definitely be hit more frequently, and if they're large I'd guess they'd be reported more, and if small I'd guess they'd be reported less.)

corvusmonedula OP t1_je94ebq wrote on March 30, 2023 at 9:22 AM

Cheers! There are a few models that try to account for this bias, here is one.

I agree WRT the species/groups with very very few records, and just adding a footnote to say so.

WRT attribution for data etc, it's something I'd like to do, but haven't learnt how, yet..

Cheers!