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.

Shameful that you didn't translate 'Roadkill' into Latin

Only 3 pheasants? For a species that seems addicted to wandering onto country roads, that seems incredibly low.

via occiditis ?

Who saw a flattened spider on the road and thought to report it as roadkill?

> 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.

Edited from the grave xD

Roadkill is roadkill!

I know. I suspect its because pheasant are such common roadkill that people don't take much notice of it. Imagine if everyone reported every squished snail! It may also be that pheasant are very light, and more quickly removed by scavengers.

Am I missing something? No cats or dogs? That seems unlikely.

iNaturalist is for the recording of wild specimens, domesticated or captive species are excluded from the records. I think you'd find reliable numbers for dogs elsewhere (by UL law every dog is RFID chipped), but for cats it may be more difficult, many are just ditched or left to rot and the bodys never recovered.
The distinction of wild/captive is something I could have mentioned clearly.

Ah. That's something I didn't know. Thanks for the info!

Not to mention, how are they even recognizable? If I smash a spider with a shoe, it's gonna look like a splat with legs.

Now with a fucking car?

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.)

Latin names are meaningless for most people, and it would have been more clear as a multi-layer pie-chart.

Should have displayed the common names, not latin names. And why not just upload the image to reddit instead of using imgur? On mobile I had to open it in imgur, then open it as a separate image before I could read the text.

There's too many shared/localised common names, besides knowing the genus gives you some kind of idea of relationships.

WRT the second point, this is my second post to dataisbeautiful, I wasn't aware that could be done.

For the niche species sure, most people don't know even insect families, let alone binomial, but common names are too fuzzy.

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Too bad that top one isn't a rhino... I had some hilarious scenarios in my mind until I looked it up and saw it was a bat.

rhino = nose , rhinoplasty etc : )

But I would be shocked if there were no roadkill rhinos, a couple of years ago there was a roadkill giraffe in Kruger! People behave terribly within nature reserves.

https://xkcd.com/2501

Are people purposely aiming for the snakes?

Why did they exclude humans? Are they seriously trying to say no humans got the vehicular snuff treatment? I know for a bloody fact there were at least two, but that is all I am going to say about that.

A small minority, yes. In a study in Ontario ~3% of motorists aimed for them. 3% of the huge volumes of drivers is lots. Add to that that many snakes reach sexual maturity late, and are slow breeders, that's a disaster. In South Africa it's very common, there's an attitude of 'kill first, identify later'.

No, iNaturalist keeps record of wild individuals, domesticated/captive specimens are excluded, records of Homo sapiens are excluded. Road traffic deaths are easily found, with breakdowns by vehicle type. Here's road traffic injuries data from the WHO, and Our World in Data.

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!

My favorite game!