Dead pets with pinwheels on roadside

Lived in the same area for the past few years and just recently started noticing that someone is putting dead dogs and cats along the road with pinwheels next to them.

At first I thought it was animals that had been run over that someone pulled off the road but the frequency, timing, and placement makes me think that isn’t the case.

Dumping dead pets next to a busy road doesn’t seem safe or sanitary. Given the pinwheels next to them, it seems they are trying to memorialize them somehow, but that seems counterintuitive to dumping them in the ditch.

So I guess my question is, what’s the reason behind this? Is it a group? Is it widespread? Is it just an individual in our area?