Speed, perhaps, but population for sure as well. There's been a citizen science study at UC Davis going on for many years now called the California Roadkill Ob

Speed, perhaps, but population for sure as well. There's been a citizen science study at UC Davis going on for many years now called the California Roadkill Observation System (CROS) http://www.wildlifecrossing.net/california/ http://www.wildlifecrossing.net/california/ It has maps of roadkill sightings, makes for interesting viewing. It used to allow you to select by species but unfortunately no longer.