Devils are the most difficult animal to see at night
Dr Alistair Hobday, a senior research scientist with the CSIRO, measured the distance that motorists need to detect different animals while driving at night. He discovered that Tasmanian devils (being mostly black) are the hardest of all species to see between dusk and dawn.
Combining these findings with reaction times and braking distances, Alistair determined that drivers can travel no faster than 54km/h with their lights on high beam, or 38km/h on low beam, if they want to give themselves enough reaction time to avoid hitting a devil on the road.
Brightness images (below) show that the Bettong is far more visible than the Tasmanian devil.
The following graphs show detection distances for various animals. Note the difference between the bettong and the Tasmanian devil.
It's the first time in Australia that safe driving speeds have been quantified across the range of our native animals.
"But the key point to remember is that roadkill isn't distributed evenly across the State," Alistair said. "About 80% of roadkill occurs on 20% of roads, and around Tasmania there are about 50 to 60 high-density roadkill ‘hotspots'.
"In terms of management, that's an advantage. It means we can target our mitigation in those areas."
The precise locations of these hotspots can be downloaded as files for your car's GPS, or as printable maps, from the roadkill website: www.roadkilltas.com.
"We're really lucky in Tasmania to have such a lot of wildlife," Alistair said, "and that requires a different kind of social responsibility to other regions in Australia. An example of what I mean would be if you lived near a school - you'd modify your driving accordingly.
"Not all species of Tasmanian wildlife are in trouble, but for animals like devils and quolls, roadkill is probably a significant impact on the population. It's estimated that roadkill contributes about 5% of the mortality rate of devils.
The next stage of Alistair's research is in partnership with DIER, who will erect warning signs in the hotspots - with suggested driving speeds, strip monitors that record speeds, and flashing lights (kind of like a school zone) - to see whether roadkill numbers can be reduced.
Find out more about Dr Hobday's research at www.roadkilltas.com.
Images and graphs courtesy of Dr Alistair Hobday.