Shane Williams is always on the lookout for dead kangaroos. She keeps a can of red spray paint and a pillowcase in her car, just in case she finds one on the side of the road.
When Williams spots a roo, she hops out of her car to check for an orphaned joey, which might still be in its now-dead mother’s pouch. She then sprays the adult with a large pink cross so drivers will know the body has been searched. If Williams, the founder of Bridgetown Wildlife Rescue, finds a baby roo, she’ll hang it up in a pillowcase inside the car for the ride home. Sometimes, she said, when the animals are too small to generate their own heat, “you just put ‘em straight down your top.”
Williams has had plenty of opportunities to refine her technique, as kangaroos are one of Australia’s biggest traffic threats.
Wildlife hazards
Australia’s National Roads and Motorist’s Association estimated that over 12,000 of its insurance claims from 2018 were from kangaroo and wallaby collisions, accidents which cost upward of $5,000 AUD on average.
Over the past 20 years, car companies have pivoted from the old strategies of structurally reinforcing cars to designing prevention technologies that avoid crashes altogether. Car companies and researchers have spent years trying to create systems to detect or deter the animals. But so far, marsupials have presented a nearly impossible tech challenge, leaving communities to come up with alternative solutions to keep roos away from busy roads.
One issue is that collision-prevention systems for large wildlife were originally designed with a very different animal in mind: moose. Wildlife collision technology began in earnest due to increasingly prevalent moose crashes in Nordic countries. These crashes are serious, and if one occurs, the sheer weight of the animal—which is sometimes over 1,200 pounds—causes extensive damage to vehicle, moose, and human.
AdvertisementTo mitigate these brutal impacts, Magnus Gens, a master’s vehicle engineering student at KTH Royal Institute of Technology partnered with Saab, a Swedish car company, to investigate how its cars could keep drivers safe in wildlife collisions. For his thesis, Gens built a life-sized moose dummy—crafted from 116 bright red rubber disks—to test on Saabs and Volvos. The dummy mimicked lethal moose accidents, which are especially dangerous when the mammal’s body mass rolls directly into (and through) the car’s windshield.
Saab’s participation in the project and continued wildlife-testing protocols initiated its reputation as a moose-proof vehicle manufacturer, while Gens won a long-belated Ig Nobel Prize for his research last year.
Volvo, however, was the first to market with a Large Animal Detection System, which debuted in 2016. It’s unique because it accurately detects and brakes for mammals when a driver doesn’t have time to respond manually. The system is equipped with a camera and radar that track how far away an animal is by using the ground as a reference point. The program can detect moose, elk, horses, and deer. But it can’t figure out kangaroos.
Completely irrational animals
That's because kangaroos are completely irrational animals, said David Pickett, Volvo Australia’s technical lead. In 2015, Pickett was a part of the Volvo team that tried to develop the world’s first kangaroo detection and avoidance system by a major car manufacturer.
Pickett and a research team from Volvo headquarters in Sweden traveled to Tidbinbilla Nature Reserve near Canberra, Australia, where they spent a week driving up and down winding roads, watching their detection system attempt to account for kangaroos.
“We were able to drive through the Tidbinbilla, looking past and filming what the car saw, and look at the way the car would sort of react,” Pickett said. “Well, the car wasn’t reacting.”
It quickly became clear that ground detection wouldn't work for animals with such a hoppy disposition. They look entirely different in full flight than when resting, and they’re fast. They jump in unpredictable ways, maneuvering mid-air to confuse and outrun predators.
“When it's airborne, you lose the point of reference for where it actually is,” Pickett said.
Volvo's camera and radar system were no match for the marsupials. Wallabies proved to be equally challenging.
Volvo’s team spent the next two years searching for a way to make Volvo's cars brake for kangaroos before the company admitted to the media in 2017 that its self-driving cars couldn't account for marsupials. Headlines like “Kangaroos are confusing self-driving cars” and “Self-driving cars can handle anything, except kangaroos” appeared all summer long. Audi, BMW, and Cadillac have their own wildlife-detection systems, but none claim to defend against marsupials. And Volvo has moved on. Australia is a small market, and these accidents are mostly dangerous to animals, not people, Pickett explained.
“If I hit a kangaroo, it's unlikely I'm going to die from the collision,” he said.
If changing the car doesn’t work, change the road
Without vehicle-based technology in the works, towns with hotspots for kangaroo collisions have had to find their own ways to mitigate accidents. Australians have used ultrasonic frequencies and bright red lights to deter the kangaroos, but there’s no conclusive evidence that kangaroos interpret these as threats to avoid.
Virtual fencing (as in lights activated by headlights to keep animals away from roads) has been used to deter deer in the United States and parts of Europe for almost 20 years. In 2014, Wildlife Safety Solutions tested the idea in Tasmania to see if it kept devils off the road.
AdvertisementEurobodalla Shire, a community in eastern Australia about 200 miles from Sydney, decided to see if it would also work for larger marsupials. Courtney Fink, the Eurobodalla Shire Council’s natural resource supervisor, spearheaded the project’s installation in the fall of 2022 after identifying the community’s worst collision hotspots for kangaroos and wallabies.
Along roughly half a mile of road, the Council installed thick green fence posts every 82 feet, one on each side of the road. Each post holds a device cryptically named the DD430. At dusk and dawn, when kangaroo collisions are most likely, the device activates when it senses oncoming headlights. The DD430 flashes blue and yellow lights away from the road and emits a high-pitched, repeating chirp. The idea is that animals will react to the alarm by pausing or fleeing back into the bush. According to Fink, it’s working.
“We were getting five wildlife hits per week,” she said, mostly kangaroos and wallabies. However, in the first eight months since the fences were installed, there were just five wildlife collisions. The Council’s data also suggests that wildlife collisions haven’t been displaced to roads that aren’t covered by the fences but are decreasing altogether.
Eurobodalla Shire plans to build virtual fencing along more collision hotspots in 2024, but hefty price tags could slow the process. The first stretch, which was less than a mile, cost over $11,000 AUD to install. Australia’s national highway system spans more than 9,000 miles, so a widespread solution to the country’s kangaroo problem seems, for now, still out of reach.
Sophie Hartley is a freelance reporter and graduate student in MIT’s program for science writing. She primarily covers conservation, environmental policy, and infectious disease in plants and animals.
