The surprising scientific value of roadkill

The surprising scientific value of roadkill

By Emma Gomez edited by Andrea Thompson

In the dead of night, a car rolled to a stop on an Australian highway in front of Christa Beckmann, a bespectacled woman kneeling on the side of the road. She remembers the confusion on the driver’s face when they saw her collecting dead frogs.

“They said, ‘What the hell are you doing?’ And I explained. It was kind of fun to see all the expressions go over their faces,” she says.

Beckmann is a wildlife ecologist at RMIT University in Australia. At the time, she studied how birds of prey ate frogs and invasive cane toads killed by cars. To get a complete picture of which amphibians the birds went for and when, she collected them in the wee hours of the night and placed them in trays filled with sand along the road. Then the birds came in and picked up their warty breakfast, and she could observe the telltale footprints they left in the boards.

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While combing through relevant past research for her work, Beckmann noticed a pattern: much of other researchers also used roadkill in their studies. Her curiosity led her to recently publish a comprehensive literature review detailing the ways people have used roadkill – and in some cases innovated new research methods. She found more than 300 examples where scientists made scientific lemonade out of lemons: roadkill helped them map where species are, obtain samples more ethically, and even discover new species.

“I was really impressed by the huge variety of research topics that people were using roadkill for,” says Beckmann. “It can become a source of inspiration for other researchers.”

Some of the more common uses of roadkill in the papers Beckmann evaluated were to help researchers determine exactly which animals were present in an area, evaluate the presence of disease among wildlife, or study animal anatomy. Roadkill can show what was going on in an animal’s body when it died, said Christopher Lepczyk, a conservation biologist at Auburn University who was not involved in the review. It has also been used to determine the spread of invasive species—or even to find new ones, such as a reptile in Brazil called a snake lizard and a rodent in India.

Many studies like these do not need to use roadkill to be successful. But researchers, including Beckmann, argue that using roadside victims may be a more ethical alternative to capturing wild animals or euthanizing them for tissue sampling. When using animals in study methods, researchers are asked to assess whether live animals can be reduced or replaced. “I think (roadkill) is a fantastic ethical source of samples,” says Beckmann.

Of course, just because roadkill is useful to science doesn’t mean it isn’t a problem. Every year, millions of animals are killed by vehicles in the United States alone. A 2016 study found that 20 percent of the world’s land was within one kilometer of a road, and researchers estimate that percentage has only grown. “We have this huge network of basically guillotines that go along the roads,” says Fraser M. Shilling, director of the Road Ecology Center at the University of California, Davis.

Shilling has no doubt that excess animal carcasses provide valuable research opportunities for wildlife ecologists. But scientists should seek out roadkill “only if it replaces potentially harmful or lethal ways of testing animals,” he says. The ultimate goal, according to Shilling and Beckmann, should be to protect living animals.

“We should use this resource, if we can, from ethical perspectives,” says Beckmann. “But I’d prefer not to have that resource available. I’d much rather we not see the carnage on the roads that we do.”

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