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Deep dive: The hidden toll of roadkill

Charli Shield
May 2, 2024

For some species being hit by a car is the number one cause of death above hunting and disease. What does this mean for wildlife populations and endangered species? How do we make roads safer for animals?

https://p.dw.com/p/4fQYX

MUSIC/SFX

Laurie Speakman: I could be in bed, I could be making dinner, doesn't matter. I would receive a phone call from trooper dispatch and they would tell me exactly where the moose was at, what mile marker. I'd get into my high visibility gear because that was a requirement. I'd get out to the moose. I'd have a winch and I would wrap it around its neck. And I'd lay the ramp out and I'd drag it up. As soon as I'd get the moose onto the truck, if I needed to secure it any other way, I would ratchet it down, put the ramps up, get back in the truck. I'd call Trooper Dispatch. They would give me the next name and number on the list for the charity that that moose was designated to. I would call the charity and I would be on my way.

Charli: For nine years, this was a pretty regular day for Laurie Speakman. She was one of the volunteer moose roadkill collectors for the Alaska Moose Federation. She'd get a call from the Alaska State Troopers when a moose had been hit by a vehicle and needed picking up. She'd haul out to collect it and deliver the animal to people in need. So they could eat the free meat. 

Laurie: And I had rope, cable, everything, and I'd be working just to get those moose through trees. And yes, I did this on my own... In the middle of it all, a lot of times I could get another phone call. There were nights where I had 9 moose in less than 24 hours. That's a lot for a night and for one truck. 

Charli:  She'd have to get out there quick before the meat started to rot or before something else came along to devour it. And quick she was. She became so well known for her volunteer work, she got a new nickname.

Laurie: One time we were out on a roadkill. It was when I first started. And I introduced myself and one of the troopers, he's like, Laurie, Laurie the Moose Lady. And off it went. And it did go nationwide.

Charli: There were some pretty hairy moments out on the job, she told me.

Laurie: I've had a few scares. We had a calf hit. It was really sad. I walked up to that calf and it took its last couple of breaths and that was a really sad situation. And then I heard a twig crack and I was about 50 feet from my truck. I turned and looked and there was the cow. I took off running and I could hear her behind me. I'm dodging trees. She's still behind me. She's only 10 feet behind me. And I dove under that truck. I always had a plan if I if I got chased, I was going under that truck. It was the only thing I could do. She was close, I could see her legs. It took me about two hours to finally get that calf to where I could get it loaded on the truck because Mama was hanging around.

Charli: But Laurie never left a scene without her moose. Not once. After all, it was for a good cause that made working for free and moving 1000-pound dead mammals in the middle of the night worthwhile.

Laurie: I pulled into a house with a moose, it was a big cow. And there was a little old lady there. She was cute as a button. She came rolling down her ramp in a wheelchair and she was in tears. She literally said 'I just put my last meal on the table. I had to hold my composure. That warmed me that I was able to help them get food on their table.

Charli: Then in 2020, the organization that provided Laurie's truck and the gas, the Alaska Moose Federation, shut down, mostly due to a lack of funds. And for a while, it wasn't clear if the moose would still be collected from Alaska's roads for people in need. Eventually, though, the state government launched the new roadkill salvage program in 2021 to make use of the moose and the other animals piling up by the roadsides. Because it's not like they'd stopped being run over. They hadn't. And it isn't just a problem in Alaska.

Alaska and beyond, cars kill a ton of animals. In fact, the world over, the roadkill toll is so high it's threatening whole species and warping the planet's ecology. Because while for humans, roads have long represented freedom, connection, and possibility. For wildlife, more often than not, roads are barricades, dividers, and death traps. They fragment habitats, cull the strong, throw ecosystems out of whack, and they get in the way of what animals need to eat, mate, and survive.

Ben Goldfarb: We're living in the middle of the sixth mass extinction event in our planet's history, and roadkill is truly one of the major reasons for that.

Charli: This is Living Planet. I'm Charli Shield. And that there is Ben Goldfarb, environmental journalist and the author of How Road Ecology is Shaping the Future of the Planet, published in 2023. In the United States, where Ben is based, and the country with the world's largest road network, more than 1 million animals are estimated to be killed on roads every single day. Globally, the figures are much more difficult to come by, but it's thought to be in the billions.

Ben: Here in the US we have ocelots and Florida panthers that we're losing very rapidly. You know, in Brazil it's maned wolves and giant anteaters. In the Middle East, it's Asiatic cheetahs, a species that is on the brink of extinction in Central and South America. You know, roads kill animals like tapirs, which are really important seed dispersers. In Europe it's badgers and hedgehogs and foxes. I think because we we see all of these dead creatures, we somewhat blind ourselves to them.

Charli: And those are just the animals that we can see.

Ben: You don't see all of the songbirds or the toads or the rodents. The smaller creatures that just tend to get obliterated by tires or eaten by scavengers soon after they're killed. Something like 300 million birds are killed every year in the US. And I think that people don't really think about birds as being a form of roadkill because we just don't really see them. We know that billions of of pollinating insects are killed by cars every single year here in North America alone. So there are these kind of ecological chain reactions that come with roadkill. It's not only killing animals, it's also disrupting all of the ecological processes that the animals set in motion.

Charli: If that comes as a shock, Ben says, that's not really surprising. Cars shield us from the outside world. They're supposed to.

Ben: When you're racing along in your car, sealed in your glass and metal bubble, driving at highway speeds, you know you don't notice all of those small animals. So cars both kill creatures and then conceal their own violence and make it hard to really quantify the death toll.

Charli: Many of us living in places where cars dominate have been there. You're cruising along in your glass and metal bubble and then, boom, the unexpected thud, followed by the drop in your stomach as you realise you've hit something. Maybe you stopped, maybe you didn't. Or, in all likelihood, you didn't even notice at all. Like Ben says, most of the carnage is hidden.

Some scientists have tried to quantify the visible death toll, though, at least in part. In 2023, researchers in the United Kingdom looked at 150 mammal populations from 69 different species around the world.

They found that being hit by a moving vehicle was the number one cause of death, for nearly one third of those populations - above hunting and disease. Some of the species most at risk include the endangered Iberian lynx, Tasmanian devils, giant anteater and maned wolf populations in Brazil, African wild dogs, the brown hyena in South Africa, and the hazel grouse in Eurasia.

High rates of roadkill don't always indicate that a species is under great threat — sometimes it can even be an indication that an animal population is large and healthy. If the group has a high enough reproduction rate, like white-tailed deer and martens in the US or the Eurasian blackbird, they can absorb the losses and maintain healthy numbers.

But one of the cruelest realities of roadkill, Ben says, is not necessarily the number of animals it culls, but which ones. It's an 'equal-opportunity predator' that not only kills the sick and old,  which usually die off in wild habitats, but the strong and healthy animals, too - affecting the structure of animal groups and their ability to survive.

And though the true scale of roadkill is almost impossible to get a grip on, it's actually one of the more tangible impacts of roads on wildlife. Most are pretty invisible — to humans anyway.

Ben: You see the deer that tries to cross a highway but gets hit by a car. What you don't see are the deer who never even attempt to cross the highway because the steady stream of traffic is so constant that they don't even step into the flow of those vehicles.

Charli: Here is a mind boggling statistic calculated in 2016 by a team of researchers from Open Street Map. Major roads like highway and freeways carve up the planet's land surface into about 600,000 patches. More than half of those patches are less than one square kilometre. That's 100 hectares. And only 7% of the patches are larger than 100 square kilometres. So 10,000 hectares.

Dear like elk, moose and pronghorn are migratory creatures. They can travel for hundreds of miles between their seasonal habitats. Unless, of course, something cuts them off.

Ben: A roadway itself might only be 50 meters wide from shoulder to shoulder. And yet it's denying animals access to in some cases hundreds of thousands of hectares of of habitat.

Charli: Scientists have observed this happening to migratory deer in Wyoming, the mountainous state in the US' west, home to the lion's share of Yellowstone National Park.

Ben: In the case of these deer, they have to migrate to get to the good food in winter, when so much of their habitat is covered in snow, there are these certain valleys that still provide them forage. But the problem is that those valleys are bisected by these major interstate highways that have such constant traffic that deer can't even, they don't even attempt to cross. And in harsh winters, they kind of pool up against the side of the highway, looking for an opportunity to run through traffic, and they just are never able to. And as a result, some years, 40% of that herd of deer will starve..

Charli: That then has all kinds of knock on effects for species, including genetic consequences.

Ben: There are lots of famous case studies, for example, a population of mountain lions that live near Los Angeles, you know, that have become so inbred as a result of freeways. You know, they can't escape their little island of habitat and no new mountain lions can cross the freeways to enter the little island of habitat. You know, that these animals, these pumas, are forced to breed with their own daughters and granddaughters and great granddaughters. and they've begun to suffer genetic defects as a result of that. So, you know, we have highway literally altering the DNA of animals. It's kind of staggering to contemplate.

Charli: Then there’s the noise roads create, the tire particles, the road salt...

Ben: Road noise is a form of habitat loss. If you're a songbird who has to sing to attract a mate, but you can't, you can't hear your mate over the noise of engines and tires. You fundamentally can't live in that place, right? So again, a road might only be 50 meters wide, and yet, that noise pollution that billows away from the roadway, might cover a few kilometers...causing habitat loss. 

Charli: And that's not something that will change on highways with the introduction of electric cars by the way, Ben adds, because the loud buzz of cars on a highway is created by the friction between tires and the asphalt. 

Ben: We know that tire particles are a gigantic problem, killing fish in many places as they enter the environment… There's road salt that's applied to highways as a de-icing agent, in the colder parts of the world, the snowier parts, and that road salt runs into rivers and lakes and turns them brackish and changes aquatic ecosystems.

Charli: In warmer countries, like Australia, scientists have found roadkill rates tend to be higher during periods of drought, when animals, like kangaroos, are often on the move in unfamiliar places in search of food and water. That's one way the climate crisis could exacerbate roadkill's toll, as fossil fuel use increases the frequency and severity of drought.

Although there are instances of wildlife out there who've figured out how to live with the infrastructure we've created — coyotes in Chicago that use the pedestrian crosswalks at the red lights, looking both ways before they scurry across, and crows observed cracking their walnuts under car tyres in Japan — on the whole, roads and traffic are a biodiversity crisis, says Ben.

Ben: We fail to recognize that roadkill is one of, if not the most prominent forms of biodiversity loss out there. There are so many species around the world for which one of the primary threats, if not the primary threat, is being hit by a car.

Charli: One response to rampant roadkill, the dead deer, elk, opossums, hedgehogs, badgers, foxes, wallabies and wombats that end up roadside has been... to eat it.

In recent decades, more and more states in the US, about 30 out of 50 total, have introduced laws permitting the harvesting of certain roadkill. Usually it's the bigger animals, like deer, elk and moose.

Of course, salvaging roadkill for food is nothing new, and since the late 1980s, the West Virginia Autumn Harvest and Roadkill Cook Off Festival has been showcasing all of the inventive, irregular delicacies you can make using animals that met death on the motorway. Like iguana nachos, elk fajitas, stew bear, squirrel gravy, deer guts, raccoon and rabbit alfredo, frog and armadillo.

You might be imagining carcasses in varying states of decay, scattered and splattered on the road. But that's a myth, the roadkill regulars say, And there are a bunch of cookbooks out there to guide you through gourmet roadkill cuisine. And there are chefs who want to normalize it, like Alan Burgo.

Alan Burgo: There's a real stigma with roadkill. Like you're eating some maggoty piece of squished meat under a tire, and it's just not the case at all. And it's absolutely a viable option for people to get free, nutrient dense, healthy, wild meat that's a lot better for the environment than factory farm food.

Charli: Alan is a forager chef from Minnesota in the US’ Midwest.

Alan: I've been writing about wild food for about 10 years. I also spent 15 years in the culinary industry running different restaurants, mostly farm to table restaurants.

Charli: Alan doesn't buy meat from the supermarket. He doesn't need to. Actually, he mostly eats deer hunted by friends of his. But were he to spot an edible deceased animal by the side of the road, he would not be looking away.

Alan: You get to the right place at the right time with the right situation. You go home with 80 to 100 pounds of free meat of incredibly high quality. You just cook the meat like you would meat from a grocery store.

Charli: There's no difference in Alan's opinion. It's superior to the meat you'd buy at a supermarket anyway. It's cleaner, leaner and not nearly as cruel.

Alan: It's absolutely more ethical than factory farms, factory farm meats, and it tastes much better too. It's pretty easy to understand that it's because of the diet. Cows in a capo contained animal feeding operation, they're just going to eat, a bunch of corn silage, the byproducts that are mostly carbohydrate based things like feed corn. When you look at a white tail deer, their diet is going to vary through the year. Wild animals that eat a natural, varied diet, including wild plants and seasonal things are always going to taste more interesting and better than animals that eat feed corn or something like that.

Charli: And should you ever happen to find yourself with some accidental bird meat on your hands, Alan has some expert tips on what to do with it.

Alan: In a perfect world, let's say that the pheasant call pheasant just hit the front of a car and his neck  snapped and nothing else is damaged. If that is the case, I'm going to pluck the entire bird so that I can have the skin. I will cut the breast off, leaving the skin on it. I'll season it with salt and pepper. I'll probably let that sit overnight, uncovered to dry out a little bit in the fridge. And then when I cook it, I'm going to… get my little carbon steel pan nice and hot. I'll put a little bit of maybe pork fat in a pan and then I'm gonna cook the pheasant breast skin side down until it's golden brown and crisp. I'll put the pan in the oven for a little bit just until the bird's about medium well or like 150 Fahrenheit. Pheasant and mushrooms is a wonderful combination my grandma always served. Add a little bit of sauteed wild mushrooms, a little bit of shallots and fresh thyme, a little chicken stock. I'll cook that down. I'll add a splash of cream. Maybe a little bit of lemon juice at the end. That's really wonderful. The crispy skin on the pheasant breast and the juicy white meat underneath the legs. I'll take the legs and I'll brown them and braise them in some meat stock or a little bit of wine. And then I'll pick out all the bones after it's cooked fork tender and soft. You can pick the meat off and add it to soup, casseroles and all kinds of things. There's no difference from the pheasant that you would get at a game farm.

Charli: Not all roadkill is edible, though, obviously, and everyone has their personal limits, Alan says.

Ben: Harvesting roadkill is not something I would do unless it was cold outside. If it's warm outside… it would have to be, like, if I hit the animal myself with a car.

Charli: The temperature factor does mean that it's not always viable in warmer countries or in warmer months, the meat goes bad too quickly. Though of course it could always be food for another scavenger. And in some places, zoos and animal sanctuaries collect roadkill as additional feed.

There are also some concerns that permitting roadkill harvests could be used as a loophole by poachers, but not much evidence has yet been found that that's the case.

So, eating roadkill can be a perfectly good use of the senseless slaughter of millions of animals. It's free, it's arguably more ethical than supermarket meat, and it's delicious — potentially. But it doesn't do anything to prevent the animals dying in the first place.

By 2050, it's estimated that they'll be another 25 million kilometres of road. built across the globe, in addition to the roughly 36 million kilometres that already exist. Road construction is also booming in some of the world's last remaining wilderness areas, like the Amazon, the Congo Basin and New Guinea. For better or worse, cars are here to stay for the foreseeable future. But with even more of them, it's hard to imagine how the trend of rising roadkill could possibly be reversed, along with the profound knock on effects that has for species survival and ecological harmony.

So how, if at all, do we make roads safer for wildlife?

Bridget Donaldson: All right. It should be working. Hi. Thanks for inviting me.

Charli:  There are some ideas out there.

Bridget: The city that I live in, we actually have a salamander tunnel under one of our roads with just like, mini fencing that helps direct the salamanders towards that tunnel. And it leads them to a wetland that they'll use seasonally. Every early March, they'll use that that tunnel to cross over to a wetland.

Charli: That's Bridget Donaldson, associate principal research scientist at the Virginia Transportation Department in the southeastern state of Virginia in the US. She's describing a kind of wildlife crossing. Tunnels, bridges and corridors built above and below roadways to help safeguard the passage of animals and connect habitats fragmented by roads.

You might have even seen some before, arching overhead as you whiz by on the freeway.

Bridget: So the ones that most people have seen when they hear about a wildlife crossing, there's beautiful photos of these. Bridges, overpasses that are covered with grass and oftentimes even trees that go over a road, so they're also called green bridges in some areas and it's really kind of a seamless habitat connection right over the road.

Charli: Green bridges and migration corridors for herd-like mammals and bears, tunnels for amphibians, otters, hedgehogs and badgers, canopy bridges and arboreal crossings for primates and squirrels, green roofs for birds, butterflies and insects, and even fish ladders. Wildlife crossings come in all different shapes and sizes.

Bridget: And a very important element of wildlife crossings is the fencing that goes along with it. So the fencing often extends usually right along the roadway so animals can't cross the fence and hopefully when they hit the fence they'll go in the right direction towards the wildlife crossing. And research has really shown that once wildlife know that the structure is there, they will go out of their way to use that structure and sometimes even change their movement patterns and their use of the habitat to be able to use that structure. And then they'll teach their young to use the structure. We have a lot of great photographs in our, some of our underpasses showing deer with their fawns or bobcats with their kittens and coyotes with their pups.

Charli: Several years back, Bridget and her team tinkered with some existing structures in the state to test how local wildlife would respond.

Bridget : So we had a project where we added a mile of eight foot tall wildlife fencing to different wildlife crossing structures or structures that weren't designed for wildlife, but that would be used by wildlife if they learned it was there. And it was very successful. So the fencing kept the deer and other animals off the road and also helped funnel them towards the structures that they might not have used before. And we found a 92 % crash reduction in wildlife, specifically deer crashes, at those sites. 

Charli: Not only did fewer animals die, fewer were left stranded at the road's edge.

Bridget: And also just as exciting, there were a huge increase in the number of animals that used the structures because they realized that the fencing wasn't going to let them get across the road. So they have to try this structure instead. And so that's a really cost effective way that transportation departments can make use of infrastructure that they already have by simply adding a less expensive countermeasure, such as wildlife fencing to enhance the use of those underpasses.

Charli: Wildlife crossings also often pay for themselves. Crashing into animals is not cheap. In the US, it's estimated to cost around $8 billion in damages every year, as well as killing around 200 people and injuring another 26,000. Well designed crossings and fences typically bring down roadkill by more than 80%.

In southwest Wyoming, where Ben Goldfarb mentioned deer were dying en masse, the state installed 7 underpasses for mule deer that paid for themselves within five years. There are now around 1,000 such crossings across the United States, which has been building them since the 1970s, though the technology has been improving over time.

Animal crossings, also called 'ecoducts', first popped up in France in the 1950s, built mostly to help hunters guide deer across country roads. Other countries like Germany, Switzerland, and Austria cottoned on to the idea and started building animal crossings in their neck of the woods too. So did the world's leading ecoduct engineer — the Netherlands, where more than 600 wildlife crossings have been built to protect endangered European species, like badgers, wild boar, red deer and roe deer. That's where you'll find the world's longest wildlife crossing — the Natuurbrug Zanderij Crailoo — that stretches over 800 metres, or half a mile, in length, covering a roadway, a railway, a sports complex, and a business park.

The crossing idea has gone global. They're all over the world now, though mostly in wealthy countries. Canada has a famous series of wildlife corridors built across Banff National Park, ferrying black bears, grizzly bears, cougars, elk and moose across the Trans-Canada-Highway. There's even a bee highway in Norway. A red crab bridge on Christmas Island in Australia. And a blue penguin underpass in Auckland, New Zealand.

The idea has been criticised for tending only to protect a selection of species and wildlife. And crossings also don't do anything to address the noise, pollution, road salt and tire particles that traffic creates.That's why roadless areas are also important.

For the roads we have though unlike those caution and watch out for wildlife signs you see by the side of the road, or even speed limits, wildlife crossings are built for the wildlife, they don't rely on drivers changing their behavior.

Bridget: They have not been shown to be effective at reducing crashes, and that's simply because people get used to them. They're up all year and they start ignoring them. Any measure that is really counting on the driver to change their behavior - in general, those methods seem a little bit less effective.

Charli: But of course, where possible, slowing down can help, Bridget says.

Bridget: I know that when I'm driving my trip from my house to my job is riddled with deer and I'm constantly staying vigilant on certain sections of highway. Where I know there's a lot of deer around, and I think that vigilance does matter. It kind of keeps your speed a little lower. It just keeps you more aware of your surroundings so that you're able to react better.

Charli: And perhaps this is where the robots come in to help with lousy human reaction times and our tendency to habituate.

Bridget: Systems that can detect wildlife on the road either via like a thermal imaging system or infrared sensors and then when the detection happens, they trigger a flashing warning light or they could even trigger an in-vehicle-system in a in a car. So things like that are being tested and nothing is really solid with regard to its effectiveness yet because they're still kind of in the study phase. But I'm hopeful that there's more systems like that that we can really make use of kind of intelligent systems to improve our safety on the roads.

Charli: But although they don't demand behavior changes from drivers, wildlife crossings do require us to think differently about how we build road networks in wild animal habitats in the first place. And doing that properly requires really seeing how roads change ecosystems and taking it seriously. Ben Goldfarb, again.

Ben: One of the really important points about roads is that, you know, look here in the US and and in most of Western Europe, we we've built most of our major roads already, right? We have these highways systems that go back to the middle of the 20th century. But you know, there are so many countries in Africa and Southeast Asia and Latin America who are building their infrastructure now - places like Kenya and Myanmar and India and Nepal. And these are countries that don't have these really well developed highway systems yet. They're building them really as we speak. And of course, we know that roads are really useful for humans, right? They're how we get to hospitals and schools and they're how farmers get crops to market.

And so it's not really just I think to prevent those countries from building out their roadways. But at the same time those countries are also hotspots of biodiversity and have some of the last intact habitats on this planet. So, I think a really important thing to remember is that as these countries build out their infrastructure, they need to build in a more ecologically sensitive way. And maybe that means avoiding certain critical habitats with roadways or building fewer but better roads or including wildlife crossings overpasses and underpasses that allow animals to safely navigate highways.

Charli: According to Ben, the precedent that's been set in wealthy, car centric countries like the US should serve as a warning, not a blueprint.

Ben: We're in the middle of what's known as the infrastructure tsunami, this wave of new construction that really threatens to sweep away biodiversity on this planet. And if we're going to save wildlife, it's really important that we build infrastructure in developing countries that doesn't repeat the mistakes that we already made here in North America and Western Europe.

MUSIC/SFX

Charli: This episode of Living Planet was written and produced by me, Charli Shield. It was edited and also produced by Neil King. Our studio technician was Simon Berkhahn. Thank you so much for listening. If you're enjoying Living Planet, we'd love it if you took a moment to give us a rating and a review on Apple Podcasts or whichever app you're listening to this right now and tell someone about the podcast. It really makes a difference. Living Planet returns with a new episode next week.

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