Roadkill Ecology

Several years ago, I woke up to find a possum the size of a small boar in my front yard. It was extremely dead. Unsure about how to handle the matter of disposal, I consulted several friends-all Texans, for what it’s worth-and got an earful of “advice.” One suggested I dump it in my neighbor’s trashcan. Another urged me to douse it in gasoline and set it on fire. A third advocated kicking it to the curb, literally.

One might conclude from these proposals that I have insane friends. But, as it turns out, their suggestions were disturbingly consistent with the solutions practiced by transportation officials across the country. Indeed, the most popular methods of managing roadkill are to dump it in a landfill, incinerate it, or leave it to decompose in roadside ditches. Needless to say, these are far from ideal solutions. But it’s generally what we do.

A decade ago, roadkill-as well as slaughterhouse and butcher waste-didn’t pose such a problem. It was conventionally and conveniently rendered. Putting aside the unsavory fact that it was often rendered into animal feed, the process itself was comparatively efficient and innocuous. But then Mad Cow Disease arrived, leading the USDA to radically tighten rendering regulations. Today, it’s very difficult to locate a rendering plant, much less an affordable one.

All of which turns contemporary carcass removal into something of an open question.? The most promising solution on the horizon appears to be composting. Just as plant matter can be aerobically baked into a valuable soil supplement, so can animal matter. It’s not rocket science, either. “Mortality composting” requires dead animals, “chunky carbonaceous material” (woodchips), a composting site (to build a windrow), and a machine to stir the seething heap every six months or so. Making composting even more attractive is that its environmental bona fides are sound and its experts are at the ready.? Scores of waste management authorities have already developed the processes by which roadkill (mainly deer) can be transformed from highway pulp into soil amendment. The leading authority on the subject, the Cornell Waste Management Institute, has published and distributed detailed guides intended to guide states and municipalities toward effective animal composting programs.

Naturally, there are limitations. Composting windrows require ample open space, and must be located in areas that are well drained and not subject to flooding. Even if adequate amounts of dry woodchips are carefully layered between decaying animals, odor can still be a problem.? It takes a long time for a 150-pound animal carcass to break down-about a year-and the bones are left behind.? There are concerns that a prion disease that deer contract (called Chronic Wasting Disease) would survive composting, which otherwise effectively kills pathogens. The compost heaps can produce mold spores that cause respiratory problems.? In the end, not a lot of compost actually materializes, and, for a variety of reasons, most states will only allow it to serve a non-agricultural public function, such as pushing up roadside daisies.

Minor problems notwithstanding, composting still strikes me as a viable answer to an inevitable problem. Before closing the book on animal composting, though, it’s worth wondering if more direct ecologies remain to be explored. I know that Alaska once fed free moose roadkill to poor people. I’ve heard that there are adventure eaters who will go gourmet with the stuff. A number of resourceful milliners are reported to have manufactured and sold roadkill hats. These ideas seem to be worthy of playing minor roles in the future portfolio of roadkill solutions. But the hidden alternative that really grabs my interest, and the one with a potentially larger role to play, is this one: feeding roadkill to carnivorous zoo animals.

It may sound overly tooth and claw, but consider the context. Zoo nutritionists have been complaining for years that confined animals are-not unlike the humans who observe them-getting fat. The Associated Press reports that there are “love handles, even on bears and gorillas.” Part of the problem is that big game animals are passively slurping pre-processed mush from a bowl rather than actively ripping flesh from bone. Some zoos even spread the packaged food out and lead the animals to it by dragging a bag of zebra poop, if only to get them off their rumps and moving around a bit before chow time. The animals have gotten that lazy.

A carcass tossed into the habitat would address all these problems. The energy required to obtain calories would go up significantly, while the rate at which animals consume food would drop (we all know it’s healthier to eat slowly rather than to gulp our food). Whereas many critics of our overly industrialized food supply lament how unnatural it has become, nothing could be more “all natural” than roadkill.

“Whereas many critics of our overly industrialized food supply lament how unnatural it has become, nothing could be more “all natural” than roadkill.”

And if local roadkill were supplied, zoos could even brag that their animals’ diets were locally sourced. Animal welfare advocates might take assurance in the fact that an animal’s seeking instinct is indulged when it picks clean a carcass. And as for the bones, animals turn them into chew toys and playthings. One can only imagine how carcass feeding would influence zoo attendance.

A few zoos, including the Folsom zoo in California, have already tried the roadkill approach and, aside from a few squeamish patrons, report no negative side effects. And while I’m sure problems would emerge should this solution go mainstream-dangerous pathogens and the expensive requirement of freezing carcasses come to mind-I still think we should give the roadkill-zoo-diet a fair hearing. The United States may very well have more deer today than at the time of European contact and, as for our cars and trucks, we’re now designing them to efficiently dispatch road-crossing beasts.? This is one collision that will only intensify. We should try to get more out of it than a better display of highway wildflowers.

Paul '52

Interesting, how a post like this illustrates the free marketers' propensity to recite some "opportunity killing" regulation without exploring, or taking into account, the rationale behind the regulation.

Now why would mad-cow cause the USDA such concern?

Could it be because the illness causes its victim to lose judgment, and walk into traffic? And therefore the chance that a roadkilled deer has mad cow is higher than that of deer killed at random?


Mike B

Heh, my mom once always hit a pheasant that flew in front of her car on the freeway. She said that had she hit it she would have definitely stopped to pick it up!


Great idea! My husband and I are hunters/fishers, and he cleans and processes the animals. Too often, he puts the leftover carcass into the garbage (in a plastic garbage bag to go to the landfill and sit forever). I urge him to dump the remains back into the woods. Nature doesn't waste anything.

Giving the roadkill to zoos would be a perfect way to lessen the waste we create, and make the animals healthier!


The idea of feeding roadkill to zoo animals is interesting; however, the majority of zoos are in cities while the majority of roadkill is miles away in the country. So, if I'm, say driving down I-70 near No Name, Colorado (yes, it's actually a town) and total my Jetta by hitting an elk, I'm not likely to transport said carcass to the Denver Zoo, nearly 200 miles away. In such a case, I'm more than happy to allow the coyotes and buzzards their feast: The only carcass I'm interested in transporting back to Denver is that of my car. So ultimately, I agree with Tonya, let nature have the remains unless you just happen to run over one of our many urban deer. In which case, the lions should feast tonight.

J Trapnell

Great article, however, its the Folsom Zoo. Think Johnny Cash's singing in the Folsom State Prison. Same place, just separated by fences.

Ed Gazvoda

Prions are a real concern. We have a way of destroying the prions and pathogens, turning the deceased animals into fertilizer with an NPK content of 3, 1, 6. We use a process known as alkaline hydrolysis. We manufacturer a mobile system with a crane that is ideal for roadkill. The cost to turn roadkill into fertilizer is about 12 cents per pound. It makes no sense to burn the anmals, as this method of disposal consumes vast quantities of fossil fuel and emits a lot of pollution. Best to return the animals natural nutrients and water content back to the earth in a sterile fashion.

We have the same process for human remains. No more burning or burying the deceased. It is the only method that benefits the living.

Kevin H

actually, the moose roadkill is still used in Alaska. I worked as a "ranger's assistant" for the state for a summer. The local rangers have first dibs on any roadkill, and we hung and dressed a couple of huge moose legs.

We BBQ'd it, but since then I've realized we really should have put it in a stew. A little tough and gamey, but good.

John Sanbonmatsu

This article, and the responses to it, are indicative of our civilizational pathology, which in essence presents our systemic structural violence against other sentient beings as "natural" and therefore acceptable features of life on earth. The untold millions of animals being maimed and killed on our nation's highways and roads each year is part and parcel of an aggressive, violent techno-capitalist that treats all other natural beings as mere objects or stuff to be manipulated, killed, and controlled at will. For a first-rate scholarly analysis of this, I recommend an article by Dennis Soron in the Canadian journal TOPIA (

How typical of journalistic reportage to reduce mass trauma and suffering in such a flippant way. But et tu, New York Times?

Eric M. Jones

Road Kill--

There are many raccoons and skunks around here. I think the legalities can be managed to harvest road kill, and I imagine raccoon rugs could be harvested from road-killed fur-bearing animals. Putting the carcass back into the woods is how nature works.

Pelts are sold on ebay. A racoon pelt is usually $30-40.

Raccoon rugs usually sell for $500 and up.

The skunks are more problematic....


I remeber reading an article about the volume of raodkill every year across the US. It would be interesting to see a followup on the amount and the practicality of this idea. What sort of time frame would you need for viability etc.

In my experience much of the road kill i smaller, think skunks, raccons turtles etc. Deer are seasonal and are more likley to be encountered at the urban/rural intersections.

James M

Feeding roadkill to Zoo Animals- if I'm not mistaken, this happens in Sussex County, New Jersey. Space Farms ( has the contract to remove roadkill from Sussex County roads and dispose of it, presumably to their zoo animals.


Very interesting. On LI there is an abundance of deer that gets hit by cars weekly, often decaying on the side of RT 25. McWilliams always uncovers the other side of a story - for that I am thankful and look forward to his next Freakonomis entry.


Fascinating stuff as usual, good work.

I'm wondering what's wrong with just letting the animals "decompose in roadside ditches"? In rural areas the smell probably won't bother anyone, and wild scavengers will benefit from the meat.


Road kill and other animal deaths, where my wife and I live in Northern VIrginia, is quickly consumed by the local wildlife. Even large animals, like deer, are gone in a day.

Perhaps one needs to live in a rural area to truly appreciate how important scavangers are to the "Circle of Life". WIthout scavangers, I fear I would live amongst piles of dead animals.

Jon L.

I am amazed that no one suggested to bury it in your backyard. Depends on the size of the animal I suppose, but handling a carcass that could have been decomposing for days or weeks is not a fun task. Dig a hole, put on some latex gloves, then put it onto a tarp. Bring it to the hole, dump, fill. In a few months there will be nothing but bones.


Sounds like zoo-food would be a good way to dispose of all the feral and stray cats in Austin.

Mike M

So why not just throw it in the roadside ditch? It seems by far the easiest, and maggots gotta eat something...

Here's a more interesting question. What happens to all the cow/pig/chicken bones from the animals we eat? They can't all be made into Sloppy Joes... I'm gonna google it right after I hit 'submit'.


What was old, is a new idea again !!!
When I was a small boy, in the 1960's, my Grandfather would take me to the local zoo in the small Wisconsin town where he lived. Back then the county road crews would pick up the road kill and drop it off at the county zoo. The zookeepers cut up the deer carcasses and gave them to the big cats. It was exciting as a young boy to watch the big cats tear at a carcass with my own eyes instead of on a television program.


I think we should do something similar with all the carcasses of animals that are euthanized in shelters. Large cities euthanize thousands of pounds of animals a year. Why not put those animals to use when they often end up in a landfill?

Mark Tueting

I don't think municipal composting is good for the environment. The gas spent on collecting the carcasses strikes me as wasted. Particularly in rural areas, carcasses should be left to compost on the side of the road - buzzards will consume the smelly, rotten stuff in a matter of days and the bones can break down in place.