Animals

Why This Brazilian Road Is the Deadliest Animal Crossing in the World

Have you ever been driving on a highway, passed a "Deer Crossing" sign, and wondered how they convinced the deer to stick to that particular stretch of road? Okay, okay, we know it doesn't really work like that. There are places where civil engineering has shaped the way that wildlife interacts with car traffic — and there are places where that kind of engineering is sorely needed. If you're an animal, Brazil's BR-262 just might be the most dangerous road in the world.

Deadliest Stretch

Dr. Wagner Fischer first noticed the deadly nature of BR-262 in the 1990s when he was a grad student working in Pantanal, an expanse of Brazilian wetlands about the size of Wisconsin. The road weaves through the great green expanse, connecting the cities of Campo Grande and Corumbá some 430 miles (692 kilometers) apart. Every time he commuted to his field office, Fischer would stop along the way to document the roadkill, remnants of every unfortunate animal who crossed the highway at exactly the wrong time.

His goal wasn't originally to publish these findings, but as time went on and the list grew more detailed, it became nearly inescapable. In May 2018, the final tally of reptiles and birds was published in the online journal Check List (the mammal count is due to be released separately in the near future). The numbers are pretty grim. Between 1996 and 2000, 930 reptiles and birds were found dead on this relatively short stretch of road, representing about 29 different types of reptiles and 43 different kinds of birds. The record of mammals is set to be much direr — he counted roughly 2,200 different specimens during the same time period, including vulnerable large mammals like the giant anteater. The problem is getting worse, too. There were 2,200 mammals that died on the road in the late '90s, but a recent study counted 1,000 large mammals killed on BR-262 in 2017 alone.

Fischer's was some of the first work to target the subject of animals killed by traffic, but it swiftly inspired similar projects in other areas. In California, the most deadly highway is I-280, which took the lives of 386 creatures between 2015 and 2016. In Great Britain, approximately 1,200 animals died on all of the country's highways in 2017. But the more work is done on the subject, the more apparent it becomes that the combination of Pantanal's biodiversity and that tempting stretch of dry land makes BR-262 the deadliest in the world.

A Cure for Roadkill

Speaking with the New York Times, Dr. Manuela González-Suárez from the University of Reading described just how big of a problem this might be. When you count all of the highways and freeways in Brazil, the number of birds killed annually explodes to 8 million. "Out of these 8 million birds, maybe some of those are fairly common ones, where maybe this is not a problem. But we don't know, exactly. Are we going to lose all birds in Brazil? Probably no. But it would be nice to know, what should we be worried about?"

Thanks to its lush rainforests, Brazil is home to a staggering 20 percent of the world's biodiversity. But that biological abundance is in danger from many different threats. With the scope of wildlife killed by traffic even higher than suspected, it's vital to consider what methods can be used to curb the problem, since "Anteater Crossing" signs only go so far. One solution? Fences surrounding the roads, leaving only a few openings for animals to cross. At those openings, civil engineers could provide safe bridges, encouraging animals to take less dangerous paths instead of faster and easier ones. It's a solution that's already working for pronghorn antelope in North America, and there's no reason why it wouldn't work for caimans as well.

Get stories like this one in your inbox or your headphones: sign up for our daily email and subscribe to the Curiosity Daily podcast.

There's a lot of beauty in Pantanal — it's not all tragic road accidents. See what the massive wetland has to offer in Russell Mittermeier's photobook of the area. We handpick reading recommendations we think you may like. If you choose to make a purchase through that link, Curiosity will get a share of the sale.

Written by Reuben Westmaas December 20, 2018

Curiosity uses cookies to improve site performance, for analytics and for advertising. By continuing to use our site, you accept our use of cookies, our Privacy Policy and Terms of Use.