IN BRAZIL, ANIMALS CROSS A ROAD OF NO RETURN

It’s one of deadliest in the world for critters, and ecologists worry problem will worsen

Whenever Wagner Fischer drives, he notices the roadkill.

As a graduate student in the 1990s, Fischer, now a biologist with the Federal University of Mato Grosso do Sul, traveled through Brazil’s Pantanal, a tropical wetland the size of Wisconsin, and the largest freshwater wetland in the world. From his motorcycle, he saw monkeys swinging from roadside trees; capybaras slept on the shoulder. He was looking for fishing bats, the subject of his graduate research. But he was fascinated and appalled by the roadside carnage: caimans, anacondas, giant blacknecked storks called jabirus and, once, a dead giant anteater with her cub, alive, clutching her back.

The region’s main road, the BR-262, is a long thread of tarmac through the carpet of green, connecting the growing cities of Campo Grande and Corumbá, 430 miles apart. Fischer began taking photographs, thousands of them, and tallying the species along the road. He shared his unpublished results with other researchers and government officials.

“Everyone from the scientific community kept asking me, ‘When are you going to publish that?’ ” Fischer recalled recently.

Two decades later, he finally has. His paper, published Oct. 19 in the online biodiversity journal Check List, is a grim tally. From 1996 to 2000, Fischer counted dead 930 animals representing 29 reptile species and 47 bird species. A separate tally of mammals, to be published soon, includes more than 2,200 specimens. But even in its unpublished phase, his study inspired others like it, all of them confirming Fischer’s initial conclusion: that for wildlife, Ecologists worry that the problem will soon worsen. Brazil is home to 20 percent of the world’s biodiversity, but the newly elected president, Jair Bolsonaro, has promised to develop large tracts of the country’s most ecologically sensitive areas.

In 2014, a team led by Julio Cesar de Souza, of the Federal University of Mato Grosso do Sul, took another look at roadkill on the BR-262. Over 15 months, they found 518 carcasses from 40 species, and noticed a roadkill site every 4 miles — a tenfold increase since 2002, when Fischer presented some of his findings at a transportation conference. That study, as well as a study in 2017 that counted more than 1,000 large mammals killed in one year on the BR-262, prompted Fischer to finally publish his data.

By contrast, on California’s Interstate 280 in the Bay Area, the state’s deadliest road for animals, 386 creatures died in collisions between 2015 and 2016. In Britain, more than 1,200 animals died in road collisions across all major highways in 2017, according to a recent report.

Throughout Brazil, roads are littered with carcasses representing the country’s 1,775 bird species and 623 mammal species. Large mammals are at greater risk in southern Brazil, including the Pantanal and dry savanna, whereas birds are at higher risk in the Amazon, according to Manuela González-Suárez, a biologist at the University of Reading in England.

In a study published in August, González-Suárez and her colleagues built a computer model to predict where animals were most likely to be struck by vehicles. Using existing roads and roadkill counts, including Fischer’s data, her team found that as many as 2 million mammals and 8 million birds may be dying on Brazilian highways each year.

“When I got the total number, I was just completely blown away,” González-Suárez said. “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?”

Ecologists worry that the problem will soon worsen. Brazil is home to 20 percent of the world’s biodiversity, but the newly elected president, Jair

Bolsonaro, has promised to develop large tracts of the country’s most ecologically sensitive areas.

Now that Fischer’s data are in the scientific literature, other researchers can more easily compare it with current data and identify trends, said Arnaud Desbiez, a conservation biologist with the Royal Zoological Society of Scotland, and a co-author of the 2017 study. Desbiez runs Brazil’s Giant Armadillo Conservation Project and a program called Anteaters and Highways.

Brazilian officials have taken some basic measures. White metal signs, bearing silhouettes of armadillos and giant anteaters, appear on the roadside every few miles, advising motorists to “Respect Wild Life” and “Preserve the Pantanal.” But signs are easily ignored, especially in the rush of freight-hauling and daily life, ecologists say. Desbiez favors fencing that keeps animals off the pavement and guides them toward safe passages under or over the road.

In the United States, fences, underpasses and bridges have been built along interstate highways to reduce collisions, which are costly for drivers and animals alike. In Wyoming, wildlife conservationists tracked pronghorn antelope to determine their favorite crossing spots, and then built sagebrush-lined bridges for the animals. In Colorado, a network of underpasses and bridges over a mountain highway has reduced collisions by 90 percent.

Fraser Shilling, director of the Road Ecology Center at the University of California, Davis, helped develop a real-time deercollision map, which connects to a car or phone app that can warn drivers when to be on high alert. A recent seminar that taught other officials how to build their such maps drew representatives from 42 states, Shilling said.

González-Suárez is now studying individual species to figure out the impact on local populations. For mammals, especially those that reproduce slowly and in small numbers, the loss of a few could have devastating effects, Desbiez noted.

Monitoring roadkill is important for more than accounting purposes, said Shilling. Roads are the primary way in which most people interact with wildlife, yet traffic collisions with animals are wildly underreported, he said. Measuring the scale of death is a way to remind people that our footprint is much larger than the carbon dioxide we emit or the waste we produce.

“The first part is discovering that there is a problem,” he said.

Gonzalez-Suarez said that deforestation poses a greater threat to Amazonian biodiversity than a new road does, but the two are linked, she added; new roads are built to harvest wood, and to transport grain and livestock from expanding farmlands.

Ricardo Fraga and Wagner Fischer / New York Times Highway BR-262 is among the deadliest in the world for wildlife. Biologist Wagner Fischer has been monitoring its grim toll for more than two decades.

Lalo de Almeida / New York Times A giant anteater and cub forage for food in the Caiman Ecological Refuge. Even occasional losses of larger mammals, which reproduce in small numbers, can threaten a population.

Ricardo Fraga and Wagner Fischer, et al. / New York Times A dead caiman lies on a highway in Brazil’s Pantanal region. Twenty percent of the world’s biodiversity is found in Brazil, where economic development is expanding the road network.