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Study investigates impact of road deaths on giant anteater population in Cerrado

  • For three years, the Bandeiras e Rodovias (Anteaters and Highways) project by the Institute for the Conservation of Wild Animals (ICAS) has investigated the impact of highway collisions on the health and population of the largest insectivorous mammal in the world: the giant anteater (Myrmecophaga tridactyla).
  • Between January 2017 and December 2019, researchers tracked 44 anteaters by GPS, interviewed truck drivers, and monitored 92,364 kilometers (57,392 miles) of highways. During this period they recorded the deaths of 725 giant anteaters, a slow-moving nocturnal species with non-reflective eyes and poor hearing.
  • The study is especially relevant because it was conducted in the Cerrado, Brazil’s grain-growing heartland that’s served by a large truck fleet and marked by significant loss of habitat for corn and soybean plantations. The findings indicate that the impact of the highways has cut the growth rate of the anteater population in half, which could speed up its demise.
  • The researchers warn that the possible extinction of the giant anteater could have wide-reaching ramifications, including on agriculture, since the species plays an important role in controlling insects and pests, thereby saving farmers from having to spend on pest control products that, among other things, contaminate the soil.
Biologist Arnaud Desbiez and one of the giant anteaters monitored by the study. Image by Aurélio Gomes.

“If there’s one thing that ruins my day, it’s running over an animal. It’s so sad. One of the worst things about the job. Because there’s nothing you can do when an animal steps in front of you. Braking or swerving in a truck this size, loaded with cargo, would be dangerous for me and everyone else. So it’s the animal who pays the price.”

That’s one of the responses in a survey of more than 300 truck drivers plying four federal interstate highways that cross the Brazilian state of Mato Grosso do Sul. One of those highways, BR-262, which runs 2,295 kilometers (1,426 miles) from the coastal city of Vitória to Corumbá near the Bolivian border, has the highest number of vehicle-wildlife collisions of any road in Brazil. The others are BR-040, BR-267 and BR-163.

The anonymous survey is part of Bandeiras e Rodovias, a project by the Institute for the Conservation of Wild Animals (ICAS), which for three years has been investigating the impact of highway collisions on the health and population of the largest insectivorous mammal in the world: the giant anteater (Myrmecophaga tridactyla).

The group’s most recently concluded report contains important findings about what causes the collisions, which look likely to increase with the fragmentation of the animal’s habitat. A preliminary study was published in October 2019, with data from 2013-2014.

Brazil’s truck fleet grew by an average of 2.8% per year from 2011 to 2017, with almost 2 million vehicles in circulation at the end of that period, according to data from the National Association of Motor Vehicle Manufacturers (Anfavea). While the number has remained stable since then, it still marks a 20% increase in the number of trucks on Brazil’s roads over the past decade.

Mato Grosso do Sul is home to a massive swath of the  Cerrado, the savanna landscape that is Brazil’s  grain-growing heartland, accounting for more than half of the nation’s soybean production. That makes it one of most dangerous areas for wildlife; besides the heavy traffic of cargo vehicles, there’s also the loss of habitat driven by monoculture, particularly through deforestation and burning.

The Cerrado is the Brazilian ecosystem with the second-highest number of wildlife deaths by automobile collision, behind only the Atlantic Forest, (which has the highest population density in the country), according to the Brazilian Center of Studies of the Ecology of Highways (CBEE) at the University of Lavras in Minas Gerais state.

The giant anteater is the largest insectivorous mammal in the world; it can eat as much as 30,000 ants and termites a day. Image by Gregoire Dubois.

Human impact

The giant anteater is among the large mammals most commonly killed in road accidents. Its eyes are small relative to its body size and don’t reflect headlights. It also has poor hearing and dark fur, moves slowly — and is a nocturnal creature. All these factors contribute to its chances of getting run over when crossing a highway.

But the risk in these encounters cuts both ways, according to biologist Arnaud Desbiez, head of the Bandeiras e Rodovias project: “First and foremost, this is a public safety initiative because when a vehicle collides with a large animal like an anteater, which weighs around 35 kilos [77 pounds], people get hurt. Lots of people die when they hit animals with their cars or try to swerve around them.”

This gave rise to the idea of including a human dimension in the study to identify the psychological factors that affect drivers’ decision-making processes when an animal appears on the road. The interviews with truck drivers revealed, for instance, that drivers rarely run over wildlife on purpose, contrary to popular belief. “Most of them end up hitting animals because they don’t have much choice, since braking or swerving is so dangerous,” says Mariana Catapani, the ICAS researcher responsible for the interviews.

“Not to mention that collisions also cause damage to trucks, and this results in wasted time and financial losses,” she says. “For instance, drivers say that hitting a giant anteater, aside from the psychological damage, can cost around 3,000 reais [$700].”

The giant anteater is the largest insectivorous mammal in the world; it can eat as much as 30,000 ants and termites a day. Image by Gregoire Dubois.

11,199 animals killed

In addition to the interviews with the truck drivers, Desbiez’s team monitored a total of 92,364 km (57,392 mi) of highway to document accidents involving giant anteaters and armadillos. Between January 2017 and December 2019, they recorded 11,199 deaths by collision. These included 1,812 six-banded armadillos (Euphractus sexcinctus), 750 nine-banded armadillos (Dasypus novemcinctus), 725 giant anteaters, 586 lesser anteaters (Tamandua tetradactyla), 65 cabassouses (Cabassous sp.) and nine giant armadillos (Priodontes maximus).

The study also tracked the movements of 44 giant anteaters via GPS devices in vests fastened around their bodies. Since the system reported the location of each animal every 20 minutes, it was possible to understand when and how the anteaters interacted with the highways. The vests also had reflectors to better alert drivers during nocturnal crossings.

Given names such as Chester, Yoki, Rodolfo and Pequi, these animals were tracked for three years. In addition to the GPS monitoring, the anteaters were also regularly captured to obtain samples of fur, blood and ticks to identify possible diseases. All the vests have since been removed and the project has now moved into the data analysis phase.

The information collected throughout the study allowed the researchers to identify an interesting statistic, according to Desbiez: the growth rate of the anteater population, at around 5% per year, was halved to 2.5% when considering the impact of the highways.

“This means that the roads won’t lead to extinction because of the accidents, but they do diminish the anteaters’ growth rate, because other threats — such as disease, fire, loss of habitat, attacks from ferocious dogs — will have a stronger impact, bringing them to a level closer to extinction,” Desbiez says. “The combination of the deaths on the highways makes the giant anteater more vulnerable to other threats.”

He says the risk of extinction of the giant anteater can have ramifications for agriculture, too, unleashing a state of environmental imbalance. The animal plays an important role in controlling insects and pests: it is estimated that an individual anteater consumes about 30,000 termites and ants per day, thanks to its immense tongue that can measure as long as 40 centimeters (15 inches).

“It plays a very important role. It even saves farmers from having to spend on pest control products, which, on top of everything else, contaminate the soil,” Desbiez says.

A equipe do Bandeiras e Rodovias em campo. Foto: divulgação

Actions of conservation

The results obtained so far are being used to develop the standards for the National Action Plan for the Conservation of Giant Anteaters and Giant Armadillos, approved in July 2019. ICAS contributed with 26 of the 31 strategies defined as priorities for the conservation of these threatened animals. They include installation of radar along the roads, speed limit signs, campaigns to raise awareness, construction of underground tunnels to allow animals to cross safely, and installation of fences to prevent them from entering the roads.

The Bandeiras e Rodovias project also encompasses an interdisciplinary operation to raise awareness in educational, medical, ecological and social ways. ICAS provides environmental education to some 2,500 students from 50 schools in Mato Grosso do Sul, including seven rural schools; trains 20 educators from the municipal Department of Education of Campo Grande, the state capital; and distributes more than 3,000 teaching books in municipalities in Minas Gerais state whose farms are part of the Wildlife Release Areas (ASAS) project where anteater pups have been sent after their mothers died.

Bandeiras e Rodovias also has the support of highway concessionaires like CCR MS. In June 2019, veterinarian Debora Yogui trained 223 employees of interstate BR-163, which stretches 850 km (528 mi), cutting a vertical line through Mato Grosso do Sul. They receive training on Brazilian wildlife, safety tips regarding venomous animals, and information about environmental laws, as well as learn how to register interstate collisions and deal with live or wounded animals on the road.

Another platform that has helped quantify the roadkill and map out the most vulnerable points is the Sistema Urubu (Black Vulture System) app, created in 2014 by the CBEE. The tool allows users to send photos and travel information. Images of dead or wounded animals captured on users’ smartphones are geotagged with GPS coordinates, making it possible to find them on a map and call for help if they’re still alive.

“At a moment of political polarization, in which the interests of the ruralist and environmentalist caucuses diverge,” Desbiez says, “this kind of teamwork, involving these agents, is fundamental.”

Banner image by Gregoire Dubois. 

This story was first reported by Mongabay’s Brazil team and published here on our Brazil site on Feb. 6, 2019.

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