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The Wildlife Conservation Society (WCS) has built a “canopy bridge” in the Amazon designed specifically to allow endangered and vulnerable primates and other tree-dwelling wildlife to safely cross a highway and reduce collisions with vehicles. It is the first time a highway in the Brazilian Amazon received an aerial road overpass for wildlife before paving.
The bridge crossing, which officially opened on July 27th, spans BR-319, a highway that crosses the Brazilian Amazon connecting Manaus, capital of Amazonas, to Porto Velho, Rondônia. The bridge project was carried out by WCS in partnership with ViaFAUNA Consultancy, funded by the Segré Foundation and with support from the Brazilian National Department of Transport Infrastructure (DNIT).
Built at canopy level, at the height of the treetops, the structure was planned specifically to help arboreal wildlife - animals that feed, move and sleep on trees. Conservationists expect primates to benefit most from the crossing. In Brazil some 40 percent of all primate species are endangered with the greatest diversity occurring in the Amazon
According to Marcos Amend, WCS Conservation Director in Brazil, the structure uses a technology that is unprecedented in the country and seeks to mitigate the direct impacts of the highway, which is in the licensing process for paving. The location chosen for the crossing is known for wildlife and plants that only exist in this region.
Said Amend: “It is an area that still has well-preserved forests, but just the prospect of paving the road already generates pressure for occupation and, along with this occupation, comes deforestation, land grabbing. In the Amazon, we need to prepare ourselves to protect areas that are not isolated. We have to create strategies that prepare the context of the road, governance and mitigation actions for direct and indirect impacts of the road.”
Focus on primates - The canopy bridge on the BR-319 was designed considering movements of big primates like the the woolly monkey (Lagothrix lagothricha cana) and the black-headed spider monkey (Ateles chamek), which have their areas of distribution affected by BR-319 and are considered, respectively, as “vulnerable” to the risk of extinction and “endangered” according to the Red List of the International Union for Conservation of Nature (IUCN). In addition to these two priority species occuring in the region, the structure will benefit other species too, like the widow monkey (Plecturocebus caligatus), black-capped capuchin (Sapajus apella), howler monkeys (Alouatta puruensis), squirrel monkeys (Saimiri ustus), white-lipped tamarin (Saguinus labiatus), and a great diversity of other arboreal mammals such as opossums, squirrels, coendous, lesser anteaters, kinkajous and, eventually, reptiles such as snakes and lizards.
These animals suffer from unnatural mortalities caused by human activity, including large-scale developments that cut through forest areas, such as highways and railways in the Amazon.
Said biologist and founding partner of ViaFAUNA Consultancy, Fernanda Abra, who coordinated the technical project: “The Amazon biome has worldwide relevance due to its ecosystem services and high biological diversity, but this richness is threatened by these large infrastructure projects. Essential for the socioeconomic development of a region, these constructions also cause a series of environmental impacts.”
Forest fragmentation reflects on the loss of fauna - In addition to preventing animals from being run over by vehicles, the canopy bridge also promotes the reconnection of forest fragments separated by the opening of the highway and contributes to the reconnection of habitats and essentially arboreal species.
Said WCS’s Conservation Director in Brazil, Marcos Amend: “Although people always relate the road overpass for wildlife with the issue of accidents, one of the major impacts that happen before being run over is the segregation of groups of primates, which no longer have genetic exchange. We want to assess whether this model, which is the first built in Brazil, will be effective in reconnecting populations. If it is effective, and built in sufficient numbers, they will also start to avoid animals being run over, which are the most obvious and impactful consequence of highways on the fauna and the safety of drivers.”
Added Abra: “Many species that are more sensitive to habitat change no longer cross from one side to the other, especially arboreal fauna, which need forest connectivity to move around. This is what we call habitat fragmentation. Therefore, it is essential that we reconnect these forest fragments.”
Sustainable engineering model for the Amazon - The technical project for the overpass for wildlife included the construction of two concrete poles, one on each side of the road, which supports the bridge, made with durable material suitable for wildlife use.
Canopy bridges such as the one built by WCS are among the most effective strategies to mitigate direct impacts of highways in the Amazon. Currently, in addition to BR-319, only BR-174, which connects Manaus to Boa Vista, in Roraima, has structures of this type: there are 30 bridges total, installed in 2022.
The BR-319 highway already had underpasses for terrestrial animals. This week, WCS installed camera traps in some of those tunnels to monitor the animals. The information gathered will help guide other mitigation actions.
In conjunction with construction of underpasses and overpasses, additional strategies are needed to address land grabbing and deforestation that often follows the development and paving of new highways.
Model to be replicated – The idea is that this canopy bridge, located at kilometer 272 of the BR-319, serves as a model for the other 70 planned by the environmental impact studies to be built in the so-called 'middle stretch' of the highway, route of approximately 400 kilometers of the road that is still unpaved.
Said Earth Engineering coordinator of DNIT-AM, Arlindo Pires Lopes: “WCS, together with ViaFAUNA, has developed these canopy bridges with the support of DNIT. These partnerships between non-governmental organizations and the federal government are extremely important, as we can join efforts in favor of the environment.”
For the Ibama representative present at the opening of the overpass for wildlife, Flávio Silveira, this highway needs a different look.
“The main issue here is that it has to be very clear that it cannot be a highway like the others. Due to the environmental sensitivity that we have in the region, the environmental bias in this construction has to be different. This event that we are participating in today, with the inauguration of this structure, is already an indication that DNIT is concerned about doing things differently. Because, here, we will need it to be a different undertaking, so we don't end up with an empty forest,” said Silveira.
The manager of the Igapó-Açu Sustainable Development Reserve, a protected area that is crossed by the BR-319, Ádila Mattos, celebrated the overpass for wildlife and highlighted the importance of replicating the model on other areas of the highway, also contemplating other protected areas.
“It is a necessity, not only for the highway as a whole, but for the Igapó-Açu reserve. We have a pilot plan and we are hoping that we will be able to expand this around the entire reserve and also to the Matupiri State Park, which suffers pressure from deforestation, hunting and illegal fishing,” Mattos said.
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