End of the line for the golden lion tamarin? A single road threatens 30 years of conservation efforts

Abstract

Roads have a myriad of negative effects on biodiversity, ultimately threatening the persistence of populations. In this Perspective we call attention to an extreme example, where the entire current geographic range of the endangered golden lion tamarin (Leontopithecus rosalia, GLT) is bisected by a major highway that is being widened to four lanes. We believe that the planned mitigation actions are not enough to reduce the expected increase of barrier effects and road mortality. These impacts may lead to a sequence of cascading effects that could jeopardize the conservation actions that prevented the extinction of GLTs three decades ago. We identify specific road sections along the highway and accompanying paved roads in the region that if equipped with tailored over passages would greatly reduce the road Fernando Ascensão and Bernardo B. Niebuhr shared first authorship.

Global importance of Indigenous Peoples, their lands, and knowledge systems for saving the world’s primates from extinction

“…Similarly, the western chimpanzee ( Pan troglodytes verus ) is negatively affected by roads across 95.7% of its present geographical distribution, with the road-effect zone (i.e., the distance up to which the presence of major roads reduces the density of a species) estimated as 17.2 km (95% confidence interval, 15.8 to 18.6 km), which is three times greater than that of minor roads ( 180 ). Likewise, several primate species endemic to the Atlantic Forest of Brazil (which has lost some 70% of its original habitat) ( 181 ), including the Endangered golden lion tamarin ( Leontopithecus rosalia ), the Critically Endangered southern muriqui ( Brachyteles arachnoides ), and the Endangered blonde capuchin ( Sapajus flavius ), are threatened with extinction due to deforestation and infrastructure development ( 173 ). Moreover, major hydroelectric projects in tropical river basin systems such as the Amazon, Congo, and the Mekong, and the expansion of large-scale industrial agriculture and road networks by multinational corporations have resulted in the widespread displacement of Indigenous Peoples, leaving all remaining biodiversity and forest habitats vulnerable to invasion and overexploitation ( 9 , 182 , 183 ).…”

“…This process will likely further disrupt natural ecosystems on the borders of and within Indigenous Peoples' lands through water, air, and soil pollution, logging, habitat fragmentation, bush-meat hunting, the live primate trade, and the spread of zoonotic diseases and invasive species. This will create permanent barriers to primate dispersal and gene flow (173)(174)(175)(176)(177)(178). A recent study identified 32 primate species that are considered highly vulnerable to the environmental impacts of infrastructure development, and whose distributional ranges already include a high density of transportation and energy infrastructures (14,15).…”

No Planet for Apes? Assessing Global Priority Areas and Species Affected by Linear Infrastructures

“…However, the infrastructure networks in this region continue to expand. For example, our assessment classified the golden lion tamarin (Leontopithecus rosalia), which is endemic to the Atlantic forest (Ascensão et al 2019), as having the highest Vulnerability to infrastructures, and inhabiting an area in the top semi-decile of infrastructure density.…”

“…Many primate species exploit home ranges that extend beyond the borders of protected areas or travel between protected areas, and thus encounter linear infrastructures in their pathway (Estrada et al 2017, Moraes et al 2018. In particular, arboreal species may have serious difficulties in crossing vegetation gaps caused by infrastructures, limiting their access to resources such as food and mating partners, and restructuring populations into smaller and often unviable populations (Grativol et al 2001, Ascensão et al 2019, Linden et al 2020. Some species may avoid infrastructures due to disturbance such as traffic noise and increased human activity (Duarte et al 2011), thus intensifying this barrier effect (Hickey et al 2013, Clauzel et al 2015.…”

Mitigating the effect of linear infrastructure on arboreal mammals in dense forest: A canopy bridge trial

“…2009; Ascensão et al . 2019). The impacts of existing linear infrastructure and the predicted expansion of the various networks in the coming decades pose significant threats to arboreal animals around the world and more must be done to prevent population declines.…”