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

Light at the end of the tunnel: Innovative opportunities for saving tropical biodiversity

The expansion of roads into wilderness areas and biodiversity hotspots in the Global South seems inevitable and is predicted to bring about significant biodiversity loss. Even so, existing widespread strategies aiming to mitigate the direct and indirect impacts of roads on the environment have been of limited effectiveness. These tactics, including construction of fencing, wildlife crossings on paved roads, and establishment of protected areas along the roads, are unlikely to be sufficient for protecting diverse species assemblages from roadkill, habitat fragmentation, and anthropogenic activity in tropics. This indicates the need for integration of more ambitious approaches into the conservation toolkit, such as the constructing tunnels, covered ways, and elevated roads. Although these tools could significantly support conservation efforts to save tropical biodiversity, to date, they are rarely considered. Here, we discuss factors which determine the need for application of these approaches in the Global South. We highlight the often-overlooked long-term benefits associated with the application of the proposed tools. We also discuss the potential challenges and risks, and the ways to minimise them. Hopefully this article will encourage practitioners to integrate these strategies into conservation toolkits and allow policy-makers and investors to make informed decisions on sustainable road infrastructure development in the Global South.

An urgent call-to-action to protect the nonhuman primates and Indigenous Peoples of the Brazilian Amazon

Primates are facing an impending extinction crisis. Here, we examine the set of conservation challenges faced by the 100 primate species that inhabit the Brazilian Amazon, the largest remaining area of primary tropical rainforest in the world. The vast majority (86%) of Brazil's Amazonian primate species have declining populations. Primate population decline in Amazonia has been driven principally by deforestation related to the production of forest-risk commodities including soy and cattle ranching, the illegal logging and setting of fires, dam building, road and rail construction, hunting, mining, and the confiscation and conversion of Indigenous Peoples' traditional lands. In a spatial analysis of the Brazilian Amazon, we found that 75% of Indigenous Peoples' lands (IPLs) remained forested compared with 64% of Conservation Units (CUs) and 56% of other lands (OLs). In addition, primate species richness was significantly higher on IPLs than on CUs and OLs. Thus, safeguarding Indigenous Peoples' land rights, systems of knowledge, and human rights is one of the most effective ways to protect Amazonian primates and the conservation value of the ecosystems they inhabit. Intense public and political pressure is required and a global call-to-action is needed to encourage all Amazonian countries, especially Brazil, as well as citizens of consumer nations, to actively commit to changing business as usual, living more sustainably, and doing all they can to protect the Amazon. We end with a set of actions one can take to promote primate conservation in the Brazilian Amazon.

A habitat stronghold on the precipice: A call-to-action for supporting lemur conservation in northeast Madagascar

The northeast of Madagascar is as diverse as it is threatened. The area bordering the Analanjirofo and SAVA regions contains six protected areas and at least 22 lemur species. Many applied research and conservation programs have been established in the region with the aim of ensuring both wildlife and people thrive in the long term. While most of the remaining humid evergreen forest of northeast Madagascar is formally protected, the local human population depends heavily on the land, and unsustainable natural resource use threatens this biodiversity hotspot. Drawing from our collective experiences managing conservation activities and research programs in northeast Madagascar, we discuss the major threats to the region and advocate for eight conservation activities that help reduce threats and protect the environment, providing specific examples from our own programs. These include (1) empowering local conservation actors, (2) ensuring effectively protected habitat, (3) expanding reforestation, (4) establishing and continuing long-term research and monitoring, (5) reducing food insecurity, (6) supporting environmental education, (7) promoting sustainable livelihoods, and (8) expanding community health initiatives. Lastly, we provide a list of actions that individuals can take to join us in supporting and promoting lemur conservation.

Human-modified landscapes driving the global primate extinction crisis

The world's primates have been severely impacted in diverse and profound ways by anthropogenic pressures. Here, we evaluate the impact of various infrastructures and human-modified landscapes on spatial patterns of primate species richness, at both global and regional scales. We overlaid the International Union for the Conservation of Nature (IUCN) range maps of 520 primate species and applied a global 100 km2 grid. We used structural equation modeling and simultaneous autoregressive models to evaluate direct and indirect effects of six human-altered landscapes variables (i.e., human footprint [HFP], croplands [CROP], road density [ROAD], pasture lands [PAST], protected areas [PAs], and Indigenous Peoples' lands [IPLs]) on global primate species richness, threatened and non-threatened species, as well as on species with decreasing and non-decreasing populations. Two-thirds of all primate species are classified as threatened (i.e., Critically Endangered, Endangered, and Vulnerable), with ~86% experiencing population declines, and ~84% impacted by domestic or international trade. We found that the expansion of PAST, HFP, CROP, and road infrastructure had the most direct negative effects on primate richness. In contrast, forested habitat within IPLs and PAs was positively associated in safeguarding primate species diversity globally, with an even stronger effect at the regional level. Our results show that IPLs and PAs play a critical role in primate species conservation, helping to prevent their extinction; in contrast, HFP growth and expansion has a dramatically negative effect on primate species worldwide. Our findings support predictions that the continued negative impact of anthropogenic pressures on natural habitats may lead to a significant decline in global primate species richness, and likely, species extirpations. We advocate for stronger national and international policy frameworks promoting alternative/sustainable livelihoods and reducing persistent anthropogenic pressures to help mitigate the extinction risk of the world's primate species.

The impacts of linear infrastructure on terrestrial vertebrate populations: A trait-based approach

While linear infrastructures, such as roads and power lines, are vital to human development, they may also have negative impacts on wildlife populations up to several kilometres into the surrounding environment (infrastructure-effect zones, IEZs). However, species-specific IEZs are not available for the vast majority of species, hampering global assessments of infrastructure impacts on wildlife. Here, we synthesized 253 studies worldwide to quantify the magnitude and spatial extent of infrastructure impacts on the abundance of 792 vertebrate species. We also identified the extent to which species traits, infrastructure type and habitat modulate IEZs for vertebrate species. Our results reveal contrasting responses across taxa based on the local context and species traits. Carnivorous mammals were generally more abundant in the proximity of infrastructure. In turn, medium- to large-sized non-carnivorous mammals (>1 kg) were less abundant near infrastructure across habitats, while their smaller counterparts were more abundant close to infrastructure in open habitats. Bird abundance was reduced near infrastructure with larger IEZs for non-carnivorous than for carnivorous species. Furthermore, birds experienced larger IEZs in closed (carnivores: ≈130 m, non-carnivores: >1 km) compared to open habitats (carnivores: ≈70 m, non-carnivores: ≈470 m). Reptiles were more abundant near infrastructure in closed habitats but not in open habitats where abundances were reduced within an IEZ of ≈90 m. Finally, IEZs were relatively small in amphibians (<30 m). These results indicate that infrastructure impact assessments should differentiate IEZs across species and local contexts in order to capture the variety of responses to infrastructure. Our trait-based synthetic approach can be applied in large-scale assessments of the impacts of current and future infrastructure developments across multiple species, including those for which infrastructure responses are not known from empirical data.

A reviewof the application of canopy bridges in the conservation of primates and other arboreal animals across Brazil

Brazil is known as a high biodiversity country, but at the same time, it has an extensive road network that threatens its wildlife and ecosystems. The impacts of roads and railways on vertebrates have been documented extensively, and the discussion concerning the implementation of mitigation measures for terrestrial wildlife has increased in the last decade. Arboreal animals are especially affected by the direct loss of individuals due to animal-vehicle collisions and by the barrier effect, because most arboreal species, especially the strictly arboreal ones, avoid going down to the ground to move across the landscape. Here we summarize and review information on existing canopy bridges across Brazil, considering artificial and natural canopy bridge initiatives implemented mainly on road and railway projects. A total of 151 canopy bridges were identified across the country, 112 of which are human-made structures of different materials, while the remaining 39 are natural canopy bridges. We found canopy bridges in three of the six biomes, with higher numbers in the Atlantic Forest and Amazon, the most forested biomes. Most of the canopy bridges are in protected areas (76%) and primates are the most common target taxa for canopy bridge implementation. Our study is the first biogeographic mapping and review of canopy bridges for arboreal wildlife conservation in a megadiverse country. We synthesize the available knowledge concerning canopy bridges in Brazil and highlight gaps that should be addressed by future research and monitoring projects.

How Many Mammals Are Killed on Brazilian Roads? Assessing Impacts and Conservation Implications

Millions of animals are killed on roads annually due to collisions with vehicles, particularly medium–large mammals. Studies on mammal road-kill flourished in Brazil in the last decade and an assessment of research on road-kill impacts at a country level will help define science-based conservation strategies. In this study, we used the compiled scientific literature to provide the state of knowledge on medium and large-sized mammals killed by road traffic in Brazil, their conservation status, and an approximation of the road-kill magnitude. We reviewed a total of 62 scientific papers that reported road-kill data accounting for 11.817 individuals. Of the 102 species of medium–large mammals found in the IUCN list, more than half (n = 62; 61%) were recorded as road-kill on Brazilian roads. The Carnivora order comprises over a quarter (n = 23; 37%) of the total road-killed species. A total of 9 species (14.5%) were classified as threatened, with a further 10 (16%) as Near Threatened. Over half of the road-killed species (n = 33, 53%) showed declining population trends according to their IUCN conservation status. Our extrapolation of the results for the entire Brazilian paved road network showed that the number of medium–large road-killed mammals can reach almost 9 million yearly (maximum 8.7 million; mean 1.3 million), representing a biomass of more than 10000 tons. The highest roadkill rates were recorded for common generalists and least concern species, although there were also threatened and near threatened species within the top 15 highest road-kill rates. The declining population trends found for most species reflect serious conservation concerns, since there is a lack of information on the mortality effects at population levels. Our results suggest that medium–large mammals are severally affected by road mortality in Brazil. More investigations are needed at local and abundance population levels, in a way that allows the inclusion of road network as an important threat for target species impacted by road-kill in the national territory, in order to develop adequate plans to mitigate those impacts.

Movement dynamics of gibbons after the construction of canopy bridges over a park road

Gibbons (Hylobatidae) are species highly adapted to tree-top living. Thus, their movement can be compromised due to the negative impact roads have on canopy habitats. In this study, we built two single-rope artificial canopy bridges and a ladder bridge at two out of five locations where a group of white-handed gibbons (Hylobates lar) in Khao Yai National Park, Thailand were known to cross a main park road. We compared road crossing frequencies, home-range characteristics, and other ad libitum observations during the periods before and after bridge installation. After bridge construction was complete, the group took 10 weeks to use the single rope bridges to navigate over the road. During 442 group follow observation hours and 539 bridge observation hours, 131 crosses over the road were observed. The adult female usually crossed the road first, and the group showed a clear preference for the single-rope bridges over the ladder bridge (92 crossings versus 5). Gibbons crossed the road approximately once a day and crossed mostly at the bridge locations both before and after bridge construction. There were not significant changes in crossing rates from before (crossing between the tree branches and on the ground) to after bridge installation at both the places where bridges were installed (crossing using the bridges). Nonetheless, with more crossings being in the bridges than on the ground after bridge installation, crossings were presumably safer. These findings suggest that gibbons will cross a road on the ground, risking predation, encountering people, or being hit by a vehicle, but artificial canopy bridges provided a safer crossing option since gibbons no longer crossed on the road or jumped across wide gaps at the two locations where bridges were constructed. Maintaining canopy connectivity over roads using artificial bridges logically improves home range connectivity, potentially gene flow, and safety of canopy dwellers. However, connecting areas which were not previously connected should be considered carefully. The new connection could disrupt group dynamics, particularly for species that defend territories, such as gibbons.

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

Primates, represented by 521 species, are distributed across 91 countries primarily in the Neotropic, Afrotropic, and Indo-Malayan realms. Primates inhabit a wide range of habitats and play critical roles in sustaining healthy ecosystems that benefit human and nonhuman communities. Approximately 68% of primate species are threatened with extinction because of global pressures to convert their habitats for agricultural production and the extraction of natural resources. Here, we review the scientific literature and conduct a spatial analysis to assess the significance of Indigenous Peoples' lands in safeguarding primate biodiversity. We found that Indigenous Peoples' lands account for 30% of the primate range, and 71% of primate species inhabit these lands. As their range on these lands increases, primate species are less likely to be classified as threatened or have declining populations. Safeguarding Indigenous Peoples' lands, languages, and cultures represents our greatest chance to prevent the extinction of the world's primates.

Monitoring the use of a canopy bridge and underpasses by arboreal mammals on a Brazilian coastal road

Roads disrupt the canopy and can affect arboreal animals in different ways, such as reducing canopy connectivity, generating habitat loss and degradation, and increasing direct mortality. Since arboreal animals mainly use the canopy for movement, mitigation measures for these species usually focus on maintaining or restoring canopy connectivity to guarantee safe crossings. Here we present a case study of a Brazilian coastal road (ES-060) for which we described the use of a canopy bridge and multiple underpasses by three arboreal mammal species and compared these data with roadkill records of the same species in the vicinity of the crossing structures. Our study includes a 75 m long steel cable canopy bridge, monitored for 3 years, and clusters of different types of underpasses, monitored for 16 years. The use of the crossing structures was monitored with sand track beds installed at entrances on both sides, and roadkill surveys were conducted daily for 16 years. We considered a crossing to be successful if tracks of the same species were recorded on either side of a structure and showed opposite movement trajectories. The canopy bridge survey resulted in an observed rate of 0.16 crossings/month for Callithrix geoffroyi, 7.79 for Coendou insidiosus, and 0.46 for Didelphis aurita, and all types of underpasses combined demonstrated a rate of 0.33, 1.94, and 8.43 crossings/month for each species, respectively. The roadkill surveys resulted in an observed rate of 1.41, 0.78, 2.94 roadkills/month for Callithrix geoffroyi, Coendou insidiosus, and Didelphis aurita, respectively. Even with mitigation structures confirmed to be used by these three species, roadkill hotspots occurred in the road sections with the crossing structures. Our study demonstrated the use of a canopy bridge and different types of underpasses by arboreal mammal species. The canopy bridge was mostly used by Coendou insidiosus, while the underpasses were mainly used by Didelphis aurita. As roadkill hotspots occurred red in the same segments where mitigation crossing structures were installed, our results indicate that some important improvements are needed to mitigate roadkills of arboreal mammals in this area, mainly preventing that these species access the road. We present recommendations for a research agenda to support mitigation planning for arboreal mammals, namely: (1) testing the efficiency of different canopy bridge designs for multispecies mitigation, (2) testing the use of connecting structures, such as ropes that connect to the surrounding forest, to encourage underpass use by arboreal species, and (3) testing fence adaptations to block the access of arboreal mammals to roads.

Impact of linear infrastructure on South Africa’s primate fauna: the need for mitigation

South Africa’s extensive linear infrastructure network (which includes roads and power lines) is severely impacting the country’s historically recognised five primate species: greater or thick-tailed bushbaby (Otolemur crassicaudatus), southern lesser bushbaby (Galago moholi), chacma baboon (Papio ursinus), vervet monkey (Chlorocebus pygerythrus) and samango monkey (Cercopithecus albogularis). We present South African mortality data from two different linear infrastructure types on a country wide scale, over a long-term sampling period. Using primate road mortality and power line electrocution data acquired from different data sources, we compare and discuss different mortality data collection methodologies, the resulting data quality and identify current limitations in understanding the direct impacts of linear infrastructure which have important implications for primate conservation planning. Between 1996-2021 a total of 483 primate mortalities were recorded on roads and power lines, the majority on the former. Vervet monkeys were most severely impacted by both linear infrastructure types whereas lesser bushbabies experienced the least number of mortalities. Both data sets showed numerous incidents where more than one individual was killed (roadkill: 4%, up to four killed in one incident; electrocutions: 13%, up to six killed in one incident). GPS coordinates were available for 61% of roadkill records and for 65% of electrocution records. Age or sex of carcasses were not available for electrocution records and only available for 11% of roadkill records. Although South Africa leads the African continent regarding roadkill and electrocution data collection, there are still areas in the collection protocol that can be improved and projects implementing mitigation measures (e.g. canopy bridges) to reduce primate roadkill are lacking. We argue that the mortality data presented here should form the basis for future mitigation implementation and recommend that linear infrastructure be more prominently recognised as a direct threat when developing national and international Red Lists.

Horizon Scan of Transboundary Concerns Impacting Snow Leopard Landscapes in Asia

The high-altitude region of Asia is prone to natural resource degradation caused by a variety of natural and anthropogenic factors that also threaten the habitat of critical top predator species, the snow leopard (Panthera uncia). The snow leopard’s landscape encompasses parts of the twelve Asian countries and is dominated by pastoral societies within arid mountainous terrain. However, no investigation has assessed the vulnerability and pathways towards long-term sustainability on the global snow leopard landscape scale. Thus, the current study reviewed 123 peer-reviewed scientific publications on the existing knowledge, identified gaps, and proposed sustainable mitigation options for the longer term and on larger landscape levels in the range countries. The natural resource degradation in this region is caused by various social, economic, and ecological threats that negatively affect its biodiversity. The factors that make the snow leopard landscapes vulnerable include habitat fragmentation through border fencing, trade corridor infrastructure, non-uniform conservation policies, human–snow leopard conflict, the increasing human population, climatic change, land use and cover changes, and unsustainable tourism. Thus, conservation of the integrated Socio-Ecological System (SES) prevailing in this region requires a multi-pronged approach. This paper proposes solutions and identifies the pathways through which to implement these solutions. The prerequisite to implementing such solutions is the adoption of cross-border collaboration (regional cooperation), the creation of peace parks, readiness to integrate transnational and cross-sectoral conservation policies, a focus on improving livestock management practices, a preparedness to control human population growth, a readiness to mitigate climate change, initiating transboundary landscape-level habitat conservation, adopting environment-friendly trade corridors, and promoting sustainable tourism. Sustainable development in this region encompasses the political, social, economic, and ecological landscapes across the borders.