Wildlife Crossings Research Articles

On the road again: A study valuing wildlife crossings for wetland mitigation on State Road 40 in Volusia County, Florida

AbstractOver the past few decades, wildlife crossings have effectively reduced wildlife–vehicle collisions and improved habitat connectivity and genetic exchange for animals. However, wildlife crossings are expensive to construct, and the cost may discourage transportation agencies from implementing new wildlife crossings on public roadways. Additionally, transportation agencies and planners rarely consider the permitting and mitigation costs that wildlife crossings can require. A road profile must be raised to accommodate a wildlife underpass on many Florida roadways, particularly in low‐lying areas. Raising the road can result in new wetland impacts that would not occur but for the wildlife crossing. Consequently, new or more compensatory wetland mitigation may be required to satisfy § 404 of the Clean Water Act—a cost to the transportation agency and taxpayers. We used Florida's Uniform Mitigation Assessment Method (UMAM) to calculate the value of functions in habitats before and after planned wildlife crossings on State Road 40 in Volusia County, Florida. The results of our analysis show that wildlife crossings will enhance the functions in remnant habitats adjacent to the wildlife crossings, generating wetland mitigation credits that reduced the amount of compensatory wetland mitigation required by the U.S. Army Corps of Engineers. Our case study provides a novel application of the UMAM in valuing wildlife crossings. We believe the UMAM can be used in cost–benefit models and transportation planning to determine the functional value of new wildlife crossings, thereby producing a monetary value that can incentivize new wildlife crossing projects.

Wildlife Crossings Pilot Program (DOT)

Federal Grants & ContractsVolume 47, Issue 10 p. 6-6 Grants Alerts Wildlife Crossings Pilot Program (DOT) First published: 18 April 2023 https://doi.org/10.1002/fgc.32985Read the full textAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL No abstract is available for this article. Volume47, Issue1020 April 2023Pages 6-6 RelatedInformation

Better safe than sorry – Understanding the attitude and habits of drivers can help mitigating animal-vehicle collisions

The rapidly growing global road networks put serious pressures on terrestrial ecosystems and increase the number and severity of human-wildlife conflicts, which in most cases manifest in animal-vehicle collisions (AVCs). AVCs pose serious problems both for biodiversity conservation and traffic safety: each year, millions of vertebrates are roadkilled globally and the related economic damage is also substantial. For a comprehensive understanding of factors influencing AVC it is essential to explore the human factor, that is, the habits and attitude of drivers; however, to date, comprehensive surveys are lacking on this topic. Here we addressed this knowledge gap and surveyed the habits of drivers and their experience and attitude towards AVCs by a comprehensive questionnaire covering a large geographical area and involving a large number of respondents (1942 completed questionnaires). We aimed to reveal how driving habits affect the chance of AVC, and explored the attitude of the drivers regarding AVC. We found that the number of lifetime AVC cases was higher for male drivers, for those who drove longer distances per year, had more driven years, used country roads or drove large vehicles. Our results showed that almost half of the drivers surveyed had experienced at least one AVC in their lifetime. Drivers’ attitudes towards the importance of nature conservation or traffic safety in the aspect of AVC, and fear of collision showed a significant correlation with experienced AVC cases. Drivers' opinions indicated that the most trusted and desired AVC prevention measures were physical objects such as fences and wildlife crossings. Our research provides guidelines for developing targeted initiatives in the future to increase awareness about the significance of AVC and target those drivers who are most vulnerable to AVC.

The Factors Influencing Wildlife to Use Existing Bridges and Culverts in Giant Panda National Park

Roads, acting as barriers, hamper wildlife movements and disrupt habitat connectivity. Bridges and culverts are common structures on roads, and some of them can function to allow wildlife passage. This study investigated the effects of traffic, the surrounding landscape, human disturbance, and bridge and culvert structures on the utilization of bridges and culverts as dedicated passages by wildlife, using motion-activated infrared camera traps along a 64 km road in Giant Panda National Park, Sichuan, China. The results show that both species richness and counts of wildlife recorded at the bridge and culvert were significantly lower than those observed at sites distant from roads. No large-sized wildlife was recorded at the bridges and culverts. Human activities and traffic volume significantly and negatively affect medium-sized wildlife utilization of bridges and culverts. We conclude that bridges and culverts serve as wildlife crossings, but their efficacy is weak. This emphasizes the necessity of retrofitting bridges and culverts via mitigation facilities such as noise and light barriers, and vegetation restoration on both sides of the roads in Giant Panda National Park.

Pollutant accumulation in road mitigation tunnels for amphibians: A multisite comparison on an ignored but important issue

Underpasses or road tunnels are increasingly installed to reconnect habitats and ensure safe wildlife passage, thus preventing habitat fragmentation caused by roads and mortality from collisions with vehicles. In the UK, such underpasses are regularly implemented for amphibians and especially the protected great crested newt, Triturus cristatus. However, roads are also a key source of environmental pollutants including trace metals, road salt, petroleum and diesel hydrocarbons and these might impact road mitigation structures where amphibians are funnelled to, yet the extent and implications of such pollutants are almost never quantified in relation to this aspect, despite the recognised sensitivity of amphibians to chemical pollutants. Sediments were analysed from four amphibian road mitigation tunnel sites across the UK and compared to natural soil formations at local reference sites to determine whether contaminants were indeed accumulating within the tunnels. Three potential contaminants (copper, lead, and total petroleum hydrocarbons) were found in greater concentrations in the underpass sediments than respective reference sites at three of four locations, while one (zinc) was found in greater concentrations at all four studied underpasses compared to reference sites. Aggregated sediment pH value was significantly greater in the underpass sediment than the respective reference sites at all four study sites and in several instances the contaminants reached values that exceeded the thresholds of environmental concern. Despite the large geographic area covered and the significant site differences the absolute values of potential pollutants in tunnels were similar across sites, thus suggesting similar pollution sources and pathways. These results suggest road tunnels installed for ecological mitigation could be a significant pathway for pollutants from road surfaces to amphibians and it is recommended that focussed monitoring and maintenance of the underpasses is enacted given that their short or long-term impacts on amphibians are currently unknown. Potential management options could include regular jet-washing of the underpasses, or alternatively, pre- or post-implementation modifications of mitigation designs should aim to minimise the pollution pathway from road surfaces.

Where to invest in road mitigation? A comparison of multiscale wildlife data to inform roadway prioritization

Roads and associated traffic have significant impacts on wildlife, from direct mortality caused by vehicle collisions to indirect effects when wildlife avoid roads, restricting access to important resources. Road mitigation measures such as constructing wildlife passages over or under the road with directional fencing have proven effective at reducing wildlife vehicle collisions while also enabling wildlife to safely cross the road. Highway mitigation projects are led by transportation agencies with a primary purpose of improving motorist safety. More recently, through the discipline of road ecology, considerations have included safe wildlife passage through transportation corridors. To prioritize road sections for mitigation, data sources include animal vehicle collision data collected by transportation agencies and connectivity models generated by wildlife professionals. We used a third data source, pronghorn observations collected by citizen scientists, and demonstrated its value to prioritize potential wildlife mitigation sites. Our results clearly demonstrate a misalignment of road mitigation sites using animal-vehicle collision data and those of rarer species of interest.

A narrative review on the use of camera traps and machine learning in wildlife research

Camera trapping has become an important tool in wildlife research in the past few decades. However, one of its main limiting factors is the processing of data, which is labour-intensive and time-consuming. Consequently, to aid this process, the use of machine learning has increased. A summary is provided on the use of both camera traps and machine learning and the main challenges that come with it by performing a general literature review. Remote cameras can be used in a variety of field applications, including investigating species distribution, disease transmission and vaccination, population estimation, nest predation, animal activity patterns, wildlife crossings, and diet analysis. Camera trapping has many benefits, including being less invasive, allowing for consistent monitoring and simultaneous observation (especially of secretive or aggressive animals even in dangerous or remote areas), providing photo/video evidence, reducing observer bias, and being cost effective. The main issues are that they are subject to their environment, dependent on human placements, can disrupt animal behaviour, need maintenance and repair, have limitations on photographic data, and are sensitive to theft and vandalism. When it comes to machine learning, the main aim is to identify species in camera (trap) images, although emerging technologies can provide individual recognition as well. The downsides in- clude the large amount of annotated data, computer power, and programming and machine learning expertise needed. Nonetheless, camera trapping and machine learning can greatly assist ecologists and conservationists in wildlife research, even more so as technology further develops.

Wildlife friendly fence designs and elk fence crossing behavior

AbstractFencing is a ubiquitous feature of our agricultural landscape. Fences necessarily have the potential to reduce habitat connectivity for resident ungulate populations. Unsuccessful fence crossings have the potential to cause injury or death to wildlife, as well as resulting in damage to the fence in terms of time and maintenance costs. Wildlife friendly fence designs may provide landowners and ungulate managers the opportunity to mitigate risks associated with wildlife crossings. Using remote cameras (n = 12) along the perimeter fence of the Wainwright Dunes Ecological Reserve, Alberta, we quantified and compared elk crossing behaviors at standard 4 strand fences and gates as well as 3 strand fences and gates both with experimentally modified top and bottom strand heights. We found that wildlife friendly designs promoted behavioral options for elk of various demographic classes to cross fences. Our results suggest that the number of strands and the height of the top and bottom strand are important determinants for animals deciding to cross over, through, or under fences. While difficult or problematic crossings were primarily determined by how the individual crossed and made up a proportionally small number of crossings, the sheer volume of crossings we observed suggests that any modification which increases fence permeability to elk will likely result in less damage to fences and the crossing individuals.

Wildlife overpass structure size, distribution, effectiveness, and adherence to expert design recommendations.

It is now well evidenced that wildlife crossing structures paired with exclusion fencing reduce wildlife vehicles collisions while facilitating wildlife connectivity across roadways. Managing animal mortality and subpopulation connectivity is crucial to successful species and landscape stewardship. Highway mitigation projects are large economic investments that remain on the landscape for many decades. Governments and planning agents thus strive to balance cost and benefit to build cost-effective structures with the greatest positive impact on local wildlife and motorists. Ideal dimensions of overpasses and underpasses vary by species, but scientists generally suggest that overpasses for large mammals should be approximately 50 m wide. Optimal width also depends on structure length, with longer structures requiring additional width. Accordingly, experts have suggested a width to length ratio of 0.8. We sought to assess how these recommendations manifested in practice-where agencies use this information to design and build structures while also balancing cost and logistical challenges-and the degree to which built structures conform to current recommendations. We identified 120 wildlife overpasses across the world that were constructed to reduce the negative impacts of roads. Using a novel measurement technique, we analyzed the dimensions of these 120 overpasses located in North America, Europe, Asia, and Oceania. The average width of the wildlife overpasses was 34 m. Most wildlife overpasses located in North America and Europe did not meet their respective dimensional expert guidelines. We investigate reasons explaining the non-compliance and provide recommendations for future overpass designs. Building on previous evidence showing that wider overpasses have increased crossing rates, we examined crossing rates for multiple large mammal species across 12 overpasses located in western North America. We qualitatively observed that wider North American overpasses (40-60 m), in or near compliance with expert guidelines, were associated with a more diverse set of species use and had nearly twice the average crossing rates when compared to non-compliant, narrow North American overpasses. In reviewing various studies from around the world, we conclude that wide overpasses (~50 m) continue to present ecologically sound and cost-effective solutions for decreasing the barrier of roadways, especially when targeting width-sensitive species and large assemblages of mammals. Future studies, however, are encouraged to further explore the specific instances when underpasses and narrower overpasses present more cost-effective ecological solutions, or how these structures can complement wide overpasses in successful wildlife crossing systems.

Ungulate use of an at-grade fauna passage and roadside animal detection system: A pilot study from Southern Sweden

Wildlife-vehicle collisions (WVC) cost millions of euros each year in loss of life and damages. Wildlife crossing structures and fencing are commonly implemented mitigation strategies to reduce WVC and increase landscape connectivity for wildlife. Typically, crossing structures are over- or under-pass structures that allow animals to safely cross the road, while separating them from the road and traffic. An alternative strategy could be an at-grade fauna passage coupled with a Roadside Animal Detection System (RADS). At-grade fauna passages are designated locations where a gap in fencing allows animals to cross over the road, while RADS alert drivers of animals at the upcoming passage, so that they can adjust their driving behaviour accordingly and avoid collisions. In this pilot study, we investigated the use of one at-grade fauna passage by roe deer (Capreolus capreolus), red deer (Cervus elaphus) and wild boar (Sus scrofa) in southern Sweden, and compared changes in the number of WVCs before, during and after the construction of the passage. We collected a total of 326 wildlife crossings from 722 individuals over 1 year of monitoring (24 January 2020–24 January 2021). We found that crossing events tended to be dominated by the time animals spent in the roadside verge from which they approached the at-grade fauna passage, particularly for roe deer that spent a lot of time browsing in the roadside verge during dusk. We also found that animals spent longer in the passage if vehicles were present. In our 1 year of surveys, we only recorded three accidents, and when comparing the annual collision statistics before, during, and after construction of the at-grade fauna passage, we demonstrated an overall reduction in collisions by 66%. While our pilot only evaluates a single site, it does provide promising preliminary results that suggest that at-grade fauna passages can help in efforts to reduce collisions, while maintaining connectivity over medium-sized roads for large ungulates.

Behavioral responses to anthropogenic noise at highways vary across temporal scales

Anthropogenic noise is pervasive across the landscape and can be present at two temporal scales: acute (occurring sporadically and stochastically over the shortest time scales, e.g., milliseconds), and chronic (more persistent than instantaneous and occurring over longer timescales, e.g., minutes, days). Acute and chronic anthropogenic noise may induce a behavioral fear-mediated response in wildlife that is analogous to a prey response to predators. Understanding wildlife responses to anthropogenic noise is especially important in the case of wildlife crossing structures that provide wildlife with access to resources across busy roadways. Focusing on two species common at wildlife crossing structures, mule deer (Odocoileus hemionus) and coyotes (Canis latrans), we addressed the hypotheses that (1) acute traffic noise causes flight behavior; and (2) chronic traffic noise causes changes in a range of behaviors associated with the vigilance–foraging trade-off (vigilance, running, and foraging). We placed camera traps at entrances to ten crossing structures for a period of ∼ 2 months each throughout California, USA. Mule deer and coyotes demonstrated a flight response to acute traffic noise at entrances to crossing structures. Both species demonstrated shifts in behavioral response to chronic traffic noise within and among structures. Coyote behavior was indicative of fear, demonstrating increased vigilance at louder times within crossing structures, and switching from vigilance to running activity at louder crossings. Mule deer responded positively, increasing foraging at both spatial scales, and demonstrating decreased vigilance at louder structures, potentially using crossing structures as a Human Shield. Our results are the first to demonstrate that anthropogenic noise at crossing structures could alter wildlife passage, and that variations in fear response to anthropogenic noise exist across temporal, spatial, and amplitude scales. This dynamic response could alter natural predator-prey interactions and scale up to ecosystem-level consequences such as trophic cascades in areas with roads.

Vehicular traffic effects on elk and white-tailed deer behavior near wildlife underpasses.

Roads fragment animal populations, vehicles kill and injure animals, and traffic may affect animal behavior. Mitigation efforts (e.g., wildlife underpasses) are constructed to prevent fragmentation and reduce wildlife-vehicle collisions. However, little is known about traffic's proximal effects on wildlife behavior and use of mitigation measures. We quantified the time that elk (Cervus elaphus) and white-tailed deer (Odocoileus virginianus) allocated to foraging, vigilance, and flight behavior before and after vehicle passage. Both species increased vigilance and flight behaviors and reduced time spent foraging in response to vehicles. Both species were more likely to move through the underpass if they exhibited foraging behavior; we also found a marginally significant trend that animals were less likely to use the underpass after vigilance behavior. Knowledge that vehicle movement influences wildlife behavior underscores the importance of consideration given to road and crossing structure design. Additionally, findings of species-specific response to vehicle passage are important in understanding potential fitness consequences of anthropogenic disturbance.

Improving trajectories of amphibians in wildlife passages

Linear transport infrastructure can alter the viability of populations and wildlife passages are used to mitigate their impacts. The assessment of their outcomes is often limited to recording the use of the tunnels by a focal species. For amphibians, the effectiveness of tunnels is poorly evaluated with little information about whether certain features encourage individuals that may be reluctant to pass through tunnels. One study showed that acoustic enrichment with anuran calls can increase the crossing of tunnels by newts. This study recorded the behavior of three European amphibian species in three tunnels, tracking them with PIT tags and detection with four RFID antennas installed on the floor of the tunnels. We tested (1) the effectiveness of the antennas in detecting the species, (2) the effect of the length of the tunnels, and (3) the effect of acoustic enrichment. Using a multi-state capture–recapture model, we evaluated the probability of an individual advancing between the tunnel sections. The effectiveness of the antennas varied according to species, higher for Urodela species than for Anuran species. Several types of paths were detected (constant and varying speeds, halt, and back-and-forth movements). The fire salamander and the great crested newt individuals exhibited a similar variety of movements in the tunnels (21 and 40 m length). Triturus cristatus made similar movements in the tunnels with and without acoustic enrichment. In water frogs, all the individuals (n = 16) made a complete crossing in the tunnel with enrichment vs. 75% (n = 71) in the tunnel without enrichment. In T. cristatus, the probability of going forward at the entrance of the tunnel was 18% higher with enrichment in one tunnel. No significant effect of acoustic enrichment was observed in two others tunnels for this species. In Pelophylax esculentus, this probability was 78% higher in the tunnel with enrichment. This multi-antenna RFID system was able to provide valuable information on the behavior of these small animals when traversing the tunnels, as well as to test the effectiveness of tunnel features. The findings indicate that acoustic enrichment to attract animals to specific locations holds promise as a new conservation tool.

The role of environmental, structural and anthropogenic variables on underpass use by African savanna elephants (Loxodonta africana) in the Tsavo Conservation Area

Wildlife crossing structures are effective interventions for mitigating fragmentation of habitats by linear infrastructure. The 2017 construction of a new railway cutting through the Tsavo Conservation Area (TCA), home to the largest elephant population in Kenya, affected wildlife movement and habitat connectivity. Although numerous studies have investigated the use of wildlife crossing structures by a wide range of species, few have focused on their use by megaherbivores. In this study, we examined use of 41 wildlife crossing structures by African savanna elephants (Loxodonta africana) along a 133 km section of new railway in Tsavo, Kenya. We used a generalized linear mixed modeling approach to assess the relationship between elephant crossing rate over 28 months between July 2017 to April 2021 and explanatory factors including crossing structure attributes, livestock presence and proximity to highways, water points and human settlement. We found that structural attributes of crossing structures were most strongly associated with the elephant crossing rate, particularly height and its interaction with type of crossing structure (bridges, wildlife underpasses and culverts). Higher crossing structures were associated with higher crossing rate, with the largest influence of height at culverts and wildlife underpasses. Although bridges comprised only 19.5 % of the 41 available crossing structures, they accounted for a disproportionately high number of elephants crossing events (56 %). The results demonstrated the importance of bridges over designated crossing structures for elephants, with predicted seasonal counts of elephant crossings being 0.31 for average sized culverts, 2.88 for wildlife underpasses and 5.86 for bridges. The environmental and anthropogenic variables were not strongly associated with elephant crossing rate. Our findings have direct application for future siting and design of crossing structures across elephant ranges.

Do Wildlife Crossings Mitigate the Roadkill Mortality of Tropical Mammals? A Case Study from Costa Rica

Although Central America is one of the most biologically diverse regions in the world, booming road construction is driving roadkill mortality that threatens to alter the demography, genetic diversity, and viability of wild mammalian populations. Costa Rica has the highest road density in Central America, but the effectiveness of wildlife crossings in mitigating roadkill mortality has not been assessed with controlled experimental studies. Hacienda Baru National Wildlife Refuge is located along a critical biological corridor bisected by one of the busiest highways in the country. The first wildlife underpasses in Costa Rica were built here in 2010 as part of the expansion of Route 34 and subsequently documented by camera-trap and roadkill surveys. Using a control-impact design, we demonstrate a considerable reduction in wildlife mortality in the presence of the crossing structures compared with controls, with the underpasses and overpasses eventually used by 21 mammalian species. Some species made use of the structures right away, while others took over a year to learn to use them. This is the first controlled study in Central America to document the effectiveness of wildlife crossings and provides evidence that well-designed mitigation structures can contribute to wildlife-friendly roadways.

Best practice—Is natural revegetation sufficient to achieve mitigation goals in road construction?

AbstractAimsThe area influenced by road construction is large, and measures to re‐establish vegetation in disturbed areas are routinely carried out to reduce impacts on biodiversity. However, goals of mitigation measures are often unclear, and the effects on biodiversity of mitigation measures is rarely monitored. We assessed the effects of different revegetation treatments (natural revegetation, seeding, planting) on vegetation development along highways, and on wildlife crossings of different age.LocationHighways in southeast Norway.MethodsWe collected data on vascular plant species, vegetation cover and height, soil grain size and organic matter content, and compared the species composition, richness, and diversity of the restored sites with reference plots in the adjacent target vegetation (mature forest).ResultsOur results show a significantly higher richness and diversity in restored plots compared to reference plots, and an increased similarity of species composition over time. Species composition was most similar to reference plots in naturally revegetated plots and seeding seemed to reduce both species and functional trait composition similarity.ConclusionsIt is unrealistic that the defined target vegetation will develop on restored sites. Defining a realistic and achievable target vegetation for each road construction project in relation to land use, adjacent vegetation type and successional stage, as e.g., forest edge instead of forest, would be useful. While this may require more effort for management it will translate to higher mitigation success.

Shall the Wild Boar Pass? A Genetically Assessed Ecological Corridor in the Geneva Region

Landscape fragmentation caused by road infrastructures represents a major threat to the genetic diversity of a region. The resulting genetic isolation between subpopulations may lead to consanguinity, and consequently to population collapse and extinction. However, the construction of wildlife crossings can help maintain connectivity. In the present paper, we evaluated the genetic spatial structuring of populations of wild boars (Sus scrofa) in three areas of the Geneva region connected by an ecological corridor. Those areas are cut off either by a highway that is crossed by a wildlife overpass or by an anthropized sector. Genetic profiling with 9 nuclear microsatellite markers yielded 61 single profiles, which allowed for clustering, parentage, and linkage disequilibrium analyses, uncovering the populations’ genetic structure. We also evaluated whether the genetic structure was affected by the sex of individuals. In our analyses, all individuals clustered into a single genetic group, suggesting that no structure limited significantly the gene flow in the region. However, a recent admixture indicated a potential increase in the gene flow between two of the subpopulations due to the wildlife overpass, while the other part of the ecological corridor was not or was only partially functional. Genetic distances between males were significantly higher than between females, although the role of sex remains unclear as to its influence on population genetics. Finally, in order to avoid a subregion becoming fully isolated, urbanization planning should consider this genetic evaluation and proceed with further monitoring, especially by focusing on species more sensitive to landscape fragmentation.

Methodology of Wildlife Underpasses Attractiveness Assessment

Abstract The permeability of line barriers in the landscape is often a prerequisite for the survival of the wide spectrum of native species. The aim of this study is to create a methodology for assessing the attractiveness of wildlife underpasses used by animals during migrations, translocations or as a habitat. Understanding the relationship between the parameters of underpasses in the broader landscape-ecological context and their attractiveness for animals is a key aspect in spatial planning and the construction of new linear transport structures, which will significantly help mitigate the barrier effect and isolation of animal populations. The attractiveness assessment is based on the evaluation of the underpass individual parameters and its surroundings through the 8 sub-indexes (openness, substrate, anthropogenic, vegetation, landscape structure elements, ecological networks, potential and real migration/habitat).

The effects of human development, environmental factors, and a major highway on mammalian community composition in the Wasatch Mountains of northern Utah, USA

AbstractHuman development and roads threaten wildlife through distinct mechanisms and understanding the influence of these elements can better inform mitigation and conservation strategies. We used camera traps to quantify the effects of major roads, environmental factors, and human development on the mammalian community composition between sites north and south of a major interstate highway in northern Utah, USA. We found no significant differences in species richness nor community similarity across the north–south divide of the highway. Through Bayesian hierarchical modeling, we compared the effects of the distance to the highway, housing and human population density, normalized difference vegetation index (NDVI), and the human footprint index to changes in mammalian community composition and species‐specific habitat usage. Community occupancy response, similarity, and species richness were negatively affected by increased housing and human population densities and positively affected by increased NDVI and decreased human footprint, whereas their response to the highway was more inconclusive. We conclude that mammalian community composition in our study area is influenced by both environmental conditions and human development while the effect of the highway was more nuanced, possibly due to the presence of a newly constructed wildlife overpass. Taken together, the lack of differences in species richness or community composition across the highway suggests that it may not currently exacerbate the effects of other anthropogenic sources of habitat fragmentation and highlights the need for additional research into human–wildlife conflict mitigation strategies.

“Ah Lai’s Crossing” – Malaysia’s first artificial road canopy bridge to facilitate safer arboreal wildlife crossings

Abstract Roads negatively affect wildlife populations globally, causing habitat fragmentation that can facilitate mortality by access to forest for poaching and wildlife collisions with vehicles. Primate habitats are vulnerable to fragmentation exposing them to anthropogenic threats. Endangered dusky langurs (Trachypithecus obscurus) in Malaysia are often found in urban areas and have been frequent victims of vehicle collisions. To mitigate the hazardous impact of a busy asphalt road on wild dusky langurs in Teluk Bahang, Penang, we built the first artificial road canopy bridge in Malaysia in February 2019 to assist arboreal wildlife to move between habitat fragments more safely. Four days after the bridge construction, the first long-tailed macaque (Macaca fascicularis) was recorded via a camera trap crossing the bridge, and plantain squirrels (Callosciurus notatus) and dusky langurs first crossed one and eight months later, respectively. The bridge was upgraded from a single-firehose rope to a double-rope in August 2020 to assess the effectiveness of the two designs. In total, 2128 animal crossings comprising three mammal species were recorded between March 2019 and May 2021. Plantain squirrels crossed the bridge most frequently with 2075 crossings, long-tailed macaques crossed 32 times, and dusky langurs 21 times. There was a significant difference in bridge use according to species between the two designs (Chi-Square, p < 0.001). Since the construction of the bridge, the rate of previously frequently reported primate roadkills near the bridge location has dropped to zero. This successful pilot project has spurred the efforts to implement more canopy bridges country-wide to support primate conservation efforts and better protect arboreal wildlife from the negative impacts of linear infrastructure.