Permeability of roads to movement of scrubland lizards and small mammals

Spatiotemporal Patterns of Reptile and Amphibian Road Fatalities in a Natura 2000 Area: A 12-Year Monitoring of the Lake Karla Mediterranean Wetland

The pervasive expansion of human-engineered infrastructure, particularly roads, has fundamentally reshaped landscapes, profoundly affecting wildlife interactions. Wildlife-vehicle collisions, a common consequence of this intricate interplay, frequently result in fatalities, extending their detrimental impact within Protected Areas (PAs). Among the faunal groups most susceptible to road mortality, reptiles and amphibians stand at the forefront, highlighting the urgent need for global comprehensive mitigation strategies. In Greece, where road infrastructure expansion has encroached upon a significant portion of the nation's PAs, the plight of these road-vulnerable species demands immediate attention. To address this critical issue, we present a multifaceted and holistic approach to investigating and assessing the complex phenomenon of herpetofauna road mortality within the unique ecological context of the Lake Karla plain, a rehabilitated wetland complex within a PA. To unravel the intricacies of herpetofauna road mortality in the Lake Karla plain, we conducted a comprehensive 12-year investigation from 2008 to 2019. Employing a combination of statistical modeling and spatial analysis techniques, we aimed to identify the species most susceptible to these encounters, their temporal and seasonal variations, and the ecological determinants of their roadkill patterns. We documented a total of 340 roadkill incidents involving 14 herpetofauna species in the Lake Karla's plain, with reptiles, particularly snakes, being more susceptible, accounting for over 60% of roadkill occurrences. Moreover, we found that environmental and road-related factors play a crucial role in influencing roadkill incidents, while spatial analysis techniques, including Kernel Density Estimation, the Getis-Ord Gi*, and the Kernel Density Estimation plus methods revealed critical areas, particularly in the south-eastern region of Lake Karla's plain, offering guidance for targeted interventions to address both individual and collective risks associated with roadkill incidents.

Ecosystem Conditions That Influence the Viability of an Old-Forest Species with Limited Vagility: The Red Tree Vole

We evaluated ecosystem conditions known to influence the viability of a strictly arboreal species (the red tree vole, Arborimus longicaudus) endemic and historically distributed in the forests across the Coast Range, Cascades, and Klamath Mountains ecoregions in the Western United States of America. We found widespread reductions in ecosystem conditions needed to support the long-term viability of the red tree vole. This was particularly evident in the Coast Range where the weighted watershed index (WWI) was 26% of its historical value, and the current probability of maintaining viability departed the most from historical viability probabilities in ecoregions that were evaluated. In contrast, in the Cascades and Klamath Mountains, the WWI was 42% and 52% of their respective historical values, and the current probabilities of maintaining viability departed less from historical conditions than in the Coast Range. Habitat loss from timber harvest represented the most immediate threat in the Coast Range, while habitat loss from wildfires represented the most risk to the red tree vole in the Cascades and Klamath Mountains. Reducing the risks to the viability of the red tree vole will depend largely on the implementation of conservation practices designed to protect remaining habitat and restore degraded ecosystems in the Coast Range. However, the risk of large, high-severity wildfires will require the protection and increased resilience of existing ecosystems. Our results indicate that considerable adaptation to climate change will be required to conserve the red tree vole in the long term. Conservation may be accomplished by revising land and resource management plans to include standards and guidelines relevant to red tree vole management and persistence, the identification of priority areas for conservation and restoration, and in assessing how management alternatives influence ecosystem resiliency and red tree vole viability.

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.

Effects of roads on small-mammal movements: Opportunities and risks of vegetation management on roadsides

Roads can block animal movement and reduce persistence of species living in road surroundings. Movement restrictions on local populations may even increase extinction risk of abundant small mammals. However, road verges (road managed area between the edge of the road and the beginning of private land) may provide refuge and corridors for small mammals when properly managed. Information on the effects of roads and roadside management on small-mammal movement is still scarce for low traffic roads (<20,000 vehicles per day) crossing well-preserved habitats. We aimed to fill this gap by comparing fine-scale movement patterns of wood mice (Apodemus sylvaticus) in a road and in a similar roadless area without management. Both areas consisted of a well-preserved Mediterranean agro-silvo pastoral system. We studied several movement patterns: road crossings, verge use, length, and direction of movement. Additionally, we assessed how roadside management, animals' sex and residency status, season and microhabitat affect movement at the road area. At the roadless area, we defined a virtual road and verges at equivalent locations to the road area for comparison purposes. We gathered capture-mark-recapture data for two years to characterize movement patterns. Wood mice tended to avoid the road by crossing it less often and moving away from it more frequently than from equivalent locations in the roadless area. Wood mice used road verges more frequently than virtual verges and moved more often parallel to the road than to the virtual road. Road crossings were more frequent after firebreak openings (strips of mowed land) in surrounding areas and near taller shrubs. Also, males used road verges more often than females. Differences on several movement patterns between areas and their trends within the road area can be explained mainly by the presence of the road and roadside vegetation management (e.g., firebreaks openings). We suggest roadside vegetation management practices (e.g., avoid land mowing; maintain vegetation strips) to promote the role of verges as refuges and/or corridors for small mammals.

Canopy bridges are an economical mitigation reducing the road barrier effect for three of four species of monkeys in Diani, Kenya

For primates, canopy bridges can reduce the road barrier effect. Yet little information exists to predict species bridge use. We examined bridge use across a 9 km suburban road in Diani, Kenya, in three survey years (Nbridges: 21 = 2004, 27 = 2011, 29 = 2020) by four sympatric species of monkeys. The asphalt road is 6 m wide with a 50 km/h speed limit. Roadside observers recorded ground () and bridge () crossings, crossing direction, and traffic volume. Colobus (Colobus angolensis palliatus), Sykes’ monkeys (Cercopithecus mitis albogularis), and vervets (Chlorocebus pygerythrus hilgerti) used the bridges while baboons (Papio cynocephalus cynocephalus) rarely did. Crossing rates (Sykes’>vervet>colobus>baboon) did not fit our predictions based on species’ attributes of stratum preference (arboreal>terrestrial) or body mass (small>large), while the interaction between these attributes was more informative. Crossings were bidirectional. Colobus crossed bridges during higher traffic volumes than on the ground, whereas we found the opposite for vervets. Sykes’ monkeys crossed at similar traffic volumes on the ground and bridges. The mean annual bridge cost was USD 157, deriving a cost per crossing as < USD 0.10, though it undervalues the savings in ecosystem services, tourism benefits, and contributions to protecting colobus, a vulnerable species. While we consider this highly economical, funders and road engineers will ultimately determine if it is so.

How do King Cobras move across a major highway? Unintentional wildlife crossing structures may facilitate movement

Global road networks continue to expand, and the wildlife responses to these landscape‐level changes need to be understood to advise long‐term management decisions. Roads have high mortality risk to snakes because snakes typically move slowly and can be intentionally targeted by drivers.

We investigated how radio‐tracked King Cobras (Ophiophagus hannah) traverse a major highway in northeast Thailand, and if reproductive cycles were associated with road hazards.

We surveyed a 15.3 km stretch of Highway 304 to determine if there were any locations where snakes could safely move across the road (e.g., culverts and bridges). We used recurse analyses to detect possible road‐crossing events, and used dynamic Brownian Bridge Movement Models (dBBMMs) to show movement pathways association with possible unintentional crossing structures. We further used Integrated Step Selection Functions (ISSF) to assess seasonal differences in avoidance of major roads for adult King Cobras in relation to reproductive state.

We discovered 32 unintentional wildlife crossing locations capable of facilitating King Cobra movement across the highway. While our dBBMMs broadly revealed underpasses as possible crossing points, they failed to identify specific underpasses used by telemetered individuals; however, the tracking locations pre‐ and post‐crossing and photographs provided strong evidence of underpass use. Our ISSF suggested a lower avoidance of roads during the breeding season, although the results were inconclusive. With the high volume of traffic, large size of King Cobras, and a 98.8% success rate of crossing the road in our study (nine individuals: 84 crossing attempts with one fatality), we strongly suspect that individuals are using the unintentional crossing structures to safely traverse the road.

Further research is needed to determine the extent of wildlife underpass use at our study site. We propose that more consistent integration of drainage culverts and bridges could help mitigate the impacts of roads on some terrestrial wildlife.

The impact of roads on the movement of arboreal fauna in protected areas: the case of lar and pileated gibbons in Khao Yai National Park, Thailand

The unavoidable impact of roads on arboreal fauna in protected areas has received little attention. We investigated this impact on two gibbon species in Khao Yai National Park, Thailand: two groups had home ranges traversed by roads (roadside groups) and another two lived nearby roads (interior groups). Roads partially delineated the edges of home ranges of roadside groups, and gibbons crossed them only at a few locations. Gibbons’ space use decreased near roads for roadside groups and showed road reluctance as their crossing rates were smaller than those produced by a null movement model. Generalised linear models (GLMs) indicated that a long canopy gap reduced gibbons’ crossing probability, whereas forest cover had a positive effect. A large part of the road network had a low probability of being crossed by gibbons according to GLMs, especially at areas around park headquarters. Roads were still relatively permeable to gibbon movement with a mean 35% crossing probability. The relatively short and narrow road network in the park constitutes a positive assessment of the standards of how roads should be built in protected areas. Nonetheless, this assessment might be the consequence of the park being set in a mountainous region with difficulties of road development.

Habitat selection by the Spiny-tailed lizard (Uromastyx aegyptia): A view from spatial analysis

Many factors affect the habitat selection for animal species, which in turn may greatly affect their distribution in different ecosystems. Understanding the processes that affect habitat selection is also critical for guiding and managing conservation initiatives. Our study aimed to assess the habitat selection by free-ranging Spiny-tailed lizard (Uromastyx aegyptia) by analyzing a geospatial data connecting its burrow parameters to different habitat characteristics within selected sites in Hail region, Saudi Arabia. We examined evidence and patterns of significant spatial clustering for (366) active burrows by linking their parameters (burrow entrance size, burrow entrance width and burrow entrance height), their reference geographical locations and, two habitat characteristics defined by soil type and vegetation cover. The objective of the analysis was to increase the understanding on the burrows aggregation process in the space and, to describe its possible relation to other spatial habitat configurations. Analysis of distances based on the Nearest Neighbor Index (NNI) and hotspots detection in Nearest neighbor hierarchical clustering (Nnh) suggested twelve (12) spatial clusters located within the study area. In addition, a spatial ordinary least square (OLS) and Poisson regression models revealed significant effects of soil type and vegetation cover on burrow parameters (OLS, p < 0.05; Poisson, p < 0.001), which indicate a strong association between burrows parameters and habitats characteristics. Findings from the study also suggest that other factors such as elevations, highways, and human settlement concentration spots could possibly play a major role in defining burrow spatial aggregation and furthermore have a significant impact on habitat selection.

Lack of detectable genetic isolation in the cyclic rodent Microtus arvalis despite large landscape fragmentation owing to transportation infrastructures

Although roads are widely seen as dispersal barriers, their genetic consequences for animals that experience large fluctuations in population density are poorly documented. We developed a spatially paired experimental design to assess the genetic impacts of roads on cyclic voles (Microtus arvalis) during a high-density phase in North-Western Spain. We compared genetic patterns from 15 paired plots bisected by three different barrier types, using linear mixed models and computing effect sizes to assess the importance of each type, and the influence of road features like width or the age of the infrastructure. Evidence of effects by roads on genetic diversity and differentiation were lacking. We speculate that the recurrent (each 3-5 generations) episodes of massive dispersal associated with population density peaks can homogenize populations and mitigate the possible genetic impact of landscape fragmentation by roads. This study highlights the importance of developing spatially replicated experimental designs that allow us to consider the large natural spatial variation in genetic parameters. More generally, these results contribute to our understanding of the not well explored effects of habitat fragmentation on dispersal in species showing "boom-bust" dynamics.

Establishment of brown anoles (Anolis sagrei) across a southern California county and potential interactions with a native lizard species

The brown anole, Anolis sagrei, is a native species to the Caribbean; however, A. sagrei has invaded multiple parts of the USA, including Florida, Louisiana, Hawai'i and more recently California. The biological impacts of A. sagrei invading California are currently unknown. Evidence from the invasion in Taiwan shows that they spread quickly and when immediate action is not taken eradication stops being a viable option. In Orange County, California, five urban sites, each less than 100 ha, were surveyed for an average of 49.2 min. Approximately 200 A. sagrei were seen and verified across all survey sites. The paucity of native lizards encountered during the surveys within these sites suggests little to no overlap between the dominant diurnal western fence lizard, Sceloporus occidentalis, and A. sagrei. This notable lack of overlap could indicate a potentially disturbing reality that A. sagrei are driving local extirpations of S. occidentalis.

Projecting terrestrial biodiversity intactness with GLOBIO 4

Scenario-based biodiversity modelling is a powerful approach to evaluate how possible future socio-economic developments may affect biodiversity. Here, we evaluated the changes in terrestrial biodiversity intactness, expressed by the mean species abundance (MSA) metric, resulting from three of the shared socio-economic pathways (SSPs) combined with different levels of climate change (according to representative concentration pathways [RCPs]): a future oriented towards sustainability (SSP1xRCP2.6), a future determined by a politically divided world (SSP3xRCP6.0) and a future with continued global dependency on fossil fuels (SSP5xRCP8.5). To this end, we first updated the GLOBIO model, which now runs at a spatial resolution of 10 arc-seconds (~300 m), contains new modules for downscaling land use and for quantifying impacts of hunting in the tropics, and updated modules to quantify impacts of climate change, land use, habitat fragmentation and nitrogen pollution. We then used the updated model to project terrestrial biodiversity intactness from 2015 to 2050 as a function of land use and climate changes corresponding with the selected scenarios. We estimated a global area-weighted mean MSA of 0.56 for 2015. Biodiversity intactness declined in all three scenarios, yet the decline was smaller in the sustainability scenario (-0.02) than the regional rivalry and fossil-fuelled development scenarios (-0.06 and -0.05 respectively). We further found considerable variation in projected biodiversity change among different world regions, with large future losses particularly for sub-Saharan Africa. In some scenario-region combinations, we projected future biodiversity recovery due to reduced demands for agricultural land, yet this recovery was counteracted by increased impacts of other pressures (notably climate change and road disturbance). Effective measures to halt or reverse the decline of terrestrial biodiversity should not only reduce land demand (e.g. by increasing agricultural productivity and dietary changes) but also focus on reducing or mitigating the impacts of other pressures.

Road avoidance and its energetic consequences for reptiles

Roads are one of the most widespread human-caused habitat modifications that can increase wildlife mortality rates and alter behavior. Roads can act as barriers with variable permeability to movement and can increase distances wildlife travel to access habitats. Movement is energetically costly, and avoidance of roads could therefore impact an animal's energy budget. We tested whether reptiles avoid roads or road crossings and explored whether the energetic consequences of road avoidance decreased individual fitness. Using telemetry data from Blanding's turtles (Emydoidea blandingii; 11,658 locations of 286 turtles from 15 sites) and eastern massasaugas (Sistrurus catenatus; 1,868 locations of 49 snakes from 3 sites), we compared frequency of observed road crossings and use of road-adjacent habitat by reptiles to expected frequencies based on simulated correlated random walks. Turtles and snakes did not avoid habitats near roads, but both species avoided road crossings. Compared with simulations, turtles made fewer crossings of paved roads with low speed limits and more crossings of paved roads with high speed limits. Snakes made fewer crossings of all road types than expected based on simulated paths. Turtles traveled longer daily distances when their home range contained roads, but the predicted energetic cost was negligible: substantially less than the cost of producing one egg. Snakes with roads in their home range did not travel further per day than snakes without roads in their home range. We found that turtles and snakes avoided crossing roads, but road avoidance is unlikely to impact fitness through energetic expenditures. Therefore, mortality from vehicle strikes remains the most significant impact of roads on reptile populations.

Long seed dispersal distances by an inquisitive flightless rail (Gallirallus australis) are reduced by interaction with humans

Human presence is becoming increasingly ubiquitous, but the influence this has on the seed dispersal services performed by frugivorous animals is largely unknown. The New Zealand weka (Gallirallus australis) is an inquisitive flightless rail that frequently congregates in areas of high human use. Weka are important seed dispersers, yet the seed dispersal services they provide are still poorly understood. We estimated seed dispersal distances of weka for two plant species (Prumnopitys ferruginea and Elaeocarpus dentatus) and tested how human interaction affected these dispersal distances. We estimated weka seed dispersal distances by combining GPS data from 39 weka over three sites with weka seed retention time data in a mechanistic model. The mean seed retention times were extremely long (38-125 h). Weka were highly effective dispersers, dispersing 93-96% of seeds away from parent canopies, and 1% of seeds over 1 km. However, we found evidence of a significant human impact on the seed dispersal distances of weka, with birds occupying areas of high human use performing 34.8-40.9% shorter distances than their more remote counterparts. This represents an example of cryptic function loss, where although weka are still present in the ecosystem, their seed dispersal services are impaired by human interaction.

Transport infrastructure severely impacts amphibian dispersal regardless of life stage

Transport infrastructure such as roads has been reported to negatively affect dispersal. Their effects on dispersal are thought to be complex, depending on the characteristics of the structure and the intensity of the traffic using it. In addition, individual factors, such as age, may strongly affect dispersal decisions and success when individuals are confronted with transport infrastructure. Despite the importance of this topic for wildlife conservation, few studies have investigated the effect of transport infrastructure on individuals’ dispersal decisions before and after sexual maturity. We examined the effects on two kinds of infrastructure, gravel tracks and paved roads, on the dispersal of an endangered amphibian, the yellow-bellied toad (Bombina variegata). We used capture–recapture data collected during a five-year period on a large, spatially structured population of B. variegata. Our study revealed that emigration rates increased with an individual’s age, while dispersal distance decreased. It also showed that both tracks and roads had negative effects on immigration. The negative effect of roads was stronger than that of tracks. We additionally found that the effect of tracks on dispersal slightly decreased with a toad’s age. In contrast, the negative effect of roads was severe and relatively similar across age classes.

Town and Country Reptiles: A Review of Reptilian Responses to Urbanization

The majority of the world population is now inhabiting urban areas, and with staggering population growth, urbanization is also increasing. While the work studying the effects of changing landscapes and specific urban pressures on wildlife is beginning to amass, the majority of this work focuses on avian or mammalian species. However, the effects of urbanization likely vary substantially across taxonomic groups due to differences in habitat requirements and life history. The current article aims first to broaden the review of urban effects across reptilian species; second, to summarize the responses of reptilian fauna to specific urban features; and third, to assess the directionality of individual and population level responses to urbanization in reptile species. Based on our findings, urban research in reptilian taxa is lacking in the following areas: (1) investigating interactive or additive urban factors, (2) measuring multiple morphological, behavioral, and physiological endpoints within an animal, (3) linking individual to population-level responses, and (4) testing genetic/genomic differences across an urban environment as evidence for selective pressures.

Reptile road-kills in Southern Brazil: Composition, hot moments and hotspots

Understanding road-kill patterns is the first step to assess the potential effects of road mortality on wildlife populations, as well as to define the need for mitigation and support its planning. Reptiles are one of the vertebrate groups most affected by roads through vehicle collisions, both because they are intentionally killed by drivers, and due to their biological needs, such as thermoregulation, which make them more prone to collisions. We conducted monthly road surveys (33months), searching for carcasses of freshwater turtles, lizards, and snakes on a 277-km stretch of BR-101 road in Southernmost Brazil to estimate road-kill composition and magnitude and to describe the main periods and locations of road-kills. We modeled the distribution of road-kills in space according to land cover classes and local traffic volume. Considering the detection capacity of our method and carcass persistence probability, we estimated that 15,377 reptiles are road-killed per year (55reptiles/km/year). Road-kills, especially lizards and snakes, were concentrated during summer, probably due to their higher activity in this period. Road-kill hotspots were coincident among freshwater turtles, lizards, and snakes. Road-kill distribution was negatively related to pine plantations, and positively related to rice plantations and traffic volume. A cost-benefit analysis highlighted that if mitigation measures were installed at road-kill hotspots, which correspond to 21% of the road, they could have avoided up to 45% of recorded reptile fatalities, assuming a 100% mitigation effectiveness. Given the congruent patterns found for all three taxa, the same mitigation measures could be used to minimize the impacts of collision on local herpetofauna.

Mitigation reduces road mortality of a threatened rattlesnake

Context Reducing road mortality is essential to reptile conservation in regions with dense road networks. The Georgian Bay, Ontario population of the eastern massasauga rattlesnake (Sistrurus catenatus) is designated as Threatened, in part because of high road mortality. In Killbear Provincial Park, four ecopassages and barrier fencing were constructed along three busy park roads to reduce road mortality of massasaugas. Aim Although mitigation of road mortality has been widely recommended and in some instances implemented for reptiles, effectiveness of mitigation efforts is often inadequately evaluated. The goals of our study were to use long-term data to quantify the effectiveness of ecopassages and barrier fencing in reducing massasauga fatalities on roads, and to evaluate the potential of these structures to serve as movement corridors for individual snakes. Methods We used five approaches to assess the overall efficacy of mitigation efforts: (1) comparison of pre- and post-mitigation road mortality; (2) camera traps in ecopassages to document massasauga and predator presence; (3) automated tag readers in ecopassage entrances to detect PIT-tagged individuals; (4) an experiment to assess massasauga willingness to enter and travel through ecopassages; and (5) measurement of temperature fluctuations in ecopassages to assess thermal suitability for massasaugas. Key results We found a significant decrease in road mortality of massasaugas on stretches of park roads associated with ecopassages and barrier fencing post construction. Automated tag readers and cameras detected the presence of massasaugas and other animals within the ecopassages, and experimental data showed that massasaugas willingly entered, and in some cases crossed through, ecopassages. Conclusion Our evaluation of mitigation structures determined that they successfully reduce road mortality and provide potential movement corridors between bisected habitats, provided that intense maintenance of the fencing is conducted yearly. We also demonstrated the need to utilise a combination of multiple post-monitoring methods to effectively evaluate mitigation structures. Implications This study provides a template for construction of similar mitigation in other key locations where reptile road mortality occurs.

Forest fire break not a barrier to movement for a threatened rodent, the smoky mouse, Pseudomys fumeus (Rodentia : Muridae)

Linear clearings associated with roads passing through vegetation communities are known to inhibit movements of many animal species. This can reduce breeding, dispersal and foraging opportunities and lead to population fragmentation, putting further pressure on populations that are small or vulnerable, such as those of threatened species. We tested the prediction that the threatened smoky mouse, Pseudomys fumeus, would not readily cross a 30-m-wide fire break constructed along a ridgeline in eucalypt forest in Victoria, south-eastern Australia. Radio-tracking was conducted along 650 m of the fire break from October to December 2011. We recorded seven individuals that crossed the break. Five individuals fitted with transmitter collars were detected crossing at least twice on 13 of 18 tracking nights. Two animals were found to have crossed by being tracked to nests during the day and/or via trapping. A nearby narrow, unsealed vehicle track was crossed by an additional animal. Our results suggest that it is unlikely that the fire break was acting as a barrier to P. fumeus movements. The presence of fire breaks in P. fumeus habitat may, however, expose individuals to a higher rate of predation when they cross large areas unprotected by vegetation cover.

Why didn't the lizard cross the road? Dunes sagebrush lizards exhibit road-avoidance behaviour

Context Research has shown many negative effects of roads and traffic on wildlife and other biodiversity. The direct and indirect mechanisms through which roads and traffic harm animal populations vary across taxa, making mitigation of road effects a great challenge for conservation. As such, a large toolkit of species-specific management techniques may be needed to mitigate the negative effects of roads for wildlife and other biodiversity. The dunes sagebrush lizard, Sceloporus arenicolus, is a psammophilic (sand-loving) habitat specialist endemic to the Mescalero–Monahans Sandhills ecosystem of New Mexico and Texas. Within this ecosystem, roads fragment shinnery oak sand-dune landforms occupied by the species. Aims In the present study, we conducted behaviour trials in experimental enclosures to test whether the smallest roads restrict movements of the dunes sagebrush lizard. In addition, we also conducted trials to evaluate whether a sand-filled wildlife-crossing feature could facilitate road crossing. Methods We conducted behavioural trials on 24 dunes sagebrush lizards in our control enclosure and 22 lizards in our road and sand-filled wildlife-crossing enclosure. Movements were recorded for 15min. The final locations at the end of each trial were analysed using circular statistics to determine whether movements in the road or the sand-filled wildlife-crossing enclosures were different from the control. Key results Our results supported the hypotheses that dunes sagebrush lizards avoid roads and do so according to a surface-avoidance mechanism. We also found that the wildlife crossing-feature design tested here had no effect on the movements or road-crossing frequency of dunes sagebrush lizard. Conclusions Surface-avoidance behaviour indicated that roads will persistently affect the movements of dunes sagebrush lizard, even when traffic is not present. Also, more research into an effective wildlife crossing is needed to increase connectivity of fragmented populations. Implications These findings help evaluate the impact of roads in creating isolated populations that experience increased demographic stochasticity and, in some instances, localised extirpation in this species. Our study can guide conservation plans for the dunes sagebrush lizard, and contribute to our understanding of road effects on biodiversity in general.

Nonmotorized recreation and motorized recreation in shrub-steppe habitats affects behavior and reproduction of golden eagles (Aquila chrysaetos)

Different forms of outdoor recreation have different spatiotemporal activity patterns that may have interactive or cumulative effects on wildlife through human disturbance, physical habitat change, or both. In western North America, shrub‐steppe habitats near urban areas are popular sites for motorized recreation and nonmotorized recreation and can provide important habitat for protected species, including golden eagles. Our objective was to determine whether recreation use (i.e., number of recreationists) or recreation features (e.g., trails or campsites) predicted golden eagle territory occupancy, egg‐laying, or the probability a breeding attempt resulted in ≥1 offspring (nest survival). We monitored egg‐laying, hatching and fledging success, eagle behavior, and recreation activity within 23 eagle territories near Boise, Idaho, USA. Territories with more off‐road vehicle (ORV) use were less likely to be occupied than territories with less ORV use (β = −1.6, 85% CI: −2.8 to −0.8). At occupied territories, early season pedestrian use (β = −1.6, 85% CI: −3.8 to −0.2) and other nonmotorized use (β = −3.6, 85% CI: −10.7 to −0.3) reduced the probability of egg‐laying. At territories where eagles laid eggs, short, interval‐specific peaks in ORV use were associated with decreased nest survival (β = −0.5, 85% CI: −0.8 to −0.2). Pedestrians, who often arrived near eagle nests via motorized vehicles, were associated with reduced nest attendance (β = −11.9, 85% CI: −19.2 to −4.5), an important predictor of nest survival. Multiple forms of recreation may have cumulative effects on local populations by reducing occupancy at otherwise suitable territories, decreasing breeding attempts, and causing nesting failure. Seasonal no‐stopping zones for motorized vehicles may be an alternative to trail closures for managing disturbance. This study demonstrates the importance of considering human disturbance across different parts of the annual cycle, particularly where multiple forms of recreation have varying spatiotemporal use patterns that create human–wildlife interactions.

Disentangle the Causes of the Road Barrier Effect in Small Mammals through Genetic Patterns

Road barrier effect is among the foremost negative impacts of roads on wildlife. Knowledge of the factors responsible for the road barrier effect is crucial to understand and predict species' responses to roads, and to improve mitigation measures in the context of management and conservation. We built a set of hypothesis aiming to infer the most probable cause of road barrier effect (traffic effect or road surface avoidance), while controlling for the potentially confounding effects road width, traffic volume and road age. The wood mouse Apodemus sylvaticus was used as a model species of small and forest-dwelling mammals, which are more likely to be affected by gaps in cover such as those resulting from road construction. We confront genetic patterns from opposite and same roadsides from samples of three highways and used computer simulations to infer migration rates between opposite roadsides. Genetic patterns from 302 samples (ca. 100 per highway) suggest that the highway barrier effect for wood mouse is due to road surface avoidance. However, from the simulations we estimated a migration rate of about 5% between opposite roadsides, indicating that some limited gene flow across highways does occur. To reduce highway impact on population genetic diversity and structure, possible mitigation measures could include retrofitting of culverts and underpasses to increase their attractiveness and facilitate their use by wood mice and other species, and setting aside roadside strips without vegetation removal to facilitate establishment and dispersal of small mammals.

Differential Effects of Roads and Traffic on Space Use and Movements of Native Forest-Dependent and Introduced Edge-Tolerant Species

Anthropogenic infrastructure such as roads and non-native species are major causes of species endangerment. Understanding animal behavioral responses to roads and traffic provides insight into causes and mechanisms of effects of linear development on wildlife and aids effective mitigation and conservation. We investigated effects of roads and traffic on space use and movements of two forest-dwelling species: endemic, forest-dependent Mount Graham red squirrels (Tamiasciurus hudsonicus grahamensis) and introduced, edge-tolerant Abert’s squirrels (Sciurus aberti). To assess the effects of roads on space use and movement patterns, we compared the probability that a squirrel home range included roads and random lines in forests, and assessed effects of traffic intensity on rate of road crossing and movement patterns. Red squirrels avoided areas adjacent to roads and rarely crossed roads. In contrast, Abert’s squirrels were more likely to include roads in their home ranges compared to random lines in forests. Both red squirrels and Abert’s squirrels increased speed when crossing roads, compared to before and after road crossings. Increased hourly traffic volume reduced the rate of road crossings by both species. Behavioral responses of red squirrels to roads and traffic resemble responses to elevated predation risk, including reduced speed near roads and increased tortuosity of movement paths with increased traffic volume. In contrast, Abert’s squirrels appeared little affected by roads and traffic with tortuosity of movement paths reduced as distance to roads decreased. We found that species with similar body size category (<1 kg) but different habitat preference and foraging strategy responded to roads differently and demonstrated that behavior and ecology are important when considering effects of roads on wildlife. Our results indicate that roads restricted movements and space use of a native forest-dependent species while creating habitat preferred by an introduced, edge-tolerant species.

Mitigating reptile road mortality: fence failures compromise ecopassage effectiveness

Roadways pose serious threats to animal populations. The installation of roadway mitigation measures is becoming increasingly common, yet studies that rigorously evaluate the effectiveness of these conservation tools remain rare. A highway expansion project in Ontario, Canada included exclusion fencing and ecopassages as mitigation measures designed to offset detrimental effects to one of the most imperial groups of vertebrates, reptiles. Taking a multispecies approach, we used a Before-After-Control-Impact study design to compare reptile abundance on the highway before and after mitigation at an Impact site and a Control site from 1 May to 31 August in 2012 and 2013. During this time, radio telemetry, wildlife cameras, and an automated PIT-tag reading system were used to monitor reptile movements and use of ecopassages. Additionally, a willingness to utilize experiment was conducted to quantify turtle behavioral responses to ecopassages. We found no difference in abundance of turtles on the road between the un-mitigated and mitigated highways, and an increase in the percentage of both snakes and turtles detected dead on the road post-mitigation, suggesting that the fencing was not effective. Although ecopassages were used by reptiles, the number of crossings through ecopassages was lower than road-surface crossings. Furthermore, turtle willingness to use ecopassages was lower than that reported in previous arena studies, suggesting that effectiveness of ecopassages may be compromised when alternative crossing options are available (e.g., through holes in exclusion structures). Our rigorous evaluation of reptile roadway mitigation demonstrated that when exclusion structures fail, the effectiveness of population connectivity structures is compromised. Our project emphasizes the need to design mitigation measures with the biology and behavior of the target species in mind, to implement mitigation designs in a rigorous fashion, and quantitatively evaluate road mitigation to ensure allow for adaptive management and optimization of these increasingly important conservation tools.

Delimiting road-effect zones for threatened species: implications for mitigation fencing

Context Roads are a pernicious form of habitat loss for many wildlife populations because their effects often extend far beyond the roads themselves, giving rise to reduced wildlife abundance in road-effect zones. Quantifying the extent of road-effect zones more accurately portrays their impact on populations and the true extent to which habitat is lost for many species. Aim The purpose of the present study was to evaluate ways of determining the extent of road-effect zones for a model study species to better quantify the effect of roads on habitat loss. Methods We conducted road-side surveys for signs of Mojave desert tortoises (Gopherus agassizii) 0, 200, 400, 800 and 1600 m from county roads and interstates, two of the most common road types in critical habitat of this threatened species. Using data from these road-side surveys, we estimated the extent of road-effect zones using piecewise regression and modified von Bertalanffy models. Key results We found reduced abundances of tortoise sign along both county roads and interstates. Reductions extended farther from the large, high-traffic interstate than from the smaller, lower-traffic county roads (306 m versus 230 m). The increase in the abundance of tortoise signs with distance from roads approximated a negative exponential curve. Conclusions Interstate and county roads both contribute to habitat loss in road-side areas by making these habitats unsuitable to desert tortoises, presumably by removing animals via mortality from collisions with vehicles. Larger roads with greater traffic have more extensive effects. Implications Roadside mitigation fencing has been proposed as one way to reduce mortality of desert tortoises and to reclaim habitat by allowing tortoises to recolonise currently depauperate road-effect zones. Immediate mortality is more likely to be prevented by fencing county roads where tortoises occur closer to roads and are more likely to be struck by vehicles and killed. However, fencing interstate should yield more reclaimed habitat than that obtained from fencing county roads. Managers must consider balancing these goals along with other concerns when deciding where to place roadside fencing.