Wildlife Crossings Research Articles

Abundance Trends of Immature Stages of Ticks at Different Distances from Hiking Trails from a Natural Park in North-Western Italy.

Hiking trails may act as hotspots at the wildlife-human interface, posing an acarological risk for people and their pets. Ticks that are maintained in the environment by wild animals may quest on people walking along the trails. Assessing the risk of tick bites for people involved in outdoor activities is a further step in mitigating the risk of tick-borne diseases. This work describes the variation of tick abundance along a gradient of distances from hiking trails, where wildlife passage is favored by higher accessibility. Hiking trails with dense vegetation on the sides were sampled for ticks along a 100 m dragging transect, located in a natural park in North-Western Italy. Additional transects were replicated at 1, 2 and 4 m away from the trail on both sides. After morphological identification, descriptive statistics and modeling were applied to determine the abundance patterns across distances. Larvae were most abundant near the trail, peaking at 1 m and dropping sharply at further distances. Nymphs showed a more gradual and consistent decrease at progressing distance from the trail. Few adults were collected, preventing the identification of a clear trend. With higher tick abundance, the immediate vicinity of hiking trails may represent a source of acarological risk for humans and pets.

Distribution and Abundance of Wildlife Roadkills in Jengka, Pahang, Peninsular Malaysia

Malaysia's growing transportation network has increased human impact on wildlife habitats, causing a rise in roadkill cases. This study aims to assess the distribution and abundance of roadkill in Jengka, Pahang. Surveys along selected roads for ten days in March 2022 recorded 72 incidents (0.36 roadkill km-1). The water monitor (Varanus salvator) was the most frequently recorded species with 12 incidents, while the least frequently recorded species, each with 1 incident, included the monocled cobra (Naja kaouthia) and the house rat (Rattus rattus). Species of particular concern based on the International Union for Conservation of Nature (IUCN) Red List Categories included the long-tailed macaque (Macaca fascicularis) (Endangered), clouded monitor lizard (Varanus nebulosus) (Near Threatened), and Malayan flat-shelled turtle (Notochelys platynota) (Vulnerable). Main Federal Roads, particularly Jalan Bukit Tajau - Bandar Pusat Jengka (FT62) and Jalan Utama Jengka Utara/Selatan (FT83), had notable roadkill rates of 0.73 and 0.35 per kilometer, respectively. Jalan FELDA 25 (FT1553), linking Bandar Tun Abdul Razak to Jerantut and Kuala Krau, recorded the highest rate at 0.78 roadkill per kilometer, highlighting the need for attention. Proposed actions include wildlife crossings, wildlife warning reflectors and wildlife warning signs in hotspots, and table drains alongside roads. It is also essential to educate drivers on the importance of reducing speed, especially in wildlife crossing zones, to minimize incidents. These findings stress the importance of proactive measures in reducing roadkill and safeguarding wildlife in Jengka, urging collaborative efforts to enhance road safety for both humans and animals.

Combining roadkill hotspots and landscape features to guide mitigation measures on highways

Identifying highway sections with high vertebrate roadkill and associated landscape features is crucial for proposing mitigation measures to reduce the negative impacts of wildlife-vehicle collisions on biodiversity, human safety, and the economy. Focusing on highways in the State of Mato Grosso do Sul, Brazil, this study proposes a prioritization of road segments for implementing mitigation measures based on landscape characteristics and roadkill hotspots recorded between 2016 and 2018. Roadkills distribution was assessed using Hotspot Identification, detecting sections with the highest collision intensity. The effect of landscape variables, such as the area and distance of natural vegetation and anthropic land use within 1 km of the highways, on roadkill was modelled using General Linear Mixed Models, which were evaluated based on two response variables: (1) roadkill presence/absence and (2) roadkill abundance, with model selection by the Akaike information criterion. Based on roadkill hotspot identification analysis and predictive models of the influence of landscape elements on roadkill occurrence and abundance, an evaluation criterion was proposed to determine the priority sites for installing wildlife crossings, speed bumps, and signposts. Wildlife-vehicle collisions were positively associated with riparian vegetation areas and urban areas, while negatively associated with silviculture and distance to “cerradão” (forest Cerrado) patches. Eleven road sections were identified as top priority, two as high priority and 78 as medium priority for the installation of mitigation measures with varying cost-benefit ratios. Our results can potentially guide decision-making at broader scales and provide mitigating alternatives applicable to dry ecosystems such as the Cerrado (Brazilian Savanna).

Spatiotemporal analysis of landscape dynamics and their use as input for the design of a habitat suitability index: A case study of Oryctolagus cuniculus in a Mediterranean region

The connectivity of landscapes is increasingly threatened by urban sprawl, which leads to the fragmentation of habitats and thus endangers the species that live there. To address this situation, landscape dynamics in the literature have mostly been analyzed using predefined land cover classes, which were then not used to assess habitat suitability, but instead relied on physical variables. As a bridge between both aspects, this study aimed to model the spatiotemporal patterns of landscape fragmentation by analyzing the landscape metrics associated with four land cover groups classified according to their naturalness. Landscape metrics were then combined with a range of terrain, climate and proximity variables to develop a Habitat Suitability Index (HSI) for terrestrial animal species. The proposed methodology was tested using a case study in the Mediterranean region of the Valencian Community (Spain): landscape dynamics were assessed over the period 1992–2015, while the HSI was tested with the European rabbit (Oryctolagus cuniculus) as the target species. The results obtained in terms of landscape dynamics showed a growing presence of artificial surfaces at the expense of fewer transformed areas, which became progressively fragmented over time. Moreover, the results of the developed HSI were highly concordant with observations of rabbit abundance in the region, based in particular on variables related to the temperature in the area and the patch shape in the preferred habitats of this species. These outputs can be used to support the implementation of habitat restoration strategies aimed at increasing ecological connectivity through measures such as wildlife crossings.

Wildlife Crossings Pilot Program (DOT)

Wildlife Crossings Pilot Program (DOT)

Combining multi-species connectivity modelling with expert knowledge to inform the green infrastructure design

The Canton of Geneva is currently working on defining and mapping its green infrastructure (GI), in order to implement its biodiversity protection directives by 2030. Ecological connectivity is considered in the definition of the GI, as it is a key factor in managing the species extinction risk. It is considered a vital aspect of the landscape, because it can indicate how landscape facilitates or influences wildlife movement. In order to assess connectivity, animal movement data is essential as it provides precise behavioral information on the movements of organisms. Unfortunately, this kind of data is often missing or available only at local scales. Ecologists therefore must deal with a lack of data when trying to supply useful spatially explicit ecological models for conservation planning. To help managers in their efforts to define the GI, an alternative is to rely on local expert knowledge. We have thus applied a structured analytical framework to parameterize an ecological connectivity model combining expert opinion with three of the most used methods to assess ecological connectivity: graph theory, circuit theory and cumulative costs algorithm. By considering a selection of focal species representative of the different ecological requirements and movement behaviour of the regional wildlife, maps of priority areas for the promotion of ecological connectivity were obtained for red deer, roe deer, brown hare and common toad. We estimated the principal cross-border corridors at the scale of the Greater Geneva region, between France and Switzerland. Three transboundary high priority areas were highlighted in our maps. The localization of these areas is principally characterized by natural habitats such as forests, grasslands and freshwater ecosystems, but depends also on the agricultural areas. The principal natural barrier to animal movement is Lake Geneva, and the principal human barriers to movement are human settlements and highways that impede the regional displacements for all of the species. Considering the highways, the barrier effect could be diminished thanks to the recent construction of wildlife overpasses. We have seen that a close collaboration between local experts and ecological modelers is necessary when interpreting the conservation value of land potentially capable of promoting wildlife ecological connectivity. When implementing the GI, it will be useful to combine our models with field campaigns to measure the real functionality of the estimated priority areas, in order to guarantee the success of conservation actions.

Placing Green Bridges Optimally, with a Multivariate Analysis

We study the problem of placing wildlife crossings, such as green bridges, over human-made obstacles to challenge habitat fragmentation. The main task herein is, given a graph describing habitats or routes of wildlife animals and possibilities of building green bridges, to find a low-cost placement of green bridges that connects the habitats. We develop three problem models for this task and study them from a computational complexity and parameterized algorithmics perspective.

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.

Managing Landscape Urbanization and Assessing Biodiversity of Wildlife Habitats: A Study of Bobcats in San Jose, California

In the rapid process of urbanization, crucial habitats for mid-sized felids such as bobcats are increasingly compromised. This study employs Geographic Information System (GIS) tools and Machine Learning to investigate the subtle impacts of urbanization on bobcat habitats. Focused on the San Jose area, our extensive geospatial analysis has developed a complex ecological model for bobcat habitats. Our findings emphasize the significant influence of factors like vegetation cover, water body distribution, road traffic volume, and intersection density on the suitability of habitats for bobcats. Specifically, we discovered that while vegetation cover typically supports habitat suitability, its proximity to busy roads significantly undermines this advantage, indicating a need for strategic urban planning that incorporates wildlife mobility. By synthesizing natural and urban elements, we offer fresh insights into urban ecosystem management and propose specific conservation tactics: identifying optimal wildlife crossings, integrating corridors with urban infrastructure, and placing fencing and signage strategically to facilitate wildlife movement safely. These measures aim to reduce road-related threats and enhance the integrity of natural habitats, strengthening bobcat conservation efforts. More than its direct implications for bobcat conservation, this study offers actionable insights for urban wildlife conservation and introduces innovative methods for assessing and mitigating the broader ecological impacts of urbanization.

An inbreeding perspective on the effectiveness of wildlife population defragmentation measures – a case study on wild boar (Sus scrofa) of Veluwe, The Netherlands

Pervasive inbreeding is a major genetic threat of population fragmentation and can undermine the efficacy of population connectivity measures. Nevertheless, few studies have evaluated whether wildlife crossings can alleviate the frequency and length of genomic autozygous segments. Here, we provided a genomic inbreeding perspective on the potential effectiveness of mammal population defragmentation measures. We applied a SNP-genotyping case study on the ~2500 wild boar Sus scrofa population of Veluwe, The Netherlands, a 1000-km2 Natura 2000 protected area with many fences and roads but also, increasingly, fence openings and wildlife crossings. We combined a 20K genotyping assessment of genetic status and migration rate with a simulation that examined the potential for alleviation of isolation and inbreeding. We found that Veluwe wild boar subpopulations are significantly differentiated (FST-values of 0.02-0.13) and have low levels of gene flow. One noteworthy exception was the Central and Southeastern subpopulation, which were nearly panmictic and appeared to be effectively connected through a highway wildlife overpass. Estimated effective population sizes were at least 85 for the meta-population and ranged from 31 to 52 for the subpopulations. All subpopulations, including the two connected subpopulations, experienced substantial inbreeding, as evidenced through the occurrence of many long homozygous segments. Simulation output indicated that whereas one or few migrants per generation could undo genetic differentiation and boost effective population sizes rapidly, genomic inbreeding was only marginally reduced. The implication is that ostensibly successful connectivity restoration projects may fail to alleviate genomic inbreeding of fragmented mammal populations. We put forward that defragmentation projects should allow for (i) monitoring of levels of differentiation, migration and genomic inbreeding, (ii) anticipation of the inbreeding status of the meta-population, and, if inbreeding levels are high and/or haplotypes have become fixed, (iii) consideration of enhancing migration and gene flow among meta-populations, possibly through translocation.

Habitat suitability assessment for tule elk in the San Francisco Bay and Monterey Bay areas

While California’s statewide tule elk (Cervus canadensis nannodes) population has recovered from two or three individual survivors in the late 19th century, the subspecies exists today in numerous widely disjunct populations, leaving vast areas of the species’ former range uninhabited. Large unoccupied areas of historic tule elk range include the Santa Cruz Mountains and the northern Diablo and northern Santa Lucia ranges. Natural range expansion by existing populations into these areas is blocked by major highways and urban development; although, before considering tule elk translocations, it is necessary to assess the habitat suitability there. To this end, we fit a resource selection function (RSF) using generalized linear mixed models to GPS collar data collected from nearby radio collared tule elk and used several environmental GIS layers to capture important habitat characteristics. We fit the RSF in a habitat use versus availability framework with only linear and quadratic terms and used stepwise model selection ranked by AICc to maximize its generalizability, enabling transferability to our unoccupied study area. We also used k-fold cross validation to evaluate our RSF and found it predicted habitat within the San Luis Reservoir herd well. The fit habitat relationships mostly followed expectations based on tule elk ecology, including positive responses to herbaceous vegetation cover and waterbody proximity, and negative responses to high tree cover and high puma habitat suitability. Our RSF accurately predicted currently occupied elk habitat as suitable and found well over 500,000 ha (2,000 mi2) of suitable but unoccupied habitat throughout the northern Diablo Range, the inland and coastal sides of the Santa Cruz Mountains, and the northern Santa Lucia Range. Assuming translocations, and construction and improvement of highway wildlife crossings, our results support the potential for re-establishing tule elk in these regions, which are more coastal and mesic than the species’ current habitat in the central Diablo and northern Gabilan ranges.

Assessment of Ecological Bridges at Wildlife Crossings in Türkiye: A Case Study of Wild Boar Crossings on the Izmir-Çeşme Motorway.

In this study, the use of an ecological bridge installed as a wildlife overpass and constructed in the Zeytinler neighborhood in 2020 was analyzed as a mitigating factor in wild-boar-vehicle collisions (WVCs) on the Izmir-Çeşme motorway. In this context, this study aimed to assess the use of the Zeytinler Ecological Bridge by wild boars (Sus scrofa Linnaeus, 1758). To this end, wildlife crossings were monitored, analyzed, and modeled with Bayesian networks. Between August 2020 and December 2022, a total of 686 instances of movement were observed among six medium to large wild mammal species. Wild boars accounted for approximately 87.5% of the recorded wildlife crossings, with foxes comprising 10%. The findings showed that the highest frequency of wildlife crossings occurred during the autumn season, particularly between 22:00 (10 p.m.) and 02:00 (2 a.m.), coinciding with the Waxing Gibbous and Waxing Crescent phases of the moon. The model outcomes highlighted that during the autumn season with a full pond, wild boar crossings increased by one and a half times in comparison to regular herd crossings. Throughout the observation period, there were no instances of wild boar fatalities subsequent to the completion of the bridge.

Priodontes maximus (Cingulata: Chlamyphoridae) using a highway wildlife underpass in a fragmented Cerrado landscape from Eastern Goias State, central Brazil

We monitored a stretch of the BR-050 highway in the State of Goias that crosses several natural environments used by the giant armadillo, a peculiar and endangered species whose survival is threatened by vehicle collisions. Here, we present the record of highway underpass use by Priodontes maximus in a fragmented Cerrado landscape in Ipameri, Goias. The finding confirms the use of highway underpasses by the giant armadillo and highlights that these structures should be promoted at points where P. maximus occurs in the habitats isolated by the BR-050.

The Design and Location Characteristics of Wildlife Overpasses in Hungary

Hungary's motorway network has developed significantly over the past twenty years. These developments have increased the length of fenced roads, which also means increased habitat fragmentation effects. Wildlife crossings have been built on new sections to reduce isolation caused by roads. This study examined 57 wildlife overpasses using satellite imagery. We determined the internal and overall widths of the crossings, their total length and the length of the noise barriers, as well as the width-to-length ratio. The crossings were classified according to ramp design, noise barrier material and noise barrier run-down. In addition, a surface cover map was used to examine landscape features within 500 m of the crossings and evaluate the crossings' placement. Our results show that the average width of the overpass corridor was 14.4 m. The width-to-length ratio was 0.16. Based on this, we concluded that the wildlife crossings in Hungary could be classified as narrow crossings. There was also considerable variation in design characteristics, with the crossings studied not being uniform in either ramp design or noise barrier characteristics. The results of the placement's landscape characterisation indicate that many overpasses in agricultural areas are particularly favourable for roe deer (Capreolus capreolus).

Potential effect of managing connectivity to contain disease spread among free‐ranging wild boar (Sus scrofa) in disparate landscapes

Abstract Landscape connectivity is a major factor shaping the spread of pathogens in wildlife populations. By managing connectivity, transmission pathways can be broken and disease spread be contained, particularly in the early phases of an outbreak. Having witnessed recent outbreaks of African Swine Fever in free‐ranging wild boar (Sus scrofa) in Belgium, Germany and Italy, offices for disease control are on the alert also in other western European countries. This study investigates the potential effect of managing landscape connectivity to contain disease spread among free‐ranging wild boar in disparate landscapes. It involves research into (1) the ease with which wildlife corridors can be blocked for wild boar, (2) the connectivity of wild boar habitat and (3) the impact of landscape fragmentation on connectivity management. This is addressed by carrying out GIS analyses and performing graph operations on the wild boar networks in different biogeographical regions of Switzerland. The results of doing research into the three above‐mentioned objects show that, regarding the first, most wildlife corridors are hard to block for wild boar, because their features or location make fencing difficult. Regarding the second, the wild boar habitat is connected. Opening wildlife passages that are currently under construction may allow wild boar to disperse to hitherto uncolonized areas. Regarding the third, all wild boar networks could be partially decomposed by blocking the easy to block corridors and closing the passages. Network decomposition would be easiest to achieve in the region where the built infrastructure is most abundant. All over Switzerland, the potential epidemic size could be reduced by 25% when blocking the minimal set of corridors and passages that cut the networks to non‐decomposable components. This study suggests that (a) combining connectivity analysis with fragmentation analysis is key to explaining why a specific measure of disease containment is more effective in one landscape than in the other, (b) complementing the permeability model with a species distribution model is essential to identify connected habitat patches for the species of concern and (c) connectivity metrics should consider also the surface area of occupied habitat patches and relative abundance of the species of concern.

Environmental protection and the road database

In recent years, we have witnessed the intensive construction of road routes through Serbia. Mitigation plans have been designed on all newly constructed sections and environmental monitoring is foreseen. In order to successfully implement mitigation and monitoring plans, there is a need to consolidate a large number and type of data. Within the PE "Roads of Serbia" there is a Database department responsible for the management, collection, updating and analysis of the data referring to roads, traffic, traffic signage and equipment, traffic accidents, structures, etc. This paper points to the necessity of upgrading the existing database with data based on applied environmental protection measures, requirements regarding regular maintenance and monitoring of their effectiveness through a monitoring plan. All the elements of mitigation plans that should be included in the database are presented in detail: noise protection walls, oil separators used to treat waste water, wire fences that are adapted to certain animal species and wildlife crossings. The database should also contain monitoring data for surface water, groundwater, air, soil and noise level. In order to improve environmental protection, proposals were also made on the use of data already entered in the existing database and their upgrading.

Is there a spatial match between roadkill and mitigation measures identified by functional connectivity modeling?

Linear transportation infrastructure affects the ability of wildlife species to live and move through anthropized landscapes. Mitigation measures are thus needed to maintain population viability. Several methods have been employed to determine optimal locations for these measures, including connectivity modeling, which targets areas with the strongest connectivity and/or potential connectivity gains. However, these results are seldom compared to biological data, such as roadkill. The objective of our study is to: i) to gain a deeper understanding of the relationships between roadkill and connectivity, ii) to spatially identify road sections with a high risk of roadkill and, iii) to compare high-risk roadkill areas with the locations identified for potential mitigation measures. We performed a generalized linear model to explain occurrence and abundance of roadkill and predict high-risk roadkill areas. The mitigation measures corresponded to either i) existing crossing structures that could be enhanced to facilitate wildlife passage, selected from the initial connectivity or ii) new wildlife crossings designed to reconnect habitats identified through connectivity gains.Our results indicate that connectivity significantly influences the occurrence and abundance of roadkill. However, the high-risk roadkill areas only partially align with the locations designated for mitigation measures. Since some roadkill occurs outside of high-connectivity areas, factors other than connectivity must also be taken into consideration. This study offers valuable insights and underscores the complexity of the relationships between connectivity, roadkill, and mitigation efforts. Furthermore, by integrating spatial modeling, mitigation strategies, and roadkill data, this study contributes to a deeper understanding of corridor restoration areas and their importance in species conservation.

Mammal use of underpasses to cross Route 606 in Guacimal, Costa Rica

Roads severely affect the health of ecosystems across the globe by fragmenting and diminishing habitats, reducing population connectivity, and increasing animal mortality. Wildlife underpasses allow for increased road permeability–the ability for animals to safely cross the road. Despite growing success in other regions, little is known about underpass usage in Central America. In this study, I monitored two dry circular culverts and two unfenced tunnels with barbed wire partially blocking their entrances on Route 606 in Guacimal, Costa Rica, from 14 November to 6 December 2021 using 15 camera traps to assess which species used them to cross. Twelve species used the culverts and tunnels for a total of 108 individual crossings. The tunnels were used, in descending order, by agouti (Dasyprocta punctata), common opossum (Didelphis marsupialis), dog (Canis familiaris), nine-banded armadillo (Dasyous novemcinctus), cat (Felis catus), Norway rat (Rattus norvegicus), ocelot (Leopardus pardalis), squirrel (Sciurus variegatoides), northern tamandua (Tamandua mexicana), and coati (Nasua narica). The circular tunnel, Tunnel 1, was used more frequently and by a greater diversity of species than observed in the square tunnel, Tunnel 2. The two smaller culverts were used by common opossum (Didelphis marsupialis), cat (Felis catus), rat opossum (Micoureus alstoni), and Watson’s climbing rat (Tylomus watsoni). Culvert 2 was used more frequently; however, Culvert 1 was used by a greater diversity of species. This study highlights wildlife underpasses as a critical strategy for biological conservation in Costa Rica through improved road safety and habitat connectivity.

Assessment of Deer–Vehicle Crash Mitigation Structures on the US 33 Nelsonville, Ohio, Bypass

The US 33 Nelsonville Bypass project involved construction of a new four-lane divided highway through the Wayne National Forest in southeastern Ohio, an area high in species diversity and home to several threatened and endangered species. The project included three wildlife underpass structures to promote habitat connectivity, 16 jump out structures to allow wildlife to exit the highway right-of-way (ROW), and 2.44-m (8-feet) tall exclusion fencing along the ROW boundary to discourage entry. This paper reports the results of a comprehensive research study undertaken to determine if these features were effective at reducing collisions between vehicles and wildlife (specifically, white-tailed deer). A multi-season camera-based monitoring plan was deployed to track the movement of animals within and around the highway ROW. The results of the analysis showed that the crossing structures were heavily used and that the tall fencing was effective at excluding deer from the highway area. Approximately 43% of deer that approached the jump out structures used them to successfully exit the ROW. Analysis of traffic crash data from six years after the opening of the highway suggests that the prevalence of deer crashes on the highway is lower than other highways in the region, indicating that the mitigation features appear to be successful at reducing such collisions. Considering the additional costs of constructing the mitigation features and the economic benefits of the associated deer crash reductions, the incremental cost-benefit ratio of the complete installation is estimated to be 1.65, indicating a net positive benefit realized by the mitigation plan. The results of this study suggest that wildlife mitigation structures can be effective in supporting highway development in wildlife-sensitive areas, particularly if the placement of the structures relates to existing wildlife patterns and the features are maintained post-construction.

Designing Wildlife Crossings

Designing Wildlife Crossings