Roadkill Patterns Research Articles

Black and white but not a crosswalk: land use and roadkill impact the survival of the striped hog-nosed skunk (Conepatus semistriatus) in a Neotropical hotspot

ABSTRACT Roadkill, the result of collisions between vehicles and wildlife, is becoming one of the most important conservation issues. This is especially evident in regions such as the Cerrado savannas which are under strong land use conversion, forcing animals to move more through the landscape and thus increasing exposure to roadkill. Herein, we assess the temporal and spatial patterns of roadkill of the striped hog-nosed skunk (Conepatus semistriatus) as well as its interaction with surrounding land use in the Brazilian Cerrado. To do so, we sampled BR-050, a nationally-important highway, for roadkilled C. semistriatus between 2015 and 2020 and used location and date to identify temporal and spatial patterns of roadkill. Furthermore, we assessed whether different land uses affected wildlife-vehicle collisions using a random forest model. We recorded 672 roadkilled individuals of C. semistriatus, and detected both monthly and yearly temporal hotspots as well as spatial hotspots. These hotspots were significantly surrounded by soy, which along with savannas and crops were the most impactful land uses. Since conservation practitioners need to know when and where there are higher risks of wildlife-vehicle collision, our results are essential for the conservation of C. semistriatus in the Cerrado by incorporating land use into roadkill.

Assessing Herpetofauna Roadkill Patterns Near a Protected Area in Argentina

Assessing Herpetofauna Roadkill Patterns Near a Protected Area in Argentina

A SURVEY OF VERTEBRATES’ ROADKILL WITHIN A 10 KM RADIUS FROM THE CENTRE OF KUALA PILAH TOWN, NEGERI SEMBILAN

Assessing animal roadkill provides valuable insights into the diversity and abundance of different species within a particular area. This study has the potential to uncover factors influencing the occurrence of animal roadkill. However, there is a scarcity of studies focusing on animal roadkill in small, secluded areas such as the Kuala Pilah district, Negeri Sembilan. Thus, this study evaluates the composition and distribution of vertebrate roadkill within a 10 km radius from the centre of Kuala Pilah Town, with a focus on temporal (time of discovery), spatial (types of roads and types of surrounding areas), and environmental factors (the presence of streetlights). The road segments located within a 10 km radius from Kuala Pilah Town have been examined in ten weeks and the found carcasses were identified by their taxonomic groups and photographed. Further, their discovery location has been observed and marked with coordinates. A chi square test was then performed to evaluate the occurrence of animal roadkill with all recorded data. This study revealed 48 animal carcasses, with a taxonomic composition of 27.08% birds (13 individuals), 50% mammals (24 individuals), 18.75% reptiles (9 individuals), and 4.17% amphibians (2 individuals). The roadkill patterns showed that squirrels and cats as the most prevalent species found, with higher carcass rates found in plantation/forest areas and on state roads. Roadkill occurrences increased between 7 a.m. and 1 p.m., while streetlights had no noticeable impact on the numbers. Overall, mammals turned out to be the most frequent vertebrate class involved in roadkill with time being the only significant factor influencing the numbers. With a better understanding of the factors influencing vertebrate roadkill, mitigation strategies such as fencing, roadside vegetation clearance, and vehicle speed restrictions might be devised to minimize the adverse impacts of road infrastructure on local animal populations.

Spatial patterns of roadkill within Ankarafantsika National Park, Madagascar

AbstractWildlife‐vehicle collisions can be a significant cause of mortality for animals with ranges that overlap roads. Not all species are equally affected by roads and thus conservation practitioners need empirical data to determine appropriate mitigation measures. However, there is a lack of data on how tropical animals, in particular those on the island of Madagascar, are affected by roads and vehicular mortality. In order to fill in this gap in the literature we investigated the ecological and spatial factors influencing roadkill observations along Route National 4 in Ankarafantsika National Park, Madagascar. We observed 80 cases of roadkill along the highway belonging to at least 13 species, including the first published record of a lemur as roadkill. We also found that the density of roadkill was lower in the area between two speedbumps, suggesting these are an effective measure to mitigate wildlife‐vehicle collisions. These results showcase that even within protected areas of Madagascar animals are at risk of vehicular mortality but mitigation measures are possible. Given the high rates of endemicity coupled with vulnerability to extinction of many Malagasy fauna there is an urgent need for more research on road ecology in Madagascar.

Using the dead to infer about the living: Amphibian roadkill spatiotemporal dynamics suggest local populations' reduction

Roads represent one of the main sources of wildlife mortality, population decline, and isolation, especially for low-vagility animal groups. It is still not clearly understood how wildlife populations respond to these negative effects over space and time. Most studies on wildlife road mortality do not consider the spatial and temporal components simultaneously, or the imperfect roadkill detection, both of which could lead to inaccurate assumptions and unreliable mitigation actions. In this study, we applied a multi-season occupancy model to a 14-year amphibian mortality dataset collected along 120 km of roads, combined with freely available landscape and remote sensing metrics, to identify the spatiotemporal patterns of amphibian roadkill in a Mediterranean landscape in Southern Portugal. Our models showed an explicit general decrease in amphibian roadkill. The Iberian painted frog (Discoglossus galganoi) experienced roadkill declines over time of ∼70 %, while the spiny common toad (Bufo spinosus) and the fire salamander (Salamandra salamandra) had a loss of nearly 50 %, and the Southern marbled newt (Triturus pygmaeus) had 40 %. Despite the decreasing trend in roadkill, spatial patterns seem to be rather stable from year to year.Multi-season occupancy models, when combined with relevant landscape and remote sensing predictors, as well as long-term monitoring data, can describe dynamic changes in roadkill over space and time. These patterns are valuable tools for understanding roadkill patterns and drivers in Mediterranean landscapes, enabling the differentiation of road sections with varying roadkill over time. Ultimately, this information may contribute to the development of effective conservation measures.

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.

Factors determining roadkills in a mammal carnivore are road-type specific

Roads threaten the conservation of many wildlife species. Carnivores are one of the most susceptible groups due to their habitat requirements. We explored the roadkill patterns of European polecats (Mustela putorious) on motorways and roads to investigate if these patterns depend on road type, a research topic frequently neglected in the literature. We studied 85 roadkills on motorways and 73 on roads, and the corresponding number of random points with no roadkills in every road type. We characterized them with 7 habitat and 7 road-related variables. Roadkill sites were significantly associated with the abundance of rabbit burrows. However, this effect was stronger on motorways, as they provide more suitable habitat for the establishment of prey species on their wider rights-of-way, or on the road interchange islands, which provide wide unused spaces. In contrast, road interchange islands on conventional roads that are simple intersections and have narrower rights-of-way. Furthermore, roadkills occurred in areas with lower agricultural cover. Thus, natural habitats on roadsides could act as alternative foraging areas for this carnivore increasing their roadkill risk. Our results showed the need to consider the characteristics such as the availability of prey or the surrounding habitat, as well as intrinsic characteristics of the road type when studying wildlife roadkills as the road-type-mediated patterns demand-specific mitigation measures.

Roadkill Patterns on Workdays, Weekends and Long Weekends: Anticipating the Implications of a Four-Day Work Week

Understanding the spatial and temporal patterns of animal road mortality is important for planning protective measures and raising driver awareness. In our study of Lithuania, spanning from 2002 to 2022, we examined these patterns based on road types and categorized them by working days, weekends, and long weekends, predicting the potential impact of transitioning to a four-day working week. We found that road type explains 22–50% of the variability in roadkill numbers for moose, red deer, wild boar, and roe deer. The highest occurrences were on main roads, while regional roads had the fewest incidents. The overall number of roadkills, especially those involving ungulates, was highest on weekends, followed by workdays, with the least on long weekends. However, these variations lacked statistical significance, and their effect size was small. We also observed a trend of increased roadkill numbers on the day before, the first day, notably on All Saints Day, or the last day of long weekends. In this context, with the introduction of a four-day work week, we are only expecting the highest roadkill numbers to move from Friday to Thursday.

The impact of RS–040 highway on wildlife roadkill patterns, Porto Alegre, Southern Brazil.

Road infrastructure has caused severe impacts on the environment and wildlife. Understanding and mitigating these effects are essential conservation measures. This study aimed to evaluate wildlife mortality due to animal-vehicle collisions along an 80-km stretch of the Tapir Rocha Highway (RS–040). The field inventory was carried out between August 2015 and March 2019. Once a week, two observers drove along the highway at an average speed of 40 km/h and all the vertebrate roadkill spotted from the car were assessed to record the species, carcass condition, and the roadkill locations along the road. In total, 2,371 dead animals were recorded and categorized into 137 species. The most affected classes were mammals (n = 1,223), and birds (n = 704). The most affected wild species were white-eared opossums (Didelphis albiventris, n = 559), black-and-white tegus (Salvator merianae, n = 129), and coypus (Myocastor coypus, n = 102). Carcass exposure assessments indicated that many (n = 637) of the animal deaths occurred the night before our arrival, which may suggest that nocturnal species were among the most vulnerable to mortality. Roadkill sighting peaked in the spring (34%) and summer (25%), probably due to reproductive activity and juvenile dispersal. Evident seasonal variations included a 50% reduction in reptile roadkill rates in autumn-winter compared to spring-summer, and a 20-percentage-point increase in the number of mammal road deaths in the winter. The reduced activity that reptiles display at low temperatures, and seasonal changes in carnivore food habits may explain these respective findings. While most of the animal victims of roadkill were common and widely distributed species with abundant populations, decreasing abundance of these species is a growing conservation concern.

Temporal and spatial patterns of small vertebrate roadkill in a supercity of eastern China.

An assessment of animal roadkill can help develop road mitigation measures. This article is the first to report data on animal-vehicle collisions (AVCs) in Nanjing, a supercity in eastern China. The research was conducted on a 224.27 km stretch of nine roads in Nanjing. In the period, between November 2020 and October 2021, 26 fortnightly monitoring missions were conducted to gather roadkill carcasses so that we could analyze their temporal and spatial distribution patterns. A total of 259 carcasses were collected, comprising 22 different species, of which 46.42% were mammals and 48.81% were birds. Cats and dogs are the most roadkill mammals, and blackbirds and sparrows are the most roadkill birds. The temporal analysis demonstrated that the peak of vertebrate roadkill occurred from May to July. Spatial analysis showed that the distribution patterns of vertebrate roadkill on different roads varied with a generally non-random distribution and aggregation. By mapping accidents using kernel density analysis, we were able to pinpoint locations that were at high risk for roadkill. Due to the fortnightly survey, our results would underestimate the casualties, even if, our study suggests that the problem of car accidents due to animals should be a cause for concern, and the results of the analysis of temporal and spatial patterns contribute to the establishment of mitigation measures.

Mammalian Roadkill in a Semi-Arid Region of Brazil: Species, Landscape Patterns, Seasonality, and Hotspots

Roadkill is one of the principal causes of the loss of biodiversity around the world. The effects of roads on mammals are still poorly understood in regions with a semi-arid climate, where many knowledge gaps persist. The present study provides an inventory of the mammalian species affected on highways in northeastern Brazil, as well as identifying roadkill hotspots and contributing to the understanding of how seasonality and the landscape may influence the roadkill patterns of wild mammals. A total of 6192.52 km of road were sampled in 53 field surveys conducted between 2013 and 2017. Landsat 8 satellite images and data from the MapBiomas platform were used to classify land use and cover for analysis. Buffers of 1 km, 5 km, and 10 km were created around the study roads to identify the landscape variables associated with roadkill events. Ripley’s 2D K-Statistics and the 2D HotSpot test were used to identify roadkill aggregations and hotspots; GLMMs were generated for the landscape variables and evaluated using the Akaike Information Criterion. The Kruskal–Wallis test was applied to investigate the potential effects of seasonality. A total of 527 wild animal carcasses were recorded as a result of vehicular collision. The species with the highest roadkill records were Cerdocyon thous, Euphractus sexcinctus, and Procyon cancrivorus, while two species—Leopardus emiliae and Herpailurus yagouaroundi—are considered to be under threat of extinction. For mammals in general, the best GLMM indicated an increase in roadkills with increasing density of local vegetation areas, and a decrease as urban areas increased. The model also found that the mammals were less impacted in the vicinity of a protected area. In the specific case of C. thous, the roadkill rate was lower when urban infrastructure was more common than dense vegetation; the rate increased as areas of dense vegetation increased. In the case of P. cancrivorus and E. sexcinctus, the best models of roadkill patterns included an area of exposed soil and sparse vegetation, respectively. Roadkill rates were higher in the rainy season for all the mammals, with the exception of C. thous. These results reflect the ecological characteristics of the species with the highest roadkill rates. The findings of the present study raise concerns with regard to the impact of highways on the populations of C. thous, as well as the region’s most threatened species. They also indicate the potential functionality of the local protected area, as well as identifying roadkill hotspots, which will support the development of effective mitigation measures.

Three decades of wildlife-vehicle collisions in a protected area: Main roads and long-distance commuting trips to migratory prey increase spotted hyena roadkills in the Serengeti

Vehicles kill many wild animals worldwide, including in protected areas, where the impacts of roads are increasing due to road development, the rise of human population at their boundaries, and the growing interest in wildlife tourism. Yet, knowledge on the factors influencing wildlife roadkills within protected areas is limited, particularly for large carnivores. Here, we investigated spotted hyena (Crocuta crocuta) roadkills inside a protected area, the Serengeti National Park, Tanzania, between 1989 and 2023 (n = 104). We examined spatial determinants of hyena roadkills using a generalized linear model, temporal and spatiotemporal patterns in hyena roadkills, and the effect of age, sex, and social status on hyena mortality due to vehicles. Roadkills were more likely on main roads and the locations and number of roadkills varied according to seasonal changes in the locations of vast migratory ungulate herds, which are the main prey of hyenas. Adult females, who travel the most to forage on these herds, suffered the highest levels of road mortality. Road mortality was independent from social status among females. Our results indicate that roadkill patterns were shaped by both road characteristics, as incidence was substantially higher on main roads, and large-scale seasonal changes in the location of migratory prey. Further, the incidence of hyena roadkills was exacerbated by long-distance ‘commuting’ trips to areas containing large aggregation of migratory herbivores. Our findings provide new insight on ecological and individual factors modulating roadkill incidence in a large carnivore.

Spatio-temporal patterns of vertebrate roadkills in a suburban area in northern Japan

Spatio-temporal patterns of vertebrate roadkills in a suburban area in northern Japan

Error Correction Based Deep Neural Networks for Modeling and Predicting South African Wildlife–Vehicle Collision Data

The seasonal autoregressive integrated moving average with exogenous factors (SARIMAX) has shown promising results in modeling small and sparse observed time-series data by capturing linear features using independent and dependent variables. Long short-term memory (LSTM) is a promising neural network for learning nonlinear dependence features from data. With the increase in wildlife roadkill patterns, the SARIMAX-only and LSTM-only models would likely fail to learn the precise endogenous and/or exogenous variables driven by this wildlife roadkill data. In this paper, we design and implement an error correction mathematical framework based on LSTM-only. The framework extracts features from the residual error generated by a SARIMAX-only model. The learned residual features correct the output time-series prediction of the SARIMAX-only model. The process combines SARIMAX-only predictions and LSTM-only residual predictions to obtain a hybrid SARIMAX-LSTM. The models are evaluated using South African wildlife–vehicle collision datasets, and the experiments show that compared to single models, SARIMAX-LSTM increases the accuracy of a taxon whose linear components outweigh the nonlinear ones. In addition, the hybrid model fails to outperform LSTM-only when a taxon contains more nonlinear components rather than linear components. Our assumption of the results is that the collected exogenous and endogenous data are insufficient, which limits the hybrid model’s performance since it cannot accurately detect seasonality on residuals from SARIMAX-only and minimize the SARIMAX-LSTM error. We conclude that the error correction framework should be preferred over single models in wildlife time-series modeling and predictions when a dataset contains more linear components. Adding more related data may improve the prediction performance of SARIMAX-LSTM.

Wildlife roadkill patterns on a major highway in Kashmir Himalaya

In the face of increasing road networks in the Western Himalayas, road-kills of wildlife are increasing. In order to generate a baseline data, we carried a preliminary study from March to August, 2019 on 45 km stretch of the Srinagar–Leh National Highway NH-1 in northern India which connects the newly formed union territories of Jammu & Kashmir and Ladakh. The highway traversing through Sindh Valley and passing adjacent to Thajwas-Baltal Wildlife Sanctuary was surveyed to describe the patterns of roadkill . The survey of six months recorded roadkill of 64 individuals (0.14 roadkill km −1 ) comprising 19 species from different terrestrial vertebrate groups, of which two species, house cat ( Felis catus ) and domestic dog ( Canis lupus ), were domesticated species. Mammals constituted 37.5% (0.055 roadkill km -1 ), followed by birds 24% (0.034 roadkill km -1 ), reptiles 21% (0.032 roadkill km -1 ) and amphibians 17% (0.025 roadkill km -1 ). Excluding amphibians and reptiles, there were significantly more roadkill on road sections adjacent to the protected areas (59%) than in sections adjacent to non-protected areas. The study besides being a baseline for future studies revealed that the roads act as potential threat to wildlife and animals killed by vehicles are driven possibly by the spatial resource arrangement.

Wildlife roadkill patterns on a major highway in Kashmir Himalaya

In the face of increasing road networks in the Western Himalayas, road-kills of wildlife are increasing. In order to generate a baseline data, we carried a preliminary study from March to August, 2019 on 45 km stretch of the Srinagar–Leh National Highway NH-1 in northern India which connects the newly formed union territories of Jammu & Kashmir and Ladakh. The highway traversing through Sindh Valley and passing adjacent to Thajwas-Baltal Wildlife Sanctuary was surveyed to describe the patterns of roadkill . The survey of six months recorded roadkill of 64 individuals (0.14 roadkill km −1 ) comprising 19 species from different terrestrial vertebrate groups, of which two species, house cat ( Felis catus ) and domestic dog ( Canis lupus ), were domesticated species. Mammals constituted 37.5% (0.055 roadkill km -1 ), followed by birds 24% (0.034 roadkill km -1 ), reptiles 21% (0.032 roadkill km -1 ) and amphibians 17% (0.025 roadkill km -1 ). Excluding amphibians and reptiles, there were significantly more roadkill on road sections adjacent to the protected areas (59%) than in sections adjacent to non-protected areas. The study besides being a baseline for future studies revealed that the roads act as potential threat to wildlife and animals killed by vehicles are driven possibly by the spatial resource arrangement.

An inventory of amphibian roadkill in the western Soutpansberg, Limpopo province, South Africa

ABSTRACT Increasing linear infrastructure development often impacts habitats and wildlife negatively. Roads, in particular, have numerous threats to wildlife with the most noticeable direct impact being roadkill, and this requires urgent conservation interventions. To assess amphibian roadkill, driven surveys were conducted on three regional roads around the western Soutpansberg in the Vhembe Biosphere Reserve, an important area for biodiversity conservation in South Africa. Six habitat types were identified along the monitored road stretches and their influence on the occurrence of amphibian roadkill was determined. The results comprised an inventory of 248 roadkill specimens, belonging to eight species and six families, and one unidentified specimen. Roadkill was strongly influenced by season, with the greatest roadkill rate recorded in the early wet season (0.051 roadkill km–1 day–1) compared to the late wet season (0.019 roadkill km–1 day–1). Amphibian roadkill patterns were related to roadside habitat. Of the roadside habitat types identified, road sections adjacent to waterbodies had the highest number of roadkill, followed by road sections closer to open savanna bushland. Roadkill frequency was low in areas that were partly located in human modified habitats (residential and agricultural areas) but highest in natural landscapes (near waterbodies and savanna bushland). The study provides baseline data that confirms the potential threat of roads and their users on the persistence of amphibians in the Vhembe Biosphere Reserve and presents the first systematic inventory of amphibian roadkill in the western Soutpansberg, South Africa.

Forecasting seasonal peaks in roadkill patterns for improving road management

For several species, roadkill is not spatially aggregated on hotspots, having instead a more diffuse pattern along the roads. For such species, management measures such as road passages may be insufficient for effective mitigation, since a large part of the road crossings is likely to occur outside the influence of those structures. One complementary approach could be to implement temporary mitigation actions, such as traffic calming. This requires understanding when roadkill peaks may occur. We tested the feasibility of predicting seasonal peaks of roadkill using data from a 3-year systematic monitoring (78 surveys over ca. 960 km of roads) from eight non-flying vertebrate species from Mato Grosso do Sul, Brazil, with different body size and life history traits (ca. 6400 records from focal species). We modelled the time-series of the roadkill of these species at large scale (state level) using generalized additive mixed models (GAMMs). We used the data of the first 2 years as training datasets, and the information from the third year of surveys as testing datasets to evaluate the prediction performance of models. Overall, the models of species feed with a higher number of records were able to follow reasonably well the variations of roadkill over time, although they were not able to correctly predict the number of collisions. For species with fewer observations, the models presented a poorer goodness-of-fit and prediction ability. Our results suggest that, at least for those species with higher roadkill rates, it can be possible to forecast periods of higher probability of occurring hot-moments of mortality. Such models can provide valuable information to implement seasonal management actions.

Roadkill patterns in Latin American birds and mammals

AbstractAimRoads are a major threat for wildlife, degrading habitat and causing mortality via wildlife–vehicle collisions. In Latin America, the conjunction of high biodiversity and a rapidly expanding road network is reason for concern. We introduce an approach that combines species traits and habitat preferences to describe vulnerability and map areas of high roadkill risk. Thus, we present the first assessment of roadkill impacts for Latin American birds and mammals.LocationLatin America.Time period1994–2020.Major taxa studiedBirds and mammals.MethodsWe compiled data from 85 roadkill surveys from Latin America that provided 1,691 roadkill rate estimates for 346 bird and 159 mammalian species, from which 520 rates from 249 birds and 457 rates from 103 mammals were used for analyses. We applied random forest models to predict observed roadkill rates considering species traits, habitat preferences and the geographical coordinates of each study to control for local and regional variation. Fitted models were used to predict spatial risks on Latin American roads for roadkilled birds and mammals across their areas of habitat.ResultsWe found higher roadkill rates for larger birds and medium‐sized mammals with faster reproduction (more clutches/litters per year and early maturity ages), higher population densities and wider use of habitats that included anthropized areas. In mammals, scavengers and those with diets based on invertebrates showed higher rates. Spatial predictions revealed higher rates on roads across Central America, northern Andean regions, eastern Brazil, Uruguay, central and eastern Argentina and southern Chile.Main conclusionsThis first comprehensive assessment for Latin America explores various drivers of roadkill risk for birds and mammals and identifies species and areas where existing roads can impact wildlife. Trait‐based models fine‐tuned with realistic spatial information that accounts for habitat suitability provide a valuable tool for the assessment of human impacts, including roads and traffic.

Spatial patterns of carnivore roadkill in a high-traffic-volume highway in the endangered Brazilian Atlantic Forest

Spatial patterns of carnivore roadkill in a high-traffic-volume highway in the endangered Brazilian Atlantic Forest