The value of monitoring wildlife roadkill

Grassland restoration on linear landscape elements - comparing the effects of topsoil removal and topsoil transfer

Artificial linear landscape elements, including roads, pipelines, and drainage channels, are main sources of global habitat fragmentation. Restoration of natural habitats on unused linear landscape elements can increase habitat quality and connectivity without interfering with agricultural or industrial development. Despite that topsoil removal and transfer are widely applied methods in restoration projects, up to our knowledge these were previously not compared in the same study system. To address this knowledge gap, we compared spontaneous vegetation recovery after the elimination of positive (embankments) and negative landscape scars (drainage channels) in lowland alkaline landscapes in South Hungary. The novelty of our study is that we compared the fine-scale and landscape-scale results of both methods. At the fine scale, we monitored the spontaneous vegetation development on the created open surfaces in the first, second and fourth year after restoration in 160 permanent plots per year. For characterizing the habitat changes on the landscape scale, we prepared habitat maps and assigned naturalness scores to each patch before and after the restoration activities. Both restoration methods resulted in a rapid vegetation recovery at the fine scale, progressing toward the reference state. In the topsoil removal treatment, a large part of the soil seed bank was removed; therefore, the colonization of the bare surface was a slower process. Seeds of halophytes, including the endemic and protected Suaeda pannonica, were probably present in the deeper soil layers, and these species became established in the restored surfaces, despite being absent in the surrounding vegetation. For restoring vegetation cover, topsoil transfer was a more rapid option; however, vegetation closure and competition by generalist species and weeds hampered the establishment of target species. The removal of the landscape scars by both methods made the sites accessible for grazing. At the landscape scale, the two methods had different effects: there was a slight increase in the habitat naturalness in the topsoil removal site, and a slight decrease in the topsoil transfer site because of weed encroachment. Spreading an upper layer of nutrient-poor soil with low amounts of weed seeds, direct propagule transfer, and targeted grazing regimes could enhance restoration success.

The synergy between protected area effectiveness and economic growth

Protected areas conserve biodiversity and ecosystem functions but might impede local economic growth. Understanding the global patterns and predictors of different relationships between protected area effectiveness and neighboring community economic growth can inform better implementation of the Kunming-Montreal Global Biodiversity Framework. We assessed 10,143 protected areas globally with matched samples to address the non-random location of protected areas. Our results show that protected areas resist human-induced land cover changes and do not limit nightlight increases in neighboring settlements. This result is robust, using different matching techniques, parameter settings, and selection of covariates. We identify four types of relationships between land cover changes and nightlight changes for each protected area: "synergy," "retreat," and two tradeoff relationships. About half of the protected areas (47.5%) retain their natural land cover and do so despite an increase of nightlights in the neighboring communities. This synergy relationship is the most common globally but varies between biomes and continents. Synergy is less frequent in the Amazon, Southeast Asia, and some developing areas, where most biodiversity resides and which suffer more from poverty. Smaller protected areas and those with better access to cities, moderate road density, and better baseline economic conditions have a higher probability of reaching synergy. Our results are promising, as the expansion of protected areas and increased species protection will rely more on conserving the human-modified landscape with smaller protected areas. Future interventions should address local development and biodiversity conservation together to achieve more co-benefits.

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.

Wildlife mortality risk posed by high and low traffic roads

Wildlife mortality due to collisions with vehicles (roadkill) is one of the predominant negative effects exerted by roads on many wildlife species. Reducing roadkill is therefore a major component of wildlife conservation. Roadkill is affected by various factors, including road attributes and traffic volume. It is theorized that the effect of traffic volume on roadkill probability should be unimodal. However, empirical evidence for this theory is lacking. Using a large-scale roadkill database of 18 wildlife species in Israel, encompassing 2846 km of roads over 10 years, we explored the effects of traffic volume and road attributes (e.g., road lighting, verge vegetation) on roadkill probability with a multivariate generalized linear mixed model. A unimodal effect of traffic volume was identified for the striped hyena (Hyaena hyaena), whereas 5 species demonstrated a novel quadratic U-shaped effect (e.g., golden jackal [Canis aureus]). Four species showed a negative linear effect (e.g., wild boar [Sus scrofa]). We also identified varying effects of road attributes on roadkill. For instance, road lighting and roadside trees decreased roadkill for several species, whereas bus stops and concrete guardrails led to increased roadkill. The theorized unimodal effect of traffic volume may only apply to large, agile species, and the U-shaped effect could be related to intraspecies variability in traffic avoidance behavior. In general, we found that both high-traffic and low-traffic roads can pose a high mortality risk for wildlife. It is therefore important to monitor roadkill on low-traffic roads and adapt road attributes to mitigate roadkill. Road design for effective roadkill mitigation includes reducing the use of concrete guardrails and median barriers where possible and avoiding dense bushes in verge landscaping. These measures are complemented by employing wildlife detection systems, driver warnings, and seasonal speed reduction measures on low-traffic roads identified as roadkill hotspots.

First evidence of widespread positivity to anticoagulant rodenticides in grey wolves (Canis lupus)

Second-generation Anticoagulant Rodenticides (ARs) can be critical for carnivores, due to their widespread use and impacts. However, although many studies explored the impacts of ARs on small and mesocarnivores, none assessed the extent to which they could contaminate large carnivores in anthropized landscapes. We filled this gap by exploring spatiotemporal trends in grey wolf (Canis lupus) exposure to ARs in central and northern Italy, by subjecting a large sample of dead wolves (n = 186) to the LC-MS/MS method. Most wolves (n = 115/186, 61.8 %) tested positive for ARs (1 compound, n = 36; 2 compounds, n = 47; 3 compounds, n = 16; 4 or more compounds, n = 16). Bromadiolone, brodifacoum and difenacoum, were the most common compounds, with brodifacoum and bromadiolone being the ARs that co-occurred the most (n = 61). Both the probability of testing positive for multiple ARs and the concentration of brodifacoum, and bromadiolone in the liver, systematically increased in wolves that were found at more anthropized sites. Moreover, wolves became more likely to test positive for ARs through time, particularly after 2020. Our results underline that rodent control, based on ARs, increases the risks of unintentional poisoning of non-target wildlife. However, this risk does not only involve small and mesocarnivores, but also large carnivores at the top of the food chain, such as wolves. Therefore, rodent control is adding one further conservation threat to endangered large carnivores in anthropized landscapes of Europe, whose severity could increase over time and be far higher than previously thought. Large-scale monitoring schemes for ARs in European large carnivores should be devised as soon as possible.

Human-Wildlife Interaction-A Social Survey

With the results of a survey presented in this paper, we provide insight into public attitudes towards dealing with wildlife. Based on 1569 data sets derived from participating stakeholders, we inquired about the individual experience the participants had made with wild animals, and asked about their personal engagement, attitude towards management, and emotions involved and tried to evaluate basic contextual knowledge. As a result, we discovered a positive effect showing that a strong opinion about dealing with wildlife is associated with increasing contextual knowledge. People that are experienced in and engaged in wildlife conservation expressed significantly stronger positive emotions in this context. We conclude that education is essential in dealing with wildlife responsibly and that positive emotions are a main trigger for such engagement. The results of the survey underline that a combination of contextual knowledge and a positive attitude towards wildlife leads to a higher awareness of possible conflicts between humans and wildlife. Furthermore, these criteria are crucial when developing strategies that strive for a sustainable coexistence.

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.

Anthropogenic mortality threatens the survival of Canarian houbara bustards

Anthropogenic mortality is a major cause of global mortality in terrestrial vertebrates. Quantifying its impact on the dynamics of threatened species is essential to improve their conservation. We investigated cause-specific mortality in Canarian houbara bustards (Chlamydotis undulata fuertaventurae), an endangered subspecies endemic to the Canary Islands. We monitored 51 individuals tagged with solar-powered GSM/GPRS loggers for an average of 3.15 years, and recorded 7 casualties at aerial lines (13.73% of the sample; 5 at power lines, 2 at telephone lines), 1 (1.96%) at a wire fence, 4 road kills (7.84%) and 1 case of predation by cat (1.96%). Cox proportional hazards models showed that anthropogenic and natural annual mortality rates were similar (respectively, 6.20% and 6.36% of the individuals). We estimate that 33-35 houbaras die each year in the Canary Islands due to anthropogenic causes. Population viability models using these data and juvenile productivity values obtained over seven years predicted the extinction of the species in 50 years. Eliminating anthropogenic mortality, the population could be recovered, but would still require management actions to improve habitat quality. Conservation measures to reduce anthropogenic mortality due to power line fatalities, roadkills and predation by cats, as well as to increase productivity, are urgently needed, particularly on Fuerteventura, where houbaras are on the brink of extinction.

Evaluating YOLO architectures for detecting road killed endangered Brazilian animals

Wildlife roadkill is a recurring, dangerous problem that affects both humans and animals and has received increasing attention from environmentalists worldwide. Addressing this problem is difficult due to the high investments required in road infrastructure to effectively reduce wildlife vehicle collisions. Despite recent applications of machine learning techniques in low-cost and economically viable detection systems, e.g., for alerting drivers about the presence of animals and collecting statistics on endangered animal species, the success and wide adoption of these systems depend heavily on the availability of data for system training. The lack of training data negatively impacts the feature extraction of machine learning models, which is crucial for successful animal detection and classification. In this paper, we evaluate the performance of several state-of-the-art object detection models on limited data for model training. The selected models are based on the YOLO architecture, which is well-suited for and commonly used in real-time object detection. These include the YoloV4, Scaled-YoloV4, YoloV5, YoloR, YoloX, and YoloV7 models. We focus on Brazilian endangered animal species and use the BRA-Dataset for model training. We also assess the effectiveness of data augmentation and transfer learning techniques in our evaluation. The models are compared using summary metrics such as precision, recall, mAP, and FPS and are qualitatively analyzed considering classic computer vision problems. The results show that the architecture with the best results against false negatives is Scaled-YoloV4, while the best FPS detection score is the nano version of YoloV5.

An evaluation of DNA extraction methods on historical and roadkill mammalian specimen

Guidelines identifying appropriate DNA extraction methods for both museum and modern biological samples are scarce or non-existent for mammalian species. Yet, obtaining large-scale genetic material collections are vital for conservation and management purposes. In this study, we evaluated five protocols making use of either spin-column, organic solvents, or magnetic bead-based methods for DNA extraction on skin samples from both modern, traffic-killed (n = 10) and museum (n = 10) samples of European hedgehogs, Ericaneus europaeus. We showed that phenol-chloroform or silica column (NucleoSpin Tissue) protocols yielded the highest amount of DNA with satisfactory purity compared with magnetic bead-based protocols, especially for museum samples. Furthermore, extractions using the silica column protocol appeared to produce longer DNA fragments on average than the other methods tested. Our investigation demonstrates that both commercial extraction kits and phenol-chloroform protocol retrieve acceptable DNA concentrations for downstream processes, from degraded remnants of traffic-killed and museum samples of mammalian specimens. Although all the tested methods could be applied depending on the research questions and laboratory conditions, commercial extraction kits may be preferred due to their effectiveness, safety and the higher quality of the DNA extractions.

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

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

Predictive Modeling of Ungulate-Vehicle Collision in the Republic of Korea

Animal-vehicle collisions (AVC) threaten animals as well as human life and property. AVC with ungulates, called ungulate-vehicle collision (UVC), often seriously endangers human safety because of the considerable body size of ungulates. In the Republic of Korea, three ungulate species, Capreolus pygargus, Hydropotes inermis, and Sus scrofa, account for a large proportion of AVC. This study aimed to understand the characteristics of UVC by examining various parameters related to habitat, traffic, and seasonality using MaxEnt. The results showed that the peak UVC seasons coincided with the most active seasonal behaviors of the studied ungulates. For the modeling results, in C. pygargus, habitat variables are most important for models across seasons, and UVC events are most likely to occur in high mountain chains. In H. inermis, habitat and traffic variables are most important for models across seasons. Although the important habitat for the models were different across seasons for S. scrofa, the maximum speed was consistently critical for models across all seasons. Factors critical to UVC in the Republic of Korea were different for the three ungulate species and across seasons, indicating that seasonal behavior should be considered along with landscape and traffic characteristics to mitigate UVC.

Aliens on the Road: Surveying Wildlife Roadkill to Assess the Risk of Biological Invasion

Monitoring the presence and distribution of alien species is pivotal to assessing the risk of biological invasion. In our study, we carried out a worldwide review of roadkill data to investigate geographical patterns of biological invasions. We hypothesise that roadkill data from published literature can turn out to be a valuable resource for researchers and wildlife managers, especially when more focused surveys cannot be performed. We retrieved a total of 2314 works published until January 2022. Among those, only 41 (including our original data) fitted our requirements (i.e., including a total list of roadkilled terrestrial vertebrates, with a number of affected individuals for each species) and were included in our analysis. All roadkilled species from retrieved studies were classified as native or introduced (domestic, paleo-introduced, or recently released). We found that a higher number of introduced species would be recorded among roadkill in Mediterranean and Temperate areas with respect to Tropical and Desert biomes. This is definitely in line with the current knowledge on alien species distribution at the global scale, thus confirming that roadkill datasets can be used beyond the study of road impacts, such as for an assessment of different levels of biological invasions among different countries.

Are Roadkills Density-Dependent? Case Study of the Barn Owl (Tyto alba)

Even though birds are some of the most common road-killed animals, it remains to be determined whether avian roadkills are related to breeding numbers and breeding success, mainly due to a lack of study areas that monitor breeding populations and roadkills. We studied whether barn owl breeding numbers and breeding success are related to roadkills. We monitored yearly barn owl breeding numbers (2174 breeding attempts and 1682 adults ringed) and breeding success (9380 nestlings ringed) and monitored 95 km of roads weekly for roadkills from 2009 to 2017 in the Beit Shean and Emek Yizreel Valleys, Israel. During the study period, we documented 1073 road-killed barn owls, of which 328 were ring recoveries. The highest mortality occurred between July to September, coinciding with the barn owl post-fledging period. The number of breeding pairs and the number of nestlings ringed were positively related to the total number of barn owl roadkill, the proportion of roadkill ring recoveries, and the proportion of ring recovered roadkills in the first year of their life. First-year owls represent the majority of ringed owls, accounting for 64.6%, while adult owls compose 35.4%. Notably, a substantial fraction of adult ring recoveries, encompassing 67.2%, may pertain to floaters since we did not observe these individuals as breeding adults. Even though more females were found as roadkill ring recoveries, the proportion of male/female ring recoveries from roadkills was similar to that of adults ringed at the nest boxes. This study is the first that shows that barn owl roadkills are density-dependent and demonstrate the importance of monitoring breeding and population numbers in roadkill studies.

Anyone Can Get Old-All You Have to Do Is Live Long Enough: Understanding Mortality and Life Expectancy in European Hedgehogs (Erinaceus europaeus)

The European hedgehog is in decline, triggering a need to monitor population dynamics to optimise conservation initiatives directed at this species. By counting periosteal growth lines, we determined the age of 388 dead European hedgehogs collected through citizen science in Denmark. The overall mean age was 1.8 years (1.6 years for females and 2.1 years for males), ranging between 0 and 16 years. We constructed life tables showing life expectancies at 2.1 years for females and 2.6 years for males. We discovered that male hedgehogs were more likely to have died in traffic than females, but traffic-related deaths peaked in July for both sexes. A sex difference was detected for non-traffic deaths, as most males died in July, and most females died in September. We created empirical survivorship curves and hazard curves showing that the risk of death for male hedgehogs remains approximately constant with age. In contrast, the risk of death for females increases with age. Most of the collected road-killed individuals died in rural habitats. The degree of inbreeding did not influence longevity. These new insights are important for preparing conservation strategies for the European hedgehog.

Vertebrates' roadkill in the southern region of the Atlantic Forest, Paraná coast - Brazil

Being a significant global biodiversity hotspot, the Atlantic Forest has been drastically reduced by human activities. Among the anthropic activities that most affect the biodiversity of this biome is the construction and operation of roads and highways. Between harmful effects of these infrastructures, wildlife roadkill is currently considered one of the biggest causes of mortality of wild vertebrates. This study evaluated patterns of vertebrates' roadkill on two roads in the coastal region of the largest continuous remnant of the Brazilian Atlantic Forest. For twelve months, we carry out weekly samples with a motor vehicle at a constant speed of 40 km/h to search for carcasses along the roads. All carcasses found were georeferenced and identified to the lowest possible taxonomic level. Then, using Siriema v.2.0 software, we analyzed roadkill aggregation and the spatial distribution of hotspots of wildlife roadkill. In 43 sampling days, 209 road-killed animals were registered (average roadkill rate of 0.105 and 0.111 animals/kilometer/day for PR-407 e PR-508, respectively). Extrapolating the rates found, we estimate that about 1,773 animals can be roadkill every year on these roads. The most affected groups were birds (33.01%) and amphibians (30.62%), followed by reptiles (19.13%) and mammals (17.33%). Warmer months had the highest roadkill rates. We found two critical roadkill hotspots for the PR-407 (kilometer 11.7 to 12.5 and kilometer 14.7 to 16.7). For the PR-508, we found a critical point of 5.2 km (kilometer 5 to 10.2). As a short-term measure, we recommend installing speed reducers in the identified stretches and implementing environmental education campaigns with residents and tourists, especially during the summer months, aiming to mitigate the roadkill on both roads. However, due to the importance and environmental fragility of the area, we emphasize the need for running periodic road ecology and local wildlife population viability studies in the medium and long term.

Spatial and temporal trends in western polecat road mortality in Wales

Roads have considerable ecological effects that threaten the survival of some species, including many terrestrial carnivores. The western polecat is a small-medium sized mustelid native to Asia and Europe, including Britain where its historical stronghold is in Wales. Polecats are frequently killed on roads and road casualties represent the most common source of data on the species in the UK. However, little is known about the factors that increase the risk of collision. We used Generalized Additive Models to explore seasonal patterns in collisions as well as using Principal Component Analysis and regression modelling to identify landscape characteristics associated with polecat road casualties in Wales. Polecat road casualties had a bimodal distribution, occurring most frequently in March and October. Casualties were more frequently associated with road density, traffic volume, presence of rabbits, habitat patchiness and the abundance of proximal improved grassland habitat. Casualties were negatively associated with elevation and the abundance of semi-natural grassland habitat. The results of this study provide a framework for understanding and mitigating the impacts of roads on polecats in their historic stronghold, hence has considerable value to polecat conservation as well as broader applicability to ecologically similar species.

Using Self-Organizing Maps to find spatial relationships between wildlife-vehicle crashes and land use classes

The construction and expansion of roads cause significant impacts on the environment. The main potential impacts to biotic environment are vegetation suppression, reduction of the amount and composition of animal distribution due to forest fragmentation and increasing risks of animal (domestic and wildlife) vehicle collisions. The objective of this work was to establish a relationship between the different spatial patterns in wildlife-vehicle crash, by using spatial analysis and machine learning tools. Self-Organizing Maps (SOM), an artificial neural network (ANN), was selected to reorganize the multi-dimensional data according to the similarity between them. The results of the spatial pattern analysis were important to perceive that the point data pattern varies from an animal type to another. The events occur spatially clustered and are not uniformly distributed along the highway. SOM was able to analyze the relationship between multiple variables, linear and non-linear, such as ecological data, and established distinct spatial patterns per each animal type. In the studied area, most of the wildlife was run over very close to forest area and water bodies, and not so close to sugarcane fields, forestry and built environment. A considerable part of the wildlife-vehicle collisions occurred in areas with diverse landscape.

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

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

Citizen science and roadkill trends in the Korean herpetofauna: The importance of spatially biased and unstandardized data

Roadkills are a major threat to the wildlife in human-modified landscapes. Due to their ecology, relatively small size, and slow movement, amphibians and reptiles are particularly prone to roadkill. While standardized roadkill surveys provide valuable data for regional roadkill trends, such surveys are often resource-intensive and have limited geographic coverage. Herein, we analyzed a roadkill dataset of the Korean herpetofauna derived from the citizen science database iNaturalist and compared the overall roadkill trends detected in the iNaturalist data with standardized survey-based literature data. Our results show that the overall citizen science data provide a good picture of roadkill trends for the Korean herpetofauna in terms of recorded species. We detected both similarities and notable differences between the iNaturalist and literature data. The most notable differences between the two datasets were found in the number of recorded species, distribution across habitat types, and distribution across elevational ranges. Even with spatially biased sampling, the iNaturalist data had a considerably broader geographic coverage compared to standardized surveys. In addition, we related the presence of roadkills of amphibians and reptiles to the presence of agricultural lands, forests, and grassland. While the unstandardized nature of the citizen science data can be criticized, we argue that this feature also acts as an advantage for this type of data, as citizen science can better detect roadkills of rare species or seasonal events, such as mass migration of amphibians, and inform population trends and threats. Thus, our results highlight the importance of spatially biased and unstandardized citizen science data for roadkill detection. This study builds on previous studies demonstrating citizen science as a viable method of roadkill surveys.

Using citizen science to study a mesocarnivore: the jungle cat Felis chaus in Sri Lanka

We used citizen science and inexpensive methodology to assess the distribution of the jungle cat Felis chaus, a relatively common species in Sri Lanka but the least studied of the four wild cat species occurring in the country. We obtained three types of records of the jungle cat: geo-referenced photographs of the species from the public; sightings obtained from print and social media, and provided via an online sighting form; and sightings by field biologists. We combined the 112 unique records obtained in this way with the 21 records from the 2012 National Red List distribution map of the species, and used MaxEnt to predict habitat suitability for the species. The new sightings were primarily in drier regions, expanding the known extent of occurrence for this species in Sri Lanka. Of the new sightings, 7.1% were road kills. Distance to nearest riverine forest, annual precipitation and distance to the nearest reservoir were the most important variables explaining habitat suitability. These findings validate our hypotheses that the species is more widespread than demonstrated previously and also ranges in human-dominated landscapes outside protected areas. Our study provides a model for how ecological and behavioural information for common species can be obtained inexpensively and incorporated into species distribution models. Studies of species such as the jungle cat, which are neither threatened nor charismatic, will help ensure that we keep common species common.

Factors Affecting Roadkills of Semi-Aquatic Mammals

We previously showed that registration efforts and traffic intensity explain 90% of variation in mammal roadkill numbers, 70% of variation in the numbers of recorded species and 40% of diversity variation. Here we analyze semiaquatic mammal roadkill in Lithuania in 2002–2021, relating these to the monitoring effort. From 39,936 analyzed roadkill, the European beaver (Castor fiber) was registered 60 times, American mink (Neovison vison) 26 times, otter (Lutra lutra) 22 times and muskrat (Ondatra zibethica) 3 times. The average roadkill indexes were 0.000065, 0.00076, 0.00061 and 0.00010 ind./km/day, and the extrapolated annual roadkill for the country was 44–357, 36–456, 49–464 and 89–144 individuals, respectively. Beaver roadkill numbers correlated with the registration effort and traffic intensity, otter roadkill with registration effort only and mink with hunting bag (number of hunted individuals per year). Roadkill was not always related to proximity to water, with 38–54% of roadkill occurring over 200 m from the nearest water source. With American mink and muskrat being invasive species in the EU and otter protected in many countries, it is valuable to enhance the registrations of their roadkill (using targeted efforts by drivers, hunters or other citizen scientists) to obtain the extrapolated amount of roadkill and to use this knowledge in species management.

Roadkill mortality decreases after road inauguration

The main factors affecting specific road casualty rates are related to life-history traits, road features, and landscape variables. After road inauguration, roadkill rate and spatial and temporal patterns can change substantially due to changes in traffic intensity, avoidance behaviour or local population decline. Despite the Canary Islands constituting a biodiversity hotspot, Canarian ecosystems are highly threatened because of the high human density, and studies on anthropogenic sources of mortality of wildlife are scarce. Here, we counted roadkills during two annual cycles after the inauguration of an 8.8-km-road section on Tenerife, the largest and most densely populated island of the Canaries. We counted 694 roadkills belonging to a minimum of 19 species of birds and six species of introduced mammals. Seasonal variation was apparent during both annual cycles, particularly for birds, being the majority of victims concentrated in May and June. Although traffic intensity increased since road inauguration, the number of roadkills decreased significantly in the second annual cycle. The reduction in road mortality in the second cycle could be related to some non-mutually exclusive factors such as population decline, road avoidance, or weather conditions. As road networks of the Canary Islands are still increasing, further studies quantifying road mortality impacts on Canarian ecosystems and threatened species are urgently needed to guarantee the management and conservation of its fragile wildlife.

Behavioural reactions to oncoming vehicles as a crucial aspect of wildlife-vehicle collision risk in three common wildlife species

Wildlife-vehicle collisions (WVC) strongly impact road safety. While technical aspects of collision risk and the effects of roads on animal populations are well studied, knowledge about wildlife behaviour prior to and during contact with oncoming vehicles as a crucial aspect of collision risk is still lacking. We analysed 28,400 hours of video data (thermal network cameras at 14 road sections in south-west Germany) with 2,841 animal-vehicle encounters (1,960 roe deer, Capreolus capreolus, 696 red fox, Vulpes vulpes and 185 wild boar, Sus scrofa) and classified animal behaviour before and during contact with a vehicle. We fitted two sets of models to the data. In the first step, we modelled the intensity of the behavioural reaction exhibited by the animals as a function of behavioural and environmental predictors using ordinal Bayesian mixed-effect regression models. In a second step, we modelled the probability of a positive vs. a negative behavioural response in terms of WVC risk using binomial mixed-effect regression models. Both the intensity of behavioural reactions as well as the degree of risk during the interaction with oncoming vehicles differed among the species and as a function of road section layout. Our results showed that animal attentiveness, the behaviour a priori, access to cover, vehicle type and biological seasonality were important predictors of an animal's response to oncoming vehicles. More specifically, roe deer reacted to oncoming vehicles mostly with short movements away from the road, foxes often reacted unpredictably and wild boar behaviour appeared to be least affected by oncoming vehicles. Thus, we suggest that collision risk for common European mammals is shaped by the interplay of vehicle type, the road layout as well as the species-specific behavioural repertoire including the attentiveness of the animal and the behavioural state prior to an approaching vehicle. In addition, wildlife warning reflectors, a frequently used technique in WVC mitigation, did not alter behavioural reactions and thus failed to reduce WVC risk.

Ecological Solutions for Linear Infrastructure Networks: The key to green infrastructure development

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‘Animals under wheels’: Wildlife roadkill data collection by citizen scientists as a part of their nature recording activities

‘Animals under wheels’ is a citizen science driven project that has collected almost 90,000 roadkill records from Flanders, Belgium, mainly between 2008 and 2020. However, until now, the platform and results have never been presented comprehensively to the scientific community and we highlight strengths and challenges of this system. Data collection occurred using the subsite www.dierenonderdewielen.be (‘animals under wheels’) or the multi-purpose biodiversity platform observation.org and the apps, allowing the registration of roadkill and living organisms alike. We recorded 4,314 citizen scientists who contributed with at least a single roadkill record (207-1,314 active users per year). Non-roadkill records were registered by 85% of these users and the median time between registration of the first and last record was over 6 years, indicating a very high volunteer retention. Based on photographs presented with the roadkill records (n = 7,687), volunteer users correctly identified 98.2% of the species. Vertebrates represent 99% of all roadkill records. Over 145,000 km of transects were monitored, resulting in 1,726 mammal and 2,041 bird victims. Carcass encounter rates and composition of the top 10 detected species list was dependent on monitoring speed. Roadkill data collected during transects only represented 6% of all roadkill data available in the dataset. The remaining 60,478 bird and mammal roadkill records were opportunistically collected. The top species list, based on the opportunistically collected roadkill data, is clearly biased towards larger, enigmatic species. Although indirect evidence showed an increase in search effort for roadkill from 2010-2020, the number of roadkill records did not increase, indicating that roadkills are diminishing. Mitigation measures preventing roadkill could have had an effect on this, but decrease in population densities was likely to (partially) influence this result. As a case study, the mammal roadkill data were explored. We used linear regressions for the 17 most registered mammal species, determining per species if the relative proportion per year changed significantly between 2010 and 2020 (1 significant decrease, 7 significant increases). We investigated the seasonal patterns in roadkill for the 17 mammal species, and patterns per species were consistent over the years, although restrictions on human movement, due to COVID-19, influenced the seasonal pattern for some species in 2020. In conclusion, citizen scientists are a very valuable asset in investigating wildlife roadkill. While we present the results from Flanders, the platform and apps are freely available for projects anywhere in the world.

Anthropause Opportunities: Experimental Perturbation of Road Traffic and the Potential Effects on Wildlife

The SARS-CoV-2 pandemic severely reduced many human activities. So pronounced was the change, it has given rise to the term “anthropause”: the considerable alteration of modern human activities. Among these was surface transportation, with prolonged traffic reductions, in excess, of 50% in many countries. Roads and traffic are responsible for functionally fragmenting ecosystems, wildlife populations, and species interactions. The unintentional “dialing-down” of traffic has given continuous monitoring systems of wildlife-vehicle conflict a unique opportunity to study the consequences of perturbing this source of wildlife disturbance and mortality. Experimental manipulation of traffic at the global scale would not have been possible without mitigation responses to SARS-CoV-2. Such a perturbation allows robust empirical investigation into wildlife responses to traffic, including changes in mortality, behavior, genetic connectivity, and knock-on ecosystem effects, the responses to which can be replicated across a global network of wildlife-vehicle conflict monitoring systems. We review the extent to which these extensive data-collection systems provide the primary source of data to study many of these responses, providing the raw material to understand some striking wildlife consequences of the anthropause.

Long Arm of Motorway-The Impact of Fenced Road on the Mortality of European Badgers

We studied the impact of the new fenced and accident-safe motorway on the mortality of European badgers Meles meles on local roads in western Poland in 2010-2015. We monitored the badgers mortality on local roads of three categories: main roads, secondary roads and county roads. The study was conducted before and after the opening of the motorway in 2012. We hypothesized that the mortality of badgers is lower due to traffic concentration on motorway. Ninety two badgers were killed in collisions with vehicles on all monitored roads. Mean number of killed badgers was lowest in 2010 before the motorway opening and the highest in 2012. The mortality of badgers on regional roads was highest after the opening of the motorway due to the changes in traffic on the access roads. Within the road network, the mortality of badgers was 5.8 individuals/10 km of road per whole study period with the highest rate on main roads 8.5 individuals/10 km. The badgers mortality was highest on county roads but it was lower than expected in relation to the road network density. The highest vehicle collision risk for badgers of both sexes occurred in June. Distance to human settlements was the only environmental factor that was positively related to badger mortality on roads. We conclude that the new motorway did not reduce the mortality rate of badgers on the adjacent roads because the status of local roads has changed and now they mainly function as access roads to the motorway.

Wildlife at the crossroads: wild animal road kills due to vehicular collision on a mountainous highway in northwestern Himalayan region

Wildlife mortality due to vehicular collision is well known across the world and the number of such incidences is steadily rising in Himalaya as well. To assess the quantum of wildlife road kills, we conducted an intensive survey spanning 33 months along a mountainous National Highway 244 in the Union Territory of Jammu & Kashmir. Forty-nine wild animal carcasses of 13 species of higher vertebrates were observed lying on the road, shoulders, edges, and valley slopes. These included seven mammals, four birds, and two reptiles. This survey, first of its kind in this part of the Himalaya would be helpful in understanding the underlying reasons of the rising wildlife fatalities on the hill roads, identifying susceptible hotspots, and developing measures to address this new threat to Himalayan wildlife. We recommend creating wildlife passages, raising speed halters, and placing warning signages in vulnerable sections to reduce the road-related wildlife mortality in such mountainous highways.

Assessing the Relative Impacts of Roadkill and Nest Poaching on the Population Viability of the Blue-and-Yellow Macaw, Ara ararauna (Aves: Psittaciformes), in a Brazilian National Park

The blue-and-yellow macaw (Ara ararauna) is suffering from higher roadkill rates (RK) at the Emas National Park (ENP), an important Brazilian National Park in the Cerrado biome. This species is also a victim of nest poaching for illegal trade. We modeled the blue-and-yellow macaw population’s viability in ENP and how this viability is affected by roadkill and nest poaching. We hereby report that the species is critically at risk and could be extinct in about a decade when considering both threats. Without considering any threat, 150 individuals are necessary to maintain a viable population. When individuals are harvested at a roadkill rate of 0.008 individuals/km/year and at twice this level, the viability figures increase to 4500 and 7500 birds, respectively. For nest poaching, we estimated that 2000 individuals are required to maintain a viable population. When both threats are present, 5000 individuals are necessary. The dynamics of the population are highly sensitive to the age at which females reproduce for the first time and the proportion of reproducing adult females, followed by the rate of adult survival. Our model demonstrates how even a non-threatened highly mobile species, such as the blue-and-yellow macaw, may be at risk due to human activities.

A decrease in reports on road-killed animals based on citizen science during COVID-19 lockdown

BACKGROUND

To avoid the uncontrolled spread of COVID-19 in early 2020, many countries have implemented strict lockdown measures for several weeks. In Austria, the lockdown in early spring has led to a significant drop in human outdoor activities, especially in road traffic. In Project Roadkill, a citizen science project which aims to collect data on road-killed animals, we observed a significant decrease in reported roadkills.

METHODS

By asking the citizen scientists through a survey how their travelling routines were affected, we investigated if the observed decrease in roadkills was grounded in less animals being killed by traffic, or in citizen scientists staying at home and thus reporting less road-killed animals.

RESULTS

A majority of the respondents stated that they felt to have reported less roadkills during the lockdown, regardless if they changed their travelling routine or not. This observation in combination with the overall decrease in road traffic indicates that fewer animals were killed during the lockdown. We conclude that when analyzing citizen science data, the effects of lockdown measures on reporting behaviour should be considered, because they can significantly affect data and interpretation of these data.

Stepping up from wildlife disease surveillance to integrated wildlife monitoring in Europe

In a context of disease emergence and faced with the ever-growing evidence of the role of wildlife in the epidemiology of transmissible diseases, efforts have been made to develop wildlife disease surveillance (WDS) programs throughout Europe. Disease monitoring is ideally composed of "numerator data" (number of infected individuals) and "denominator data" (size of the target population). Too often however, information is available for only one. Hence, there is a need for developing integrated and harmonized disease and population monitoring tools for wildlife: integrated wildlife monitoring (IWM). IWM should have three components. Passive disease surveillance improves the likelihood of early detection of emerging diseases, while active surveillance and population monitoring are required to assess epidemiological dynamics, freedom of disease, and the outcome of interventions. Here, we review the characteristics of ongoing WDS in Europe, observe how pathogens have been ranked, and note a need for ranking host species, too. Then, we list the challenges for WDS and draw a roadmap for stepping up from WDS to IWM. There is a need to integrate and maintain an equilibrium between the three components of IWM, improve data collection and accessibility, and guarantee the adaptability of these schemes to each epidemiological context and temporal period. Methodological harmonization and centralization of information at a European level would increase efficiency of national programs and improve the follow-up of eventual interventions. The ideal IWM would integrate capacities from different stakeholder; allow to rapidly incorporate relevant new knowledge; and rely on stable capacities and funding.

Roadkills as a Method to Monitor Raccoon Dog Populations

The raccoon dog (Nyctereutes procyonoides) is one of the most frequently killed species on Lithuanian roads. As an invasive species, up-to-date knowledge of population size, trends and spatial distribution is critically important both for species assessment and for the planning of control measures. In Lithuania, however, raccoon dog surveys have not been carried out since 1997. We investigated, therefore, whether roadkill counts on predefined routes could be used as a proxy for a survey. Our dataset includes survey numbers for the period 1956-1997, hunting bag sizes for 1965-2020 (including the spatial distribution of the hunting bag in 2018-2020) and roadkill data relating to 1551 individuals between 2002-2020. At the most local scale, that of the hunting areas of hunting clubs, correlations between the numbers of hunted and roadkilled individuals were negative and insignificant or absent. At the country scale, however, we found significant correlation both between the numbers surveyed and hunted in 1965-1997 (r = 0.88), and between those hunted and the number of roadkills in 2002-2020 (r = 0.56-0.69). Therefore, we consider that roadkill counts on predefined and stable routes may be used as a proxy for a survey at the country scale. Practical implementation of the method is proposed.

Implications for conservation and game management of the roadkill levels of the endemic Iberian hare (Lepus granatensis)

The Iberian hare (Lepus granatensis) is an important small game species endemic to the Iberian Peninsula for which the incidence of roadkill is unknown. We surveyed Iberian hare-vehicle accidents on road networks in southern Spain, focusing on roads that mainly run through favorable habitats for this species: Mediterranean landscapes with plots of arable crops, olive groves, and vineyards. We recorded roadkills over a 5-month period, estimated hare accident densities on roads, and compared these numbers to hare hunting yields in adjoining hunting estates. We also analyzed the spatial patterns of and potential factors influencing hare roadkills. We detected the existence of black spots for hare roadkills in areas with high landscape heterogeneity that also included embankments and nearby crossroads and had high traffic intensity. Hare roadkill levels ranged from 5 to 25% of the annual harvest of hares killed on neighboring hunting estates. We suggest that road collisions should be considered in Iberian hare conservation in addition to hunting, since they may represent an additive source of mortality. Game managers should address the issue of hare roadkill in harvest planning to compensate for hare accidents, adjusting hunting quotas to account for this unnatural source of mortality. Our results suggest future directions for applied research in road ecology, including further work on demographic compensation and roadkill mitigation.

A Method Scope Extension for the Simultaneous Analysis of POPs, Current-Use and Banned Pesticides, Rodenticides, and Pharmaceuticals in Liver. Application to Food Safety and Biomonitoring

The screening of hundreds of substances belonging to multiple chemical classes in liver is required in areas such as food safety or biomonitoring. We adapted a previous QuEChERS-based method in blood to the liver matrix and applied to these fields of study. The validation of the method allowed the inclusion of 351 contaminants, 80% with a LOQ < 2 ng/g. In the analysis of 42 consumer liver samples, we detected trace levels of 29 different contaminants. The most frequent and concentrated was 4,4’-DDE. POPs accounted for 66% of the compounds detected. In no case was the MRL reached for any of the contaminants detected. We also applied the method to 151 livers of wild birds to perform a biomonitoring pilot study in the Canary Islands. We detected 52 contaminants in 15 bird species. These were also mostly POPs, although high frequencies and concentrations of anticoagulant rodenticides (AR) and some other agricultural pesticides also stand out. POPs and AR contamination levels were significantly higher in terrestrial birds, raptors and particularly in nocturnal birds. Pesticide contamination levels were also higher in terrestrial birds, as well as in non-raptors and diurnal birds. The validated method is simple, robust, and sensitive and performs well in a variety of practical scenarios, where it can be carried out relatively quickly and inexpensively.

The distribution of American mink (Neovison vison) in Greece

The distribution of the American mink in the wild, originating either from accidental escapes or intentional releases from fur farms, was mapped for the first time in Greece, based on opportunistic data collected from 2010 to 2020. Greece is a key actor in Europe’s fur industry, with most mink farms operating in the northwest. Massive intentional releases by activists took place in the late 2000s, while accidental escapes regularly occur. Most mink were recorded in the Region of Western Macedonia, in NW Greece, within and around the core areas of fur farms, where feral populations became established. Animals were also found further south in the Regions of Thessaly (central Greece) and Central Macedonia (northern Greece). Half of mink records were close to protected areas and almost two-thirds near to watercourses. Many animals were away from the water and on high altitudes, with theoretically less favourable conditions for their survival. We also examine possible directions of further mink range expansion in Greece and neighbouring countries through the river network. Mink invasion progress in Greece is little known, thus, the subject is in urgent need of study, as mink is the alien mammal with the highest impact on the European native fauna.

Exploring hybrid consensus models to assess roadkill

Accurate information provided by reliable models is essential for identifying hotspots and mitigating roadkill. However, existing methods, such as kernel density estimation (KDE) and maximum entropy modeling (ME) may individually identify only a subset of the suitable locations for mitigation, because KDE cannot detect hotspots once local abundances are depressed, and ME may only partially identify current hotspots due to imperfect discrimination skill. Here, we propose a hybrid consensus modeling (HCM) approach that leverages the strengths of both KDE and ME by using their consensus to identify the core subset of hotspots. We collected herpetofauna (amphibians and reptiles) roadkill data (N = 839) along four roads in Taiwan (R.O.C.) to evaluate the statistical performance and theoretical mitigation efficiency of HCM, KDE and ME, and to compare the allocation among roads, spatial clustering, and environmental conditions in the identified hotspots. HCM was applied on the herpetofauna dataset as well as separately on amphibians and reptiles. Although the discrimination skill of KDE and ME models for both target clades together was good to excellent (AUC_KDE = 0.944, AUC_ME = 0.822), the highest theoretical mitigation efficiency, was displayed by HCM Consensus (2.89), followed by KDE (2.58), and ME (1.91). Furthermore, we show that theoretical mitigation efficiency increases with decreasing spatial clustering (Moran's I). Given pervasive budget constraints, we recommend to limit permanent mitigation measures such as fenced culverts to HCM Consensus hotspots, temporary measures to KDE hotspots, and to target additional monitoring at ME hotspots.

A comparison of microsatellites and genome-wide SNPs for the detection of admixture brings the first molecular evidence for hybridization between Mustela eversmanii and M. putorius (Mustelidae, Carnivora)

Introgressive hybridization can pose a serious threat to endangered species which have an overlapping distribution such as in the case of two polecat species, Mustela eversmanii and M. putorius, in Europe. The population size of steppe polecat is known to continuously shrink, whereas its sister species, the European polecat, is still somehow widespread. In this study, we perform an analysis using microsatellite (SSR) and genomic (SNP) data sets to identify natural hybrids between polecats. Four populations were genotyped for eight polymorphic SSR loci, and thousands of unlinked SNPs were generated using a reduced-representation sequencing approach, RADseq, to characterize the genetic make-up of allopatric populations and to identify hybrids in the sympatric area. We applied standard population genetic analyses to characterize the populations based on their SSR allelic frequency. Only a single sample out of 48 sympatric samples showed exact intermediacy that we identified as an F1 hybrid. Additionally, one specimen was indicated in the genomic data sets as backcrossed. Other backcrosses, indicated by SSRs, were not validated by SNPs, which highlights the higher efficacy of the genomic method to identify backcrossed individuals. The low frequency of hybridization suggests that the difference in habitat preference of the two species may act as a barrier to admixture. Therefore, it is apparently unlikely that polecat populations are threatened by significant introgression. The two species showed a clear genetic differentiation using both techniques. We found higher genetic diversity values in the sympatric steppe polecat population than in the other studies on polecat populations. Although M. putorius is a hunted species in most countries, genetic diversity values indicate worse conditions in Europe than in the protected sibling species M. eversmanii. Suspending hunting and providing protected status of the former seems to be reasonable and timely.

Optimising the cost of roadkill surveys based on an analysis of carcass persistence

Reliable estimates of wildlife mortality due to wildlife-vehicle collisions are key to understanding its impact on wildlife populations and developing strategies to prevent or reduce collisions. Standardised approaches for monitoring roadkill are needed to derive robust and unbiased estimates of mortality that are comparable across different study systems and ecological contexts. When designing surveys, there is a trade-off between survey frequency (and hence logistical effort and financial cost) and carcass detection. In this regard, carcass persistence (the period a carcass remains detectable before being removed by decomposition or scavengers) is important; the longer a carcass persists, the greater the likelihood it will be detected with lower survey effort by conducting more infrequent surveys. Using multi-taxon carcass data collected over a month of repeated driven surveys, combined with five covariates (species functional group, body weight, carcass position on road, carcass condition [either flattened or not after impact], and rainfall prior to each survey), we explored the drivers of carcass persistence with the overall aim of providing information to optimise the design of carcass surveys along linear infrastructure. Our methodological approach included a survival analysis to determine carcass persistence, linear regressions to test the effect of covariates, a subsampling analysis (using field data and a simulation exercise) to assess how the proportion of carcasses detected changes according to survey frequency, and an analysis to compare the costs of surveys based on study duration, transect length and survey frequency. Mean overall carcass persistence was 2.7 days and was significantly correlated with position on road and within-functional group body weight. There was no evidence for a significant effect of rainfall, while the effect of carcass condition was weakly non-significant. The proportion of carcasses detected decreased sharply when survey intervals were longer than three days. However, we showed that survey costs can be reduced by up to 80% by conducting non-daily surveys. Expanding on the call for a standardised methodology for roadkill surveys, we propose that carcass persistence be explicitly considered during survey design. By carefully considering the objectives of the survey and characteristics of the focal taxa, researchers can substantially reduce logistical costs. In addition, we developed an R Shiny web app that can be used by practitioners to compare survey costs across a variety of survey characteristics. This web app will allow practitioners to easily assess the trade-off between carcass detection and logistical effort.

Stable Isotope Analysis of Specimens of Opportunity Reveals Ocean-Scale Site Fidelity in an Elusive Whale Species

Elusive wildlife are challenging to study, manage, or conserve, as the difficulty of obtaining specimens or conducting direct observations leads to major data deficiencies. Specimens of opportunity, such as salvaged carcasses or museum specimens, are a valuable source of fundamental biological and ecological information on data-deficient, elusive species, increasing knowledge of biodiversity, habitat and range, and population structure. Stable isotope analysis is a powerful indirect tool that can be used to infer foraging behavior and habitat use retrospectively from archived specimens. Beaked whales are a speciose group of cetaceans that are challenging to study in situ, and although Sowerby's beaked whale (Mesoplodon bidens) was discovered &gt;200 years ago, little is known about its biology. We measured δ13C and δ15N stable isotope composition in bone, muscle, and skin tissue from 102 Sowerby's beaked whale specimens of opportunity collected throughout the North Atlantic Ocean to infer movement ecology and spatial population structure. Median δ13C and δ15N values in Sowerby's beaked whale bone, muscle, and skin tissues significantly differed between whales sampled from the east and west North Atlantic Ocean. Quadratic discriminant analysis that simultaneously considered δ13C and δ15N values correctly assigned &gt;85% of the specimens to their collection region for all tissue types. These findings demonstrate Sowerby's beaked whale exhibits both short- and long-term site fidelity to the region from which the specimens were collected, suggest that this species is composed of two or more populations or exhibits a metapopulation structure, and have implications for conservation and management policy. Stable isotope analysis of specimens of opportunity proved a highly successful means of generating new spatial ecology data for this elusive species and is a method that can be effectively applied to other elusive species.