Number Of Roadkills Research Articles

Roe Deer, Lithuania’s Smallest and Most Abundant Cervid

A review of 113 scientific and other publications on the smallest and most abundant deer in Lithuania, the roe deer (Capreolus capreolus), is presented, along with an analysis based on compound annual population growth rates of population numbers, hunting bags, and roadkill. This review covers the species’ history in the country from the last glaciation onwards, the changes in numbers from 1934 to 2023, hunting bag changes from 1965 to 2022, roadkill numbers from 2002 to 2022, data on roe deer reproduction, habitat selection, genetic diversity, pathogens, and damage to forest stands. It also provides an overview of species management and selection for trophies. Despite the exponential increase in roe deer numbers since 1990 and the dominance of this species in roadkill, even on urban roads, the number and density of animals and the damage they cause to forest stands are relatively low compared to other European countries. Within the observed period, drops in numbers were related to harsh winters in 1969/1970 and 1995/1996. Poaching, especially coinciding with weakened enforcement during the period of political–economic transition in the early 1990s, has also had a negative impact on population numbers, as have recent increases in the number of large predators. Population growth over the recent period does not correlate with hunting mortality, which has remained stable at an average of 16.9% since 2002.

Mammal Roadkills in Lithuanian Urban Areas: A 15-Year Study.

We investigated roadkills in urban areas in Lithuania from 2007 to 2022, including two periods with COVID-19 restrictions on people's movement. We analyzed the proportions of wild and domestic animals in roadkill, annual trends, the predominant species involved, and monthly changes during the restrictions. Urban roads were characterized by a low species diversity of roadkilled mammals, with roe deer (Capreolus capreolus) dominating. Total numbers increased exponentially during the study period. The proportion of domestic animals, 12.2%, significantly exceeded that on non-urban roads in the country. The proportion of domestic animals decreased from over 40% in 2007-2009 to 3.7-5.4% in 2020-2022, while the proportion of wild mammals increased from 36.1-39.6% to 89.9-90.6%, respectively. During the periods of COVID-19 restrictions, the number of roadkills in urban areas was significantly higher than expected based on long-term trends. Compared to 2019, the number of roadkilled roe deer in 2020-2021 almost doubled from 700 to 1281-1325 individuals. These anthropause effects were, however, temporary. The imbalance between the roadkill number and transport intensity might require new mitigation strategies to sustain mammal populations in urban areas, at least through improving driver awareness on the issue.

Lockdown's Silver Lining? Different Levels of Roadkill during the COVID-19 Times in Lithuania.

The impact of COVID-19 restrictions on human and vehicular mobility on the number of roadkills of wild mammals, and roe deer in particular, was assessed in Lithuania. We statistically analyzed the distribution of all mammals and roe deer (Capreolus capreolus) as the most abundant species annually from 2002 to 2022 and monthly from 2020 to 2021, including during the two restriction periods. Notably, there was a marked decrease in roadkill incidents on main, national and regional roads, particularly in April-May 2020 (the beginning of lockdown period I) and November-December 2020 (the beginning of lockdown period II), 5.1-20.8% and 33.6-54.4%, respectively. During these months, collisions with mammals on the A14 main road were reduced by 75-90%. However, there was a significant increase in the number of roadkills in urban areas, resulting in the total number of mammal-vehicle and roe deer-vehicle collisions in 2020 and 2021 being higher than expected based on long-term trends. However, after restrictions were eased, collision numbers with wildlife on the main, national and regional roads increased again and became higher than expected.

Immediate impact of fires on roadkilling of wild vertebrates on a highway in southeast Brazil

Fires cause wild vertebrates to try to escape, thereby leading to an increase in attempts to cross roads and consequently an increase in the number of roadkills. However, the study of the impact of fires on roadkilling of wild vertebrates is practically nonexistent. In this study, we analyzed the relationship between fires near a 180 km highway stretch in Southeast Brazil and wild vertebrate roadkills using a 7-year dataset on roadkills and satellite data on fires, hypothesizing that roadkills would increase after fires. We found that the number of roadkilled wild vertebrates increased by about 144% (P = 0.020) in highway sections up to 1 km from fires, within 7–8 days after the fires. The number of roadkills in highway sections affected by fires was also higher than that of neighboring (control) section (P = 0.028). Taken together, these results show there was a significant increase in the number of roadkills on road sections close to or within burned areas. This work emphasizes the importance of analyzing the synergistic effects of fires and roadkill of wild vertebrates and guides research on adopting an experimental design which allows for temporal and spatial controls using retrospective data on fires and roadkilling. We recommend decreasing traffic flow and/or vehicle speed near areas recently affected by fires, as a preventive management strategy.

Road mortality in the blue‐black grassquit (Volatinia jacarina) is seasonally driven and sex‐biased

AbstractRoads are responsible for different negative effects on wildlife, including the isolation of populations and the direct reduction of biodiversity. Millions of animals are killed in traffic every year. Despite that, the influence of animal behaviour on the probability of animal‐vehicle collisions has been overlooked by the literature. The blue‐black grassquit (Volatinia jacarina) is a small, migratory, dichromatic species. During the breeding period, males vigorously defend small, clustered territories. Here, we investigated how the number of roadkills varied spatially and temporally in relation to the breeding activity, density, and sex of grassquits. We demonstrated that the variation in the movement dynamics and reproductive behaviour of the grassquits are associated with a great number of casualties. Road mortality is higher during the breeding period but is not associated with juvenile dispersion. As expected, males have a higher probability of being road‐killed than females, suggesting that territory defence and mate searching may increase the risk of mortality. On the other hand, the clustering of individuals may not increase the risk of road fatalities, suggesting that other environmental attributes may influence the probability of being killed on roads.

Impact of Road Traffic on Mysore Slender Loris Loris lydekkerianus lydekkerianus in Keelaveliyur, Tamil Nadu, India

Roads directly affect the wildlife by mortality through collisions with vehicles. Mysore slender loris Loris lydekkerianus lydekkerianus is distributed in drier regions of southern India. The present paper deals with the impact of road traffic on Mysore slender loris in Keelaveliyur, Tamil Nadu, India. Road kills were recorded from four roads varied in distance from 8 km to 11 km: Keelaveliyur to Thogaimalai, Keelaveliyur to Melapatti, Keelaveliyur to Othakadai, and Keelaveliyur to Pathiripatti. In total, 41 lorises, consisting of 21 adult females, 12 adult males, three subadult females, and five subadult males, were found killed on road by the road traffic from January 2017 to December 2021. Of the four roads differed in traffic volume, more number of roadkills was found on Keelaveliyur to Othakadai road, followed by Keelaveliyur to Pathiripatti, Keelaveliyur to Melapatti, and Keelaveliyur to Thogaimali. Keelaveliyur to Pathiripatty, though with lesser vehicular traffic, was found with more number of roadkills and can be attributed to the availability of more number of trees not only along the roadside but also perpendicular to the road. Besides, abundance of loris was more along this roadside. Extensive removal of trees along the roadside for developmental activities not only reduced the availability of trees but also the population of loris in and around Keelaveliyur in recent years.

Hotspots and hotmoments of wildlife roadkills along a main highway in a high biodiversity area in Brazilian Amazonia

ABSTRACT Wildlife roadkills have become a concern in the Amazon biome due to the opening of major roads in recent decades. In this study, we aimed to describe wildlife roadkills in a 100-km stretch of the BR-163 highway, in western Pará state, determining which vertebrate groups are most affected and whether there are spatial (hotspots) and temporal (hotmoments) aggregations of roadkills. From July 2019 to June 2020, we carried out 25 surveys at 15-day intervals, from a vehicle at a maximum speed of 40 km h-1. We recorded 351 individuals at an observed rate of 0.14 ind km-1 day-1. Despite their lower detectability and faster carcass removal rate from the road due to small size, most recorded roadkills were amphibians (0.066 ind km-1 day-1). We mapped several hotspots along the study stretch considering the total number of animals recorded, and separately for amphibians and reptiles. Multiple linear regression analyses indicated that the number of roadkills of all vertebrates, amphibians and reptiles recorded are influenced by temperature and precipitation. Information on places with the highest incidence of roadkills can support actions such as the installation of underpasses and fences, aimed at reducing the impacts on wild vertebrates of this Amazonian highway.

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.

Estimating roadkill rates while accounting for carcass detection and persistence using open-population capture–recapture models

Context Accurately estimating wildlife roadkill is necessary to compare different roads, periods, and species, and to plan and assess mitigation effectiveness. We must account for the two main sources of errors associated with carcass sampling – carcass detection and persistence. Open-population models are used to estimate abundance, survival probabilities, and recruitment in living animal populations, accounting for imperfect detection, and they can be used in the context of animal fatalities. Aims The aim of this study was to explore an open-population approach to estimate comparable roadkill rates from carcass capture–recapture data, accounting for carcass detection and persistence. Methods We surveyed carcasses of the white-eared opossum (Didelphis albiventris) and black-and-white tegu lizard (Salvator merianae) on four road stretches using two sampling designs with different number of visits and sampling sessions. Carcasses were marked to be recaptured over visits within the same sampling session, resulting in a capture history for each carcass. Encounter history data were modelled using the superpopulation formulation of the open-population capture–recapture model under Bayesian inference for different datasets. A daily roadkill rate per kilometre was derived from the model entry probability estimate. Key results We estimated a daily roadkill rate with 1501 captures from 447 opossum carcasses and 511 captures from 218 tegu carcasses. For full data, mean carcass detection over the sessions ranged from 0.49 to 0.85 for the opossum and from 0.27 to 0.80 for the tegu, and mean carcass persistence ranged from 0.60 to 0.94 for the opossum and from 0.64 to 0.91 for the tegu. Scenarios with more occasions and captures increased precision of roadkill rates. Conclusions We were able to explicitly estimate roadkill rates using an open-population capture–recapture model under a Bayesian framework. It provides accurate roadkill numbers for a known time frame and road extension, accounting for imperfect detection and its associated uncertainty. Under scenarios of few carcasses, users should consider a higher number of occasions. Implications Not addressing carcass sampling errors or simplistically addressing them (e.g. only once during the study period) could mislead mitigation efforts. The approach used here can be used to estimate fatalities in other locations, such as windfarms and powerlines, for which repeated observations of marked carcasses are an option.

Spatial and temporal distribution of bat mortality on a highway in southeast Brazil

Roads and highways can work as barriers to the movement of many species, thereby preventing the individuals from accessing feeding and reproduction sites and the immediate risk of colliding wild species with vehicles. Identifying the impacts of roads on wildlife can contribute to the establishment of actions that promote conservation. In Brazil, data on collisions between bats and vehicles are scarce and underestimated in the literature. We described bat roadkill from 2008 to 2019 on a stretch of the BR-040 highway, which crosses an area of Atlantic Forest. Roadkill species were identified and the sites with high collision frequencies were characterized. A total of 923 individuals of 57 species and five families of chiropterans were identified. Frugivore bats showed the largest number of affected individuals, with Artibeus lituratus, a common species in the study region, with the highest number of roadkills. The diet and foraging behaviour were the most likely factors explaining most of the bats killed on the highway. The highest roadkill rate was documented in the fall, and the critical points located nearby the APA Petrópolis and REBIO of Tinguá, environmental protection areas. We reinforce the need to mitigate these roadkills, ensuring that road systems, which constitute municipal, state and federal highways, are built to prevent major disturbance of habitat and displacement routes of these species. We believe in the need for mitigations, and considering the various species involved, we suggest speed bumps construction reducing the speed limit, installing bridges, and signaling the presence of wildlife, before the stretches identified as hotspots.

Factors Affecting Roadkills of Semi-Aquatic Mammals.

Simple SummarySemiaquatic mammal roadkill, specifically the European beaver, Eurasian otter, American mink and muskrat was analyzed in Lithuania in the period 2002–2021. From almost 40,000 recorded roadkill cases for all species, these species were registered 60, 22, 26 and 3 times, respectively, thus being rare events. Registered beaver roadkill numbers correlated with an increased registration effort and traffic intensity, while otter roadkill correlated with a registration effort only, and mink roadkill correlated with an increased population (estimated through its proxy and the number of hunted individuals per year). The roadkill was not always in close proximity to waterbodies, with 38–54% of roadkill of these species occurring over 200 m from the nearest water source. With the American mink and muskrat being invasive species in the EU and the Eurasian otter protected in many countries, it could be considered valuable to enhance the registrations of their roadkill (using targeted efforts by drivers, hunters or other citizen scientists) in order to obtain the extrapolated amount of roadkill and to use this knowledge in species management.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.

Differences in Wildlife Roadkill Related to Landscape Fragmentation in Central Brazil.

The interaction between animal movement and roads is pervasive, but little is known of the effects of the land-use patterns in roadside landscapes on roadkill events. Here, we compared wildlife roadkill along two road stretches that cross landscapes with different land-use patterns, including the presence of protected areas in Central Brazil. Sampling was conducted in 2017 and 2018 in two seasons (dry and rainy). We expected roadkill events to be more frequent bordering the protected area. Roadkill occurred more frequently in the rainy season in the unprotected landscape. Birds were most frequently recorded in the unprotected (44%, n = 76) than in the protected landscape (37%, n = 48). The least recorded group in the unprotected landscape was Squamata (11%, n = 18), while mammals were less detected in the protected landscape (14%, n = 18). Classes 'agriculture' and 'savanna' were related to amphibian roadkill numbers. For Squamata, we observed the effect of the presence of forests in the protected landscape. Bird roadkill was affected by protection level, while the presence of pasture and the level of protection explained mammal roadkill. Differences in roadkill patterns reinforce the need for long-term management of this source of mortality for the Cerrado fauna.

Decreased traffic volume during COVID-19 did not reduce roadkill on fenced highway network in Japan

The COVID-19 pandemic has significantly reduced human activities through city lock-downs and restricted traffic flows. It had been suggested that roadkill occurrences are strongly associated with traffic volume. I evaluated the association between traffic volume and roadkill during COVID-19, from March to May 2020, using 26,130 roadkill data points recorded from the highway network in Hokkaido from 2010 to 2020, Japan. Results showed that there was a significant positive correlation between roadkill numbers and traffic volume over the past decade. However, the roadkill during COVID-19 restricted human activity did not diminish, although traffic volume decreased during this period.

Roadkills as a Method to Monitor Raccoon Dog Populations.

Simple SummaryThe raccoon dog (Nyctereutes procyonoides) is a highly invasive species, therefore knowledge regarding the population size, trends and spatial distribution is important for species assessment and for the planning of control measures. In Lithuania, however, as such surveys would require the concerted action of many hunting clubs, raccoon dog surveys have not been carried out since 1997. In this study, we investigated whether roadkill data for the species could be used as a means for monitoring the population. For the period in which surveys were conducted, we found a strong correlation between the numbers surveyed and the numbers of animals hunted and between those hunted and the number of roadkills. Therefore, we consider that roadkill counts may be used as a proxy for a survey at the countrywide scale. Practical implementation of the method is proposed.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.

Spatio‐temporal analysis of kangaroo–vehicle collisions in Canberra, Australia

SummaryOver the last 30 years, there has been a steady increase in the number of kangaroo–vehicle collisions in Canberra, in the Australian Capital Territory (ACT), especially of the Eastern Grey Kangaroo (Macropus giganteus). Motor vehicle collisions with kangaroos are a threat to people and kangaroos, causing not only costly vehicle damage but also potentially leading to injury or loss of human life as well as animal welfare issues. Species, sex, moonlight, season and rainfall have previously been noted as potential influences on the number and frequency of kangaroo–vehicle collisions. In December 2015, a smartphone application using Collector for ESRI ArcGIS was implemented to enable ACT rangers to collect accurate information about each call‐out or carcass attendance in real time. A total of 3346 kangaroo–vehicle collision points were collected by rangers over a 15‐month period from March 2016 to June 2017. The data lend limited support to a concentration of kangaroo–vehicle collisions around the full moon, although 45% of collisions were recorded when the moon was less than 50% illuminated. Although the highest roadkill numbers were recorded in winter (June‐August), kangaroo–vehicle collisions were not directly correlated with season: there is a complex interaction with other variables. This study revealed that the relationship between the movement between patches of habitat and roads is dynamic and that further research is warranted into potential methods for reducing the number of kangaroo–vehicle collisions on Canberra roads, particularly in relation to speed limits, seasonality and kangaroo movements proximate to roads and areas of core habitat.

Roadkills in Northern Peninsular Malaysia

As Malaysia’s economy continues to grow, an ever-expanding road network is being built to support the new developments. Whilst roads increase accessibility to resources and connect human communities, they also bring with them a host of environmental problems such as destruction and fragmentation of habitat, poaching, pollution, and roadkills. Of these, roadkills are the most direct and visible impact of building roads, yet few dedicated studies have been conducted on the extent of roadkills and how to minimize them in Malaysia. In this study, we examined the species richness and abundance of vertebrate roadkills along eight one-km stretches (two in each habitat) of highways in Terengganu and Pahang across four habitat types: rainforest, oil palm plantation, subsistence agricultural land, and village. Each stretch of highway was surveyed by walking it six times between May to October 2017 for the Terengganu segments and May to October 2018 for the Pahang segments. A total of 305 roadkilled animals were recorded, consisting of at least 24 species. Three of these are protected by Malaysian law. The most common roadkilled animals were frogs (102 individuals) followed by birds (70 individuals), mammals (67 individuals) and reptiles (66 individuals). The highest number of roadkills were recorded in roads going through villages (112 individuals), followed by oil palm plantations (81 individuals), forests (65 individuals) and subsistence agricultural land (47 individuals). For every roadkill we also recorded the location’s specific habitat and landscape characteristics such as distance to the nearest fruit tree, tree, shrub, water body, human structure, and overhead cable. Most roadkills were found close to vegetation cover and water bodies. However, we found that roadkills decreased to near zero between 30 and 80 m from the nearest shrub or tree. Roadkills decreased over larger distances from the nearest water body, but in oil palm and village habitats, reducing water bodies within 20–50 m from a road would almost half the number of roadkills. We suggest that making changes to the structure and composition of roadside vegetation and other landscape features, such as thinning vegetation to discourage wildlife from gathering near roads, could significantly reduce the number of roadkills.

Landscape features of endangered Ryukyu long-furred rat (Diplothrix legata) roadkill sites in Yambaru, Okinawa-jima Island

ABSTRACT Roadkill poses a significant threat to many wildlife species. To implement habitat management and conservation measures in protected areas, it is important to identify the factors related to roadkill at the landscape scale. The purpose of this study was to clarify the landscape factors involved in roadkill of the endangered Ryukyu long-furred (Diplothrix legata) rat in Yambaru, the northern Okinawa-jima Island, Japan. We analyzed the relationship between roadkill sites and landscape factors (evergreen broad-leaved forest area, artificial pine forest area, average vegetation height, and minimum radius of road curve) using a generalized linear model, incorporating spatial autocorrelation using Moran’s eigenvector maps along a 13.9 km route using census data from May 2011 to April 2017. In addition, we clarified the relationship between the number of roadkills and national park zoning. Roadkill incidence was found to be positively correlated with average vegetation height and the percentage of pine forest area. The number of roadkill incidents was also higher in zones with higher levels of protection compared to areas with lower or no protection. These results suggest the need for measures in areas containing these landscape elements, such as mature forests and higher percentage of pine forests.

How far from the road should land cover be assessed? A case study on mesopredator mortality on roads

The methods used to assess the significance of land cover in the vicinity of a road for the mortality of mesopredators are diverse. In assessing the effect of land cover along the road on road causalities, scientists use various buffer sizes, or even no buffer along the road. The aim of this study was to verify how results of land cover effects on the mortality of mesopredators on roads may differ when analyzing various buffer sizes from the road. We assessed road causalities in the Warmian-Masurian voivodeship (Poland) from 3 consecutive years: 2015, 2016, and 2017. The roads were divided into equal sections of 2000 m each with buffer size of radius: 10, 250, 500, and 1000 m. We analyzed the number of road kills of red fox and European badger separately in a generalized linear model, whereas explanatory variables we used land cover types (based on the Corine Land Cover inventory) and traffic volume. Mean annual mortality from road collisions amounts to 2.36% of the red fox population and 3.82% of the European badger population. We found that the buffer size determines the results of the impact of land cover on mesocarnivore mortality on roads. The red fox differed from the European badger in response to land cover depending on the buffer size. The differences we have shown relate in particular to built-up areas. Our results indicate a 500-m buffer as best reflecting the land cover effects in road kills of both species. This was confirmed by model evaluation and a tendency to use or avoid the vicinity of human settlements of the analyzed species. We concluded that buffer size will probably affect mostly the significance of cover types that are spatially correlated with roads, positively or negatively. We suggest that the home range size of given species in local conditions should be assessed before determining the size of the buffer for analysis.

An estimate of wild mammal roadkill in São Paulo state, Brazil

Roadkill estimates for different species and species groups are available for many countries and regions. However, there is a lack of information from tropical countries, including from Latin America. In this study, we analyzed medium and large-sized mammal roadkill data from 18 toll road companies (TRC) in São Paulo State (6,580 km of monitored toll roads), Brazil. We extrapolated these roadkill numbers to the entire system of major paved roads in the State (36,503 km). The TRC collected mammal-road- mortality data both before (2-lanes) and after (4-lanes) road reconstruction. We used the “before” data from the TRC to estimate annual mammal-road-mortality along 2-lane roads that remained public roads. Combined with the data for the new 4-lane highways, this allowed us to estimate annual mammal road mortality for all the paved roads in the State. During 10 years of roadkill monitoring along toll roads, a total of 37,744 roadkilled mammals were recorded, representing a total of 32 medium to large-sized mammal species (average number of roadkilled individuals/year = 3,774 ± 1,159; min = 1,932; max = 5,369; 0.6 individuals roadkilled/km/year). Most roadkilled species were common generalists, but there were also relatively high roadkill numbers of threatened and endangered species (4.3% of the data), which is a serious conservation concern. Most of the roadkill was reported occurred during the nocturnal period (66%, n = 14,189) and in the rainy months (October–March) (55%, n = 15,318). Reported mammal roadkill tended to increase between 2009 and 2014 (R2 = 0.614; p = 0.065), with an average increase of 313.5 individuals/year. Extrapolation of the results to the entire São Paulo State, resulted in an average estimate of 39,605 medium and large-sized mammals roadkilled per year. Our estimates of the number of roadkilled individuals can be used as one of the input parameters in population viability analyses to understand the extinction or extirpation risk, especially for threatened and endangered species.