More connected, more collisions? Documenting nonlinear relationships between habitat connectivity and wildlife-vehicle collision hotspots

Road networks fragment wildlife habitat and impede wildlife connectivity, which leads to elevated wildlife-vehicle collision (WVC) risk and increased danger to humans and wildlife. Habitat connectivity has been linked to WVC hotspot location and intensity, but this relationship likely depends on landscape context and road characteristics, which may be nonlinear due to varying habitat availability. Our objective was to evaluate factors affecting WVC location and intensity across New Hampshire, USA, with a focus on habitat connectivity. We assessed the relationship between WVCs and five connectivity models using generalized additive models and compared connectivity effects to road and land cover characteristics. We found that a barrier-sensitive wildlife species connectivity model was the best predictor of WVC hotspots and had a strong, negative nonlinear relationship with collision intensity. We also found that a simple forest variable performed almost as well as the complex connectivity model. WVC hotspots did not differ from adjacent roads or regional roads in terms of connectivity, except that traffic volume was higher at hotspots. Our findings suggest that the relationship between habitat connectivity and WVCs depends on broader landscape context and likely exhibits nonlinearity. Our work also demonstrates that some connectivity models are better predictors of WVCs than others, emphasizing the role of species-specific habitat connectivity assessments. These results can inform WVC mitigation planning and enhance understanding of habitat connectivity's role in broader landscapes.

Roadkill in a Mediterranean island: Evaluating ten-years of official records

Roadkill is a global issue contributing to biodiversity decline which is increasingly recognized by scientists and decision-makers. In Cyprus, a biodiversity hotspot with one of the highest road densities in Europe, the impact of roads on wildlife has been largely overlooked due to the absence of life-threatening collisions. We analysed data from a 10-year roadkill dataset (2013-2022) collected systematically by the Department of Public Works across 27 main roads, primarily aimed at driver safety. Due to the absence of spatial attributes for roadkill locations, the dataset was analysed to identify taxonomic, seasonal, and temporal roadkill trends in Cyprus for the first time. A total of 1,985 roadkill incidents were recorded, involving seven wildlife taxa: foxes (44%), birds (26%), hedgehogs (11.5%), snakes (7%), hares, rats, and lizards. Most roadkill occurred in the Nicosia district (65%). Statistical analyses using chi-square tests with post-hoc Bonferroni corrections revealed strong associations between road types and taxa. Fox and bird roadkill incidents were most common on highways, while hedgehogs and snakes were frequent on secondary interurban or rural roads. Roads near protected areas exhibited higher roadkill frequencies than highways. A positive relationship between traffic volume and roadkill risk was evident, with higher traffic roads posing greater risks. Seasonal patterns showed increased roadkill during spring and summer, peaking in June. This synthesis provides crucial insights into roadkill patterns, offering guidance for conservation and mitigation actions. However, the current monitoring system, focused on driver safety, is inadequate for comprehensive roadkill reporting. Key limitations, such as the absence of spatial data and weaknesses in the protocol, have been identified, with recommendations for improvement proposed to enhance future monitoring efforts.

Environmental Health and Societal Wealth Predict Movement Patterns of an Urban Carnivore

How societal, ecological and infrastructural attributes interact to influence wildlife movement is uncertain. We explored whether neighbourhood socioeconomic status and environmental quality were associated with coyote (Canis latrans) movement patterns in Los Angeles, California and assessed the performance of integrated social-ecological movement models. We found that coyotes living in more anthropogenically burdened regions (i.e. higher pollution, denser development, etc.) had larger home ranges and showed greater daily displacement and mean step length than coyotes in less burdened regions. Coyotes experiencing differing levels of anthropogenic burdens demonstrated divergent selection for vegetation, pollution, road densities and other habitat conditions. Further, movement models that included societal covariates performed better than models that only assessed ecological features and linear infrastructure. This study provides a unique social-ecological lens examining the anthropogenic drivers of urban wildlife movement, which should be applicable to urban planners and conservationists when building more equitable, healthy and wildlife-friendly cities.

Wildlife-Vehicle Collisions in Tasmania: Tourists' Attitudes and Behaviour

The surge in wildlife-vehicle collision research has not yet translated into a substantial decrease in animal fatalities. In line with the prevailing view, we suspect that drivers' behaviour may be the most crucial element. We address a research gap in drivers' attitudes towards and behaviour in response to wildlife-vehicle collisions from a tourist perspective. We designed a questionnaire to examine tourists' attitudes and behaviour in relation to wildlife-vehicle collisions while driving in Tasmania. We found that the respondents' sociodemographic attributes had minimal effect on their practical responses to roadkill. Tourists consider wildlife-vehicle collisions a serious problem for both biodiversity loss and animal welfare reasons, and their willingness to change their behaviour was high. However, many respondents did not stop to check for surviving pouch young. This inaction resulted either from overlooking the importance of pouch checking or a lack of knowledge on what action needed to be taken. There may also be a lack of understanding that roadkill left on the road leads to secondary roadkill incidents. Even though tourist behaviour does not automatically represent residents' behaviour, these findings will help to improve and tailor educational approaches to rectify the driver awareness/behaviour gap for both tourists and residents.

Anthropogenic, environmental and temporal associations with vertebrate road mortality in a wildland-urban interface of a biodiverse desert ecoregion

Road mortality adversely affects wildlife populations. As urbanization and infrastructure densities expand, transportation and wildlife management aim to mitigate wildlife-vehicle conflicts while conserving biodiversity. Roadways in aridland ecosystems can invariably and adversely impact wildlife differently from temperate and other biomes, yet these rapidly urbanizing regions are understudied as are urban-rural gradients. We conducted road-cruise surveys (n = 204; 2018-2023) to assess anthropogenic, environmental, and temporal factors associated with vertebrate roadkill across the wildland-urban interface of Arizona's biodiverse Sonoran Desert ecoregion-already subjected to increased human development and climate change. Of n = 2019 vertebrates observed, 28.5% were roadkill. Increasing urbanization levels were associated with reduced vertebrate abundance on roads and increased road-killed endothermic vertebrates. Traffic volume was strongly associated with reduced vertebrate abundance and increased roadkill; additive effects on roadkill began at approximately 20 vehicles. Daily low temperature and/or relative humidity were also associated with roadkill across vertebrate groups. We provide empirical evidence to understand wildlife-roadkill associations across expanding wildland-urban interfaces to inform effective roadkill mitigation and wildlife conservation management strategies in biodiverse aridland regions. We recommend that managers mitigate or avoid development in rural areas that possess high biodiversity, valuable waterways or migration corridors, and populations of vulnerable species.

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.

Urban tolerance is phylogenetically constrained and mediated by pre-adaptations in African bats

With increasing urbanization, particularly in developing countries, it is important to understand how local biota will respond to such landscape changes. Bats comprise one of the most diverse groups of mammals in urban areas, and many species are threatened by habitat destruction and land use change. Yet, in Africa, the response of bats to urban areas is relatively understudied. Therefore, we collated data on urban presence, phylogenetic relationship, and ecological traits of 54 insectivorous bats in Africa from available literature to test if their response to urbanization was phylogenetically and/or ecologically driven. Ancestral state reconstruction of urban tolerance, defined by functional group and presence observed in urban areas, suggests that ancestral African bat species could adapt to urban landscapes, and significant phylogenetic signal for urban tolerance indicates that this ability is evolutionarily conserved and mediated by pre-adaptations. Specifically, traits of high wing loading and aspect ratio, and flexible roosting strategies, enable occupancy of urban areas. Therefore, our results identify the traits that predict which bat species will likely occur in urban areas, and which vulnerable bat clades conservation efforts should focus on to reduce loss of both functional and phylogenetic diversity in Africa. We, additionally, highlight several gaps in research that should be investigated in future studies to provide better monitoring of the impact urbanization will have on African bats.

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.

Fear in urban landscapes: conspecific flock size drives escape decisions in tropical birds

Human-induced disturbances affect animal behaviours such as anti-predatory responses. Animals in urban environments tend to exhibit a reduced escape response, measured as a shorter flight initiation distance (FID), compared to their rural counterparts. While FID has been evaluated in animals dwelling in contrasting habitats (e.g. urban versus rural), little is known about how this response varies within urban environments, especially in tropical cities. Here, we studied the FID of 15 resident bird species in Bogota, Colombia, at 22 sites grouped into four categories (natural sites, metropolitan parks, zonal parks and residential areas) that differed in landscape features and evaluated which factors affected the escape responses of birds. We showed that birds foraging in larger flocks are more tolerant when being approached but they do not seem to be influenced by other factors such as heterospecific flock size, noise levels, pedestrian density, predator density, natural cover or body length. Also, birds inhabiting residential areas and parks showed a shorter FID compared to birds in natural areas suggesting that they are more tolerant of human-related disturbances compared to their conspecifics that live in natural areas within the city. Our study shows important differences in bird anti-predatory responses within the city and suggests that social strategies (i.e. flocking patterns) may be a mechanism for adapting to human-induced disturbances in urban tropical environments.

Patch, matrix and disturbance variables negatively influence bird community structure in small-sized managed green spaces located in urban core areas

Patch, matrix and human-induced disturbance variables are important in determining the structure of urban bird communities. Although green spaces in urban core areas are usually small and disturbed, they can be important for local bird diversity. Because such areas are often overlooked, their study is critical for successfully incorporating biodiversity conservation in urban planning. Furthermore, comparing bird communities from different biogeographical areas would help identify generalizable patterns and propose common management actions. We compared the structure of breeding season bird assemblages of managed small public green spaces in the urban core areas of two similar-sized European cities, Kavala (Greece) and Rovaniemi (Finland), and studied the influence of environmental variables on community structure. Species composition differed between the cities. Abundance and evenness were higher in Kavala, while richness and diversity did not differ between the cities. Abundance did not respond in a general way to the same variables in the two cities. It increased with decreasing shrub cover and distance from the city center and with increasing midday noise and ground cover in Kavala, but increased with increasing distance from the city center and decreased with increasing car traffic and midday noise in Rovaniemi. This might be explained by the lower abundance of bird dwellers in Rovaniemi. Primarily gray cover, but also other variables, at both the patch and matrix levels (e.g., noise, car traffic, distance from the city center), negatively affected richness, evenness and diversity in both cities. Green space size was positively correlated with richness and diversity in Kavala, but not in Rovaniemi, possibly due to the smaller size variation in Rovaniemi. Results emphasized that increasing gray cover is harmful for birds in small-sized green spaces in urban core areas. However, urban managers should note that not all bird community metrics responded in similar ways to same environmental variables.

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.