Assessing road effects on bats: the role of landscape, road features and bat activity on road kills

Estudos recentes sugerem que as estradas podem ter um impacto significativo nas populações de morcegos. Este é um dos grupos de vertebrados europeus mais ameaçado, porém continua a faltar informação sobre quais os principais factores que determinam este impacto e quais as possíveis medidas de mitigação. Entre Março e Outubro de 2009, foram amostrados diariamente 51 km de três tipos de rodovias. Recolhemos 154 morcegos atropelados, pertencentes a 11 espécies, as mais frequentes foram Pipistrellus kuhlii e P. pygmaeus, representando cerca de 64% da amostra. Foram também recolhidas espécies com estatuto de ameaça ou pouco conhecidas, talcomo, Rhinolophus ferrumequinume Barbastella barbastellusA maioria da mortalidade ocorreu entre o final do Verão e o princípio do Outono. Aactividade dos morcegos foi também monitorizada na área de estudo e encontrou-se uma relação positiva forte entre as áreas com maior actividade e os hotspots de mortalidade de morcegos. As características da paisagem foram o conjunto mais importante na explicação do padrão da mortalidade, tendo sido registado um maior número de atropelamentos em locais onde a estrada atravessa habitats de grande qualidade. Os resultados indicam também que o volume do tráfego e a proximidade aos abrigos contribui para o incrementoda mortalidade. Relativamente à actividade dos morcegos, não encontramos uma clara evidência de que os morcegos evitem a proximidade das estradas; ABSTRACT:Recent studies suggest that roads can significantly impact bat populations. Thought bats are one of the most threatened groups of European vertebrates, studies aiming to quantify bat mortality and determine the main factors driving it are still scarce. Between March and October 2009, we daily surveyed road killed bats in a transect of 51 km including different types of roads, in southern Portugal. Bat activity was also evaluated on roads and their surroundings. We found 154 road-killed bats of 11 species. Pipistrellus kuhlii andP. pygmaeusrepresented 64% of total specimens collected. We also found threatened and poorly known species like Barbastella barbastellusand Rhinolophus ferrumequinum. A peak of mortality occurred mostly in late summer and early autumn. Spatial analysis revealed a strong positive relationship between core activity areas and the bat mortality hotspots. Landscape features were the most important variable set in explaining bat casualties. Nevertheless, bat activity, distance to known roosts and traffic volume also had a significant influenceon it. Concerning activity data, we found no clear evidence of road avoidance by bats

New data on the distribution range of Hemidactylus turcicus in Portugal

En Portugal, la salamanquesa rosada Hemidactylus turcicus solamente está presente en la costa sur y en zonas interiores del sudeste. En este trabajo se describe la existencia de una nueva población que expande la distribución de esta especie por la costa portuguesa. El hallazgo ocurrió en primavera y verano de 2010 durante los inventarios de fauna realizados en una cantera restaurada en Setúbal. La nueva localidad se halla a 70 km de la población más cercana hasta ahora conocida y se especulan dos posibles hipótesis para su aparente aislamiento: (1) un deficiente esfuerzo de prospección en la zona, o (2) una dispersión a larga distancia debida al transporte humano involuntario

Major roads have a negative impact on the Tawny Owl Strix aluco and the Little Owl Athene noctua populations

The increasing road networks threaten ecosystems by direct effects such as increased mortality due to collision with vehicles and by various indirect effects leading to road avoidance. We censused Tawny Owls Strix aluco and Little Owls Athene noctua in 2005, 2007 and 2009 in a rural landscape in Southern Portugal in order to study the effects of roads and habitat characteristics on Tawny Owl density and Little Owl presence. The presence of both owl species in the 70 census locations was coherent among years. Our results showed that Tawny Owl density near major roads was lower, with the negative effects extending possibly up to 2 km. The probability of Little Owl presence was also negatively affected by the proximity to major roads. The negative effects of roads were significant even considering habitat preferences and spatial autocorrelation, which had the most marked effect on the density or presence of both owls. The reduced occupancy by Tawny Owls and Little Owls of habitats near major roads may be caused by several factors, including increased mortality, disturbance caused by high traffic density, and increased fragmentation. Traffic noise in particular may affect intra-specific communication and hunting efficiency. Consequently, habitat near roads may represent lower-quality territories for owls

New data on the distribution range of Hemidactylus turcicus in Portugal

En Portugal, la salamanquesa rosada Hemidactylus turcicus solamente está presente en la costa sur y en zonas interiores del sudeste. En este trabajo se describe la existencia de una nueva población que expande la distribución de esta especie por la costa portuguesa. El hallazgo ocurrió en primavera y verano de 2010 durante los inventarios de fauna realizados en una cantera restaurada en Setúbal. La nueva localidad se halla a 70 km de la población más cercana hasta ahora conocida y se especulan dos posibles hipótesis para su aparente aislamiento: (1) un deficiente esfuerzo de prospección en la zona, o (2) una dispersión a larga distancia debida al transporte humano involuntario

Generalities of vertebrate responses to landscape composition and configuration gradients in a highly heterogeneous Mediterranean region

Aim To examine the distributional patterns of vertebrates (including birds, bats, carnivores and lagomorphs) along landscape composition and configuration gradients to better understand the effects of landscape modification on occurrence patterns at both species and community level. Location The region of Alentejo, a forest-dominated area of southern Portugal. Methods The study area was framed using 1647 hexagonal plots, each of 259 ha in size. Composition and configuration gradients were obtained for each plot by integrating the proportions of the main land cover types and their configuration patterns using multivariate analyses. Species-specific vertebrate responses were investigated using data from 75 plots in which carnivores, bats and lagomorphs were sampled, and from 135 plots in the case of birds. Community- level responses were investigated through changes in species richness and beta-diversity in 57 plots where all vertebrate groups were simultaneously sampled. At the species-level, an information-theoretic approach was used to determine the effects of landscape gradients on species’ responses. At the community level, Mantel tests were used to determine between-plot differences in species composition using the Sørensen dissimilarity index. Results We found that the occurrence patterns of most vertebrate species were best predicted by composition-related gradients, although configuration gradients were also frequently included in species-specific occurrence models. We also found a weak correlation between species richness and most landscape gradients suggesting a turnover in the identity of species, something that was corroborated by the stronger correlation between environmental gradients and beta-diversity measures. The amount of forest cover and landscape complexity (estimated as the heterogeneity in the size and number of land cover types) were the main composition and configuration gradients determining vertebrate responses at both species and community level. Main conclusions Our work contributes to a more refined understanding of the mechanisms underlying species distributional patterns in real-world human-modified landscapes. By uncovering generalities of species with multiple ecological requirements and by describing the entire landscape mosaic through landscape gradients, we also suggest that our work greatly helps to fill the gap between existing conceptual landscape models aimed to understand species distributional patterns in human-modified landscapes

Avian trait-mediated vulnerability to road traffic collisions

Collision with vehicles is an important source of bird mortality, but it is uncertain why some species are killed more often than others. Focusing on passerines,we testedwhether mortality is associated with bird abundances, and with traits reflecting flight manoeuvrability, habitat, diet, and foraging and social behaviours. We also tested whether the species most vulnerable to road-killing were scarcer near (b500 m) or far (N500–5000 m) from roads. During the breeding seasons of 2009–2011,we surveyed roadkills daily along 50 km of roads, and estimated bird abundances from 74 point counts. After correcting for phylogenetic relatedness, there was strong correlation between roadkill numbers and the abundances of 28 species counted near roads. However, selectivity indices indicated that Blue tit (Parus caeruleus), Blackcap (Sylvia atricapilla) and European goldfinch (Carduelis carduelis) were significantly more road-killed than expected from their abundances, while the inverse was found for seven species. Using phylogenetic generalised estimating equations, we found that selectivity indexes were strongly related to foraging behaviour and habitat type, and weakly so to body size, wing load, diet and social behaviour. The most vulnerable passerines were foliage/bark and swoop foragers, inhabiting woodlands, with small body size and low wing load. The species most vulnerable to road collisions were not scarcer close to roads. Overall, our study suggests that traits provide a basis to identify the passerine species most vulnerable to road collisions, which may be priority targets for future research on the population-level effects of roadkills

Sampling effects on the identification of roadkill hotspots: Implications for survey design

Although locating wildlife roadkill hotspots is essential to mitigate road impacts, the influence of study design on hotspot identification remains uncertain. We evaluated how sampling frequency affects the accuracy of hotspot identification, using a dataset of vertebrate roadkills (n = 4427) recorded over a year of daily surveys along 37 km of roads. “True” hotspots were identified using this baseline dataset, as the 500-m segments where the number of road-killed vertebrates exceeded the upper 95% confidence limit of the mean, assuming a Poisson distribution of roadkills per segment. “Estimated” hotspots were identified likewise, using datasets representing progressively lower sampling frequencies, which were produced by extracting data from the baseline dataset at appropriate time intervals (1e30 days). Overall,24.3% of segments were “true” hotspots, concentrating 40.4% of roadkills. For different groups, “true” hotspots accounted from 6.8% (bats) to 29.7% (small birds) of road segments, concentrating from 60% (lizards, lagomorphs, carnivores) of roadkills. Spatial congruence between “true” and “estimated” hotspots declined rapidly with increasing time interval between surveys, due primarily to increasing false negatives (i.e., missing “true” hotspots). There were also false positives (i.e., wrong “estimated” hotspots), particularly at low sampling frequencies. Spatial accuracy decay with increasing time interval between surveys was higher for smaller-bodied (amphibians, reptiles, small birds, small mammals) than for larger-bodied species (birds of prey, hedgehogs, lagomorphs, carnivores). Results suggest that widely used surveys at weekly or longer intervals may produce poor estimates of roadkill hotspots, particularly for small-bodied species. Surveying daily or at two-day intervals may be required to achieve high accuracy in hotspot identification for multiple species

Effects of grazing pressure on activity and richness of bats in a Portuguese silvo-pastoral system

Background High Nature Value Farmlands (HNVF) harbor species dependent upon habitats maintained by low-intensity farming. Among HNVF, the montado (dehesa in Spain) is a multifunctional system declining due to droughts, pathogens, and increasing grazing pressure. Specifically, grazing pressure leads to compact soils and hinders natural tree regeneration. Regrettably, there is a dearth of information supporting management decisions on the side-effects of high grazing pressure on HNVF-dwelling biodiversity. In particular, little is known about the impact of grazing pressure on bats, a group of species of special conservation concern that may provide key ecosystem services such as biological pest control. Purpose We investigated patterns of activity levels and community composition of insectivorous bats to test the hypothesis that there is a significant relationship between the level of livestock grazing pressure within montado HNVF parcels and patterns of insectivorous bats’ presence and activity. Our specific aims were to (i) assess separately the effects of grazing pressure on bat activity and species composition, (ii) test the predictive significance of key covariates (e.g., insect availability). Methods We conducted this study in 2014 in the Natura 2000 network site “Monfurado”, southern Portugal. This site is specifically acknowledged for its well-preserved montados providing feeding areas for bat species. We quantified acoustically bat flight activity and species richness in farm parcels dominated by cork oak trees. Per parcel, we selected two separate locations (high vs. low grazing pressure) based on landowners’ interviews and grazing pressure indicators, totaling 42 sampling locations. We then used linear mixed-effects modeling to evaluate the effects of grazing pressure and covariates on activity and species richness. Results Bat activity and bat species richness peaked at low grazing pressure locations. Bat activity also increased with tree cover and in locations where livestock grazing signs were old or absent. Conversely, bat activity at low grazing pressure locations decreased with distance to the nearest standing water body. Discussion Our study clearly demonstrated that locations maintained under high grazing pressure within HNVF can have negative consequences for bats, which are acknowledged as good bioindicators of habitat quality. In order to promote better habitat for bats, practitioners should avoid favoring grazing-prone areas (e.g., rotating the location of livestock feeders, drinkers, and gates) across montado HNVF. Broadly, ecosystem services provided by bats for HNVF must be enhanced through sustainability oriented agro-environment schemes under the Economic Community Rural Development Program, including the reduction of stocking density

Spatiotemporal persistence of bat roadkill hotspots in response to dynamics of habitat suitability and activity patterns

Wildlife roadkill hotspots are frequently used to identify priority locations for implementing mitigation measures. However, understanding the landscape-context and the spatial and temporal dynamics of these hotspots is challenging. Here, we investigate the factors that drive the spatiotemporal variation of bat mortality hotspots on roads along three years. We hypothesize that hotspot locations occur where bat activity is higher and that this activity is related to vegetation density and productivity, probably because this is associated with food availability. Statistically significant clusters of bat-vehicle collisions for each year were identified using the Kernel Density Estimation (KDE) approach. Additionally, we used a spatiotemporal analysis and generalized linear mixed models to evaluate the effect of local spatiotemporal variation of environmental indices and bat activity to predict the variation on roadkill hotspot locations and to asses hotspot strength over time. Between 2009 and 2011 we conducted daily surveys of bat casualties along a 51-km-long transect that incorporates different types of roads in southern Portugal. We found 509 casualties and we identified 86 statistically significant roadkill hotspots, which comprised 12% of the road network length and contained 61% of the casualties. Hotspots tended to be located in areas with higher accumulation of vegetation productivity along the three-year period, high bat activity and low temperature. Furthermore, we found that only 17% of the road network length was consistently classified as hotspots across all years; while 43% of hotspots vanished in consecutive years and 40% of new road segments were classified as hotspots. Thus, non-persistent hotspots were the most frequent category. Spatiotemporal changes in hotspot location are associated with decreasing vegetation production and increasing water stress on road surroundings. This supports our hypothesis that a decline on overall vegetation productivity and increase of roadside water deficit, and the presumed lower abundance of prey, have a significant effect on the decrease of bat roadkills. To our knowledge, this is the first study demonstrating that freely available remote sensing data can be a powerful tool to quantify bat roadkill risk and assess its spatiotemporal dynamics

Integrating remote sensing data on habitat suitability and functional connectivity to inform multitaxa roadkill mitigation plans

Context Road impacts on biodiversity are increasing worldwide. Few attempts have been made to integrate multiple taxonomic groups into roadkill mitigation plans, while using remotely sensed habitat suitability and functional connectivity. Objectives We pinpoint high-risk road locations (road planning units) for 19 woodland species from different taxonomic groups (non-flying mammals, birds, and bats) to enhance prioritisation and versatil- ity of roadkill mitigation plans.Methods In Southern Portugal, we collected species occurrence data, roadkill, and high-resolution satel- lite imageries, along 15 years. We identified remotely sensed habitat metrics, in turn weighted together with functional connectivity models and road metrics to estimate roadkill vulnerability, using random forests. The roadkill cumulative risk across species is then estimated, as well the likelihood variation within and between taxonomic groups to verify prediction consistency. Results Remote sensing information thoroughly explained habitat suitability, identifying similar met- rics within each group, and non-uniform environ- mental tolerance across species. Functional connec- tivity and habitat suitability significantly explained mortality, highlighting connected woodlands and neighbouring matrices. The roadkill cumulative risk endorses a conspicuous prioritisation of road plan- ning units for implementing mitigation structures use- ful for multiple species, with high precision and low probability variation within each group. Some dis- crepancies in prediction consistency still emerge after group comparisons regarding bats. Conclusions We provide novel insights for multi- taxa ecological responses and roadkill evaluations, demonstrating a possible spatial prioritisation in mortality patterns from species with different traits. The identified road units support resilience and mul- tifunctionality over long-term, enabling to assist cost-effective mitigation plans. Findings ultimately offer versatility during the mitigation planning phase throughout  the identification of road sub-optimal units, and opportunity costs given their potential for different taxa