High vulnerability of juvenile Nathusius' pipistrelle bats (Pipistrellus nathusii) at wind turbines

Large numbers of bats are killed by wind turbines globally, yet the specific demographic consequences of wind turbine mortality are still unclear. In this study, we compared characteristics of Nathusius' pipistrelles (Pipistrellus nathusii) killed at wind turbines (N = 119) to those observed within the live population (N = 524) during the summer migration period in Germany. We used generalized linear mixed-effects modeling to identify demographic groups most vulnerable to wind turbine mortality, including sex (female or male), age (adult or juvenile), and geographic origin (regional or long-distance migrant; depicted by fur stable hydrogen isotope ratios). Juveniles contributed with a higher proportion of carcasses at wind turbines than expected given their frequency in the live population suggesting that juvenile bats may be particularly vulnerable to wind turbine mortality. This effect varied with wind turbine density. Specifically, at low wind turbine densities, representing mostly inland areas with water bodies and forests where Nathusius' pipistrelles breed, juveniles were found more often dead beneath turbines than expected based on their abundance in the live population. At high wind turbine densities, representing mostly coastal areas where Nathusius' pipistrelles migrate, adults and juveniles were equally vulnerable. We found no evidence of increased vulnerability to wind turbines in either sex, yet we observed a higher proportion of females than males among both carcasses and the live population, which may reflect a female bias in the live population most likely caused by females migrating from their northeastern breeding areas migrating into Germany. A high mortality of females is conservation concern for this migratory bat species because it affects the annual reproduction rate of populations. A distant origin did not influence the likelihood of getting killed at wind turbines. A disproportionately high vulnerability of juveniles to wind turbine mortality may reduce juvenile recruitment, which may limit the resilience of Nathusius' pipistrelles to environmental stressors such as climate change or habitat loss. Schemes to mitigate wind turbine mortality, such as elevated cut-in speeds, should be implemented throughout Europe to prevent population declines of Nathusius' pipistrelles and other migratory bats

Identifying migratory pathways of Nathusius' pipistrelles (Pipistrellus nathusii) using stable hydrogen and strontium isotopes

Rationale Identifying migratory corridors of animals is essential for their effective protection, yet the exact location of such corridors is often unknown, particularly for elusive animals such as bats. While migrating along the German coastline, Nathusius' pipistrelles (Pipistrellus nathusii) are regularly killed at wind turbines. Therefore, we explored the paths taken on their annual journey. Methods We used isotope ratio mass spectrometry to measure stable hydrogen and strontium isotope ratios in fur keratin of 59 Nathusius' pipistrelles captured on three offshore islands. Samples were pre-treated before analysis to report exclusively stable isotope ratios of non-exchangeable hydrogen. We generated maps to predict summer origins of bats using isoscape models. Results Bats were classified as long-distance migrants, mostly originating from Eastern Europe. Hydrogen analysis suggested for some bats a possible Fennoscandian origin, yet additional information from strontium analysis excluded this possibility. Instead, our data suggest that most Nathusius' pipistrelles migrating along the German coastline were of continental European summer origin, but also highlight the possibility that Nathusius' pipistrelles of Baltorussian origin may travel offshore from Fennoscandia to Germany. Conclusions Our findings demonstrate the benefit of using complementary isotopic tracers for analysing the migratory pathways of bats and also potentially other terrestrial vertebrate species. Furthermore, data from our study suggest an offset of fur strontium isotope ratios in relation to local bedrock

Migration Patterns of European Bats Assessed with Stable Isotopes

Migration is an essential process in animals’ lives, which they use to avoid adverse weather conditions and resource scarcity. Migratory animals are considered particularly vulnerable to anthropogenic changes to their environment because they require a specific temporal and spatial progression of appropriate habitats for foraging and reproduction, and a refuge from harsh environmental conditions. Anthropogenic activities that change the environment such as habitat loss, habitat fragmentation, and climate change have had a global effect on migratory species resulting in widespread population declines. Climate change is a particularly serious threat for migratory species as it can have impacts across all the habitats within which migratory animals must move. Efforts to mitigate climate change may also have adverse effects on migratory species. The trade-off between renewable energy use and wildlife conservation is not always straightforward. Changes in energy systems have the potential to alter the functioning of ecosystems and wildlife populations by affecting species' access to resources, habitat availability, and connectivity. The use of wind energy poses a particular threat for many migratory species. Studies have shown that wind energy farms pose a mortality risk to flying migratory individuals both inland and on the coast, and new concerns are being raised around offshore establishments. Conservation of migratory species in the face of such threats is of vital importance and will likely require the protection of the multiple habitats that are used during the migratory journey. However, there is often limited knowledge about the migratory pathways and stopover sites used by migratory species, posing a major challenge for effective conservation. Stable isotope analysis can be used to trace terrestrial migratory routes and identify migratory origins. The development of such techniques to determine the corridors and pathways migratory animals are using to move between habitats has assisted us in further honing conservation efforts. Stable isotope analysis allows the use of a small number of samples, which can be collected in one sampling event, to detect environmental tracers that are related to the spatial-temporal movement of animals. The application of stable isotopes in conservation biology is growing rapidly and shows great promise for the conservation of endangered species. Bats are one of the most taxonomically diverse groups of mammals, however, only a few species are known to migrate long distances. These species have evolved a combination of physiological and morphological traits to allow long-distance migration. The European Nathusius’ pipistrelle (Pipistrellus nathusii) is one of the most well-studied migratory bat species worldwide. The species is known to maintain a long-distance migration with both coastal and offshore pathways. Recent studies have shown that Nathusius’ pipistrelles have been increasing their geographical range, even reaching 60° N in latitude. Their long-distance migratory behaviour and the increase in European wind farms make them highly vulnerable to environmental changes. Considering their broad European range, high vulnerability to environmental changes, and the current need to protect migratory species, Nathusius’ pipistrelles are an interesting model species in which to apply stable isotope analysis to investigate migration patterns. In this thesis, I use stable isotope analysis to identify the northern migratory corridors of Nathusius’ pipistrelles (chapter 1) and differentiate the mortality risk posed by wind turbines on different demographic groups during migration (chapter 2). In chapter 1, I use a dual-isotope approach (δ2H and 87Sr/86Sr) to determine the origin of bats found on three islands in the north of Germany. Although δ2H analysis suggested a possible Fennoscandian origin, 87Sr/86Sr analysis refuted this possibility and proposed they would be originating in Russia and the Baltic states. In chapter 2, I use a comprehensive dataset of fur samples from carcasses collected beneath wind turbines and living individuals across Germany to assess the vulnerability of different demographic groups to wind turbine mortality. Compared to adults, juveniles were more vulnerable at low wind turbine densities; this effect was minimised at high density, with both ages equally affected. In addition, I found more females and regional migrants in both living and carcass populations. Overall, this dissertation demonstrates the importance of stable isotope analysis in wildlife research and provides a practical example of how it can help inform species conservation

High vulnerability of juvenile Nathusius' pipistrelle bats (Pipistrellus nathusii) at wind turbines

Large numbers of bats are killed by wind turbines globally, yet the specific demographic consequences of wind turbine mortality are still unclear. In this study, we compared characteristics of Nathusius' pipistrelles (Pipistrellus nathusii) killed at wind turbines (N = 119) to those observed within the live population (N = 524) during the summer migration period in Germany. We used generalized linear mixed-effects modeling to identify demographic groups most vulnerable to wind turbine mortality, including sex (female or male), age (adult or juvenile), and geographic origin (regional or long-distance migrant; depicted by fur stable hydrogen isotope ratios). Juveniles contributed with a higher proportion of carcasses at wind turbines than expected given their frequency in the live population suggesting that juvenile bats may be particularly vulnerable to wind turbine mortality. This effect varied with wind turbine density. Specifically, at low wind turbine densities, representing mostly inland areas with water bodies and forests where Nathusius' pipistrelles breed, juveniles were found more often dead beneath turbines than expected based on their abundance in the live population. At high wind turbine densities, representing mostly coastal areas where Nathusius' pipistrelles migrate, adults and juveniles were equally vulnerable. We found no evidence of increased vulnerability to wind turbines in either sex, yet we observed a higher proportion of females than males among both carcasses and the live population, which may reflect a female bias in the live population most likely caused by females migrating from their northeastern breeding areas migrating into Germany. A high mortality of females is conservation concern for this migratory bat species because it affects the annual reproduction rate of populations. A distant origin did not influence the likelihood of getting killed at wind turbines. A disproportionately high vulnerability of juveniles to wind turbine mortality may reduce juvenile recruitment, which may limit the resilience of Nathusius' pipistrelles to environmental stressors such as climate change or habitat loss. Schemes to mitigate wind turbine mortality, such as elevated cut-in speeds, should be implemented throughout Europe to prevent population declines of Nathusius' pipistrelles and other migratory bats

Human-modified landscape acts as refuge for mammals in Atlantic Forest

<div><p>Abstract: Human-modified landscapes (HMLs) are composed by small, isolated and defaunated forest fragments, which are surrounded by agricultural and urban areas. Information on species that thrives in these HMLs is essential to direct conservation strategies in local and regional scales. Since HMLs are dominant in the Atlantic Forest, we aimed to assess the mammalian diversity in a HML in southeastern Brazil and to propose conservation strategies. We collected data of terrestrial (small-, medium- and large-sized) and volant mammals in three small forest fragments (10, 14 and 26 ha) and adjacent areas, between 2003 and 2016, using complementary methods: active search, camera trapping, live-traps, mist nets and occasional records (i.e., roadkills). In addition, we used secondary data to complement our species list. We recorded 35 native mammal species (6 small-sized, 16 medium- and large-sized, and 13 bats) and seven exotic species in the HML. The recorded mammal assemblage (non-volant and volant), although mainly composed of common and generalist species, includes three medium- and large-sized species nationally threatened (Leopardus guttulus, Puma concolor and Puma yagouaroundi) and two data deficient species (Galictis cuja and Histiotus velatus), highlighting the importance of this HML for the maintenance and conservation of mammal populations. Despite highly impacted by anthropogenic disturbances, the study area harbors a significant richness of medium- and large-sized mammals, being an important biodiversity refuge in the region. However, this biodiversity is threatened by the low quality of the habitats, roadkills and abundant populations of domestic cats and dogs. Therefore, we stress the need of conservation strategies focusing on the medium- and large-sized mammals as an umbrella group, which could benefit all biodiversity in the landscape. We recommend actions that promotes biological restoration, aiming to increase structural composition and connectivity of the forest fragments, reducing roadkills and controlling the domestic cats and dogs' populations, in order to maintain and improve the diversity of mammals in long-term.</p></div