Resource Documents: Bats (57 items)
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Evidence of region-wide bat population decline from long-term monitoring and bayesian occupancy models with empirically informed priors
Author: Rodhouse, Thomas; et al.
Strategic conservation efforts for cryptic species, especially bats, are hindered by limited understanding of distribution and population trends. Integrating long‐term encounter surveys with multi‐season occupancy models provides a solution whereby inferences about changing occupancy probabilities and latent changes in abundance can be supported. When harnessed to a bayesian inferential paradigm, this modeling framework offers flexibility for conservation programs that need to update prior model‐based understanding about at‐risk species with new data. This scenario is exemplified by a bat monitoring program in the Pacific Northwestern United States in which results from 8 years of surveys from 2003 to 2010 require updating with new data from 2016 to 2018. The new data were collected after the arrival of bat white‐nose syndrome and expansion of wind power generation, stressors expected to cause population declines in at least two vulnerable species, little brown bat (Myotis lucifugus) and the hoary bat (Lasiurus cinereus). We used multi‐season occupancy models with empirically informed prior distributions drawn from previous occupancy results (2003–2010) to assess evidence of contemporary decline in these two species. Empirically informed priors provided the bridge across the two monitoring periods and increased precision of parameter posterior distributions, but did not alter inferences relative to use of vague priors. We found evidence of region‐wide summertime decline for the hoary bat (λ trend = 0.86 ± 0.10) since 2010, but no evidence of decline for the little brown bat (λ trend = 1.1 ± 0.10). White‐nose syndrome was documented in the region in 2016 and may not yet have caused regional impact to the little brown bat. However, our discovery of hoary bat decline is consistent with the hypothesis that the longer duration and greater geographic extent of the wind energy stressor (collision and barotrauma) have impacted the species. These hypotheses can be evaluated and updated over time within our framework of pre–post impact monitoring and modeling. Our approach provides the foundation for a strategic evidence‐based conservation system and contributes to a growing preponderance of evidence from multiple lines of inquiry that bat species are declining.
Thomas J. Rodhouse, National Park Service and Human and Ecosystem Resiliency and Sustainability Lab, Oregon State University—Cascades, Bend
Rogelio M. Rodriguez, Human and Ecosystem Resiliency and Sustainability Lab, Oregon State University—Cascades, Bend
Katharine M. Banner, Department of Mathematical Sciences, Montana State University, Bozeman
Patricia C. Ormsbee, Willamette National Forest, Springfield, Oregon
Jenny Barnett, Mid‐Columbia River National Wildlife Refuge Complex, U.S. Fish and Wildlife Service, Burbank, Washington
Kathryn M. Irvine, Northern Rocky Mountain Science Center, U.S. Geological Survey, Bozeman, Montana
Ecology and Evolution. 2019;00:1–11.
First published: 11 September 2019
Author: Law, Peter; and Fuller, Mark
Anthropogenic alterations to landscape are indicators of potential compromise of that landscape’s ecology. We describe how alterations can be assessed as ‘hazards’ to wildlife through a sequence of three steps: diagnosing the means by which the hazard acts on individual organisms at risk; estimating the fitness cost of the hazard to those individuals and the rate at which that cost occurs; and translating that cost rate into a demographic cost by identifying the relevant demographically-closed population. We exploit the conservation-oriented literature on wind farms to illustrate this conceptual scheme. For wind farms, the third component has received less attention than the first two, which suggests it is the most challenging of the three components. A wind farm provides an example of a ‘spatially localized hazard’, i.e., a discrete alteration of landscape hazardous to some population but of which there are some individuals that do not interact directly with the hazard themselves but nevertheless suffer a reduction in fitness in terms of their contribution to the next generation. Spatially localized hazards are identified via the third component of the scheme and are of particular conservation concern as, by their nature, their depredations on wildlife may be underestimated without an appropriate population-level estimation of the demographic cost of the hazard.
Peter R. Law, Centre for African Conservation Ecology, Department of Zoology, Nelson Mandela University, South Africa
Mark Fuller, Forest and Rangeland Ecosystem Science Center, U.S. Geological Survey, Boise, Idaho
Ecological Indicators 94 (2018) 380–385
Download original document: “Evaluating anthropogenic landscape alterations as wildlife hazards, with wind farms as an example”
Migratory bats are attracted by red light but not by warm-white light: Implications for the protection of nocturnal migrants
Author: Voight, Christian; et al.
The replacement of conventional lighting with energy‐saving light emitting diodes (LED) is a worldwide trend, yet its consequences for animals and ecosystems are poorly understood. Strictly nocturnal animals such as bats are particularly sensitive to artificial light at night (ALAN). Past studies have shown that bats, in general, respond to ALAN according to the emitted light color and that migratory bats, in particular, exhibit phototaxis in response to green light. As red and white light is frequently used in outdoor lighting, we asked how migratory bats respond to these wavelength spectra. At a major migration corridor, we recorded the presence of migrating bats based on ultrasonic recorders during 10‐min light‐on/light‐off intervals to red or warm‐white LED, interspersed with dark controls. When the red LED was switched on, we observed an increase in flight activity for Pipistrellus pygmaeus and a trend for a higher activity for Pipistrellus nathusii. As the higher flight activity of bats was not associated with increased feeding, we rule out the possibility that bats foraged at the red LED light. Instead, bats may have flown toward the red LED light source. When exposed to warm‐white LED, general flight activity at the light source did not increase, yet we observed an increased foraging activity directly at the light source compared to the dark control. Our findings highlight a response of migratory bats toward LED light that was dependent on light color. The most parsimonious explanation for the response to red LED is phototaxis and for the response to warm‐white LED foraging. Our findings call for caution in the application of red aviation lighting, particularly at wind turbines, as this light color might attract bats, leading eventually to an increased collision risk of migratory bats at wind turbines.
Christian C. Voigt, Katharina Rehnig, Oliver Lindecke, Gunārs Pētersons
Leibniz Institute for Zoo and Wildlife Research, Berlin, Germany (CCV, KR, OL)
Institute of Biology, Freie Universität Berlin, Germany (CCV, OL)
Faculty of Life Science, University of Vienna, Austria (KR)
Faculty of Veterinary Medicine, Latvia University of Life Sciences and Technologies, Jelgava (GP)
Ecology and Evolution. Published online August 25, 2018. doi: 10.1002/ece3.4400
Author: Millon, Lara; et al.
Previous studies have mainly focused on bat mortality through collision by wind turbines, and very few studies have assessed the indirect impacts on bat activity and on foraging habitat availability. Also, there is a global lack of knowledge on the vulnerability of tropical bat fauna due to wind energy production, even though it is well known that windpower can affect bat communities and biodiversity hotspots are widespread in the tropics. We present one of the first studies to quantify the indirect impact of wind farms on insectivorous bats in tropical hotspots of biodiversity. Bat activity was compared between wind farm sites and control sites, via ultrasound recordings at stationary points. The activity of bent winged bats (Miniopterus spp.) and wattled bats (Chalinolobus spp.) were both significantly lower at wind turbine sites. The result of the study demonstrates a large effect on bat habitat use at wind turbines sites compared to control sites. Bat activity was 20 times higher at control sites compared to wind turbine sites, which suggests that habitat loss is an important impact to consider in wind farm planning. We strongly recommend that the loss of the foraging habitat loss is considered in mitigation hierarchy (avoiding, reducing, offsetting) when compensating for negative impacts of wind farms.
Lara Millon, Célia Colin, Fabrice Brescia, IAC (Institut Agronomique néo-Calédonien), Equipe ARBOREAL (Agriculture Biodiversité et Valorisation) Païta, New Caledonia
Christian Kerbiriou, Muséum National d’Histoire Naturelle, Centre d’Ecologie et des Sciences de la Conservation, UMR 7204 MNHN-CNRS, France, and Station de Biologie Marine, Concarneau, France
Ecological Engineering 112 (2018) 51–54. doi: 10.1016/j.ecoleng.2017.12.024
Download original document: “Wind turbines impact bat activity, leading to high losses of habitat use in a biodiversity hotspot”