The Use of Intrinsic Markers for Studying the Migratory Movements of Bats

Brewer, Caralie T; Rauch-Davis, William A; Fraser, Erin E.

doi:10.3390/ani11123477

Cited by 3 publications

(5 citation statements)

References 226 publications

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“…Nonetheless, combining approaches represents a step forward in refining the geographic catchment of the impacts of wind-energy facilities on populations of the most impacted species in the United States as we can predict less area ( Wieringa et al, 2023 ). Further analyses using additional biomarkers, such as strontium isotopes, could lead to further refinement of the scale of these impacts ( Brewer, Rauch-Davis & Fraser, 2021 ).…”

Section: Discussionmentioning

confidence: 99%

Geographic source of bats killed at wind-energy facilities in the eastern United States

Wieringa,

Nagel,

Campbell

et al. 2024

PeerJ

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Bats subject to high rates of fatalities at wind-energy facilities are of high conservation concern due to the long-term, cumulative effects they have, but the impact on broader bat populations can be difficult to assess. One reason is the poor understanding of the geographic source of individual fatalities and whether they constitute migrants or more local individuals. Here, we used stable hydrogen isotopes, trace elements and species distribution models to determine the most likely summer geographic origins of three different bat species (Lasiurus borealis, L. cinereus, and Lasionycteris noctivagans) killed at wind-energy facilities in Ohio and Maryland in the eastern United States. In Ohio, 41.6%, 21.3%, 2.2% of all individuals of L. borealis, L. cinereus, and L. noctivagans, respectively, had evidence of movement. In contrast, in Maryland 77.3%, 37.1%, and 27.3% of these same species were classified as migrants. Our results suggest bats killed at a given wind facility are likely derived from migratory as well as resident populations. Finally, there is variation in the proportion of migrants killed between seasons for some species and evidence of philopatry to summer roosts. Overall, these results indicate that the impact of wind-energy facilities on bat populations occurs across a large geographic extent, with the proportion of migrants impacted likely to vary across species and sites. Similar studies should be conducted across a broader geographic scale to understand the impacts on bat populations from wind-energy facilities.

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Section: Discussionmentioning

confidence: 99%

Geographic source of bats killed at wind-energy facilities in the eastern United States

Wieringa,

Nagel,

Campbell

et al. 2024

PeerJ

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“…Lasionycteris noctivagans has been hypothesized to have an east/west split (Cryan, 2003), and previous work using mtDNA has shown some indication of genetic structure (Monopoli et al, 2020). Finally, possible data sources include sulfur isotope analysis (Kabalika et al, 2020), tagging technology (Castle et al, 2015), MOTUS network (Dowling & O'Dell, 2018), and many others (see Brewer et al, 2021). However, while these should be investigated, combined approaches should first be tested on known‐origin individuals to validate their usefulness (Hobson et al, 2019).…”

Section: Discussionmentioning

confidence: 99%

“…For each individual of each species, we used individual probability surfaces generated from SDM, trace element, and δ 2 H data sets and then combined individual probability layers into a single surface using two approaches. The first approach is a direct multiplication of normalized probability surfaces as under the assumption of independence among the biomarkers, the combined probability is the product of the probability surfaces (Brewer et al, 2021). We also utilized a Bayesian approach introduced in Rundel et al (2013), cross‐validated calibrated combined (CVCC) model tuning, in which each parameter is independently flattened or sharpened to generate and then multiplied to create an overall surface.…”

Section: Methodsmentioning

confidence: 99%

“…We assessed whether there was any increase in the precision of assignment resulting from combining data from δ 2 H analysis of fur, trace element analysis of fur, and seasonally explicit SDMs to generate a single joint probability surface for each known-origin individual, as has been suggested for bats (Brewer et al, 2021). For each individual of each species, we used individual probability surfaces generated from SDM, trace element, and δ 2 H data sets and then combined individual probability layers into a single surface using two approaches.…”

Section: Combining Assignment Modelsmentioning

confidence: 99%

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Combining stable isotopes, trace elements, and distribution models to assess the geographic origins of migratory bats

et al. 2023

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The expansion of industrial-scale wind-energy facilities has not only increased the production of low-carbon emission energy but has also resulted in mortality of wildlife, including migratory bats. Management decisions can be limited by a lack of understanding of the geographic impact of bats killed at wind-energy facilities. Several studies have leveraged stable hydrogen isotope ratios (δ 2 H) of bat fur to illuminate this issue but are limited in the precision of conclusion because δ 2 H values vary primarily across latitudinal and elevational bands. One approach to increase the precision of geographic assignment is to combine independent inferences about spatial location from additional biomarkers and other related information. To test this possibility, we assigned known-origin individuals of three bat species (Lasiurus borealis, L. cinereus, and Lasionycteris noctivagans) commonly killed at on-shore wind-energy facilities in North America to a probable origin using δ 2 H values, trace element concentrations, and species distribution models. We used cross-validated calibrated combined model tuning to determine the degree to which assignment probabilities improved when combining datasets. We found that combining markers typically performed better than single approaches.For Lasiurus borealis and L. cinereus, combining all three data sources outperformed any single or other combined approach. With an accuracy set at 80%, an average of 39.7% and 36.0% of each species' total geographic range was considered a potential origin, respectively; stable hydrogen alone included 51.8% and 50.6% of the total geographic area. In contrast, for Lasionycteris noctivagans, including trace elements did not increase precision and adding distribution data to δ 2 H values only improved precision by 0.6%. Thus, we found that a combination of multiple biomarkers typically, but not always, outperforms single-marker approaches and optimized combinations of different markers outperform equal weighting of each marker. From a practical perspective, δ 2 H values performed better than trace elements alone; in cases where cost is a limiting factor, the stable hydrogen should be the single

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“…Here, we implemented a framework for unraveling migratory strategy and its interactions from the sampling of endogenous markers of individual organisms. Such approaches are growing in popularity, and include applications with stable isotopes, trace elements, genetics, and traitbased markers (70)(71)(72)(73)(74)(75)(76). By sampling with the greatest possible breadth with respect to the geographic range of the species, geographic variance of the marker, and annual cycle of both the species and the endogenous marker, we built a representative model using data from thousands of individuals to represent migratory strategy over the entire population and annual cycle of the species.…”

Section: A Framework For Making Broad Inference From Endogenous Marke...mentioning

confidence: 99%

Unusual migratory strategy a key factor driving interactions at wind energy facilities in at-risk bats

Campbell,

Nelson,

Nagel

et al. 2024

Preprint

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Seasonal movement strategies are poorly understood for most animals, impeding broader understanding of processes underlying migration and limiting practical conservation needs. Here we develop and implement a framework for integrating multiple sources of endogenous markers, in particular stable hydrogen isotope data, that capture and scale dynamics from the movements of individuals to that of continental migration. We assembled and integrated thousands of new isotopic measurements from bat fur with existing datasets and applied this framework to reveal migratory patterns of three broadly distributed bat species most at risk for fatalities at wind energy facilities. Our findings show that the species comprising the lowest proportion of wind turbine fatalities (silver-haired bats) exhibits expected movements to lower latitudes in autumn and higher latitudes in spring. Surprisingly, the two species with higher wind turbine fatality rates (hoary and eastern red bats) have more complex movements, including significant movement to higher latitudes during autumn. We term this unique strategy 'pell-mell' migration, during which some individuals are as likely to move to higher latitudes as lower latitudes, relative to their individual summering grounds, in early autumn, after which they move to similar or lower latitudes to overwinter. The pell-mell migratory period corresponds with peak fatalities at wind energy facilities, and bats moving northward during autumn are associated with mortality at those facilities. Our results provide direct support for the hypothesis that bat fatalities at wind energy facilities are related to migration and highlight the importance of migratory distance as an ultimate driver of increased interactions with wind energy facilities, which appears significantly greater for species that travel widely across latitudes in the autumn.

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The Use of Intrinsic Markers for Studying the Migratory Movements of Bats

Cited by 3 publications

References 226 publications

Geographic source of bats killed at wind-energy facilities in the eastern United States

Geographic source of bats killed at wind-energy facilities in the eastern United States

Combining stable isotopes, trace elements, and distribution models to assess the geographic origins of migratory bats

Unusual migratory strategy a key factor driving interactions at wind energy facilities in at-risk bats

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