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Sil S, Visconti F, Chaverri G, Santana SE. Effects of Habitat and Fruit Scent on the Interactions between Short-tailed Fruit Bats and Piper Plants. Integr Org Biol 2024; 6:obae028. [PMID: 39129783 PMCID: PMC11316396 DOI: 10.1093/iob/obae028] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2023] [Revised: 07/03/2024] [Accepted: 07/27/2024] [Indexed: 08/13/2024] Open
Abstract
Piper is a mega-diverse genus of pioneer plants that contributes to the maintenance and regeneration of tropical forests. In the Neotropics, Carollia bats use olfaction to forage for Piper fruit and are a main disperser of Piper seeds via consumption and subsequent defecation during flight. In return, Piper fruits provide essential nutrients for Carollia year-round. There is evidence that the types and diversity of Piper frugivores are influenced by the primary habitat type of different Piper species (forest and gap), with forest Piper depending more on bats for seed dispersal; however, this pattern has not been tested broadly. We aimed to characterize and compare the interactions between Carollia and Piper across forested and gap habitats, and further investigate whether differences in fruit traits relevant to bat foraging (i.e., scent) could underlie differences in Carollia-Piper interactions. We collected nightly acoustic ultrasonic recordings and 24 h camera trap data in La Selva, Costa Rica across 12 species of Piper (six forest, six gap) and integrated this information with data on Carollia diet and Piper fruit scent. Merging biomonitoring modalities allowed us to characterize ecological interactions in a hierarchical manner: from general activity and presence of bats, to visitations and inspections of plants, to acquisition and consumption of fruits. We found significant differences in Carollia-Piper interactions between forested and gap habitats; however, the type of biomonitoring modality (camera trap, acoustics, diet) influenced our ability to detect these differences. Forest Piper were exclusively visited by bats, whereas gap Piper had a more diverse suite of frugivores; the annual diet of Carollia, however, is dominated by gap Piper since these plants produce fruit year-round. We found evidence that fruit scent composition significantly differs between forest and gap Piper, which highlights the possibility that bats could be using chemical cues to differentially forage for gap vs. forest Piper. By integrating studies of Piper fruit scent, plant visitation patterns, and Carollia diet composition, we paint a clearer picture of the ecological interactions between Piper and Carollia, and plant-animal mutualisms more generally.
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Affiliation(s)
- S Sil
- Department of Chemistry, University of Washington, Seattle, WA 98195, USA
| | - F Visconti
- Department of Biology, University of Washington, Seattle, WA 98195, USA
- Burke Museum of Natural History and Culture, University of Washington, Seattle, WA 98195, USA
| | - G Chaverri
- Sede del Sur, Universidad de Costa Rica, Golfito 60701, Costa Rica
- Smithsonian Tropical Research Institute, 0843-03092 Balboa, Ancón, Panamá
| | - S E Santana
- Department of Biology, University of Washington, Seattle, WA 98195, USA
- Burke Museum of Natural History and Culture, University of Washington, Seattle, WA 98195, USA
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2
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Leroux C, Barré K, Valet N, Kerbiriou C, Le Viol I. Distribution of common pipistrelle (Pipistrellus pipistrellus) activity is altered by airflow disruption generated by wind turbines. PLoS One 2024; 19:e0303368. [PMID: 38820349 PMCID: PMC11142562 DOI: 10.1371/journal.pone.0303368] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2023] [Accepted: 04/11/2024] [Indexed: 06/02/2024] Open
Abstract
The mechanisms underlying bat and bird activity peaks (attraction) or losses (avoidance) near wind turbines remain unknown. Yet, understanding them would be a major lever to limit the resulting habitat loss and fatalities. Given that bat activity is strongly related to airflows, we hypothesized that airflow disturbances generated leeward (downwind) of operating wind turbines-via the so-called wake effect-make this area less favorable for bats, due to increased flight costs, decreased maneuverability and possibly lower prey abundance. To test this hypothesis, we quantified Pipistrellus pipistrellus activity acoustically at 361 site-nights in western France in June on a longitudinal distance gradient from the wind turbine and on a circular azimuth gradient of wind incidence angle, calculated from the prevailing wind direction of the night. We show that P. pipistrellus avoid the wake area, as less activity was detected leeward of turbines than windward (upwind) at relatively moderate and high wind speeds. Furthermore, we found that P. pipistrellus response to wind turbine (attraction and avoidance) depended on the angle from the wake area. These findings are consistent with the hypothesis that changes in airflows around operating wind turbines can strongly impact the way bats use habitats up to at least 1500 m from the turbines, and thus should prompt the consideration of prevailing winds in wind energy planning. Based on the evidence we present here, we strongly recommend avoiding configurations involving the installation of a turbine between the origin of prevailing winds and important habitats for bats, such as hedgerows, water or woodlands.
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Affiliation(s)
- Camille Leroux
- Centre d’Ecologie et des Sciences de la Conservation (CESCO), Muséum National d’Histoire Naturelle, Centre National de la Recherche Scientifique, Sorbonne Université, Station Marine, Concarneau, France
- Auddicé biodiversité– ZAC du Chevalement, Roost-Warendin, France
| | - Kévin Barré
- Centre d’Ecologie et des Sciences de la Conservation (CESCO), Muséum National d’Histoire Naturelle, Centre National de la Recherche Scientifique, Sorbonne Université, Station Marine, Concarneau, France
| | - Nicolas Valet
- Auddicé biodiversité– ZAC du Chevalement, Roost-Warendin, France
| | - Christian Kerbiriou
- Centre d’Ecologie et des Sciences de la Conservation (CESCO), Muséum National d’Histoire Naturelle, Centre National de la Recherche Scientifique, Sorbonne Université, Station Marine, Concarneau, France
| | - Isabelle Le Viol
- Centre d’Ecologie et des Sciences de la Conservation (CESCO), Muséum National d’Histoire Naturelle, Centre National de la Recherche Scientifique, Sorbonne Université, Station Marine, Concarneau, France
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3
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Leroux C, Le Viol I, Valet N, Kerbiriou C, Barré K. Disentangling mechanisms responsible for wind energy effects on European bats. JOURNAL OF ENVIRONMENTAL MANAGEMENT 2023; 346:118987. [PMID: 37741193 DOI: 10.1016/j.jenvman.2023.118987] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/20/2023] [Revised: 08/31/2023] [Accepted: 09/09/2023] [Indexed: 09/25/2023]
Abstract
Mitigating anthropogenic climate change involves deployments of renewable energy worldwide, including wind energy, which can cause significant impacts on flying animals. Bats have highly contrasted responses to wind turbines (WT), either through attraction increasing collision risks, or avoidance leading to habitat losses. However, the underlying mechanisms remain largely unknown despite the expected rapid evolution of WT size and densities. Here, using an extensive acoustic sampling (i.e. 361 sites-nights) up to 1483 m from WT at regional scale, we disentangle the effects of WT size (ground clearance and rotor diameter), configuration (density and distance), and operation (blade rotation speed and wake effect) on hedgerow use by 8 bat species/groups and one vertical community distribution index. Our results reveal that all WT parameters affected bat activity and their vertical distribution. Especially, we show that the relative activity of high-flying species in the community was lower for higher WT density and lower ground clearance. Medium-flying species were sensitive to wind turbine distance, with either attraction or avoidance depending on proximity to the wake area and wind conditions. Specifically, wind turbine distance, wake effect and their interaction each affected the activity of one, three, and three species out of eight, respectively. Blade rotation and rotor diameter affected the activity of four and three species/groups, respectively, and ground clearance affected the activity of five ones. Taken together, WT configuration, operation, and size parameters affected the activity of three, five, and seven out of eight species/groups, respectively. These results call for the consideration of all these factors when assessing the ecological sustainability of future wind farms. The study especially advocates to avoid high WT densities, large rotors, and to site WT as far as possible from optimal habitats such as woody edges and not between them and the source of prevailing winds, in order to limit bats-WT interactions.
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Affiliation(s)
- Camille Leroux
- Centre d'Ecologie et des Sciences de la Conservation (CESCO), Muséum national d'Histoire naturelle, Centre National de la Recherche Scientifique, Sorbonne Université Station Marine, 1 place de la Croix, 29900, Concarneau, France; Auddicé Biodiversité - ZAC du Chevalement, 5 rue des Molettes, 59286, Roost-Warendin, France.
| | - Isabelle Le Viol
- Centre d'Ecologie et des Sciences de la Conservation (CESCO), Muséum national d'Histoire naturelle, Centre National de la Recherche Scientifique, Sorbonne Université Station Marine, 1 place de la Croix, 29900, Concarneau, France.
| | - Nicolas Valet
- Auddicé Biodiversité - ZAC du Chevalement, 5 rue des Molettes, 59286, Roost-Warendin, France
| | - Christian Kerbiriou
- Centre d'Ecologie et des Sciences de la Conservation (CESCO), Muséum national d'Histoire naturelle, Centre National de la Recherche Scientifique, Sorbonne Université Station Marine, 1 place de la Croix, 29900, Concarneau, France.
| | - Kévin Barré
- Centre d'Ecologie et des Sciences de la Conservation (CESCO), Muséum national d'Histoire naturelle, Centre National de la Recherche Scientifique, Sorbonne Université Station Marine, 1 place de la Croix, 29900, Concarneau, France.
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4
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Foxley T, Lintott P, Stone E. What drives bat activity at field boundaries? JOURNAL OF ENVIRONMENTAL MANAGEMENT 2023; 329:117029. [PMID: 36577300 DOI: 10.1016/j.jenvman.2022.117029] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/30/2022] [Revised: 12/05/2022] [Accepted: 12/11/2022] [Indexed: 06/17/2023]
Abstract
Field boundaries are important habitat for bats in agricultural landscapes, serving as commuting and foraging areas for many species. The goal of our study was to better understand the drivers of bat activity in agricultural landscapes to inform conservation policy and make specific recommendations for habitat management. We placed sixty-four full spectrum bat detectors at random recording locations, weekly, along field boundaries in North Somerset between July and October 2020. We used an automated classifier to analyse recordings and performed error rate modelling to account for and remove the majority of error in automated classifications. We used generalised additive models to explore bat response to recording location metrics, controlling for spatial-autocorrelation and temporal differences in sampling. We validated our models with k-fold cross-validation and explored the utility of our models for predicting bat activity at new sites. We found that field boundary characteristics better describe bat activity than adjacent field characteristics or measures of local landscape for the majority of species studied. Bat activity was higher along tall, wide, vegetated field boundaries containing trees; there was lower activity at arable recording locations. Still, bat activity was highly variable and predictive error was high. We found a large spatial effect driving activity patterns, meaning models are not able to predict activity beyond the extent of the study area. We recommend management strategies that give incentives to farmers for replacing fences with hedgerows, planting hedgerow trees, and maintaining tall and outgrown field boundaries.
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Affiliation(s)
- Thomas Foxley
- Bat Conservation Research Lab, School of Applied Sciences, University of the West of England, Coldharbour Lane, Bristol, BS16 1QY, UK.
| | - Paul Lintott
- Bat Conservation Research Lab, School of Applied Sciences, University of the West of England, Coldharbour Lane, Bristol, BS16 1QY, UK
| | - Emma Stone
- Bat Conservation Research Lab, School of Applied Sciences, University of the West of England, Coldharbour Lane, Bristol, BS16 1QY, UK
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Lo Cascio A, Kasel S, Ford G. A new method employing species‐specific thresholding identifies acoustically overlapping bats. Ecosphere 2022. [DOI: 10.1002/ecs2.4278] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
Affiliation(s)
- Amanda Lo Cascio
- School of Ecosystem and Forest Sciences, Faculty of Science The University of Melbourne Parkville Victoria Australia
| | - Sabine Kasel
- School of Ecosystem and Forest Sciences, Faculty of Science The University of Melbourne Burnley Victoria Australia
| | - Greg Ford
- Balance! Environmental Toowoomba Queensland Australia
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Khalighifar A, Gotthold BS, Adams E, Barnett J, Beard LO, Britzke ER, Burger PA, Chase K, Cordes Z, Cryan PM, Ferrall E, Fill CT, Gibson SE, Haulton GS, Irvine KM, Katz LS, Kendall WL, Long CA, Mac Aodha O, McBurney T, McCarthy S, McKown MW, O’Keefe J, Patterson LD, Pitcher KA, Rustand M, Segers JL, Seppanen K, Siemers JL, Stratton C, Straw BR, Weller TJ, Reichert BE.
NABat ML
: Utilizing deep learning to enable crowdsourced development of automated, scalable solutions for documenting North American bat populations. J Appl Ecol 2022. [DOI: 10.1111/1365-2664.14280] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Ali Khalighifar
- Colorado Cooperative Fish and Wildlife Research Unit Colorado State University Fort Collins USA
| | | | - Erin Adams
- U.S. Fish and Wildlife Service, Upper Mississippi River National Wildlife and Fish Refuge Onalaska USA
- U.S. Fish and Wildlife Service Washington Fish and Wildlife Office Lacey USA
| | | | | | - Eric R. Britzke
- Environmental Laboratory US Army Engineer Research & Development Center Vicksburg USA
| | | | - Kimberly Chase
- Florida Fish and Wildlife Conservation Commission Tallahassee USA
| | - Zackary Cordes
- Ecological Services Section, Kansas Department of Wildlife and Parks Pratt KS USA
| | - Paul M. Cryan
- Fort Collins Science Center, U.S. Geological Survey Fort Collins USA
| | - Emily Ferrall
- Wildlife Conservation Section, Georgia Department of Natural Resources Social Circle USA
| | - Christopher T. Fill
- Nebraska Cooperative Fish and Wildlife Research Unit University of Nebraska Lincoln Lincoln USA
| | | | - G. Scott Haulton
- Division of Forestry, Indiana Department of Natural Resources Indianapolis USA
| | - Kathryn M. Irvine
- U.S. Geological Survey, Northern Rocky Mountain Science Center Bozeman USA
| | - Lara S. Katz
- Department of Wildlife, Fisheries, and Conservation Biology University of Maine Orono ME USA
| | - William L. Kendall
- U.S. Geological Survey, Colorado Cooperative Fish and Wildlife Research Unit Colorado State University Fort Collins USA
| | | | | | - Tessa McBurney
- Canadian Wildlife Health Cooperative, Atlantic Region, Atlantic Veterinary College University of Prince Edward Island Charlottetown Prince Edward Island Canada
| | - Sara McCarthy
- Wildlife Division, Fisheries, Forestry and Agriculture, Happy Valley‐Goose Bay Newfoundland and Labrador Canada
| | | | - Joy O’Keefe
- Natural Resources and Environmental Sciences University of Illinois Urbana Champaign USA
| | - Lucy D. Patterson
- Pukaskwa National Park, Parks Canada Agency, Heron Bay Ontario Canada
| | | | - Matthew Rustand
- Royal Gorge Field Office, Bureau of Land Management Canon City USA
| | - Jordi L. Segers
- Canadian Wildlife Health Cooperative Charlottetown Prince Edward Island Canada
| | - Kyle Seppanen
- Keweenaw Bay Indian Community Natural Resources Department, L'Anse USA
| | - Jeremy L. Siemers
- Colorado Natural Heritage Program Colorado State University Fort Collins USA
| | - Christian Stratton
- Department of Mathematical Sciences Montana State University Bozeman USA
| | - Bethany R. Straw
- Fort Collins Science Center, U.S. Geological Survey Fort Collins USA
| | - Theodore J. Weller
- U.S. Department of Agriculture Forest Service Pacific Southwest Research Station Arcata USA
| | - Brian E. Reichert
- Fort Collins Science Center, U.S. Geological Survey Fort Collins USA
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7
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Mariton L, Kerbiriou C, Bas Y, Zanda B, Le Viol I. Even low light pollution levels affect the spatial distribution and timing of activity of a "light tolerant" bat species. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2022; 305:119267. [PMID: 35398157 DOI: 10.1016/j.envpol.2022.119267] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/15/2021] [Revised: 03/29/2022] [Accepted: 04/03/2022] [Indexed: 06/14/2023]
Abstract
By disrupting nocturnal landscapes worldwide, light pollution caused by Artificial Light At Night (ALAN) is recognized as a major threat to biodiversity. As even low light intensities might affect some taxa, concerns are arising about biological responses to widespread low light levels. We used data from a French citizen science bat monitoring program (1894 full-nights monitored on 1055 sites) to explore the landscape-scale effects of light on an open-space-foraging bat species, the Serotine bat (Eptesicus serotinus). We assessed this species' abundance and timing of night-time activity (median time of activity) at foraging sites. ALAN, and to a lesser extent moonlight, reduced E. serotinus abundance. ALAN delayed activity, and this delay was amplified during overcast nights. On the contrary, where there was no ALAN, the higher the cloud cover, the earlier the activity occurred. Cloud cover likely darkened the night sky in rural locations, whereas it amplified skyglow in light-polluted places, increasing ALAN effects on bats. Interestingly, moonlight also delayed activity but this effect was weakened where there was ALAN. Our study shows that even fine variations of light levels could affect the spatiotemporal distribution of a common species usually considered to be "light tolerant", with potential cascading effects on individual fitness and population dynamics. It stresses how urgent it is to preserve and restore dark areas to protect biodiversity from light pollution while working on light intensity and directivity where ALAN is needed.
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Affiliation(s)
- Léa Mariton
- Centre d'Écologie et des Sciences de la Conservation (CESCO), Muséum national d'Histoire naturelle, Centre National de la Recherche Scientifique, Sorbonne Université, CP 135, 57 Rue Cuvier, 75005, Paris, France; Centre d'Écologie et des Sciences de la Conservation (CESCO), Muséum national d'Histoire naturelle, Station de Biologie Marine, 1 Place de La Croix, 29900, Concarneau, France; Institut de Minéralogie, de Physique des Matériaux et de Cosmochimie (IMPMC), Sorbonne Université, Centre National de la Recherche Scientifique, Muséum national d'Histoire naturelle, Institut de Recherche pour le Développement, 61 Rue Buffon, 75005, Paris, France.
| | - Christian Kerbiriou
- Centre d'Écologie et des Sciences de la Conservation (CESCO), Muséum national d'Histoire naturelle, Centre National de la Recherche Scientifique, Sorbonne Université, CP 135, 57 Rue Cuvier, 75005, Paris, France; Centre d'Écologie et des Sciences de la Conservation (CESCO), Muséum national d'Histoire naturelle, Station de Biologie Marine, 1 Place de La Croix, 29900, Concarneau, France.
| | - Yves Bas
- Centre d'Écologie et des Sciences de la Conservation (CESCO), Muséum national d'Histoire naturelle, Centre National de la Recherche Scientifique, Sorbonne Université, CP 135, 57 Rue Cuvier, 75005, Paris, France; Centre d'Écologie Fonctionnelle et Evolutive (CEFE), Centre National de la Recherche Scientifique, Université de Montpellier, Université Paul Valéry Montpellier 3, École Pratique des Hautes Études, Institut de Recherche pour le Développement, Montpellier, France.
| | - Brigitte Zanda
- Institut de Minéralogie, de Physique des Matériaux et de Cosmochimie (IMPMC), Sorbonne Université, Centre National de la Recherche Scientifique, Muséum national d'Histoire naturelle, Institut de Recherche pour le Développement, 61 Rue Buffon, 75005, Paris, France.
| | - Isabelle Le Viol
- Centre d'Écologie et des Sciences de la Conservation (CESCO), Muséum national d'Histoire naturelle, Centre National de la Recherche Scientifique, Sorbonne Université, CP 135, 57 Rue Cuvier, 75005, Paris, France; Centre d'Écologie et des Sciences de la Conservation (CESCO), Muséum national d'Histoire naturelle, Station de Biologie Marine, 1 Place de La Croix, 29900, Concarneau, France.
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8
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Irvine KM, Banner KM, Stratton C, Ford WM, Reichert BE. Statistical assessment on determining local presence of rare bat species. Ecosphere 2022. [DOI: 10.1002/ecs2.4142] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Affiliation(s)
- Kathryn M. Irvine
- Northern Rocky Mountain Science Center U.S. Geological Survey Bozeman Montana USA
| | - Katharine M. Banner
- Department of Mathematical Sciences Montana State University Bozeman Montana USA
| | - Christian Stratton
- Department of Mathematical Sciences Montana State University Bozeman Montana USA
| | - William M. Ford
- Virginia Cooperative Fish and Wildlife Unit U.S. Geological Survey Blacksburg Virginia USA
| | - Brian E. Reichert
- Fort Collins Science Center U.S. Geological Survey Fort Collins Colorado USA
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Wu SH, Chang HW, Lin RS, Tuanmu MN. SILIC: A cross database framework for automatically extracting robust biodiversity information from soundscape recordings based on object detection and a tiny training dataset. ECOL INFORM 2022. [DOI: 10.1016/j.ecoinf.2021.101534] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
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Barré K, Vernet A, Azam C, Le Viol I, Dumont A, Deana T, Vincent S, Challéat S, Kerbiriou C. Landscape composition drives the impacts of artificial light at night on insectivorous bats. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2022; 292:118394. [PMID: 34687777 DOI: 10.1016/j.envpol.2021.118394] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/02/2021] [Revised: 10/17/2021] [Accepted: 10/19/2021] [Indexed: 05/23/2023]
Abstract
Among the most prevalent sources of biodiversity declines, Artificial Light At Night (ALAN) is an emerging threat to global biodiversity. Much knowledge has already been gained to reduce impacts. However, the spatial variation of ALAN effects on biodiversity in interaction with landscape composition remains little studied, though it is of the utmost importance to identify lightscapes most in need of action. Several studies have shown that, at local scale, tree cover can intensify positive or negative effects of ALAN on biodiversity, but none have - at landscape scale - studied a wider range of landscape compositions around lit sites. We hypothesized that the magnitude of ALAN effects will depend on landscape composition and species' tolerance to light. Taking the case of insectivorous bats because of their varying sensitivity to ALAN, we investigated the species-specific activity response to ALAN. Bat activity was recorded along a gradient of light radiance. We ensured a large variability in landscape composition around 253 sampling sites. Among the 13 bat taxa studied, radiance decreased the activity of two groups of the slow-flying gleaner guild (Myotis and Plecotus spp.) and one species of the aerial-hawking guild (Pipistrellus pipistrellus), and increased the activity of two species of the aerial-hawking guild (Pipistrellus kuhlii and Pipistrellus pygmaeus). Among these five effects, the magnitude of four of them was driven by landscape composition. For five other species, ALAN effects were only detectable in particular landscape compositions, making the main effect of radiance undetectable without account for interactions with landscape. Specifically, effects were strongest in non-urban habitats, for both guilds. Results highlight the importance to prioritize ALAN reduction efforts in non-urban habitats, and how important is to account for landscape composition when studying ALAN effects on bats to avoid missing effects.
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Affiliation(s)
- Kévin Barré
- Centre d'Ecologie et des Sciences de la Conservation (CESCO), Muséum National d'Histoire Naturelle, Centre National de la Recherche Scientifique, Sorbonne Université, CP 135, 57 Rue Cuvier, 75005, Paris, France; Centre d'Ecologie et des Sciences de la Conservation (CESCO), Muséum National d'Histoire Naturelle, Station de Biologie Marine, 1 Place de la Croix, 29900, Concarneau, France.
| | - Arthur Vernet
- Ligue pour la Protection des Oiseaux Auvergne Rhône Alpes, Maison de l'environnement, 14 Avenue Tony Garnier, 69007, Lyon, France
| | - Clémentine Azam
- Union Internationale pour la Conservation de la Nature, Musée de l'Homme, 17 Place Du Trocadéro, 75016, Paris, France
| | - Isabelle Le Viol
- Centre d'Ecologie et des Sciences de la Conservation (CESCO), Muséum National d'Histoire Naturelle, Centre National de la Recherche Scientifique, Sorbonne Université, CP 135, 57 Rue Cuvier, 75005, Paris, France; Centre d'Ecologie et des Sciences de la Conservation (CESCO), Muséum National d'Histoire Naturelle, Station de Biologie Marine, 1 Place de la Croix, 29900, Concarneau, France
| | - Agathe Dumont
- Ligue pour la Protection des Oiseaux Auvergne Rhône Alpes, Maison de l'environnement, 14 Avenue Tony Garnier, 69007, Lyon, France
| | - Thomas Deana
- Ligue pour la Protection des Oiseaux Auvergne Rhône Alpes, Maison de l'environnement, 14 Avenue Tony Garnier, 69007, Lyon, France
| | - Stéphane Vincent
- Ligue pour la Protection des Oiseaux Auvergne Rhône Alpes, Maison de l'environnement, 14 Avenue Tony Garnier, 69007, Lyon, France
| | - Samuel Challéat
- UMR CNRS 5602 GÉODE, INÉE-CNRS 3 Rue Michel-Ange, 75016, Paris, France
| | - Christian Kerbiriou
- Centre d'Ecologie et des Sciences de la Conservation (CESCO), Muséum National d'Histoire Naturelle, Centre National de la Recherche Scientifique, Sorbonne Université, CP 135, 57 Rue Cuvier, 75005, Paris, France; Centre d'Ecologie et des Sciences de la Conservation (CESCO), Muséum National d'Histoire Naturelle, Station de Biologie Marine, 1 Place de la Croix, 29900, Concarneau, France
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11
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Roemer C, Julien J, Bas Y. An automatic classifier of bat sonotypes around the world. Methods Ecol Evol 2021. [DOI: 10.1111/2041-210x.13721] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Affiliation(s)
- Charlotte Roemer
- Centre d’Ecologie et des Sciences de la Conservation (Muséum national d’Histoire naturelle, CNRS, Sorbonne Université) Paris France
- CEFEUniversité de MontpellierCNRSEPHEIRDUniversité Paul Valéry Montpellier 3 Montpellier France
| | - Jean‐François Julien
- Centre d’Ecologie et des Sciences de la Conservation (Muséum national d’Histoire naturelle, CNRS, Sorbonne Université) Paris France
| | - Yves Bas
- Centre d’Ecologie et des Sciences de la Conservation (Muséum national d’Histoire naturelle, CNRS, Sorbonne Université) Paris France
- CEFEUniversité de MontpellierCNRSEPHEIRDUniversité Paul Valéry Montpellier 3 Montpellier France
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12
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López-Baucells A, Yoh N, Rocha R, Bobrowiec PED, Palmeirim JM, Meyer CFJ. Optimizing bat bioacoustic surveys in human-modified Neotropical landscapes. ECOLOGICAL APPLICATIONS : A PUBLICATION OF THE ECOLOGICAL SOCIETY OF AMERICA 2021; 31:e02366. [PMID: 33938592 DOI: 10.1002/eap.2366] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/03/2020] [Accepted: 01/15/2021] [Indexed: 06/12/2023]
Abstract
During the last decades, the use of bioacoustics as a non-invasive and cost-effective sampling method has greatly increased worldwide. For bats, acoustic surveys have long been known to complement traditional mist-netting, however, appropriate protocol guidelines are still lacking for tropical regions. Establishing the minimum sampling effort needed to detect ecological changes in bat assemblages (e.g., activity, composition, and richness) is crucial in view of workload and project cost constraints, and because detecting such changes must be reliable enough to support effective conservation management. Using one of the most comprehensive tropical bat acoustic data sets, collected in the Amazon, we assessed the minimum survey effort required to accurately assess the completeness of assemblage inventories and habitat selection in fragmented forest landscapes for aerial insectivorous bats. We evaluated a combination of 20 different temporal sampling schemes, which differed regarding number of hours per night, number of nights per site, and sampling only during the wet or dry season, or both. This was assessed under two different landscape scenarios: in primary forest fragments embedded in a matrix of secondary forest and in the same forest fragments, but after they had been re-isolated through clearing of the secondary forest. We found that the sampling effort required to achieve 90% inventory completeness varied considerably depending on the research aim and the landscape scenario evaluated, averaging ~80 and 10 nights before and after fragment re-isolation, respectively. Recording for more than 4 h per night did not result in a substantial reduction in the required number of sampling nights. Regarding the effects of habitat selection, except for assemblage composition, bat responses in terms of richness, diversity, and activity were similar across all sampling schemes after fragment re-isolation. However, before re-isolation, a minimum of four to six sampling hours per night after dusk and three to five nights of sampling per site were needed to detect significant effects that could otherwise go unnoticed. Based on our results, we propose guidelines that will aid to optimize sampling protocols for bat acoustic surveys in the Neotropics.
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Affiliation(s)
- Adrià López-Baucells
- Centre for Ecology, Evolution and Environmental Changes (cE3c), Faculdade de Ciências, Universidade de Lisboa, Lisbon, 1749-016, Portugal
- Natural Sciences Museum of Granollers, Av/Francesc Macià 51, Granollers, Catalonia, 08402, Spain
- Biological Dynamics of Forest Fragments Project (PDBFF), National Institute for Amazonian Research and Smithsonian Tropical Research Institute, Manaus, AM, 69011-970, Brazil
| | - Natalie Yoh
- Ecosystems and Environment Research Centre (EERC), School of Science, Engineering and Environment, University of Salford, Salford, M5 4WT, United Kingdom
- Durrell Institute of Conservation & Ecology (DICE), University of Kent, Canterbury, CT2 7NZ, United Kingdom
| | - Ricardo Rocha
- Centre for Ecology, Evolution and Environmental Changes (cE3c), Faculdade de Ciências, Universidade de Lisboa, Lisbon, 1749-016, Portugal
- Biological Dynamics of Forest Fragments Project (PDBFF), National Institute for Amazonian Research and Smithsonian Tropical Research Institute, Manaus, AM, 69011-970, Brazil
- CIBIO-InBIO, Research Center in Biodiversity and Genetic Resources, University of Porto, Vairão, 4485-661, Portugal
- CIBIO-InBIO, Research Center in Biodiversity and Genetic Resources, Institute of Agronomy, University of Lisbon, Lisbon, 1349-017, Portugal
| | - Paulo E D Bobrowiec
- Biological Dynamics of Forest Fragments Project (PDBFF), National Institute for Amazonian Research and Smithsonian Tropical Research Institute, Manaus, AM, 69011-970, Brazil
| | - Jorge M Palmeirim
- Centre for Ecology, Evolution and Environmental Changes (cE3c), Faculdade de Ciências, Universidade de Lisboa, Lisbon, 1749-016, Portugal
| | - Christoph F J Meyer
- Centre for Ecology, Evolution and Environmental Changes (cE3c), Faculdade de Ciências, Universidade de Lisboa, Lisbon, 1749-016, Portugal
- Biological Dynamics of Forest Fragments Project (PDBFF), National Institute for Amazonian Research and Smithsonian Tropical Research Institute, Manaus, AM, 69011-970, Brazil
- Ecosystems and Environment Research Centre (EERC), School of Science, Engineering and Environment, University of Salford, Salford, M5 4WT, United Kingdom
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Effects of Environmental Clutter on Synthesized Chiropteran Echolocation Signals in an Anechoic Chamber. ACOUSTICS 2021. [DOI: 10.3390/acoustics3020026] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Ultrasonic bat detectors are useful for research and monitoring purposes to assess occupancy and relative activity of bat communities. Environmental “clutter” such as tree boles and foliage can affect the recording quality and identification of bat echolocation calls collected using ultrasonic detectors. It can also affect the transmission of calls and recognition by bats when using acoustic lure devices to attract bats to mist-nets. Bat detectors are often placed in forests, yet automatic identification programs are trained on call libraries using echolocation passes recorded largely from open spaces. Research indicates that using clutter-recorded calls can increase classification accuracy for some bat species and decrease accuracy for others, but a detailed understanding of how clutter impacts the recording and identification of echolocation calls remains elusive. To clarify this, we experimentally investigated how two measures of clutter (i.e., total basal area and number of stems of simulated woody growth, as well as recording angle) affected the recording and classification of a synthesized echolocation signal under controlled conditions in an anechoic chamber. Recording angle (i.e., receiver position relative to emitter) significantly influenced the probability of correct classification and differed significantly for many of the call parameters measured. The probability of recording echo pulses was also a function of clutter but only for the detector angle at 0° from the emitter that could receive deflected pulses. Overall, the two clutter metrics were overshadowed by proximity and angle of the receiver to the sound source but some deviations from the synthesized call in terms of maximum, minimum, and mean frequency parameters were observed. Results from our work may aid efforts to better understand underlying environmental conditions that produce false-positive and -negative identifications for bat species of interest and how this could be used to adjust survey accuracy estimates. Our results also help pave the way for future research into the development of acoustic lure technology by exploring the effects of environmental clutter on ultrasound transmission.
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López-Bosch D, Huang JCC, Wang Y, Palmeirim AF, Gibson L, López-Baucells A. Bat echolocation in continental China: a systematic review and first acoustic identification key for the country. MAMMAL RES 2021. [DOI: 10.1007/s13364-021-00570-x] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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Froidevaux JSP, Barbaro L, Vinet O, Larrieu L, Bas Y, Molina J, Calatayud F, Brin A. Bat responses to changes in forest composition and prey abundance depend on landscape matrix and stand structure. Sci Rep 2021; 11:10586. [PMID: 34011934 PMCID: PMC8134465 DOI: 10.1038/s41598-021-89660-z] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2020] [Accepted: 04/16/2021] [Indexed: 11/09/2022] Open
Abstract
Despite the key importance of the landscape matrix for bats, we still not fully understand how the effect of forest composition interacts at combined stand and landscape scales to shape bat communities. In addition, we lack detailed knowledge on the effects of local habitat structure on bat-prey relationships in forested landscapes. We tested the assumptions that (i) forest composition has interacting effects on bats between stand and landscape scales; and (ii) stand structure mediates prey abundance effects on bat activity. Our results indicated that in conifer-dominated landscapes (> 80% of coniferous forests) bat activity was higher in stands with a higher proportion of deciduous trees while bats were less active in stands with a higher proportion of deciduous trees in mixed forest landscapes (~ 50% of deciduous forests). Moth abundance was selected in the best models for six among nine bat species. The positive effect of moth abundance on Barbastella barbastellus was mediated by vegetation clutter, with dense understory cover likely reducing prey accessibility. Altogether, our findings deepen our understanding of the ecological processes affecting bats in forest landscapes and strengthen the need to consider both landscape context and trophic linkage when assessing the effects of stand-scale compositional and structural attributes on bats.
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Affiliation(s)
- Jérémy S P Froidevaux
- Université de Toulouse, INRAE, UMR DYNAFOR, Castanet-Tolosan, France. .,University of Bristol, School of Biological Sciences, Life Sciences Building, Bristol, UK. .,Biological and Environmental Sciences, Faculty of Natural Sciences, University of Stirling, Stirling, FK9 4LA, UK.
| | - Luc Barbaro
- Université de Toulouse, INRAE, UMR DYNAFOR, Castanet-Tolosan, France.,CESCO, Museum National D'Histoire Naturelle, CNRS, Sorbonne-Université, Paris, France
| | - Olivier Vinet
- Office National Des Forêts (ONF), Agence Etudes Midi-Méditerranée, Montpellier, France
| | - Laurent Larrieu
- Université de Toulouse, INRAE, UMR DYNAFOR, Castanet-Tolosan, France.,CRPF-Occitanie, Antenne de Tarbes, Tarbes, France
| | - Yves Bas
- CESCO, Museum National D'Histoire Naturelle, CNRS, Sorbonne-Université, Paris, France.,Centre D'Ecologie Fonctionnelle Et Evolutive (CEFE), Université de Montpellier, CNRS, EPHE, IRD, Université Paul Valéry Montpellier 3, Montpellier, France
| | - Jérôme Molina
- Université de Toulouse, INRAE, UMR DYNAFOR, Castanet-Tolosan, France
| | | | - Antoine Brin
- Université de Toulouse, Ecole d'Ingénieurs de PURPAN, UMR INRAE-INPT DYNAFOR, Toulouse, France
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Puig-Montserrat X, Flaquer C, Gómez-Aguilera N, Burgas A, Mas M, Tuneu C, Marquès E, López-Baucells A. Bats actively prey on mosquitoes and other deleterious insects in rice paddies: Potential impact on human health and agriculture. PEST MANAGEMENT SCIENCE 2020; 76:3759-3769. [PMID: 32431084 DOI: 10.1002/ps.5925] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/24/2019] [Revised: 04/28/2020] [Accepted: 05/20/2020] [Indexed: 05/11/2023]
Abstract
BACKGROUND The fact that bats suppress agricultural pests has been measured for some particular dyads of predator and prey species in both economic and food security terms. The recent emergence of new molecular techniques allows for more precise screenings of bat's diet than the traditional visual identification systems and provides further evidence that bats consume an ample array of agricultural pest species. The main focus of the regulatory services that bats provide in agroecosystems has been on crop pests that cause yield losses. Rice paddies constitute a particular agronomic system with specific challenges, not only related to crop productivity but also to human health. Dipteran density in such ecosystems poses a serious threat to human wellbeing and hinders crop production. Mosquitoes cause direct harm to human populations, transmitting a number of infectious diseases. Non-biting midges (Chironomidae) can consume and weaken rice seedlings and can cause major yield losses. RESULTS Mosquito populations and bat activity were assessed in rice paddies of Montgrí, Medes i Baix Ter Natural Park (NE Iberian Peninsula). Molecular analyses of bats faeces (6-weekly samples of 15 faeces each between mid-August and September) proved the presence of both mosquitoes and nonbiting midges in all diet samples. Furthermore, bat activity at the sampling locations was related to adult mosquito density. CONCLUSION Our results suggest that bats actively exploit the emergence of adult mosquitoes and further prove that they prey on mosquitoes, nonbiting midges and other deleterious insects. Promoting the presence of bats next to human settlements in such agroecosystems may constitute a biological control system with direct impact on both human health and crop yield. © 2020 Society of Chemical Industry.
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Affiliation(s)
- Xavier Puig-Montserrat
- Natural Sciences Museum of Granollers, Granollers, Spain
- Galanthus Association, Celrà, Spain
| | - Carles Flaquer
- Natural Sciences Museum of Granollers, Granollers, Spain
| | | | | | - Maria Mas
- Natural Sciences Museum of Granollers, Granollers, Spain
| | - Carme Tuneu
- Natural Sciences Museum of Granollers, Granollers, Spain
| | - Eduard Marquès
- Servei de Control de Mosquits de la Badia de Roses i del Baix Ter, Castelló d'Empúries, Spain
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Knight EC, Sòlymos P, Scott C, Bayne EM. Validation prediction: a flexible protocol to increase efficiency of automated acoustic processing for wildlife research. ECOLOGICAL APPLICATIONS : A PUBLICATION OF THE ECOLOGICAL SOCIETY OF AMERICA 2020; 30:e02140. [PMID: 32335994 DOI: 10.1002/eap.2140] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/11/2019] [Revised: 12/18/2019] [Accepted: 03/19/2020] [Indexed: 06/11/2023]
Abstract
Automated recognition is increasingly used to extract species detections from audio recordings; however, the time required to manually review each detection can be prohibitive. We developed a flexible protocol called "validation prediction" that uses machine learning to predict whether recognizer detections are true or false positives and can be applied to any recognizer type, ecological application, or analytical approach. Validation prediction uses a predictable relationship between recognizer score and the energy of an acoustic signal but can also incorporate any other ecological or spectral predictors (e.g., time of day, dominant frequency) that will help separate true from false-positive recognizer detections. First, we documented the relationship between recognizer score and the energy of an acoustic signal for two different recognizer algorithm types (hidden Markov models and convolutional neural networks). Next, we demonstrated our protocol using a case study of two species, the Common Nighthawk (Chordeiles minor) and Ovenbird (Seiurus aurocapilla). We reduced the number of detections that required validation by 75.7% and 42.9%, respectively, while retaining at least 98% of the true-positive detections. Validation prediction substantially improves the efficiency of using automated recognition on acoustic data sets. Our method can be of use to wildlife monitoring and research programs and will facilitate using automated recognition to mine bioacoustic data sets.
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Affiliation(s)
- Elly C Knight
- Department of Biological Sciences, CW405 Biological Sciences Centre, University of Alberta, Edmonton, Alberta, Canada
| | - Péter Sòlymos
- Department of Biological Sciences, CW405 Biological Sciences Centre, University of Alberta, Edmonton, Alberta, Canada
| | - Chris Scott
- Bishon House, Bishopstone, HR4 7HZ, Herefordshire, UK
| | - Erin M Bayne
- Department of Biological Sciences, CW405 Biological Sciences Centre, University of Alberta, Edmonton, Alberta, Canada
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Revilla-Martín N, Budinski I, Puig-Montserrat X, Flaquer C, López-Baucells A. Monitoring cave-dwelling bats using remote passive acoustic detectors: a new approach for cave monitoring. BIOACOUSTICS 2020. [DOI: 10.1080/09524622.2020.1816492] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Affiliation(s)
- Natalia Revilla-Martín
- Biodiversity and Bioindicators (BiBIO), Natural Sciences Museum of Granollers, Granollers, Spain
- University of Barcelona, Barcelona, Spain
| | - Ivana Budinski
- Biodiversity and Bioindicators (BiBIO), Natural Sciences Museum of Granollers, Granollers, Spain
- Department of Genetic Research, Institute for Biological Research “Siniša Stanković” - National Institute of Republic of Serbia, University of Belgrade, Belgrade, Serbia
| | - Xavier Puig-Montserrat
- Biodiversity and Bioindicators (BiBIO), Natural Sciences Museum of Granollers, Granollers, Spain
- Galanthus Association, Celrà, Spain
| | - Carles Flaquer
- Biodiversity and Bioindicators (BiBIO), Natural Sciences Museum of Granollers, Granollers, Spain
| | - Adrià López-Baucells
- Biodiversity and Bioindicators (BiBIO), Natural Sciences Museum of Granollers, Granollers, Spain
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Wright WJ, Irvine KM, Almberg ES, Litt AR. Modelling misclassification in multi‐species acoustic data when estimating occupancy and relative activity. Methods Ecol Evol 2019. [DOI: 10.1111/2041-210x.13315] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
| | - Kathryn M. Irvine
- U.S. Geological Survey Northern Rocky Mountain Science Center Bozeman MT USA
| | | | - Andrea R. Litt
- Department of Ecology Montana State University Bozeman MT USA
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Darras K, Batáry P, Furnas BJ, Grass I, Mulyani YA, Tscharntke T. Autonomous sound recording outperforms human observation for sampling birds: a systematic map and user guide. ECOLOGICAL APPLICATIONS : A PUBLICATION OF THE ECOLOGICAL SOCIETY OF AMERICA 2019; 29:e01954. [PMID: 31206926 DOI: 10.1002/eap.1954] [Citation(s) in RCA: 44] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/02/2018] [Revised: 04/17/2019] [Accepted: 04/23/2019] [Indexed: 06/09/2023]
Abstract
Autonomous sound recording techniques have gained considerable traction in the last decade, but the question remains whether they can replace human observation surveys to sample sonant animals. For birds in particular, survey methods have been tested extensively using point counts and sound recording surveys. Here, we review the latest evidence for this taxon within the frame of a systematic map. We compare sampling effectiveness of these two survey methods, the output variables they produce, and their practicality. When assessed against the standard of point counts, autonomous sound recording proves to be a powerful tool that samples at least as many species. This technology can monitor birds in an exhaustive, standardized, and verifiable way. Moreover, sound recorders give access to entire soundscapes from which new data types can be derived (vocal activity, acoustic indices). Variables such as abundance, density, occupancy, or species richness can be obtained to yield data sets that are comparable to and compatible with point counts. Finally, autonomous sound recorders allow investigations at high temporal and spatial resolution and coverage, which are more cost effective and cannot be achieved by human observations alone, even though small-scale studies might be more cost effective when carried out with point counts. Sound recorders can be deployed in many places, they are more scalable and reliable, making them the better choice for bird surveys in an increasingly data-driven time. We provide an overview of currently available recorders and discuss their specifications to guide future study designs.
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Affiliation(s)
- Kevin Darras
- Agroecology, Department of Crop Sciences, University of Goettingen, Grisebachstrasse 6, 37077, Göttingen, Germany
| | - Péter Batáry
- Agroecology, Department of Crop Sciences, University of Goettingen, Grisebachstrasse 6, 37077, Göttingen, Germany
- Lendület Landscape and Conservation Ecology, Institute of Ecology and Botany, MTA Centre for Ecological Research, Alkotmány u. 2-4, 2163, Vácrátót, Hungary
| | - Brett J Furnas
- Wildlife Investigations Laboratory, California Department of Fish and Wildlife, 1701 Nimbus Road, Suite D, Sacramento, California, 95670, USA
| | - Ingo Grass
- Agroecology, Department of Crop Sciences, University of Goettingen, Grisebachstrasse 6, 37077, Göttingen, Germany
| | - Yeni A Mulyani
- Department of Forest Resources Conservation and Ecotourism, Faculty of Forestry, Bogor Agricultural University, Bogor, Indonesia
| | - Teja Tscharntke
- Agroecology, Department of Crop Sciences, University of Goettingen, Grisebachstrasse 6, 37077, Göttingen, Germany
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Bat Pass Duration Measurement: An Indirect Measure of Distance of Detection. DIVERSITY 2019. [DOI: 10.3390/d11030047] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Few reports have been published on detection distances of bat calls because the evaluation of detection distance is complicated. Several of the approaches used to measure detection distances are based on the researcher’s experience and judgment. More recently, multiple microphones have been used to model flight path. In this study, the validity of a low-cost and simple detectability metric was tested. We hypothesize that the duration of an echolocating-bat-pass within the area of an ultrasonic bat detector is correlated with the distance of detection. Two independent datasets from a large-scale acoustic bat survey—a total of 25,786 bat-passes from 20 taxa (18 species and two genera)—were measured. We found a strong relationship between these measures of bat-pass duration and published detection distances. The advantages of bat-pass duration measures are that, for each study, experimenters easily produce their own proxy for the distance of detection. This indirect measure of the distance of detection could be mobilized to monitor the loss in microphone sensitivity used to monitor long-term population trends. Finally, the possibility of producing an index for distance of detection provides a weight for each bat species’ activity when they are aggregated to produce a bat community metric, such as the widely used “total activity”.
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