Explore the vast range of titles available.

Though some bat species spend the colder months deep in caves and abandoned mines, tree-roosting bats travel south for the winter, just like birds. Young readers are sure to enjoy learning about the fascinating life and impressive journey of bats, a creature every child can easily recognize, yet few know much about.

Bat movement and behaviour are still mostly understudied over large scales. High‐altitude, nocturnal activity makes visual identification of bats from the ground virtually impossible, dramatically hindering our ability to study their movement ecology. Despite the wide use of radar in aeroecology, its application to study specific taxa is limited due to incomplete target classification abilities. BATScan is a bat classifier for vertical‐looking radar data, which enables identifying bats and characterizing their unique aeroecology. We constructed the classifier using data from 10 radar deployments, covering a wide range of habitats on a central bird migration flyway over a 7‐year period, comprising ~18 million observations. We analysed animal migration above the Hula Valley, home to over 30 species of bats spanning a range of 5–150 g in size and exhibiting a variety of ecological characteristics. We distinguished bat‐labelled radar echoes for training according to phenology, morphology and movement ecology of bats, birds and insects. Several non‐bat datasets were constructed and joined to train classifiers under increasing levels of difficulty. Class imbalance in the resulting training data was handled using a generative adversarial network for up‐sampling the much smaller bat dataset. The resulting classification tool reached a high level of accuracy and precision, and was further scrutinized with an extensive set of ecological validations. Bats perform seasonal migrations over long distances, but little is known about the spatial and temporal characteristics of this movement, and the ability to study it at a large scale has so far been limited. We present the Israeli BATScan dataset, containing over 60,000 bat observations spanning the entire country and representing multiple habitats. Using this data, we produce an unprecedented large scale, highly detailed documentation of the yearly movements of bats on a major migration flyway, and distinguish this pattern from bird migration over space and time. So far, radar aeroecology dealt primarily with birds, increasingly with insects, and only rarely with bats. We present BATScan, a classification tool that can incorporate bats into the framework of radar aeroecology to finally enable a comprehensive description of animal aeroecology. אבסטרקט בשנים האחרונות השימוש במכ”מ לחקר בעלי חיים אוויריים איפשר לענות על שאלות אקולוגיות בסיסיות בזמן ובמרחב בפירוט חסר תקדים. יחד עם זאת, עד כה טרם ניתן היה להפריד בין החזרי מכ”ם מציפורים ומעטלפים, ובכך הוגבלה מאוד האפשרות לבחינת השפע, התפוצה והתנועה של עטלפים והשלכותיהם היישומיות הנוגעות להאבקה, הפצת זרעים ושמירת טבע. כתוצאה מכך, הידע שלנו על קבוצה חשובה זו של יונקים מוגבל מאוד. במסגרת פרויקט מחקר זה, פיתחנו את ה‐BATScan שהינו המסווג הראשון שפותח אי פעם לזיהוי עטלפים במידע מכ”מי. מסווג זה מבוסס בינה מלאכותית ונבנה תוך שימוש במאגר מידע ייחודי שנאסף ע”י מכ”ם אנכי שהוצב במוקד מחקרי החולה, בסמוך לאגמון החולה. תהליך איסוף המידע ובניית המסווג נעשו על בסיס מידע שנאסף בתקופה בה הפעילות האווירית של ציפורים בלילה היא מינימלית, בשילוב סינונים מבוססי צורה ותנועה. תצפיות עטלפים בודדו על בסיס זמני פעילות, ביומכאניקה של תנועת כנפיים וגודל. BATScan מגיע לרמות דיוק גבוהות (מעל 90%) ועבר בהצלחה סדרת ולידציות חיצוניות. מסווג זה שימש ליצירה של מסד נתונים ייחודי בעולם של כ‐60,000 עטלפים אשר נאסף באמצעות שימוש במכ”מים האנכיים שהוצבו בעשרה מקומות שונים בארץ לאורך שבע השנים האחרונות. מסד נתונים זה מציג לראשונה בעולם דפוס תנועה מלא של עטלפים לאורך כל חודשי השנה. מצאנו כי היקף נדידת העטלפים מהווה כ‐ 10‐25% מהיקף נדידת ציפורי השיר בישראל וכן שלנדידת העטלפים יש פנולוגיה שונה מנדידת הציפורים. נדידת העטלפים מתחילה מאוחר יותר ביחס לנדידת הציפורים בשתי עונות הנדידה, וכן שעונות הנדידה קצרות יותר ביחס לציפורים. בנוסף נצפה כי טווח הגבהים בו עטלפים נודדים (200‐600 מטר מעל פני הקרקע) צר יותר מטווח הנדידה של ציפורי שיר (100‐1,000 מטר מעל פני הקרקע). יישום מסווג העטלפים שפותח במסגרת פרויקט זה על נתוני מכ”ם מאתרים נוספים בעולם צפוי לייצר מסד נתונים עולמי ובכך לחולל מהפכה בהבנתנו את האקולוגיה האווירית של קבוצה זו.

Seasonal movements between the summer and winter areas are a widespread phenomenon in bats So far, most information on the migration ecology of bats has been obtained by studies in terrestrial habitats, whereas scientific knowledge on migration over sea is scarce. We performed continuous ultrasonic acoustic monitoring at 13 locations in the southern North Sea during four consecutive years (2017–2020) and analysed the spatiotemporal occurrence of Nathusius’ pipistrelle Pipistrellus nathusii during autumn migration in relation to weather parameters and lunar phase. Our analysis showed that the main autumn migration of Nathusius’ pipistrelle at the southern North Sea occurs from mid-August until late October and most bats within the study area occur off the Noord Holland coast. North Sea crossings frequently last longer than one night; the day is spent roosting at an offshore structure. The strongest migration occurs during nights with tailwinds from the east-northeast, but bats are also recorded offshore with low to moderate headwinds or crosswinds. Bat presence decreased between the full moon and the last quarter and increased just before the new moon. Finally, our observations show that the occurrence of bats at sea was reduced in 2020 in comparison to the previous years. The results of this study show clear spatiotemporal patterns of migratory bat occurrence at the southern North Sea. The spatial distribution can be used in spatial planning of future offshore wind farms, whereas the temporal occurrence and environmental factors that shape offshore migration can be used to develop mitigation measures to reduce the number of bat fatalities.

Wind turbines used to combat climate change pose a green-green dilemma when endangered and protected wildlife species are killed by collisions with rotating blades. Here , we investigated the geographic origin of bats killed by wind turbines along an east-west transect in France to determine the spatial extent of this conflict in Western Europe. We analysed stable hydrogen isotopes in the fur keratin of 60 common noctule bats ( Nyctalus noctula ) killed by wind turbines during summer migration in four regions of France to predict their geographic origin using models based on precipitation isoscapes. We first separated migratory from regional individuals based on fur isotope ratios of local bats. Across all regions , 71.7% of common noctules killed by turbines were of regional and 28.3% of distant origin , the latter being predominantly females from northeastern Europe. We observed a higher proportion of migratory individuals from western sites compared to eastern sites. Our study suggests that wind-turbine-related losses of common noctule bats may impact distant breeding populations across whole Europe , confirming that migratory bats are highly vulnerable to wind turbines and that effective conservation measures , such as temporary curtailment of turbine operation , should be mandatory to protect them from colliding with the rotating blades of wind turbines.

The endangered Indiana bat (Myotis sodalis) congregates in large hibernation groups in winter and travels after spring emergence to form summer maternity colonies, but information on migration behavior in this species remains limited to mostly band recovery observations. We tracked female Indiana bats in spring migration toward summer grounds using aerial radiotelemetry. Adult female Indiana bats were radiotagged in spring from 2009 through 2017, with 15 individuals successfully tracked to summer grounds and an additional 11 bats located in summer grounds via aerial telemetry after migration was complete. This resulted in the location of 17 previously unknown summer grounds for female Indiana bats, including adding Georgia, Alabama, and Mississippi to the summer maternity range. Two of the colonies identified in this study were south of the previously known southernmost colony in Tennessee, expanding the summer maternity range for the species by 178 km. Time-stamped location fixes along the migration path provided information about nightly and overall distances traveled, duration of travel, migration speed, and weather-related influences on bat behavior. Bats traveled 164.6 ± 26.2 km (± SE) on average from hibernacula to summer grounds and were migrating for an average of 7.3 ± 1.4 calendar nights. Bats alternated between foraging and traveling throughout each night of their migration route. Nightly migration rate was 9.9 ± 0.8 km/h and bats were active on the landscape for an average of 6.1 ± 0.4 h/night. Lower nighttime temperatures and lower barometric pressure correlated with use of layover areas during a migration night. Understanding bat behavior during migration can provide pertinent information for land managers to consider in efforts to conserve potential migration corridors, foraging areas, and roosting habitats of species in decline.

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. Migratory bats are attracted to LED light by positive phototaxis. Red aviation lighting and other red light sources at night might lead to disorientation in migratory bats and thus interferes with the seasonal movements of this protected taxon.

Background Migratory bats perform seasonal movements between their summer and winter areas. When crossing ecological barriers, like the open sea, they are exposed to an increased mortality risk due to energetically demanding long-distance flights and unexpected inclement weather events. How such barriers affect bat migratory movements is still poorly known. Methods To study bat migration patterns in response to an ecological barrier, we tagged 44 Nathusius’ pipistrelles Pipistrellus nathusii with radio-transmitters on the East coast of the United Kingdom (UK) in spring 2021 and 2022. Subsequently, we assessed their movements to continental Europe using the MOTUS Wildlife Tracking System. We investigated route selection, timing of migration, overall migration speed and the influence of wind on airspeed, groundspeed and flight altitude during migratory overseas flights. Results Barrier effects cause migratory movements along the coast, and crossings over sea are shortened by deviating from the general migration direction. Males depart from the UK later in the season compared to females. The overall migration speed of females was 61 km/day and 88 km/day after their last detection in the UK. Our estimated airspeeds during oversea flights correspond well with airspeeds measured in a wind tunnel. Bats use wind adaptively to reduce airspeed when flying under tailwind and increase airspeed when flying under crosswind conditions. Departures over sea coincidence with tailwinds, enabling bats to more than double their airspeed, reaching ground speeds of up to 16.8 m/s (60.5 km/h). Our analysis suggests that bats select altitudes with favourable wind conditions and that they seek altitudes of several hundred meters, possibly extending up to 2,500 m. Low-altitude migration occurs when wind conditions are less favourable. Conclusions Our study demonstrates that bat migratory movements are highly influenced by barrier effects, sex-biased timing of migration and the adaptive use of winds. The results of our study contribute to a more comprehensive understanding of the decision-making process and adaptations bats employ during their migration. Elucidating bat migration patterns will enable us to develop effective conservation measures, for example in relation to the development and operation of coastal and offshore wind farms.

Latitudinal migration increases fitness of migrants by allowing them to exploit favorable conditions in nonadjacent geographic regions. Other consequences also may follow, such as interactions with parasites. Migrants may have lower parasite prevalence and abundance than resident individuals because of their ability to abandon infested areas or due to mortality of highly infested hosts. To further understand whether variation in ectoparasite loads is influenced by migration, we investigated whether prevalence and abundance of two species of obligate ectoparasites, the wing mite Periglischrus paracaligus (Mesostigmata: Spinturnicidae) and the bat fly Nycterophilia coxata (Diptera: Streblidae, Nycterophiliinae), of the lesser long-nosed bat, Leptonycteris yerbabuenae, varied between migratory and resident populations throughout their range in Mexico. We examined the presence or absence of migratory behavior, as well as sex and reproductive status of the host because ectoparasitism differentially affects the sexes. Our results showed that the prevalence of both ectoparasites did not vary between migrant and resident females or males, but abundance of the wing mite P. paracaligus was lower in migrant females compared with resident females, with an important influence from the reproductive status of the host. A partial negative relationship between ectoparasite loads and latitudinal migration therefore was demonstrated.

Bats undertaking seasonal migration between summer roosts and wintering areas can cross large areas of open sea. Given the known impact of onshore wind turbines on bats, concerns were raised on whether offshore wind farms pose risks to bats. Better comprehension of the phenology and weather conditions of offshore bat migration are considered as research priorities for bat conservation and provide a scientific basis for mitigating the impact of offshore wind turbines on bats. This study investigated the weather conditions linked to the migratory activity of Pipistrellus bats at multiple near- and offshore locations in the Belgian part of the North Sea. We found a positive relationship between migratory activity and ambient temperature and atmospheric pressure and a negative relationship with wind speed. The activity was highest with a wind direction between NE and SE, which may favor offshore migration towards the UK. Further, we found a clear negative relationship between the number of detections and the distance from the coast. At the nearshore survey location, the number of detections was up to 24 times higher compared to the offshore locations. Our results can support mitigation strategies to reduce offshore wind farm effects on bats and offer guidance in the siting process of new offshore wind farms.

In Eastern Europe, wind energy production is currently promoted as an important source of renewable energy, yet in most cases without appropriate consideration of the negative impacts wind turbines (WT) may have on protected species such as bats. Here, we present first data on fatality rates, fatality factors and the likely origin of bats killed by WT in the Dobrogea region (Romania), located in a major migratory corridor for wildlife in Eastern Europe. Over a 4-year period, we found a total of 166 bat carcasses from 10 species, mostly representing migratory species such as Pipistrellus nathusii and Nyctalus noctula. Most fatalities at WT occurred in July and August. We documented 15 cases of barotrauma and 34 cases of blunt-force trauma in carcasses found below WT. After adjusting for carcass removals and variations in searcher efficiency, we estimated for the 4-year study period a total of 2394 bat casualties at the studied WT facility consisting of 20 units, resulting in a mean fatality rate of 30 bats/WT/year, or 14.2 bats/MW/year. By implementing a curtailment measure at wind speeds below 6.5 m/s, we reduced fatality rates by 78%. Isoscape origin models based on hydrogen stable isotope ratios in fur keratin revealed that the majority of N. noctula that were killed by WT or captured nearby in mist nets originated from distant areas in the North (Ukraine, Belarus, Russia). The estimated high fatalitjegangy rates of bats at WT in this area have far-reaching consequences, particularly for populations of migratory bats, if no appropriate mitigation schemes are practised.