Dispersal behavior and survival are critical properties of animal populations and are known to determine the success of reintroduction and reinforcement programs. We tracked 53 juvenile Aquila fasciata (Bonelli's Eagle), including wild-hatched and captive-bred individuals released via two different protocols, to test how early-life experiences shape dispersal and fitness outcomes. Captive-bred eagles were released either on their rearing site near their natal enclosure and foster parents or at a distant site without the parents. Dispersal patterns diverged strongly by group: distant-released individuals dispersed farther, and in markedly more directional, migration-like patterns, reaching as far as East Africa and the Arabian Peninsula. In contrast, on-site and wild-hatched eagles remained closer to their natal areas, showing variable and shorter dispersal trajectories on average. Despite comparable ages at dispersal onset, habitat use differed significantly, with distant-released individuals consistently occupying drier desert habitats. These patterns suggest that post-fledging experience promotes philopatry and shapes movement decisions, likely via natal habitat preference induction. Wild-hatched eagles exhibited significantly higher survival rates and recruitment success than both captive-bred groups, which suffered elevated mortality primarily due to electrocution and other anthropogenic threats. Surprisingly, shorter-range dispersal by on-site releases did not improve survival, likely reflecting high risk from local infrastructure (notably high incidents of electrocution). The high mortality of captive-bred birds raises concerns about the long-term effectiveness of current release strategies and highlights the paramount importance of conserving existing wild breeding pairs and their territories. Our findings demonstrate that both dispersal and fitness outcomes are influenced by the timing and spatial context of the release to the wild, with strong implications for raptor conservation and reintroduction programs. In particular, we highlight the importance of acquiring natal habitat preference during the post-fledging dependence period and recommend that release protocols preserve continuity with natal habitat when possible. Ultimately, this study underscores that fine-scale management of early-life experience can have enduring consequences for the spatial ecology and viability of reintroduced populations. center dot Captive breeding helps save endangered species, but we need to understand how release methods affect survival and behavior of captive-bred animals. center dot We tracked 53 Aquila fasciata (Bonelli's Eagle)-both wild-hatched and captive-bred birds-released using two different methods to study their movements and survival. center dot Captive-bred eagles released far from their parents and rearing sites traveled much longer distances than wild-hatched eagles or eagles released near their rearing site, often reaching East Africa and Southern Arabia. center dot However, all captive-bred eagles had lower survival than wild birds, with most deaths caused by electrocution from powerlines. The high number of powerlines near the release sites likely obscured survival differences between the long-range and short-range dispersers. center dot These findings show that early life conditions and release strategies can shape the behavior and success of animals in the wild. This can help improve conservation efforts by guiding more effective release practices for threatened species. El comportamiento de dispersi & oacute;n y la supervivencia son propiedades cr & iacute;ticas de las poblaciones animales y se sabe que determinan el & eacute;xito de los programas de reintroducci & oacute;n y refuerzo poblacional. Seguimos a 53 juveniles de Aquila fasciata, incluyendo individuos nacidos en estado silvestre y criados en cautiverio, & eacute;stos & uacute;ltimos liberados mediante dos protocolos diferentes, para evaluar c & oacute;mo las experiencias tempranas moldean la dispersi & oacute;n y los resultados en t & eacute;rminos de aptitud biol & oacute;gica. Las & aacute;guilas criadas en cautiverio fueron liberadas ya sea en su sitio de crianza, cerca de su recinto natal y de sus padres adoptivos, o en un sitio distante y sin los padres. Los patrones de dispersi & oacute;n divergieron marcadamente entre grupos: los individuos liberados en un sitio distante se dispersaron m & aacute;s lejos y en trayectorias mucho m & aacute;s direccionales, similares a migraciones, llegando hasta & Aacute;frica oriental y la pen & iacute;nsula Ar & aacute;biga. En contraste, las & aacute;guilas liberadas en el sitio de crianza y las nacidas en estado silvestre permanecieron m & aacute;s cerca de sus & aacute;reas natales, mostrando trayectorias de dispersi & oacute;n m & aacute;s cortas y variables en promedio. A pesar de presentar edades comparables al inicio de la dispersi & oacute;n, el uso del h & aacute;bitat difiri & oacute; significativamente, ya que los individuos liberados en un sitio distante ocuparon de manera consistente h & aacute;bitats des & eacute;rticos m & aacute;s secos. Estos patrones sugieren que la experiencia posterior al emplumamiento promueve la filopatr & iacute;a y moldea las decisiones de movimiento, probablemente mediante la inducci & oacute;n de una preferencia por el h & aacute;bitat natal. Las & aacute;guilas nacidas en estado silvestre presentaron tasas de supervivencia y & eacute;xito de reclutamiento significativamente mayores que ambos grupos criados en cautiverio, los cuales sufrieron mortalidad elevada principalmente por electrocuci & oacute;n y otras amenazas antropog & eacute;nicas. Sorprendentemente, la dispersi & oacute;n a menor distancia de los individuos liberados en el sitio de crianza no mejor & oacute; la supervivencia, lo que probablemente refleja el alto riesgo asociado a la infraestructura local (en particular, una alta incidencia de electrocuciones). La alta mortalidad de las aves criadas en cautiverio genera preocupaci & oacute;n sobre la eficacia a largo plazo de las estrategias actuales de liberaci & oacute;n y resalta la importancia primordial de conservar las parejas reproductoras silvestres existentes y sus territorios. Nuestros resultados demuestran que tanto la dispersi & oacute;n como los resultados en t & eacute;rminos de aptitud biol & oacute;gica est & aacute;n influidos por el momento y el contexto espacial de la liberaci & oacute;n al medio natural, con importantes implicancias para la conservaci & oacute;n de rapaces y los programas de reintroducci & oacute;n. En particular, destacamos la importancia de adquirir una preferencia por el h & aacute;bitat natal durante el per & iacute;odo posterior al emplumamiento y recomendamos que los protocolos de liberaci & oacute;n preserven, cuando sea posible, la continuidad con el h & aacute;bitat natal. En & uacute;ltima instancia, este estudio subraya que el manejo a escala fina de las experiencias tempranas puede tener consecuencias duraderas para la ecolog & iacut

Dispersal is an important ecological process influencing population viability, demography, and gene flow. For non-migratory raptors like the Aquila fasciata (Bonelli's Eagle), natal dispersal-the movement between the birthplace and the first breeding site-is a critical life stage. However, the role of natal habitat on the dispersal process and its implications for population viability and conservation remains poorly understood. This study examined how natal habitat across three distinct biogeographic regions influences dispersal movement, habitat use and survival of juvenile A. fasciata in the Levant (within areas administered by Israel and the Palestinian authority). Using global positioning system (GPS) telemetry, 55 juvenile eagles originating from Mediterranean, semi-desert, and desert habitats were tracked over their dispersal journeys. Key aspects such as dispersal direction, distance, temporary settlement areas (TSAs), territorial recruitment and mortality were analyzed in relation to the natal climatic conditions. Results revealed clear habitat-based differences in dispersal patterns. Desert-hatched eagles dispersed the farthest, with some crossing the Sahara and Arabian deserts to reach sub-Saharan Africa or southern Arabia, while Mediterranean and semi-desert eagles remained more localized. Water bodies acted as barriers, shaping dispersal routes and TSA distribution. Throughout dispersal, eagles occupied areas with precipitation levels similar to their natal sites, supporting natal habitat preference induction (NHPI) hypothesis. Recruitment data further indicated strong fidelity to natal climatic zones, with only 1 out of 11 eagles settling outside its natal zone. Mortality patterns varied by habitat types, with desert-hatched eagles experiencing the highest proportion of deaths outside the study area. These findings underscore the influence of natal habitat on dispersal, highlighting how local environmental conditions shape movement patterns, species distributions, and population trajectories. Understanding these patterns is crucial for raptor conservation, particularly in managing habitat-specific risks and transboundary movements. We studied how young Aquila fasciata (Bonelli's Eagle) move from their hatch places until they mature and settle to breed, over a period of 2-4 years. Using global positioning system (GPS) tracking, we followed 55 eagles from 3 habitat types-Mediterranean, semi-desert, and desert-to examine their movement and settlement patterns. Eagles hatched in desert areas traveled much farther and more directly south, often crossing vast deserts like the Sahara and Arabian. Eagles typically settled in habitats resembling their hatch place, suggesting early-life habitat imprinting that influences their long-term behavior. These movement strategies affected survival and breeding recruitment, with notable differences in where and how eagles from different habitats died. This research provides valuable insights for more effective conservation of endangered A. fasciata in harsh and fragmented landscapes, suggesting that conservation efforts need to additionally focus on conserving key movement corridors and settlement areas. La dispersi & oacute;n es un proceso ecol & oacute;gico importante que influye en la viabilidad poblacional, la demograf & iacute;a y el flujo g & eacute;nico. Para rapaces no migratorias como Aquila fasciata, la dispersi & oacute;n natal-el movimiento entre el lugar de nacimiento y el primer sitio de reproducci & oacute;n-es una etapa cr & iacute;tica de la vida. Sin embargo, el rol del h & aacute;bitat natal en el proceso de dispersi & oacute;n y sus implicaciones para la viabilidad poblacional y la conservaci & oacute;n sigue siendo poco comprendido. Este estudio examin & oacute; c & oacute;mo el h & aacute;bitat natal en tres regiones biogeogr & aacute;ficas distintas influye en el movimiento de dispersi & oacute;n, el uso de h & aacute;bitat y la supervivencia de juveniles de A. fasciata en el Levante (dentro de las & aacute;reas administradas por Israel y la Autoridad Palestina). Mediante telemetr & iacute;a GPS, se rastrearon 55 & aacute;guilas juveniles originarias de h & aacute;bitats mediterr & aacute;neos, semides & eacute;rticos y des & eacute;rticos a lo largo de sus trayectorias de dispersi & oacute;n. Aspectos clave como la direcci & oacute;n y distancia de dispersi & oacute;n, las & aacute;reas de asentamiento temporal (AAT), el reclutamiento territorial y la mortalidad fueron analizados en relaci & oacute;n con las condiciones clim & aacute;ticas natales. Los resultados revelaron claras diferencias en los patrones de dispersi & oacute;n seg & uacute;n el h & aacute;bitat. Las & aacute;guilas nacidas en el desierto se dispersaron m & aacute;s lejos, con algunas cruzando los desiertos del Sahara y de Arabia para llegar al & Aacute;frica subsahariana o al sur de Arabia, mientras que las & aacute;guilas mediterr & aacute;neas y semides & eacute;rticas permanecieron m & aacute;s localizadas. Los cuerpos de agua actuaron como barreras, moldeando las rutas de dispersi & oacute;n y la distribuci & oacute;n de las AAT. Durante la dispersi & oacute;n, las & aacute;guilas ocuparon & aacute;reas con niveles de precipitaci & oacute;n similares a sus sitios natales, lo que respalda la hip & oacute;tesis de inducci & oacute;n de preferencia por el h & aacute;bitat natal. Los datos de reclutamiento indicaron adem & aacute;s una fuerte fidelidad a las zonas clim & aacute;ticas natales, con solo 1 de 11 & aacute;guilas asent & aacute;ndose fuera de su zona natal. Los patrones de mortalidad variaron seg & uacute;n el tipo de h & aacute;bitat, con las & aacute;guilas nacidas en el desierto experimentando la mayor proporci & oacute;n de muertes fuera del & aacute;rea de estudio. Estos hallazgos subrayan la influencia del h & aacute;bitat natal en la dispersi & oacute;n, destacando c & oacute;mo las condiciones ambientales locales moldean los patrones de movimiento, las distribuciones de las especies y las trayectorias poblacionales. Comprender estos patrones es crucial para la conservaci & oacute;n de las rapaces, particularmente en la gesti & oacute;n de riesgos espec & iacute;ficos del h & aacute;bitat y de los movimientos transfronterizos.

Insect migration is a massive and broad phenomenon, yet there are major knowledge gaps regarding the migration properties of this group. Many dragonfly species are considered migrants but only a few have been thoroughly studied, none of which migrate from Europe to other areas. The red-veined darter Sympetrum fonscolombii (Insecta: Odonata) is a common and widespread species which has recently expanded its range northwards in Europe and Asia. Recently, stable hydrogen isotope analysis showed that individuals from the Levant migrate north during spring, but no concrete evidence of a return southward autumn migration exists. To clarify the migratory status of S. fonscolombii in Israel, we collected observations from various sources (experts, citizen science and social media platforms), spanning all seasons and multiple years, and provide a first phenological description for the species in the area. Natal origins of individuals appearing on the Israeli coastline during autumn were inferred using stable hydrogen isotope analysis from wing samples in a spatially explicit probabilistic assignment. We found that the phenological pattern, with a peak in abundance between August and November, fits a migratory influx. The wing stable isotopes analysis resulted in a broad potential natal origin zone, covering a substantial part of the species' Eurasian range. These results provide the first direct evidence for a southward migration out of Europe and West Asia of S. fonscolombii or any other dragonfly species, with some individuals likely originating from the extreme northern parts of the species' known range.

Raptor populations in Africa are rapidly declining, yet causes of mortality are insufficiently known for most resident species understudied beyond poisoning. This study aimed to investigate the causes of raptor mortality on the African continent. We compiled 1012 mortality records from 43 raptor species tracked with GPS transmitters in Africa between 2003 and 2026 to identify the main causes of mortality, estimate the relative contribution of anthropogenic vs natural causes of mortality, and the factors affecting mortality. Human-induced mortality accounted for 58.8% of known mortality in migratory raptors (n = 233) and 74.3% in non-migratory raptors (n = 241). The main causes of known mortality were direct killing (24.4% of 474 records), poisoning (23.6%), and electrocution (10.1%). Predatory raptors were at higher risk of direct killing than vultures, had higher risk in urbanised than rural landscapes, for non-migrants compared to migrants, and during the non-breeding season compared to the breeding and migration seasons. Vultures had a higher risk of poisoning among adults compared to immatures and in more rural/protected areas relative to urbanised areas. Among poisoned vultures (n = 103), 40.2% were poisoned intentionally. Electrocution occurred at similar rates in vultures and predatory raptors, and more frequently with more urbanisation. The proportion of tracked birds for which cause of mortality could be identified increased over time but remained lower for non-migrants compared to migrants. Our results show the predominantly anthropogenic origin of raptor mortality in Africa, stressing the need for stronger conservation actions directed against direct killing, poisoning, and electrocution.

Radar technology has become a powerful tool for studying animal aeroecology in the lower atmosphere, particularly bird migration across large spatio-temporal scales. Quantifying bird density from radar data requires radar cross-section (RCS) estimates. Although RCS data exist for small bird species, large birds, especially soaring and flocking species, remain poorly characterized, partly due to technical challenges in measuring and modelling their complex morphology. This study introduces a practical and accessible modelling framework for estimating species-specific RCS in large birds, using the T-matrix electromagnetic scattering method, based on geometrically simplified representations of bird morphology. We computed spherical RCS values for 11 large bird species across C- and S-band radar wavelengths and compared them with both spherical and prolate spheroidal RCS estimates obtained using the WIPL-D software, a method previously validated for biological targets. As expected, the spherical simplification led to a systematic overestimation of RCS relative to a more anatomically representative model. However, the bias was consistent and can be corrected using regression-derived scaling factors. This approach addresses the critical lack of empirical RCS data for large birds, offering an alternative that can be implemented in open-source platforms. It can be integrated with automated detection tools to enhance our understanding of migration patterns in understudied bird groups and to support efforts to mitigate bird-aircraft collisions.

We investigated the spatial behavior of a recently discovered breeding population of Egyptian Nightjars (Caprimulgus aegyptius) near the Dead Sea. While there is a prevalent migratory tendency in other populations of this species, it is unknown whether this recently discovered population is migratory or sedentary. To resolve this uncertainty, we examined their daily and annual movements by equipping five individuals (two adults, three juveniles) with GPS tags and retrieved data from the two adults (a female and a male). Sampling Nightjar’s location twice a day (once during the nighttime and once during the daytime) over a period of eleven months, we found that they exhibited resident behavior. They remained in the same area for the entire tracking period, travelling as little as 15.1 km from the tagging location, and 2.4 ± 1.7 km (mean ± SD) daily. We also documented high roost fidelity, showing a tendency to return to the same day-roost site every day within a radius of 30 m, usually in a shady spot under a small bush, and a continuous use of the same site for up to five months, during both summer and winter. Our findings confirm that at least a part of the Egyptian Nightjar population in the Dead Sea region is resident, and highlight the ecological and conservation importance of their specific, and repeatedly used, daily roost sites and year-round activity areas.

Vertical-looking radars (VLRs) detect individual flying animals up to ∼2 km above ground and characterize their flight track, timing, wing movement, size, and shape. We present a protocol for calculating individual vertical movement characteristics and producing diel vertical movement profiles using the BirdScan MR1 VLR, based on flight altitude detection and timing. The protocol includes steps for data preparation and analysis. This protocol promotes a more detailed understanding of migration ecology, stopover behavior, and movement phenology. For complete details on the use and execution of this protocol, please refer to Werber and Sapir.1.

The rapid pace of human-related development and environmental instability has placed significant pressure on global ecosystems, threatening the existence of numerous threatened wildlife species, including birds. Accurate and detailed monitoring can play a crucial role in safeguarding biodiversity, supporting conservation efforts and enhancing ecosystem management. Traditional monitoring methods, such as direct observation and manual image analysis, are labor-intensive, prone to bias, and often inadequate for large and densely populated breeding colonies. In this study, we developed a fully automated deep-learning-based algorithm to identify, count, and map breeding seabirds in a large and densely populated mixed breeding colony containing breeding pairs of two visually similar species, the regionally-threatened Common Tern (Sterna hirundo) and the Little Tern (Sternula albifrons). Using YOLOv8 for initial object detection using remote-controlled cameras, we enhanced classification performance by integrating ecological and behavioral features, including spatial fidelity, movement patterns and size, through camera calibration techniques. Our algorithm successfully identified, counted, and mapped breeding individuals from both species with an average discrepancy of only 2 % compared to manual counts, and achieved over 90 % accuracy in correctly identifying the species of nesting individuals from both species. By providing high-resolution spatial mapping of nesting individuals, the system also offers valuable insights into habitat use and intra-colony dynamics. Additionally, incorporating behavioral tracking via video analysis allows for a more accurate differentiation between nesting and non-nesting individuals. Our methodology represents a significant advancement in automated wildlife monitoring by integrating artificial intelligence for automatic counting, mapping and classifying birds to enhance our understanding of ecological processes and to aid conservation. This study presents a robust, automated framework for seabird colony monitoring that minimizes human disturbance while maximizing accuracy and efficiency. By leveraging deep learning and ecological knowledge, this approach can revolutionize conservation monitoring, offering a scalable and cost-effective solution for tracking wildlife populations in an era of rapid environmental changes.

Tissue wear in animals occurs consistently and can impair their functionality. In birds, abrasion - which reduces the feathered surface area - is caused by various factors. However, little is known about the underlying mechanisms, patterns and immediate consequences of feather abrasion. Given the lack of reliable and widely accepted methods for quantifying feather abrasion, we present the Minimum Convex Abrasion Area (MCAA), a novel approach for its measurement. This method facilitates the estimation of feather abrasion in both museum specimens and living birds, enabling an exploration of the factors influencing abrasion across different phases of the avian annual- and life-cycle. We analysed 283 feathers from 21 passerine species, revealing that the highest rate of feather abrasion occurs during the breeding season, with a significant reduction in feather surface area compared to other periods of the annual cycle. Surprisingly, migration periods, despite their high metabolic demands and long-distance movement, do not significantly contribute to feather abrasion. The timing of feather moult plays a pivotal role in influencing abrasion rates during the breeding season, with species that undergo moult nearer to the breeding season, during winter (pre-breeding moult), showing significantly lower abrasion rates than those moulting before the autumn migration (post-breeding moult), likely a result of the weakening of the feather structure over time. These findings highlight the importance of moult timing for feather abrasion rate and maintaining plumage integrity during the reproduction season. The application of the proposed abrasion measurement method is expected to facilitate better understanding of plumage function and properties, as well as bird moult strategies, thereby enhancing our comprehension of avian ecology, biomechanics, life-history traits and sexual selection, as well as their evolution.

Effective conservation of migratory birds requires gathering of information about their population trends, often acquired using migratory bird counts. These schemes ideally operate at migratory bottlenecks, through which a significant portion of the counted migratory populations is funneled. Yet it is rare to validate the conservation value of the data from these counts. Here we perform this validation using GPS tracking data collected from two migratory species during their movement over two count schemes: the globally endangered steppe eagle counted in Eilat, Israel, and the black kite, counted in Batumi, Georgia. We use tracking data to answer two questions: which populations are counted and what affects the probability that a given individual will be counted. Our results illustrate variability in the effectiveness of these two migratory bird counting schemes. Considering the goal of estimating population trends, we show that Eilat does not represent a good location for understanding population trends of steppe eagles, while Batumi appears to provide better information on demographic trends of black kites. We further present differences in annual and individual variability, evidence regarding the breeding area origins of the counted populations and effects of environmental factors on the raptors' routes and, consequently, on the probabilities of being counted. Beyond the direct implications of our results, this study provides an example of using telemetry data to parameterize inference from bird counts. Further coupling of migratory bird count data and GPS data can improve our understanding of migration ecology and the conservation of migratory species.

Optimal foraging theory posits that foragers adjust their movements based on prey abundance to optimize food intake. While extensively studied in terrestrial and marine environments, aerial foraging has remained relatively unexplored due to technological limitations. This study, uniquely combining BirdScan-MR1 radar and the Advanced Tracking and Localization of Animals in Real-Life Systems biotelemetry system, investigates the foraging dynamics of Little Swifts ( Apus affinis ) in response to insect movements over Israel’s Hula Valley. Insect movement traffic rate (MoTR) substantially varied across days, strongly influencing swift movement. On days with high MoTR, swifts exhibited reduced flight distance, increased colony visit rate, and earlier arrivals at the breeding colony, reflecting a dynamic response to prey availability. However, no significant effects were observed in total foraging duration, flight speed, or daily route length. Notably, as insect abundance increased, inter-individual distances decreased. These findings suggest that Little Swifts optimize their foraging behavior in relation to aerial insect abundance, likely influencing reproductive success and population dynamics. The integration of radar technology and biotelemetry systems provides a unique perspective on the interactions between aerial insectivores and their prey, contributing to a comprehensive understanding of optimal foraging strategies in diverse environments.

Movements throughout the annual cycle evolved as an adaptation to seasonality across different bird species with a continuum of migration strategies and behaviours at the non-breeding range. Swifts are particularly mobile, aerial insectivores with a distinctive lifestyle. However, the spatiotemporal properties of swift migration, including timing, routes, and non-breeding movements, remain poorly understood in populations from the Levant. To address these knowledge gaps, we tracked Common Swift (Apus apus), Pallid Swift (A. pallidus), and Alpine Swift (Tachymarptis melba) from breeding colonies in Israel, using light-level geolocation. The three swift species differ significantly in their timing and movement patterns, especially in their non-breeding range. The Common Swift had the shortest breeding period, though it was longer than northern populations, and they exhibited distinct between-individual variation in itinerancy, with some individuals performing long-distance movements over 10,000 km. The Pallid Swift showed a hitherto undescribed longitudinal itinerancy pattern, moving from the Central Sahel to the east, as well as a prolonged stopover at the eastern coast of the Red Sea during spring migration. The Alpine Swift spent a substantially longer period at the breeding range; both compared to the other two swift species studied and to other Alpine Swift populations. At their confined non-breeding range, Alpine Swift remained stationary, though for only a relatively short period, in contrast to the other two species. These new insights regarding the timing and movement patterns of Levant swift populations, emphasises the need for further comprehensive and spatially expanded studies on swifts’ movement ecology.

Insect migration is crucial to many natural processes and human activities, yet large-scale patterns remain poorly understood. On the Mediterranean’s eastern shores lies a 70 km-wide stretch of hospitable habitat between the sea and the Arabian Desert, which we term the Levantine Corridor, extending ~400 km south from Turkey to the edge of the Sahara. We deployed 7 biological radars over 8 years, recording 6.3 million individual large insects (>10 mg) and revealing an important migration route at the nexus of three continents, with over 700 million large insects estimated to cross annually. However, a comparison with European insect migration flows suggests that Levantine insect fluxes are lower than at higher latitudes, challenging the conjecture that the Levantine Corridor acts as a funnel for insect migration as reported for birds. Insects showed strong migratory directionality differing from prevailing wind direction in spring and autumn, with mass migrations separated by periods of weaker movements. Migration intensity strongly depended on the weather, with insects preferentially migrating in seasonally beneficial tailwinds when possible and in warmer temperatures. The study reveals an unexplored insect migration route with implications for food webs, pollination, disease transmission, pest outbreaks and species invasions across West Asia, East Europe and Northeast Africa.

Who conducts biological research, where they do it and how results are disseminated vary among geographies and identities. Identifying and documenting these forms of bias by research communities is a critical step towards addressing them. We documented perceived and observed biases in movement ecology, a rapidly expanding sub-discipline of biology, which is strongly underpinned by fieldwork and technology use. We surveyed attendees before an international conference to assess a baseline within-discipline perceived bias (uninformed perceived bias). We analysed geographic patterns in Movement Ecology articles, finding discrepancies between the country of the authors’ affiliation and study site location, related to national economics. We analysed race-gender identities of USA biology researchers (the closest to our sub-discipline with data available), finding that they differed from national demographics. Finally, we discussed the quantitatively observed bias at the conference, to assess within-discipline perceived bias informed with observational data (informed perceived bias). Although the survey indicated most conference participants as bias-aware, conversations only covered a subset of biases. We discuss potential causes of bias (parachute-science, fieldwork accessibility), solutions and the need to evaluate mitigatory action effectiveness. Undertaking data-driven analysis of bias within sub-disciplines can help identify specific barriers and move towards the inclusion of a greater diversity of participants in the scientific process.

Successful accomplishment of long-distance migration necessitates optimal decision-making processes. Throughout their migration, birds need to constantly choose to fly or to stop. Passerine migrants integrate internal (e.g., lipid deposition) and external (e.g., prevailing winds) factors resulting in specific departure or landing times. We calculated individual departure and landing timing using vertical-looking radar in the Hula Valley, compiled nightly departure and landing ratios (departure and landing amounts relative to total migration flux), and explored how these are affected by meteorological conditions. Crosswind direction emerged as a key factor affecting departure and landing decisions during autumn migration in the area. Birds avoided drifting toward the Mediterranean Sea by landing and preferred taking off when winds blew away from the sea. Our findings represent an undescribed migration initiation and termination switch with implications for flight and stopover scheduling. The method extends the scope of aeroecological research for addressing individual-level migration behavior.

Decisions made by migrating animals can impact individual fitness and population dynamics.1,2 For avian migrants, these decisions can be affected by environmental3,4,5,6,7 and anthropogenic8,9,10,11,12 factors and by internal13,14,15,16,17,18 states. However, recent reviews have pointed to multiple gaps in our understanding of these decisions.19,20,21,22 We studied the decisions made by migrating endangered Steppe Eagles Aquila nipalensis by tracking individuals for up to 7 years with GPS transmitters. We used weather reanalysis models and high-resolution remote sensing to obtain environmental and anthropogenic information.23,24 Using complementary statistical methods, we differentiated between two behavioral states, migratory flights and stopovers, and studied how different factors shape the birds' movements and the transition between these states.25,26 Most prominently, we detected effects of experience on the birds' response to anthropogenic habitats, with juvenile eagles drawn to them, adults avoiding them, and sub-adults showing no preference. Experience also affected the choice of tailwind and flight direction during migration, with juvenile individuals choosing stronger winds and more direct routes than more experienced eagles. During stopover, experienced eagles flew greater distances than less experienced eagles, and during both stopover and migratory periods, stronger tailwinds increased the distance birds moved. Finally, winds blowing toward the migratory direction increased the probability that a bird would initiate migration after a stopover, while opposite winds had the opposite effect. Our results advance our understanding of the ontogeny of bird migration and the effects of environmental and anthropogenic factors on migratory decision-making, with implications for the conservation of migratory species.

In war and conflict zones, the jamming of Global Navigation Satellite System (GNNS) signals by military forces disrupts the tracking of tagged animals, and has increased in frequency following the recent escalation of conflicts in Eastern Europe and the Middle East. Such disruption to data collection strongly hampers research into the protection and conservation of endangered animals.

ABSTRACT A major problem in studying bird movement in many countries is data scarcity, precluding information about the spatial and temporal properties of avian distribution and dynamics as well as their consequences for human lives. We address this problem by proposing an innovative approach based on the relation between counts of signal attenuation of wireless communication to the presence of birds across or near wireless links of cellular backhaul networks. Wireless point-to-point communication links, on either ground level or earth-satellite links, cover the globe. We statistically relate between signal attenuation in terrestrial Commercial Microwave Links (CMLs) and bird migration. Because modern communication systems measure and often log signal levels routinely, we propose using existing signal level measurements of cellular and other wireless communication systems around the world as sensors for monitoring bird movement. Using actual measurements from operational CMLs, we show that the daily cycle of signal attenuation during bird migration periods matched that of the water-bird migration traffic rate recorded by nearby bird radar. This demonstrates the potential of the proposed method for opportunistic bird movement monitoring by CMLs across the globe, with no additional hardware installation, maintenance, or communication costs.