Bird Migration: A General Survey
Abstract
The question of how birds migrate over enormous distances with apparently minimal guidance continues to excite both professional and amateur ornithologists. Nearly ten years have elapsed since Peter Berthold, a leading researcher in the field, wrote the first edition of this highly readable and fascinating book. During that time the field has advanced by strides, so that this new edition has been extensively revised, expanded, and updated. No other book exists that brings together the vast amount of information that is available on the subject of bird migration, so that the book will be an inspiration to birdwatchers, naturalists, and ornithologists alike.
... condition these migrations, which has led to the formation of the eastern and western migration corridors. The later crosses the Iberian Peninsula and other western Mediterranean passes (Moreau, 1972;Mead, 1983;Berthold, 2001;Elphick, 2007;Newton;Filippi-Codaccioni et al., 2010), where several monitoring projects are being carried out (SEO/Birdlife 2000;Pérez-Tris & Santos, 2004;Filippi-Codaccioni et al., 2010;Isturiz et al., 2022). ...
... Birds fly by either gliding or flapping their wings. This has produced a selection for structures and body systems (Alerstam, 1990;Berthold, 2001;Newton, 2008;Pennycuick, 1975Pennycuick, , 2008. Gliding birds usually have a large wing surface and depend on airflows formed on the earth's surface to move with a small energetic expenditure (Onrubia, 2015). ...
... The flapping birds weren't found to concentrate their crossing in the midday, as previously described (Alerstam, 1990;Berthold, 2001;Newton, 2008;Pennycuick, 1975Pennycuick, , 2008. They seem not to depend on thermal flows to cross the Pyrenees. ...
Estudiamos la migración pos nupcial de aves a través de los Pirineos en los puertos de montaña de Somport y Portalet durante 2016 y 2017. Se siguieron cuatro especies: (aves planeadoras) abejero europeo Pernis apivorus, milano negro Milvus migrans y aves batiendo alas, aleteadoras o remeras (avión común Delichon urbicum y golondrina común Hirundo rustica). Las planeadoras utilizaron las horas centrales del día para migrar debido a los flujos térmicos. Las aleteadoras evitaron los fuertes vientos. El abejero europeo migra desde mediados de agosto hasta mediados de septiembre, el milano negro desde mediados de julio hasta mediados de agosto, el avión común desde finales de julio hasta finales de septiembre y la golondrina común desde finales de agosto hasta mediados de octubre. La selección de la dirección del viento es diferente en cada especie. La temperatura es el factor meteorológico más relevante que explica su migración.
... While seasonally moving between geographically distant breeding and non-breeding areas, each year thousands of bird species adjust their phenology to fluctuating environmental conditions (Newton, 2007). This captivating process, namely migration, allows individuals to increase their survival and reproductive success (Berthold, 2001;Dingle & Alistair Drake, 2007), with profound consequences for the demography and persistence of natural populations (Wittwer et al., 2015), predator-prey interactions (Hansen et al., 2020), seed dispersal (Gonz alez-Varo et al., 2021;Viana et al., 2013aViana et al., , 2013bViana et al., , 2016 and the dynamics of entire ecosystems (Bauer & Hoye, 2014). ...
... While factors such as the genetic, the individual physical condition or the energy reserve levels are particularly important (Newton, 2007), the photoperiod (i.e. changes in day length throughout the year) and weather conditions are also cues widely used by animals to make decisions regarding migration (Berthold, 2001). ...
... One explanation for these contradictory results is that different migratory species may respond to different cues (Gordo, 2007;Schmaljohann et al., 2017). For example, some species base their migration on weather factors, but others are primarily controlled by endogenous rhythms and photoperiodic cues (Berthold, 2001). A further explanation is that the influence of weather on migration for each species and population is often specific to a particular year in a particular location (Ahola et al., 2004;Gordo, 2007). ...
Migration plays a central role in many ecological and evolutionary processes. Global patterns of climatic variation are having a profound influence upon animal migration patterns. Even though regular counts of bird migrations at bottleneck sites can certainly offer insights into how natural populations of different species at different scales are responding to changes in weather conditions, they have not yet been widely used. By analysing a time series of regular counts, collected during autumn, of 126 species migrating during the daytime through one of the most important migratory bottlenecks in Western Europe, we found that an increase in temperature at the regional scale, as well as a decrease in precipitation level during the breeding period, may result not only in a decrease in the migration rate during autumn but also in a delay in the timing of fall migration. Furthermore, adverse weather conditions at the local scale interrupted bird migration through the bottleneck until favourable weather conditions returned. Importantly, temporal variation in the number of migratory birds followed a nonlinear pattern, something which might be partially due to the idiosyncratic responses of migratory species with different life-history characteristics to changes in weather conditions. Our results highlight that migration is a nonlinear, multiscale and multi-faceted process, suggesting that it will be difficult to predict the responses of idiosyncratic migratory species to the unpredictable effects of climate change.
... While seasonally moving between geographically distant breeding and non-breeding areas, each year thousands of bird species adjust their phenology to fluctuating environmental conditions (Newton, 2007). This captivating process, namely migration, allows individuals to increase their survival and reproductive success (Berthold, 2001;Dingle & Alistair Drake, 2007), with profound consequences for the demography and persistence of natural populations (Wittwer et al., 2015), predator-prey interactions (Hansen et al., 2020), seed dispersal (Gonz alez-Varo et al., 2021;Viana et al., 2013aViana et al., , 2013bViana et al., , 2016 and the dynamics of entire ecosystems (Bauer & Hoye, 2014). ...
... While factors such as the genetic, the individual physical condition or the energy reserve levels are particularly important (Newton, 2007), the photoperiod (i.e. changes in day length throughout the year) and weather conditions are also cues widely used by animals to make decisions regarding migration (Berthold, 2001). ...
... One explanation for these contradictory results is that different migratory species may respond to different cues (Gordo, 2007;Schmaljohann et al., 2017). For example, some species base their migration on weather factors, but others are primarily controlled by endogenous rhythms and photoperiodic cues (Berthold, 2001). A further explanation is that the influence of weather on migration for each species and population is often specific to a particular year in a particular location (Ahola et al., 2004;Gordo, 2007). ...
Migration plays a central role in many ecological and evolutionary processes. Global patterns of climatic variation are having a profound influence upon animal migration patterns. Even though regular counts of bird migrations at bottleneck sites can certainly offer insights into how natural populations of different species at different scales are responding to changes in weather conditions, they have not yet been widely used. By analysing a time series of regular counts, collected during autumn, of 126 species migrating during the daytime through one of the most important migratory bottlenecks in Western Europe, we found that an increase in temperature at the regional scale, as well as a decrease in precipitation level during the breeding period, may result not only in a decrease in the migration rate during autumn but also in a delay in the timing of fall migration. Furthermore, adverse weather conditions at the local scale interrupted bird migration through the bottleneck until favourable weather conditions returned. Importantly, temporal variation in the number of migratory birds followed a nonlinear pattern, something which might be partially due to the idiosyncratic responses of migratory species with different life‐history characteristics to changes in weather conditions. Our results highlight that migration is a nonlinear, multiscale and multi‐faceted process, suggesting that it will be difficult to predict the responses of idiosyncratic migratory species to the unpredictable effects of climate change.
... Además, la situación de las poblaciones de aves en la Península Ibérica desde el punto de vista de la migración es muy compleja, y a diferencia de las poblaciones del centro y norte de Europa en la que las distintas especies suelen ser estrictamente migradoras o sedentarias, en la península podemos encontrar poblaciones de esas mismas especies que pueden ser desde migradoras hasta sedentarias, según la localización de sus poblaciones. (Bernis 1966, Asensio 1998, Berthold, 2002, Perez-tris 2001. ...
... Existen numerosos estudios encaminados a aportar nuevas perspectivas acerca de estas cuestiones, que utilizan técnicas cada vez más sofisticadas, como el trampeo y anillamiento científicos, radiotelemetría, o radar. Sin embargo, la técnica de estudio más primitiva, la observación directa, puede aportar también una valiosa información hoy día (Berthold 2002). Esto es particularmente cierto en zonas donde los datos disponibles sobre información básica acerca de la migración son más escasos, como por ejemplo aquellos concernientes a las rutas, fechas de llegada y paso, localización de áreas de descanso y sedimentación, o duración de las sedimentaciones. ...
... Alternativamente, podría ocurrir que realmente el Campo de Calatrava sea usado con mayor frecuencia durante la migración prenupcial, o, al menos, que las especies sean más detectables por alguna razón en la migración prenupcial. En muchas especies de aves se han detectado migraciones "en bucle", es decir en las que las rutas de viaje son diferentes en invierno y primavera (Berthold 2002). El significado adaptativo de estas migraciones en bucle no es bien conocido en la mayor parte de los casos, pero en principio los movimientos migratorios de las aves deberían estar optimizados, de forma que las rutas y fechas de viaje serían las óptimas para contrarrestar los riesgos de supervivencia de estos largos viajes. ...
Este trabajo pretende contribuir al mejor conocimiento de la fenología de los movimientos migratorios de las aves a su paso por el Campo de Calatrava. Se presentan datos para un total de 43 especies con diferente estatus fenológico. Fueron más frecuentes las especies observadas en migración prenupcial que en migración postnupcial. La fenología migratoria en general encaja con lo descrito anteriormente para estas especies, pero apreciamos una tendencia a adelantar la fecha de llegada y retrasar la de migración al sur, mientras que son más escasas las observaciones de fechas de llegada tardías y de marcha tempranas. Discutimos las posibles causas de estos resultados, y remarcamos la importancia relativa del Campo de Calatrava para muchas de las especies detectadas.
... Other effective methods include ornithological radar or other automatic recording techniques (Schmaljohann et al. 2008;Schmidt et al. 2017). However, if we lack such data, the method that allows the most complete understanding of the migration dynamics and phenology of the entire assemblage of diurnal migrants at occur along the river valleys (Bingman et al. 1982;Berthold 2001;Lugovoy 2005) and in mountainous regions (Dorka 1966;Dyrcz 1981;Bruderer & Jenni 1990;Korner-Nievergelt et al. 2007), as high ridge chains shape the migration routes (Bruderer 1996;Williams et al. 2001;Bruderer & Liechti 2004;Newton 2008). However, data and analyses from the Carpathians are scarce in this regard. ...
... Overflying birds were detected and identified visually and by voice, with the naked eye and with the help of binoculars/observation scopes. All birds a given site, and furthermore an assessment of its species composition, is classical visual observations (Berthold 2001;Schmaljohann et al. 2008;Schmidt et al. 2017). This method has been successfully used in studies of diurnally migrating birds, both in Poland (Abraszewska-Kowalczyk 1974;Dyrcz 1981;Bela et al. 2011), and other countries (Dorka 1966;Alerstam 1978;Williams et al. 2001;Hüppop et al. 2006;Korner-Nievergelt et al. 2007;Sackl et al. 2014;Vavřík et al. 2016). ...
... Most Polish migration studies focus on the Baltic coast region, where migration is concentrated (Busse 1976;Busse & Halastra 1981;Bela et al. 2011) due to the presence of an extensive marine area, which for most landbirds is an obstacle (barrier) to migration (Berthold 2001;Newton 2008). Passage in the inland part of Poland is less concentrated due to the small number of large-scale topographic structures affecting migration routes (leading lines; Mueller & Berger 1967;Alerstam 1978;Åkesson 1993), which translates into dispersal of the migrating birds' flux over a large area and so-called broad front migration (Bruderer 1996;Berthold 2001). ...
Despite the development of technically advanced methods of studying bird migration, classical visual observations remain a source of valuable data allowing a broad analysis of the picture of diurnal migration at a given site. We employed visual observations to investigate the spatial and temporal pattern of diurnal migration of birds in the Polish part of the Carpathians. During autumns 2011-2013, 28 localities distributed over the area were surveyed by experienced observers, while 12 localities were researched in spring 2015. The data collected allowed the determination of passage intensity indices and the timing of migration for more than 100 species in autumn and about 70 species in spring. Mean passage intensity was more than 3 times higher in autumn than in spring, with the highest recorded in the first half of October and mid-March, respectively. Compared to autumn, the peak of diurnal migration was shifted to later hours in spring. The passage occurred primarily along the N-S axis, followed by the NE-SW axis. No consistent evidence of a barrier effect of the Carpathians – expressing as a reduction in passage intensity in intra-mountain locations or in higher elevated areas – has been detected in this study. The cluster analysis showed that the assemblage structure of migrants in the mountain regions located in the south of Poland (Carpathian Mts., Karkonosze Mts., Świętokrzyskie Mts.) were more similar to each other than to a region situated far to the north on the Baltic coast.
... The average migratoriness has been shown to increase in populations toward areas with harsher winter environments, such as higher latitudes in the northern hemisphere (Main 2002, Newton 2008, Boyle et al. 2010, Somveille et al. 2013, Ambrosini et al. 2016) and altitudes (Boyle et al. 2010, Lundblad & Conway 2020. It has been hypothesized that partial migrants may step towards year-round residency, as a way to adapt to climate warming, when the survival prospects of overwintering near breeding latitudes improve (Berthold 1996, 2001, Pulido & Berthold 2010, Chapman et al. 2011, Meller et al. 2016. While the spatial patterns in migratoriness may result from local adaption over time, and for a few species show temporal responses to annual temperature, there are limited examples showing how migratoriness could directionally divert over time, currently suggesting heterogeneous trends across species (Nilsson et al. 2006, Van Vliet et al. 2009, Meller et al. 2016. ...
... While the spatial patterns in migratoriness may result from local adaption over time, and for a few species show temporal responses to annual temperature, there are limited examples showing how migratoriness could directionally divert over time, currently suggesting heterogeneous trends across species (Nilsson et al. 2006, Van Vliet et al. 2009, Meller et al. 2016. While the individual migration decision is binary, the migratory propensity is continuous and heritable (Berthold & Querner 1982, Berthold 1988, 2001, Biebach 1983, Pulido & Berthold 2010), but to a variable degree plastically modified by environmental components (Able & Belthoff 1998). Besides long-term selection by temperature, the fitness prospects by residency may be additionally affected by factors such as food abundance (Lindén et al. 2011, Meller et al. 2016, extreme weather (Acker et al. 2021) and density dependence (Kokko & Lundberg 2001, Lundberg 1988, Meller et al. 2016), potentially at a shorter temporal scale. ...
Partial migrants have populations consisting of both migratory and resident individuals. These migrants and residents experience unequal ecological conditions during winter and the underlying factors driving their decision to stay on their breeding grounds or to migrate remain debated—both from the viewpoint of populations and individuals. Here, we studied partial migration in a small raptor, the Eurasian Sparrowhawk (Accipiter nisus), from two different but interconnected perspectives: 1) explaining the patterns and variation in the ratio of migrants to residents (migratoriness) at the population level and 2) revealing how age and sex may affect the individual decision to be migratory or resident. We used citizen observation data over four decades to explore the temporal and spatial variation in the age and sex ratio of wintering resident sparrowhawks in Sweden. We found that the migratoriness unexpectedly increased with higher annual temperatures and showed long-term trend across the study period. Also, this migrant-to-resident ratio increased with smaller winter prey abundance. The average winter sex ratio was male-biased and became increasingly so over the years. We suggest that residency benefits territory-establishing males as early presence gives a competitive advantage in obtaining high-quality territories. Moreover, the distribution of overwintering individuals (regardless of sex) moved gradually northwards as the winter progressed, suggesting that smaller-scale migration occurs among the resident fraction of the population. These results provide suggestions for the underlying drivers and regulation of partial migration.
... The third and current era of North American bird migration research was facilitated by the development and rapid miniaturization of several technologies that provide the means of tracking smaller individuals and derive movement data remotely with high temporal and spatial resolution. (Berthold 2001, Bridge et al. 2011, Dingle 2014). These technologies ushered forth a flood of new information on annual movements, seasonal ranges, and staging areas, especially for large-bodied migrants that make extensive seasonal movements that could not otherwise be monitored effectively during migration (Berthold 2001). ...
... (Berthold 2001, Bridge et al. 2011, Dingle 2014). These technologies ushered forth a flood of new information on annual movements, seasonal ranges, and staging areas, especially for large-bodied migrants that make extensive seasonal movements that could not otherwise be monitored effectively during migration (Berthold 2001). Light-level geolocators (hereafter, "geolocators"), lightweight (< 0.5 g) devices that use variation in seasonal daylight patterns to derive location estimates (Hill 1994 The ongoing miniaturization of VHF transmitters (tag mass < 0.2 g) and improvements to automated receivers have also facilitated the expansion of passive telemetry arrays that record the passage of individually marked migratory birds as small as hummingbirds (Trochilidae ]) at specific points along migratory routes (e.g., Deppe et al. 2015, Schofield et al. 2018 and their movements across continents (e.g., Motus Wildlife Tracking System [Gómez et al. 2017, Taylor et al. 2017). ...
Conservation of North American migratory birds requires information about their movements and regulating factors throughout the annual cycle. Over the past 10 or more years, improvements in tracking technology and quantitative approaches to assessing resulting data have yielded advances in understanding many aspects of North American bird migration with relevance to conservation. To date, much of the synthesis of this information has focused on describing patterns and drivers of migration without directly addressing how these advances can inform migratory bird conservation. We begin by describing broad patterns of migration behavior observed in North American birds and briefly summarize the technological advances that have characterized different eras of bird migration research that have provided data relevant to conservation. We then illustrate how data derived from migration studies can inform conservation strategies, including addressing regulating factors outside the breeding period for North American migratory birds, and highlight how different types of migration data have shaped conservation of three well-studied species. Lastly, we discuss critical knowledge gaps and future directions for research needed to better inform North American migratory bird conservation. In particular, we highlight how further technological developments could contribute to the development of effective conservation action in the context of climate change. We also recommend that future research and conservation efforts incorporate means of evaluating the success of conservation actions that target North American migratory birds outside the breeding period.
... Migratory decisions in some avian species on the other hand are shown to be influenced by the local temperature. Berthold (2001) reported delayed departures from breeding grounds in autumn and early returns from wintering grounds in the spring for at least 30 avian species in Central Europe. As per a report of 2003, the departure from wintering sites and arrival at breeding sites of 17 out of 20 species of birds has advanced over the past 30 years in response to increased temperature trends in their African over-wintering grounds. ...
... Interannual variations of ambient temperature can lead to delay or advancement of migratory departure (Berthold, 2001;Cotton, 2003). The molecular processes associated with the departure decision can also vary between spring and autumn migration, as shown in redheaded buntings (Sharma et al., 2018). ...
Organisms adapt to daily and seasonal environmental changes to maximise their metabolic and reproductive fitness. For seasonally breeding animals, photoperiod is considered the most robust cue to drive these changes. It, however, does not explain the interannual variations in different seasonal phenotypes. Several studies have repeatedly shown the influence of ambient temperature on the timing of different seasonal physiologies including the timing of migration, reproduction and its associated behaviours, etc. In the present review, we have discussed the effects of changes in ambient temperature on different seasonal events in endotherms with a focus on migratory birds as they have evolved to draw benefits from distinct but largely predictable seasonal patterns of natural resources. We have further discussed the physiological and molecular mechanisms by which temperature affects seasonal timings. The primary brain area involved in detecting temperature changes is the hypothalamic preoptic area. This area receives thermal inputs via sensory neurons in the peripheral ganglia that measure changes in thermoregulatory tissues such as the skin and spinal cord. For the input signals, several thermal sensory TRP (transient receptor potential ion channels) channels have been identified across different classes of vertebrates. These channels are activated at specific thermal ranges. Once perceived, this information should activate an effector function. However, the link between temperature sensation and the effector pathways is not properly understood yet. Here, we have summarised the available information that may help us understand how temperature information is translated into seasonal timing.
... Secondly, there could be migratory individuals that remain in the wintering ranges, breeding with sedentary individuals. This is feasible since the migration of some hummingbirds of the genus Selasphorus is structured by age, with adults being the first individuals to arrive and leave the winter ranges, while juveniles arrive later with a delay of between one or two weeks (64,65,(69)(70)(71)(72)(73)(74). This age-structured migration is an indication of low migratory connectivity, where populations would not be migrating together, which facilitates the dispersal and site fixation of young individuals to winter ranges, 56 especially as young individuals are more likely to disperse as competition for resources tends to displace them. ...
... This age-structured migration is an indication of low migratory connectivity, where populations would not be migrating together, which facilitates the dispersal and site fixation of young individuals to winter ranges, 56 especially as young individuals are more likely to disperse as competition for resources tends to displace them. [73][74][75] Finally, it is possible that there are individuals in sedentary populations that disperse north along with migratory individuals, especially since Malpica and Ornelas 19 observed a demographic expansion north after the last glaciation. Genetic traits that regulate migratory behaviour can be explained by the threshold model of quantitative genetics, 76 On the other hand, genetic structure and gene flow indicated that Sheartail hummingbirds populations are three distinct populations, with significant genetic differences and low gene flow. ...
Gene flow, the movement of genes between populations, profoundly influences genetic and phenotypic homogeneity among populations. This study investigates gene flow patterns in two migratory hummingbird species, Selasphorus platycercus and Calothorax lucifer, shedding light on the intricate interplay between migration, resource availability, and genetic diversity. Using previously published information on microsatellites, we examine the genetic makeup and the movement of genes within populations. Selasphorus platycercus displays distinct genetic groups which can be associated with its migratory behaviour. Gene flow analysis suggests a higher level of connectivity among populations sharing winter ranges. In contrast, Calothorax lucifer populations exhibit genetic divergence despite overlapping winter ranges, possibly due to environmental niche adaptation and limited reproductive opportunities for dispersing individuals. While geographical distance does not explain genetic differentiation in these species, environmental niche similarities appear to facilitate gene flow. This study underscores the significance of migratory routes, resource availability, and niche adaptation in shaping gene flow dynamics in hummingbirds. Understanding these dynamics is crucial for the conservation and management of these unique avian populations.
... Wetland benefits are not exclusively ecological; in fact, climate regulation, the support of productive fisheries, and recreational opportunities have important economic impacts as well [3]. Wetlands also supply habitats, food, and shelter for waterbirds [4,5] and act as stopover sites that allow waterbirds to migrate [6]. Despite their exceptional ecological and economic value [7,8], more than half of the world's wetlands have been altered, degraded, or lost in the last 150 years [2,3]. ...
... We focused on the summer period because it is a bottleneck time for waterbirds due to higher levels of tourism activities and anthropization (illegal dumpsites, camping sites, caravan parks, and so forth) and the concomitant decrease in water levels ascribable to water diversions, evaporation, and low rainfall [19][20][21]. In addition, because the Sicilian wetlands belong to the central-eastern Mediterranean bird flyway, in summer, it hosts the highest number of individual birds and species during migration [5,16]. Thus, the proper management of these wetlands is particularly challenging during this critical period of the year and demands scientifically supported planning strategies to assist with preserving, or restoring, the levels of avian diversity. ...
In this study, we (a) formulated a general hypothesis about how wetland (functional and structural) traits influence avian diversity, (b) turned this hypothesis into a non-parametric Bayesian network, (c) disentangled the direct and indirect effects of the variables influencing waterbird species, and (d) simulated the changes expected to the levels of avian diversity as a result of numerous counterfactual and management scenarios. We applied our framework to the Sicilian wetlands as a whole; then, we downscaled simulations locally to a wetland of particular interest (Pantano Bruno). We found that (1) waterbird species are highly sensitive to wetland traits; (2) wetland traits have both direct and indirect effects upon alpha avian diversity; (3) the direct and indirect effects of wetland traits can be contrasting; (4) water level fluctuations (benefit), diversions (cost), and salinity (cost) are key factors for waterbird conservation; (5) these wetlands have the potential for hosting a level of alpha avian diversity that is double the baseline (from 19 to 38 species); (6) these wetlands are prone to ecological collapse if all traits deteriorate (from 19 to 6 species per wetland); and (7) the ecological information gained at the regional scale can be properly downscaled to the local scale to make inferences on single wetlands.
... Year Round (YR): A form that is likely to occur throughout the entire year. Partial Migrant (PM): One of the most common types of bird migration globally (Berthold, 2001;Jahn et al., 2006). Partial migration is defined as a withinpopulation variation in migratory behavior, signifying that some individuals migrate while others remain year-round residents in a given habitat. ...
The Annotated Checklist of the Birds of Cuba is a year publication with the goal to update the Cuban bird list, including important comments to clarify many scientific questions about the cuban ornithology. This is the most updated Checklist about cuban birds. The current main list of the birds of Cuba contain 405 species in total, 29 of each (including one extint) are endemic of the Cuban archipélago.
... Every year, millions of raptors and other soaring birds undertake extensive migratory journeys between their breeding grounds in the Palearctic region and their wintering sites [1]. Seasonal changes in resource availability drive these migrations and are among the most remarkable phenomena in the natural world [2]. ...
Timing and spatial distribution patterns of migratory birds are crucial for their conservation, particularly in Greece, which serves as a vital migratory corridor between Europe, Asia, and Africa. Traditional monitoring methods face challenges due to resource limitations and the country’s complex geography. This study aimed to determine the migration phenology and spatial distribution of 18 species of raptors and soaring birds in Greece using citizen science data from eBird, analyzed with generalized additive models (GAMs). We processed 15,940 checklists for spring migration and 9131 for autumn migration from 2010 to 2023. GAMs successfully modeled the migration phenology for most species, revealing variable peak migration dates in spring and more synchronized migration in autumn, with most species migrating in early September. A spatial analysis highlighted the importance of coastal areas and islands (particularly the Aegean islands and Crete) as key migratory routes and stopover sites. Validation with standardized counts from the Antikythira Bird Observatory showed some discrepancies, emphasizing the limitations of relying on a single monitoring site and the value of broad-scale citizen science data. Our findings demonstrate the effectiveness of integrating citizen science data with robust analytical techniques to fill knowledge gaps, providing valuable insights for designing monitoring programs and informing conservation strategies.
... Environmental changes, such as alterations in weather conditions, have strong effects on bird migration. Weather conditions influence almost all aspects of migration, such as the route, duration, and timing (Berthold 2001, Elkins 2005, Klinner & Schmaljohann 2020, Bairlein 2022. Migratory patterns differ across species, conspecific populations, and even individuals of the same population (Newton 2008, Chapman et al. 2014, Schmaljohann 2018, Phipps et al. 2019, Tedeschi et al. 2020, Falchi et al. 2023. ...
Based on GPS tracking, we describe short-distance movements of two Eurasian Curlews Numenius arquata from the breeding population in northwest Germany during a cold spell that lasted about 10 days in February 2021. One bird wintering on the Dutch Wadden Sea moved towards its traditional wintering site on the
Welsh coast, but stopped on the east coast of England. At the same time, another individual moved from its traditional wintering site in the Rhine-Meuse-Delta to the Bay of Veys in northern France. Such movements were not observed in the absence of cold spells in the following year. Before the movements, both birds were primarily found in coastal farmland. We suggest that the frozen soil adversely affected foraging activities of Eurasian Curlews wintering in these
habitats. Our observations suggest behavioural plasticity that can enable Eurasian Curlews to withstand extreme weather events, such as cold weather.
... Desert flora has adapted to the arid environment; for example, cacti possess leathery skin to minimize water loss and long taproots to access deep soil moisture [30]. Organisms can adapt to behavioral changes; for example, certain bird species travel several kilometers to find regions with a more moderate and favorable climate during winter [6]. Morphological adaptations include physiological responses such as hibernation and energy conservation during resource shortages or adverse climatic conditions. ...
Climate change is a significant threat to ecosystems and communities, and challenges global sustainability; therefore, more research on climate change adaptations should be conducted. This scientometric study presents databases on global trends in academic research, specific contributions, and thematic evolution of environmental adaptations to climate change. Using the Scopus database of publications, this study focuses on publications between 2009 (January) and 2024 (August), with an emphasis on the interpretation of primary research interests, authors, contributions from countries, and collaborative networks. According to the findings, there has been a shift in focus to more adaptive management in agricultural and biological diversity practices, with more emphasis on the integration of ecological, technological, and social science disciplines. This work also reveals that countries have gaps in regional research, especially in developing countries, and highlights the need to work collectively across the globe. Through citation analysis, thematic evolution, and future research recommendations, this study enriches the knowledge of the line of research on environmental adaptation and underlines its significance in addressing climate change effects.
... Each quadrat was surveyed twice, the former in April-May 2024 (sampling session 1) and the latter in May-June 2024 (sampling session 2); hence, it was possible to detect the bird species present in both the first and second halves of the breeding season. In addition, the second sampling session served to confirm and refine the first one, and detect those trans-Saharan migratory bird species that generally arrive later in the Italian breeding sites [21]. Bird surveys started after sunrise (about 5:30 A.M.) and continued until 10:00 A.M. because the singing of birds to mark territory and seek mates is more frequent in this time interval. ...
In this study, we (a) inventoried the breeding bird community of a town located in Northern Italy using quadrat sampling, (b) quantified bird richness and abundance, (c) measured sample completeness, (d) tested whether the bird community assembly was driven by environmental filtering (i.e., local properties of every single quadrat), e) explained bird richness and abundance in light of the land cover types present in each quadrat, (f) disentangled the marginal effects of every land cover type, and (g) simulated the effects on birds of different planning decisions. We recorded 36 breeding bird species, of which 17 were resident, 10 were mid-range migrants, and 9 were trans-Saharan migrators. The sampling completeness estimated ranged from 82.73% to 99.66% depending on the estimator procedure. Environmental filtering affected significantly (p < 0.10) the bird community assembly. Generalized Additive Models (GAMs) explained both bird richness (R2 = 91.7%) and abundance (R2 = 87.4%) satisfactorily in light of the land cover types. Simulations based on GAMs showed that local planners can largely influence bird richness in the study area, with both positive (urban greening) and negative (urban densification and sprawl) strategies.
... Baerwald & Barclay (2016) reached the same conclusion for two migratory bat species in North America (Lasiurus cinereus and Lasionycteris noctivagans), based on genetic samples taken from wind turbine fatalities. Instead, it appears plausible that Nathusius' pipistrelles are born with a genetically pre-de ned migratory vector, as observed in many migratory songbirds (Berthold 2001), and use the Earth's magnetic eld to navigate (Holland et al. 2006;Lindecke et al. 2021) towards their goal. ...
Migratory bats are experiencing substantial increases in mortality risk from wind energy developments, but data on their migratory behavior and population dynamics are often lacking. Here, we develop a novel microsatellite panel for one such migratory bat species, the Nathusius’ pipistrelle ( Pipistrellus nathusii ), and apply it to 448 samples collected at stopover sites along the Dutch coast during autumn migration over four consecutive years. With this dataset, we assessed whether the population is genetically sub-structured, characterize its current genetic diversity, and evaluate whether mothers guide their offspring during migration. We found that the population is panmictic and diverse, with an effective population size estimate that cannot be distinguished from infinite. However, we also observed a consistent decline in allelic richness across the sampling period, as well as a heterozygote excess in individuals sampled as juveniles, both suggesting an ongoing population decline. We did not find any parent-offspring pairs in our dataset, which included 30 box captures where adult female and juvenile bats were found roosting together, suggesting that juvenile bats do not follow their mothers during their first migration. Our findings provide an initial characterization and baseline measure of genetic diversity for the Nathusius’ pipistrelle that can be used as a reference for subsequent studies and systematic efforts to monitor the genetic diversity of the species. Given that monitoring population trends of migratory bat species with traditional methods remains challenging, such tracking of genetic diversity may offer a valuable proxy by which to observe substantial population declines if they occur.
... Its wetlands are located along the Sardinia-Corsica corridor of the central-eastern Mediterranean bird flyway [2]; accordingly, they act as a natural bridge between Europe and Africa for numerous bird species confronted with travelling across the Mediterranean sea. In addition, they support resident waterbirds that do not migrate [3]. ...
The wetlands of Sardinia (Italy) supply the food and shelter for many waterbird species that migrate along the central-eastern Mediterranean bird flyway. Despite many different policies and laws (the Birds and Habitats Directives, the European Water Framework Directive, and the Ramsar Convention), the Sardinian wetlands are seriously threatened by human activities and climate change, which in turn menace the associated avifauna. In this study, we (a) inventoried (four sampling dates) the avian metacommunity of the largest coastal wetlands in Sardinia during the crucial period of the year for the avifauna (August-September), (b) explored the spatiotemporal dynamics in bird species assemblage, (c) used results to refine planning for bird habitat management and bird diversity conservation. We recorded 60 bird species, of which 54 were migratory and 21 belonged to Annex I of the Birds Directive. During August-September, (a) a, ß and ? avian diversity showed no significant temporal trends, (b) the contributions of space (wetlands) and time (dates of sampling) in determining the presence/absence of the waterbird species were comparable, (c) wetlands formed three statistically significant clusters with regard to the species richness; (d) a significant increase in the number of the species belonging to the "mixed" migration guild, and "divers from the surface" foraging guild occurred; (e) there was a statistically significant chronological succession of the occurrence of waterbird species; (f) twenty-five species made use of the Sardinian wetlands all summer long, while ten further species were present in three sampling dates out of four; (g) the spatial distributions of the waterbird species in the Sardinian wetlands were significantly different between the sampling dates; (h) the Little Egret, the Grey Heron and the Greater Flamingo were primarily responsible for the observed difference in the spatial distributions of species between the sampling dates; (i) Is Brebeis, Pilo and S. Giovanni were the wetlands that changed their species composition the most during the studied period; (j) twenty-two waterbird species resulted at high priority for conservation, and thirteen species at medium priority. Based on these results, we have proposed new strategies for the conservation of the waterbird species of the Sardinian wetlands during the post-breeding migration period.
... It is a fundamental aspect of avian species, shaped by intricate behaviors, physiological adaptations, and environmental cues. This phenomenon, driven by seasonal changes, resource availability, and reproductive imperatives [2], is not just a natural wonder but a crucial part of our ecosystem. From the small songbirds that traverse continents to the powerful birds of prey that conquer mountains, bird migration encompasses a diverse array of strategies and challenges. ...
Bird migration is a remarkable phenomenon that captures the essence of nature's ingenuity and resilience. Millions of birds embark on incredible journeys yearly, traversing vast distances across continents, oceans, and landscapes. Birds are the most mobile creatures on the earth. Birds migrate seasonally from an unfavorable location to some favorable location to breed, feed and raise the young ones. Not all birds migrate. About 40% of the world's total bird species perform migration. Birds migrate for food, shelter, reproduction, predator avoidance, and to avoid climate extremes. Seasonal photoperiodic cues also trigger migratory behavior. There are certain centers in the brain which are integrated with the external stimulus and the secretion of hormones takes place which triggers the migration. It often occurs along a flyway. It is a to & fro movement between breeding and non-breeding grounds and vice-versa. It is an instinctive behavior. Migration began to evolve when individuals who moved from one area to another ultimately produced younger ones than those who remained in one location. Birds use celestial cues, smell, landmarks, and magnetic cues for navigation during the migration. Over 300 species of migratory birds visit India annually. India forms a part of the Central Asian Flyway. Habitats of migratory birds should be conserved, especially wetlands. Birds are an important part of the ecosystem; they are the bioindicators of the ecosystem.
... An estimated 50 billion birds, the majority of which are passerines, undertake migration twice annually (Berthold, 1993;Kirby et al., 2008;Newton & Brockie, 2007). They do so to take advantage of seasonal abundances in food and avoid extreme climates. ...
Half of all migratory bird species have declined over the past 30 years, with intercontinental migrants declining faster than their short‐distance migratory counterparts. One potential cause of these declines is habitat loss and degradation on tropical wintering grounds, where agricultural conversion of natural habitats and intensification of traditional, low‐intensity agricultural systems are frequently occurring. Although the broad patterns of wintering migrant abundance are well understood along most flyways, how species' habitat associations vary across disturbance gradients in agricultural landscapes remains a key question, with implications for landscape‐level farm management and restoration activities. We used 328 point count locations and associated habitat assessments targeted at a cohort of eight severely declining Afro‐Palaearctic migratory passerines in the Guineo–Congolian transition zone of Western Africa to model the probability of the presence of migrants within grass, shrub, forb and forest‐covered areas. We found support for the widespread use of early successional habitats retained within traditionally managed farmland by migrants. Most species utilize scrubland on fallows within the agricultural mosaic, especially Spotted Flycatcher, Garden Warbler, Melodious Warbler, Whinchat and Common Nightingale. Only Pied Flycatcher relied upon mature forested areas. The avoidance of mature forested habitats by most species suggests that habitat requirements of severely declining migrant birds must be explicitly considered within conservation and restoration schemes, via mechanisms to retain low‐intensity farming, especially short‐term abandoned fallows that regenerate scrubby areas within the agricultural matrix. Any habitat management within the agricultural matrix should be considered in the context of the needs of local communities.
... Therefore, the timing of the flight feather replacement rarely coincides with such an energy-demanding stage of the annual cycle as migration (Kjellén 1994). Even though birds may compensate for increased wing loading by reducing their body mass (Holmgren et al. 1993;Swaddle and Witter 1997;Lind and Jakobsson 2001), migrants need to accumulate energy reserves (mainly fat) for non-stop migratory flights (Berthold 1993). Hence, there is a trade-off between the necessity to increase body mass before migratory flight and reduced wing area during feather moult. ...
... While saw-whet owls may occupy large home ranges in parts of their range, the sporadic intraindividual detections observed in this study may also be explained by regional nomadism. Nomadism can be identified by a species moving substantial distances, rather than remaining within a defined home range (Berthold 2001 Korpimäki 1987), the latter a close relative of the saw-whet owl. ...
... This is in line with the results of the studies of Bende [72] and Bende et al. [88], based on 23,261 observations over a 10 year study period. Migration is influenced by a number of intrinsic factors (e.g., endogenous rhythms, changes in day length at wintering sites), especially in long-distance migrants [27,[97][98][99][100]. A similar variance in return dates is only possible for short-distance migrants, as the genetic regulation of their migration is much lower, making the timing of migration much more flexible than for long-distance migrants. ...
In the present study, 7344 spring observations of a short-distance migratory species, the Eurasian Woodcock, from the Carpathian Basin between 1894 and 1926 were used to investigate the timing of the species’ migration and how different environmental factors influenced it. We used a generalized additive model (GAM) to explore migratory patterns by using environmental and geographical variables. In years when the weather was colder and snowier, the birds migrated weeks later than in years with milder weather. This may be due to the availability of earthworms, which are the most important food for the species. In areas at lower altitudes, migration occurred earlier than in mountainous areas, which may also be due to the different weather. Furthermore, a two week difference was observed between the south-western and north-eastern parts of the Carpathian Basin. This difference is still present nowadays, but the timing of migration has shifted earlier than in the past, probably due to climate change. It would also be important to compare the historical data with recent data to gain a better understanding of the effects of climate change on the migration of the Eurasian Woodcock.
... The seasonal changes in the availability of their prey might be the most important factor driving the annual migration cycle of the woodcocks (Berthold, 2001;Newton, 2007). In autumn, they move from Northeastern Europe and Central Siberia to Western and Southern European areas, mostly coastal, forested areas with mild and humid winter climates. ...
The Eurasian woodcock prefers habitats where its main prey, earthworms, can be found in higher densities. Although they are forest‐dwelling birds, they regularly visit pastures and natural grasslands at night, where earthworm abundance is generally higher. However, there is little information on fine‐scale habitat use in relation to variation in habitat characteristics and prey availability, particularly beyond the breeding season. In our study, we investigated if the nocturnal occurrence of woodcocks during migratory stopover periods differed between two neighbouring fields, or management units, with similar vegetation structure, and if within‐field variation in the spatial patterns of woodcock sightings were associated with fine‐scale earthworm densities and soil parameters. Specifically, we used GPS tracking data of two tagged woodcocks and direct observation data to study patterns of occurrence of birds in a mixed forest‐pasture landscape in Hungary during pre‐ and post‐breeding periods. We compared these patterns with fine‐scale soil characteristics and earthworm abundance, acquired by field sampling. We found that the field with higher earthworm abundance was visited by woodcocks more frequently, and this correlation was similarly observed at the intra‐field level. Our results demonstrate that woodcocks select foraging sites with higher earthworm densities at multiple spatial scales, both between fields (coarse scale), and within fields (fine‐scale). Considering that woodcocks tended to return to the same field to forage at night, the strong associations between occupancy and resources provide a basis for developing habitat management strategies at the field level for conservation. As earthworm densities and soil parameters are good indicators of woodcock foraging habitat, measuring those variables, at least at a coarse scale, could aid in predicting important habitats for the species across the landscape.
... Here, we use this approach to evaluate long-standing, competition-based hypotheses aiming to explain leapfrog migration using the common ringed plover (Charadrius hiaticula). The common ringed plover (henceforth ringed plover) has a wide latitudinal breeding range (Davidson & Scott, 2009) and constitutes a textbook example of a leapfrog migrant (Berthold, 2001;Newton, 2008). In Europe, Arctic breeding populations migrate to Africa, primarily wintering south of the Sahara, whereas temperate breeding populations mainly winter in Western Europe and as far south as northern Morocco ( Figure 1A) (Hedh et al., 2022;Hedh & Hedenström, 2020;Lislevand et al., 2016;Taylor, 1980;Thorisson et al., 2012), although some temperate populations are more or less sedentary on the British Isles (Salomonsen, 1955;Taylor, 1980). ...
Leapfrog migration is a common migration pattern in birds where the breeding and wintering latitudes between populations are in reversed latitudinal sequence. Competition for wintering and breeding sites has been suggested to be an ultimate factor, and several competitor‐based hypotheses have been proposed to explain this pattern. If wintering sites close to the breeding sites are favored, competitive exclusion could force subdominant individuals to winter further away. Competitive exclusion could be mediated either through body size or by prior occupancy. The alternative “spring predictability” hypothesis assumes competition for sufficiently close wintering areas, allowing the birds to use autocorrelated weather cues to optimally time spring migration departure. To test predictions and assumptions of these hypotheses, we combined morphometrics, migration, and weather data from four populations of common ringed plover breeding along a latitudinal (56–68° N) and climatic gradient (temperate to Arctic). Critical for our evaluation was that two populations were breeding on the same latitude in subarctic Sweden with the same distance to the closest potential wintering site, but differed in breeding phenology, and wintered in West Africa and Europe, respectively. Thus, while breeding on the same latitude, their winter distribution overlapped with that of an Arctic and temperate population. Body size was largest within the temperate population, but there was no size difference between the two subarctic populations. Populations wintering in Europe arrived there before populations wintering in Africa. The largest variation in the arrival of meteorological spring occurred at the temperate breeding site, while there was almost no difference among the other sites. In general, temperatures at the northernmost wintering area correlated well with each breeding site prior to breeding site‐specific spring arrival. Based on these observations, we conclude that competitive exclusion through body‐size‐related dominance cannot explain leapfrog migration. Furthermore, the assumptions on which the “spring predictability” hypothesis is based did not match the observed wintering ranges either. However, we could not reject the hypothesis that competitive exclusion mediated by prior occupancy in the wintering area could lead to leapfrog migration, and therefore, this hypothesis should be retained as working hypothesis for further work.
... Following the autumn migration, there is presumably less competition for wintering territories, allowing the birds to minimize the energetic cost of the travel and to consider time economy to a lesser extent. The consequences of adopting a time-minimizing strategy in the spring and energy-minimizing behaviour during autumn are reflected in the migration flight speeds of the nocturnal migrants [9], with spring nocturnal migration being usually faster than autumn migration [6,[10][11][12]. This difference is also evident in the will have a more substantial negative effect on migration intensity than winds blowing towards the east because birds will try to avoid drifting over the sea [49]; (iv) the effects of temperature on migration intensity will be positive in the spring [26,27] and negative in the autumn [21,22]; and (v) between-season differences in bird migration speed will include higher groundspeed in the autumn and higher airspeed in the spring, as reported earlier in this region [19]. ...
During spring migration, nocturnal migrants attempt to minimize their travel time to reach their breeding grounds early. However, how they behave and respond to unfavourable conditions during their springtime travels is much less understood. In this study, we reveal the effects of atmospheric factors on nocturnal bird migration under adverse conditions during spring and autumn, based on one of the most detailed bird migration studies globally, using radar data from 13 deployments over a period of seven years (2014–2020) in the Levant region. Using ERA5 reanalysis data, we found that migratory birds maintain similar ground speeds in both autumn and spring migrations, but during spring, when encountering unfavourable winds, they put more effort into maintaining their travel speed by increasing self-powered airspeed by 18%. Moreover, we report for the first time that spring migrants showed less selectivity to wind conditions and migrated even under unfavourable headwind and crosswind conditions. Interestingly, we discovered that temperature was the most important weather parameter, such that warm weather substantially increased migration intensities in both seasons. Our results enhance our understanding of bird migration over the Levant region, one of the world’s largest and most important migration flyways, and the factors controlling it. This information is essential for predicting bird migration, which—especially under the ongoing anthropogenic changes—is of high importance.
... For the four species in which we evaluated a latitude effect, populations breeding at higher latitudes remained unchanged, or increased their average migratory distances, in contrast to southern breeding populations which moved north. Latitudinal variation in migratory movements by populations is common in geese and other species, often resulting in a pattern known as leap-frog migration in which northern populations fly farther south than southern populations (Salomonsen 1955, Berthold 2001, Newton 2008, Nilsson et al. 2022. Leapfrog migration is a strategy to avoid competition from earlier conspecific arrivals on breeding or wintering grounds (Alerstam and Hedenström 1998). ...
Migration is a prevalent strategy among birds used to track seasonal resources throughout the year. Individual and population‐level migratory movements provide insight to life‐history variation, carry‐over effects, and impacts of climate change. Our understanding of how geographic variation in a species' breeding or wintering grounds can impact migration distances is limited. However, changes in migration distances can have important fitness consequences for individuals and conservation implications for populations, particularly if migratory connectivity is altered during the annual cycle. In this study, we use three decades of data from the United States Geological Survey Bird Banding Laboratory for six migratory species of Arctic and subarctic breeding geese. We employ a Bayesian hierarchical framework to test if the distance between breeding and wintering locations has changed over time, while accounting for the latitude of the breeding grounds. A model that included only a temporal trend estimated the average rate of change in migration distance, across all six species, at −3.0 km/year over the period 1990–2019. Five of the six species showed a significant decrease in migration distances. Including an interaction effect with breeding latitude revealed that the reduction in migration distance was strongest in the southernmost populations for four of the six species. For those species, migration distance in northern populations were all either relatively unchanged or increasing. This indicates that southern breeding populations of geese had a stronger association with the observed spatiotemporal changes in wintering ranges, potentially influenced by a combination of climatic and biotic factors (e.g. resource availability or competitive interactions) that uniquely impact these populations. Abundant, long‐term banding data shows promise for use in illuminating changes in migratory patterns under climate change, leading to improved management and conservation outcomes, from regional to continental scales.
... For instance, in long-lived social bird species such as storks, geese or cranes, innate programs alone are not sufficient for them to migrate successfully; therefore, a learning process in which experienced individuals transfer knowledge to unexperienced ones is required for navigation success (Chernetsov et al. 2004). On the other end are short-lived night-migrating birds that are thought to do the journey on their own, often across continents to the same wintering areas as their conspecifics, a process where the genetic influence appears predominant (Berthold 2001). An extreme example is the common cuckoo Cuculus canorus in which juveniles, which never had any contact with their biological parents, follow in solitary the same migratory route as adult conspecifics to population-specific winter grounds (Vega et al. 2016). ...
Animal migration is a fascinating phenomenon that has puzzled mankind since the time of ancient Greece. It is a process widespread across a varied range of taxa and it shines especially in birds which, because of their mobility, display an amazing diversity of routes and strategies. With the advances in tracking devices and improvements of sequencing technologies, recent work provides support for a strong genetic influence of several migratory traits across different species. However, there is little to no evidence of any common sequence‐based mechanism behind this complex behaviour, nor any unifying principle explaining it. We review how the focus in understanding the genetic basis for migratory traits should be shifted towards studying regulatory mechanisms of gene expression instead of the traditional candidate gene approach. Importantly, a role for gene expression as the underlying driver of the migratory phenotype can resolve the opposing and often strong views that migration is mainly either under genetic or environmental influence. We emphasise that research should take new directions, reinforcing that there is probably not a common genetic basis for how migration is regulated in birds. Here, we support the notion that 1) migration can only evolve this fast if it is a quantitative trait with a large standing variation; 2) the main drivers for migration evolution seem to be diverse expression–regulation mechanisms rather than gene‐level polymorphisms; and 3) non‐coding sequences of the genome, epigenetics and structural variation might be more important in shaping complex traits than previously thought. Further, we present several hypotheses outlining how these regulatory mechanisms might work across different bird species defining certain migratory traits.
... Therefore, the timing of the flight feather replacement rarely coincides with such an energy-demanding stage of the annual cycle as migration (Kjellén 1994). Even though birds may compensate for increased wing loading by reducing their body mass (Holmgren et al. 1993;Swaddle and Witter 1997;Lind and Jakobsson 2001), migrants need to accumulate energy reserves (mainly fat) for non-stop migratory flights (Berthold 1993). Hence, there is a trade-off between the necessity to increase body mass before migratory flight and reduced wing area during feather moult. ...
We analysed primary and secondary feather moult and fat reserves in 539 Common Snipes captured in the middle Pripyat River Valley, an important stopover site for waders in Central Europe, between 2002 and 2022. The average daily rate of feather growth was 1.89% in primaries and 2.27% in secondaries, being one of the highest documented in waders. The estimated duration of growth for a single flight feather varied from 11 to 21 days in primaries and from 8 to 11 days in secondaries. Moreover, multiple flight feathers (up to 14) were replaced simultaneously. As a result, the wing moult in Common Snipes was rapid with the mean primary moult duration estimated at 53 days (28 June–20 August) according to the Underhill–Zucchini model, and only 20 days in secondaries (31 July–20 August) based on moult estimates of individual secondaries. Hence, although secondary feathers began to grow when primary moult was already advanced, moulting of both flight feather groups was completed in most birds at almost the same time. Our study shows that Common Snipe in the middle Pripyat River Valley exhibit very rapid wing moult with large wing gaps. Fat reserves and thus body mass of Common Snipes were the lowest when the wing gap was greatest, compensating for their reduced wing area. Late and slow movement towards wintering grounds, allows them to moult rapidly at the early stage of autumn migration, which is likely to occur only in sites with abundant food resources.
... Weather variables are known to correlate with bird and bat movements during migration (Richardson 1990, Berthold 1993, Cryan and Brown 2007, Hatch et al. 2013, Mellone et al. 2015. For example, movement of hoary bats (Lasiurus cinereus) to and from Southeast Farallon Island were influenced by changes in wind speed, moon illumination, cloud cover, and barometric pressue. ...
... Alongside the explanation of Speakman (1990), this type of behavior may be particularly effective prior to or after adverse weather conditions, which has repeatedly been referred to as a proximate reason of diurnal activity in bats. Analogical changes in circadian activity during Downloaded from https://academic.oup.com/jmammal/article/105/3/643/7632666 by ASM Member Access user on 30 July 2024 migration are well documented in many migratory birds, which use nighttime for endurance flights and daytime for refueling (Berthold 2001). ...
Diurnal flight activity in otherwise strictly nocturnal bats has typically been linked to random disturbance from day roosts, an urgent need to balance food shortage caused by adverse weather during nighttime, or the absence of diurnal predators. However, migration may be another reason why bats fly during daylight, at least in some areas. Using community-science data collection, we obtained more than 500 records of over 15,000 bats displaying diurnal flight activity, suggesting that it is relatively common in Central Europe. The vast majority of sightings were of common noctules (Nyctalus noctula), with most records concentrated in spring and autumn. The seasonal dynamics of diurnal flights exactly coincided with migratory periods, and directional movements in autumn—when diurnal activity was most frequent and included highest numbers of observed bats—suggest that the behavior may ultimately be linked to migration ecology. The highest frequency of diurnal flights in autumn coincided with highest body mass in the studied territory, thereby refuting the hypothesis of early roost emergence due to poor body condition or decreased predation risk related to increased maneuverability. A shift from strictly nocturnal to partly diurnal activity may balance increased energetic demands imposed by migration, which is temporally synchronized with periods of cold nights when prey density is limited. Common noctule diurnal activity during the migratory period may be beneficial as they can acquire energy by foraging on daily abundant prey while saving nighttime for long endurance flights—alternatively, they may forage on the way to their migratory destination, thereby saving time. Predation risk from diurnal predators may be significantly decreased by choosing high flight altitudes, as observed particularly during autumn. We suggest that observations on the geographic distribution of diurnally flying noctules may help identify migration corridors.
... Aerial foragers represent a set of bird species specialized in feeding on flying insects (Ehrlich et al. 1998). Because of their dependence on a high density of flying insects, most aerial forager species breeding in northern temperate regions migrate southwards in winter (Møller 1989, Berthold 1993, Gordo et al. 2007, Gordo & Sanz 2008. ...
We carried out an intensive sampling (point count method) on three common
species of aerial forager birds (barn swallow Hirundo rustica, house martin delichon urbicum, swift apus apus) occurring in two remnant wetlands located along the Tyrrhenian coast (central Italy). Our aim was to define their seasonal patterns in abundance during the period when these long distance migrant species occur at central Mediterranean latitudes (February-October). Each species showed different peaks in abundance due to their different migratory dynamics and eco
logical traits. Barn swallow showed the highest mean abundance in summer in both studied wetlands. This species arrived in spring from wintering sites mainly as solitary individuals, while in late summer larger social groups were observed with a significantly higher frequency: these wetlands probably have a role in late summer as premigratory roosts. house martin showed asynchronous yearly patterns between the two wetlands. Swifts had the highest values in April and patterns appeared highly synchronous between areas. Swifts observed in April
probably included both individuals nesting in the towns near the study area and vagrants, which nest elsewhere. For all species, differences in abundance and/or seasonal phenology between sites were probably due to differences in surrounding landscape habitats. Our data highlight the importance of wet zones (reedbeds and rushbeds) for the conservation of aerial insectivorous migrant birds, both transient individuals and local breeders. Moreover, these findings support the hypothesis that different wetlands, even though close-by, may have different ecological roles for different species, mainly depending on the type of landscape surrounding them.
... Various functions of melatonin are at the interface of diel and annual behaviours. A striking example is avian migration, a time during which many species carry out migratory flights during the night [80]. During this migratory phase, nocturnal migrants show a damped melatonin rhythm, even under constant LD-cycles. ...
Biological clocks are evolved time-keeping systems by which organisms rhythmically coordinate physiology within the body, and align it with rhythms in their environment. Clocks are highly sensitive to light and are at the interface of several major endocrine pathways. Worryingly, exposure to artificial-light-at-night (ALAN) is rapidly increasing in ever more extensive parts of the world, with likely impact on wild organisms mediated by endocrine–circadian pathways. In this overview, we first give a broad-brush introduction to biological rhythms. Then, we outline interactions between the avian clock, endocrine pathways, and environmental and internal modifiers. The main focus of this review is on the circadian hormone, melatonin. We summarize information from avian field and laboratory studies on melatonin and its relationships with behaviour and physiology, including often neglected developmental aspects. When exposed to ALAN, birds are highly vulnerable to disruption of behavioural rhythms and of physiological systems under rhythmic control. Several studies suggest that melatonin is likely a key mediator for a broad range of effects. We encourage further observational and experimental studies of ALAN impact on melatonin, across the full functional range of this versatile signalling molecule, as well as on other candidate compounds at the endocrine–circadian interface.
This article is part of the theme issue ‘Endocrine responses to environmental variation: conceptual approaches and recent developments’.
... Nocturnal activity, an indicator of migratory state (Berthold 1973, Gwinner and Czeschlik 1978, Watts et al. 2017, is predicted to decline as birds transition to breeding. Body mass is generally elevated during migration (Berthold 2001, Robart et al. 2018, Cornelius et al. 2021) and can either decline as birds transition to breeding or remain elevated due to short breeding windows, to support facultative responses to inclement weather or in preparation for breeding (Ricklefs 1974, Ramenofsky andWingfield 2006). Further, in preparation to breed, a male's cloaca swells and lengthens (termed a cloacal protuberance) whereas females defeather and vascularize their abdomen (termed a brood patch; Ramenofsky and Wingfield 2006). ...
Many animals rely on photoperiodic and non-photoperiodic environmental cues to gather information and appropriately time life-history stages across the annual cycle, such as reproduction, molt, and migration. Here, we experimentally demonstrate that the reproductive physiology, but not migratory behavior, of captive Pine Siskins (Spinus pinus) responds to both food and social cues during the spring migratory-breeding period. Pine Siskins are a nomadic finch with a highly flexible breeding schedule and, in the spring, free-living Pine Siskins can wander large geographic areas and opportunistically breed. To understand the importance of non-photoperiodic cues to the migratory-breeding transition, we maintained individually housed birds on either a standard or enriched diet in the presence of group-housed heterospecifics or conspecifics experiencing either the standard or enriched diet type. We measured body condition and reproductive development of all Pine Siskins and, among individually housed Pine Siskins, quantified nocturnal migratory restlessness. In group-housed birds, the enriched diet caused increases in body condition and, among females, promoted reproductive development. Among individually housed birds, female reproductive development differed between treatment groups whereas male reproductive development did not. Specifically, individually housed females showed greater reproductive development when presented with conspecifics compared to heterospecifics. The highest rate of female reproductive development, however, was observed among individually housed females provided the enriched diet and maintained with group-housed conspecifics on an enriched diet. Changes in nocturnal migratory restlessness did not vary by treatment group or sex. By manipulating both the physical and social environment, this study demonstrates how multiple environmental cues can affect the timing of transitions between life-history stages with differential responses between sexes and between migratory and reproductive systems.
... Terdalkar et al., (2005) justify the reason for available of more avifaunal diversity depend on physical structure of the habitat, food availability and biotic interactions. Berthold (2001) stated that mostly the birds prefer to migrate within the geographical realm of the same continent for breeding and nesting purposes. Avifauna are also recognized as a quick responders to any kind of changes which occur in their ambient conditions lead them to be consider as one of the bio-indicator tool to study environmental monitoring and assessment for any type of ecosystem (Padoa-Schioppa et al., 2006). ...
... Of the three countries where birds were tagged, there was a tendency for those from the southernmost area (Spain) to spend the most time in long- distance movements and travel farthest and those from the northernmost area (Iceland) to undertake long-distance movements the least. This appears counter to 'leapfrog' migrations (Berthold 2001, Newton 2008, where conspecifics breeding in more northern populations can occupy winter ranges farther south than more southern breeders. Potential factors contributing to Short-eared Owls travelling less from Iceland may include: (1) the challenge of the long sea crossing necessary to leave Iceland; and (2) a reduced assemblage of competitor and prey species. ...
Nomadic species can rely on unpredictable resources making them challenging to understand and, consequently, to conserve. Here, we present knowledge advancement for a nomadic predator, the Short-eared Owl Asio flammeus, by tracking individuals from a wide latitudinal range inclusive of most breeding populations in western Europe (Iceland, Scotland and Spain). Tracked owls showed pronounced plasticity in both inter- and intra-individual behaviour. Distances between sequential breeding areas of individual owls ranged from 41 to 4216 km, with similar low fidelity to areas used at other times of year. Owls spent most (> 60%) of their time occupying home-ranges (including breeding) and least (< 10%) undertaking long-distance movements. The propensity for long-distance movements was least for the most geographically isolated population, Iceland. Annual survival rates of 47% were lower than expected for an owl of comparable body mass with mortality concentrated during long-distance displacements and immediately after breeding. Extensive, nomadic travel to find areas where large broods might be reared may incur carry-over costs that lower survival. Conservation planning and assessment for nomadic species and their habitats must acknowledge the uncertainties associated with nomadism at scales from local to international.
... The year-to-year return of migratory animals has long been a source of wonder for humans [1]. Methods to identify individuals, such as marking birds individually using metal rings [2], lead to the discovery that not only the same species, but often the same individual returned to the same place year after year [3][4][5][6]. Ecologists have used the terms site fidelity, faithfulness, or philopatry for this tendency to return to a previously visited site. ...
Background
Site fidelity, the tendency to return to a previously visited site, is commonly observed in migratory birds. This behaviour would be advantageous if birds returning to the same site, benefit from their previous knowledge about local resources. However, when habitat quality declines at a site over time, birds with lower site fidelity might benefit from a tendency to move to sites with better habitats. As a first step towards understanding the influence of site fidelity on how animals cope with habitat deterioration, here we describe site fidelity variation in two species of sympatric migratory shorebirds (Bar-tailed Godwits Limosa lapponica and Great Knots Calidris tenuirostris). Both species are being impacted by the rapid loss and deterioration of intertidal habitats in the Yellow Sea where they fuel up during their annual long-distance migrations.
Methods
Using satellite tracking and mark-resighting data, we measured site fidelity in the non-breeding (austral summer) and migration periods, during which both species live and co-occur in Northwest Australia and the Yellow Sea, respectively.
Results
Site fidelity was generally high in both species, with the majority of individuals using only one site during the non-breeding season and revisiting the same sites during migration. Nevertheless, Great Knots did exhibit lower site fidelity than Bar-tailed Godwits in both Northwest Australia and the Yellow Sea across data types.
Conclusions
Great Knots encountered substantial habitat deterioration just before and during our study period but show the same rate of decline in population size and individual survival as the less habitat-impacted Bar-tailed Godwits. This suggests that the lower site fidelity of Great Knots might have helped them to cope with the habitat changes. Future studies on movement patterns and their consequences under different environmental conditions by individuals with different degrees of site fidelity could help broaden our understanding of how species might react to, and recover from, local habitat deterioration.
... Further studies are needed to understand the proximate and ultimate causes of partial migration in this species (Chapman et al. 2011), and to determine whether this behavior is obligate and fixed within individuals (Berthold 2001); or facultative, varying within individuals according to environmental conditions (Cristol et al. 1999). The advantages of this Magellanic penguin behavior are unclear, although a meta-analysis of flying birds has shown that resident birds have higher fitness return than migrants (Buchan et al. 2020). ...
We studied the migration of Magellanic penguins near the southern tip of the breeding distribution, and for the first time found evidence of partial migration for this species within the same colony. Forty‐three percent of the penguins studied stayed within ~ 290 km of the colony (residents), while others went northwards as far as 2000 km. All penguins spent the same amount of time at sea and traveled similar total distances, but residents experienced colder waters (2°C lower) and habitats with lower Chlorophyll‐a concentrations than migrants. The two habitats are inhabited by different prey items, consequently offering the penguins distinct prey options. We have shown high variability in the non‐breeding dispersion behavior of Magellanic penguins within the same colony; nonetheless, further research is required to understand the proximate and ultimate causes, and the consequences, of this behavior.
Umbilicaria africana, hitherto only known from Africa, South America, Antarctica, and the Malay Archipelago in Southeast Asia is reported from the West Chukotkan sector of the Arctic and North Eurasia as whole. Morphological details of the Arctic material are provided. Umbilicaria aprina is excluded from the flora of the Chukotkan sector of the Arctic as a previous erroneous identification of the specimen of U. africana. The bipolar distribution of U. africana is discussed. Based on analyses of migratory bird species composition and their ecology in localities where arctic-alpine U. africana was collected, we suggest that the Northern Wheatear (Oenanthe oenanthe) might play an important role in the long-distance dispersal of specific propagula (thalloconidia) of U. africana from East Africa, and the Arctic Warbler (Phylloscopus borealis), the Eastern Yellow Wagtail (Motacilla tschutschensis), or less probably the Pechora Pipit (Anthus gustavi), from Australasia (Malay Archipelago).
The logistics of measuring activities that occur at fine temporal scales, such as short stopovers that last a few hours, has proven very challenging when studying small migratory birds. Here, we deployed multi-loggers equipped with an accelerometer and thermometer on Chilean Elaenias (Elaenia chilensis) to evaluate their activity patterns while they undertook their annual migration from their Patagonian breeding grounds to non-breeding zones in Brazil. Results showed that elaenias migrated nocturnally, providing the first evidence of this behavior in a Neotropical austral migrant. Although most migration flights lasted less than eight hours, one individual flew non-stop for more than 28 h. Overall activity patterns (e.g., flight and stopover duration) were not statistically different between pre- and post-breeding migration. This technology offers a window into the migratory behavior of small birds that migrate within the Neotropics at a finer temporal scale than previously possible.
We investigated the non-breeding movements and distribution of West African Crested terns (Thalasseus albididorsalis) breeding in one of the largest colonies of the species, in Guinea-Bissau. Through GPS tracking of six individuals, we show that half of the birds performed long-distance migrations to non-breeding sites located up to 5039 km south of the colony, mostly in Nigeria and Angola. The other half performed short-distance migrations to areas within 340 km of the breeding colony, mainly in Guinea. These results show high variability on the migratory strategies of the West African Crested Tern and suggest low migratory connectivity within the studied population. Regardless of their migratory strategy, all tracked birds visited at least one additional breeding colony both after and before the breeding season. This behaviour might be particularly relevant for species breeding in unstable environments, which is the case of the studied species, nesting in highly dynamic coastal sandbanks. During the non-breeding season West African Crested terns used coastal areas falling within 18 different jurisdictions, highlighting the need for concerted action between all coastal countries of Western Africa, from Senegal to Angola, for the conservation of this species.
The annual cycles of long-distance migrant species are synchronized with the local climatic conditions at their breeding areas, as they impact the availability of food resources. A timely arrival of individuals to the breeding grounds is crucial for achieving high fitness. Variation in factors influencing timing, including climate, may thus impact the life history of individuals. We studied between-individual variation in migration timing, in particular how local breeding climate influences arrival time and how early-arriving individuals achieve a timely arrival. We tracked individual Lesser Kestrel (Falco naumanni) with GPS tags across a gradient of latitude (37°–42° N) and longitude (6.5° W–16.5° E). Arrival time was influenced by the breeding latitude, the breeding longitude, and the local temperature, without any apparent influence of sex. The time of arrival at the breeding grounds was 6 days later for every degree increase in latitude and 2 days later for every degree increase in longitude. Lesser Kestrels from southwestern colonies achieve earlier arrival than conspecifics breeding at northeastern colonies, mostly due to earlier departure from their non-breeding grounds. While we found some effects of travel speed and stopover duration on arrival date, the latter was primarily influenced by food abundance and wind conditions en route. The large effect of departure date from West Africa on arrival date, relative to the more moderate influence of stopover duration close to breeding colonies, supports the idea that geographically uneven climate change may negatively affect fitness via ecological mismatches in the breeding area.
Physical effort requires a number of energetic, metabolic, hormonal, and cardiovascular responses that can be highly costly for the organism to sustain. Even physical inactivity, typical of animals during hibernation or aestivation, requires several physiological adjustments of the metabolic machinery, which have also to prepare the organism for the reoxygenation and increased metabolic activity that will characterise the phase of arousal. A number of studies described the many ways in which animals regulate their oxidative status during different phases of physical (in)activity, such as strenuous migratory flight, dormancy, or arousal. Many authors also pointed to a role of exercise-induced reactive oxygen species in mediating hormetic responses to physical effort. In this chapter, I have examined the role of oxidative stress induced by physical effort as cost of and constraint on migration strategies and sibling competition. I have also analysed the oxidative challenges that animals face during periods of inactivity, and the transition from dormancy to arousal due to tissue reoxygenation and consequent burst of reactive oxygen species generation in body tissues.
Migratory birds are important vectors for the spread of zoonotic and antimicrobial-resistant (AMR) bacteria, posing a global public health risk. The River Ravi in Pakistan, is a crucial stopover for migratory birds, is seeing increased anthropogenic activity, which contributes to the spread of AMR bacteria. Objective: To assess the prevalence of specific antibiotic-resistant bacterial species among different migratory birds, and significance of migrating birds as possible reservoirs and disseminators of AMR bacteria. Methods: The study was carried out along the Ravi River in Lahore. Fecal samples from five migrating bird species were gathered at five distinct locations utilizing non-invasive mist netting and fresh fecal collection. The bacteria were isolated and identified using Gram staining and biochemical analysis. The Kirby-Bauer technique of disc diffusion was employed to assess the sensitivity of microorganisms. Results: All sites showed significant contamination from Gram-positive and Gram-negative bacteria. Enterococcus spp. and Escherichia coli were most common, indicating fecal contamination. It was found that E. coli and S. aureus are highly resistant to Azithromycin and Gentamycin, whereas K. pneumoniae is resistant to Norfloxacin. However, erythromycin and tetracycline were effective against P. aeruginosa and C. septicum, respectively. Conclusions: The research concluded that the River Ravi was significantly contaminated with germs from humans and the surroundings, along with distinct AMR patterns. The elevated levels of S. aureus, E. coli, Enterococcus spp. and Pseudomonas spp. point to serious health risks for the general public. AMR patterns emphasize the difficulty in controlling bacterial infections, emphasizing the importance of targeted antimicrobial treatments and ongoing surveillance.
Some publications report that passerine birds, compared with geese and waders, show much less annual faithfulness to migration routes and stopover sites, and that faithfulness to them decreases with increasing length of the migration path. The analysis of numerous recaptures of ringed birds in the Curonian Spit (Eastern Baltic) led to the opposite conclusions. The calculations were carried out on thousands of recaptures obtained over 30 years (1957–1986) from two of the most numerous species, chaffinch Fringilla coelebs Linnaeus, 1758 (Fringillidae) and willow warbler Phylloscopus trochilus (Linnaeus, 1758) (Phylloscopidae). It turned out that a significant part of the migratory populations (34–41% of recaptured birds) retains the same migration path and approximately the same migration timing in other years after ringing. Assumptions about the dependence of the degree of fidelity to migration routes on their length have not been confirmed, since the fidelity indicators of willow warbler, which has a much longer route than chaffinch, were even higher than those of the chaffinch. The data on the individual life longevity of the recaptured migrants (up to 9 years in the chaffinch and up to 4 years in the willow warbler) confirm the fidelity to the same migration path throughout the life of the studied birds.
In this study, we detected and compared changes in the annual and daily captures of the Eurasian (Certhia familiaris) and Short-toed Treecreeper (C. brachydactyla) in the timing of their post-breeding movements, in the length of minimum stopover duration (MSD) in the area, and also in biometrics in western Hungary. The birds were captured and ringed, or recaptured from the end of July to the first weekend of November in all years from 2001 to 2023. The annual captures of both species indicated stable populations in this period, with milder February months having a positive effect on annual captures. There were similarities and differences in the movement strategies and habitat selection of the species. During the post-breeding season, the Eurasian Treecreeper was more strongly associated with the scrubland and forest edge than the Short-toed Treecreeper. There were two autumn capture waves in September and October for the Eurasian Treecreepers and just one in September for the Short-toed Treecreepers, which were primarily consisted of birds captured only once. There were no significant differences in wing length of the three capture intervals (July-August, September, October-November) in either species, which suggests that the dynamics of post-breeding movements cannot be explained on the bases of possible differences in the behavior of sexes, ages, or populations. The proportion of birds captured only once was about double of that of stopovers in both species each year. The average real length of stopover duration in the area for Eurasian Treecreepers was 94.25 days, and 84.31 days for Short-toed Treecreepers. The length of MSD in the area was not significantly associated with wing length and body mass in either species. Individuals of both species did not gain fat stores significantly during post-breeding season.
Seasonal migration is a widespread behavior relevant for adaptation and speciation, yet knowledge of its genetic basis is limited. We leveraged advances in tracking and sequencing technologies to bridge this gap in a well-characterized hybrid zone between songbirds that differ in migratory behavior. Migration requires the coordinated action of many traits, including orientation, timing, and wing morphology. We used genetic mapping to show these traits are highly heritable and genetically correlated, explaining how migration has evolved so rapidly in the past and suggesting future responses to climate change may be possible. Many of these traits mapped to the same genomic regions and small structural variants indicating the same, or tightly linked, genes underlie them. Analyses integrating transcriptomic data indicate cholinergic receptors could control multiple traits. Furthermore, analyses integrating genomic differentiation further suggested genes underlying migratory traits help maintain reproductive isolation in this hybrid zone.
Avian long-distance migration requires refined programming to orchestrate the birds’ movements on annual temporal and continental spatial scales. Programming is particularly important as long-distance movements typically anticipate future environmental conditions. Hence, migration has long been of particular interest in chronobiology. Captivity studies using a proxy, the shift to nocturnality during migration seasons (i.e., migratory restlessness), have revealed circannual and circadian regulation, as well as an innate sense of direction. Thanks to rapid development of tracking technology, detailed information from free-flying birds, including annual-cycle data and actograms, now allows relating this mechanistic background to behaviour in the wild. Likewise, genomic approaches begin to unravel the many physiological pathways that contribute to migration. Despite these advances, it is still unclear how migration programmes are integrated with specific environmental conditions experienced during the journey. Such knowledge is imminently important as temporal environments undergo rapid anthropogenic modification. Migratory birds as a group are not dealing well with the changes, yet some species show remarkable adjustments at behavioural and genetic levels. Integrated research programmes and interdisciplinary collaborations are needed to understand the range of responses of migratory birds to environmental change, and more broadly, the functioning of timing programmes under natural conditions.
Supplementary Information
The online version contains supplementary material available at 10.1007/s00359-023-01688-w.
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