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Electron spin relaxation is, on many occasions, considered an elephant in the room that challenges the idea of a radical-pair compass, a leading hypothesis for the navigation of migratory avian species. It has been widely recognized that an effective radical-pair magnetoreceptor requires a relaxation time that is long enough for an external magnetic field as weak as the geomagnetic field to significantly modify the coherent spin dynamics. However, previous studies proposed that certain spin relaxation, far quicker than the radical recombination reactions, could enhance, rather than degrade, the directional sensitivity of a radical-pair magnetoreceptor. Here, I investigate relaxation effects on the singlet–triplet interconversion of a model radical pair and find that the enhancement effect originates from population relaxation over a period of several microseconds as a result of efficient spin decoherence. Insights into the truncated spin systems shed light on the physics behind them. I further investigate the possibilities of such enhancement in cryptochrome-based magnetoreception, in which electron hopping takes place between tryptophan residues. [ABSTRACT FROM AUTHOR]

Migration is an integral part of the annual cycle of many bird species that have evolved to take advantage of spatially segregated, seasonally abundant food resources while avoiding harsh winter conditions. Increasing evidence suggests that long-distance migrants are shortening their migration routes and wintering at higher latitudes closer to their breeding grounds. One potential example of this process are the observations of Egyptian vultures during the winter on the island of Crete. In this study we provide an overview of wintering Egyptian vulture occurrences on the island of Crete, seeking to shed additional light on the species’ wintering ecology. To this aim we collated extensive field observations spanning 28 winters from 1995 to 2023 and analysed telemetry data from three tracked vultures. Our results revealed a change in the wintering frequency of Egyptian vultures in the island with an increasing trend since 2015, especially regarding the presence of subadult and adult birds. We found an increased habitat use intensity for open landscapes and agricultural areas compared to other habitat types within Crete, emphasizing the influence of food availability on space utilization. We suggest that the interplay between climate changes, lack of experienced conspecifics and local food availability could have triggered the increasing number of wintering Egyptian vultures in Crete. The implications of this short-stopping behaviour extend to conservation strategies, highlighting the need for the consideration of new wintering sites and the potential threats faced by vultures during this period. We recommend the operation of supplementary feeding stations and actions to reduce the risk of electrocution to be considered as valuable conservation actions in the species’ wintering sites in Crete. Monitoring and further research are recommended to assess the long-term impact and viability of this new migration tactic, providing insights into adaptive responses to environmental change. [ABSTRACT FROM AUTHOR]

Most major rivers in Europe have been dammed for hydropower or other purposes. Such river alterations have decimated natural reproduction of many migratory fish species, including that of the anadromous European whitefish, Coregonus lavaretus, which is now maintained by extensive stocking programmes. In addition to stocking, limited natural reproduction may occur downstream of dams, where peak flow bouts from the dams threaten to flush the eggs into unsuitable habitats. Here, we assessed the effects of water flow velocity and substrate coarseness on downstream drift of whitefish eggs under laboratory conditions. The experiment's two different gravel substrates retained eggs better than cobble or sand substrates; the water velocity needed for notable egg drift was higher for the gravel substrates. The results indicate that egg drift is one of the factors that should be considered when evaluating the effects of hydropower plant operations. Moreover, measures mitigating the effects of the artificial flow regimes should incorporate the type and coarseness of the riverbed's substrate. [ABSTRACT FROM AUTHOR]

The Amazon basin, spanning approximately 540,000 km2, exhibits distinct fluviometric surfaces that differentiate between the dry and rainy seasons. This seasonality, along with hydrological connectivity and the creation of new habitats during the rainy season, significantly promotes the migration, reproduction, and feeding of potamodromous fishes. To estimate the realized niches of species, species distribution models (SDMs) employ the extrapolation of environmental predictors and species occurrence data. Our objective was to compare the spatial distribution of migratory fish species in the Amazon basin using SDMs based on variables characterizing the dry season, rainy season, and a combination of both. All evaluated treatments demonstrated high performance and exhibited different distribution ranges in the applied SDMs, particularly when combining environmental variables with occurrence data during the rainy season. These findings support the hypothesis that spatial distribution is influenced by seasonality. The increased fluviometric surface and enhanced connectivity of the rainy season favor both longitudinal and lateral migrations of Amazonian migratory catfishes. Moreover, the spatial distribution reveals four critical spatial overlap (CSO) regions with higher population densities regardless of the season. These CSOs primarily coincide with the Amazon alluvial plain, which exhibits the highest rates of endemism, species richness, and abundance of organisms. Considering the discontinuous and heterogeneous nature of fluviometry when performing niche modeling processes is pivotal, although SDMs applied in the Amazon generally ignore such regional seasonality. [ABSTRACT FROM AUTHOR]

The seasonal pattern of species diversity and abundance of waterbirds of the Chambal River in the extent of Mukundra Hills National Park, Rajasthan, India was evaluated. The pre-monsoon (March-April 2021) and post-monsoon surveys (August-September 2021) were carried out using the direct count method with the help of a motorboat to monitor the population status of waterbirds. A total of 44 species of waterbirds belonging to 15 families and nine orders were identified, including 11 winter migratory species. Forty species of birds were recorded during pre-monsoon and 27 species during post-monsoon seasons. The species richness and relative abundance varied significantly between observed seasons (x2 = 532.77, df = 43, p <0.05). Breeding activities of three species were recorded, namely, Grey Heron, Black-crowned Night Heron, and the 'Near Threatened' Woolly-necked Stork. The present study reveals the status of waterbirds in the protected area of Mukundra Hills National Park. [ABSTRACT FROM AUTHOR]

When the conditions encountered by a migratory species are highly variable, the timing of migration and migrant condition are critical to survival. Spring/summer‐run Chinook salmon in the Snake River of the Northwestern United States are listed as threatened under the US Endangered Species Act because of decades of poor adult returns; juvenile smolt‐to‐adult survival is often 0.5% or less. Juveniles pass through eight dams en route to the ocean, and despite changes to the hydropower system, there has been little recent improvement in survival. We analysed the effect of migration date, fish length and their interaction on the survival to adulthood of 409,747 wild juvenile Chinook salmon as they migrated through a large, dynamic riverine ecosystem and through the ocean, measured over 20 years. Parametric 2D smoothers are often used to quantify unexplained heterogeneity across space; however, these same statistical models can be applied to 2D datasets to uncover patterns of covariance of two biological processes important to management actions. We employ Gaussian Markov random fields (GMRF) and a 2D smoother to estimates of fish survival to identify the nature of variation in survival with respect to length and date. We found significant effects of fish length, migration date and the date‐by‐length interaction on resulting riverine and marine survival. Unlike the gradual shifts in survival in relation to length and timing that marginal estimates demonstrate, we show that within year, changes in survival with length and timing are often more abrupt than previously thought. Synthesis and applications: Inter‐annually, we identified distinct combinations of fish length and migration timing leading to elevated smolt‐to‐adult survival. Often these ‘hotspots’ are compressed into fish sizes greater than 100 mm and passage timings of only a week or two, demonstrating that even modest shifts in body size and migration timing can have a significant effect on survival. Further research can concentrate on these distinct annual periods to identify sources of mortality that have previously been elusive. [ABSTRACT FROM AUTHOR]

Global migrations of diverse animal species often converge along the same routes, bringing together seasonal assemblages of animals that may compete, prey on each other, and share information or pathogens. These interspecific interactions, when energetic demands are high and the time to complete journeys is short, may influence survival, migratory success, stopover ecology, and migratory routes. Numerous accounts suggest that interspecific co-migrations are globally distributed in aerial, aquatic, and terrestrial systems, although the study of migration to date has rarely investigated species interactions among migrating animals. Here, we test the hypothesis that migrating animals are communities engaged in networks of ecological interactions. We leverage over half a million records of 50 bird species from five bird banding sites collected over 8 to 23 y to test for species associations using social network analyses. We find strong support for persistent species relationships across sites and between spring and fall migration. These relationships may be ecologically meaningful: They are often stronger among phylogenetically related species with similar foraging behaviors and nonbreeding ranges even after accounting for the nonsocial contributions to associations, including overlap in migration timing and habitat use. While interspecific interactions could result in costly competition or beneficial information exchange, we find that relationships are largely positive, suggesting limited competitive exclusion at the scale of a banding station during migratory stopovers. Our findings support an understanding of animal migrations that consist of networked communities rather than random assemblages of independently migrating species, encouraging future studies of the nature and consequences of co-migrant interactions. [ABSTRACT FROM AUTHOR]

Tracking climatic conditions throughout the year is often assumed to be an adaptive behaviour underlying seasonal migration patterns in animal populations. We investigate this hypothesis using genetic markers data to map migratory connectivity for 27 genetically distinct bird populations from 7 species. We found that the variation in seasonal climate tracking across our suite of populations at a continental scale is more likely a consequence, rather than a direct driver, of migratory connectivity, which is primarily shaped by energy efficiency—i.e., optimizing the balance between accessing available resources and movement costs. However, our results also suggest that regional‐scale seasonal precipitation tracking affects population migration destinations, thus revealing a potential scale dependency of ecological processes driving migration. Our results have implications for the conservation of these migratory species under climate change, as populations tracking climate seasonally are potentially at higher risk if they adapt to a narrow range of climatic conditions. [ABSTRACT FROM AUTHOR]

Migratory connectivity describes the linkage between breeding and nonbreeding sites, having major ecological implications in birds: 1 season influence the success of an individual or a population in the following season. Most studies on migratory connectivity have used large-scale approaches, often considering regional populations, but fine-scale studies are also necessary to understand colony connectivity. The lesser kestrel Falco naumanni , an insectivorous migratory raptor which form colonies during the breeding period, was considered to have strong connectivity based on regional populations. However, no small-scale studies on migratory connectivity have been conducted. Therefore, we GPS (Global Positioning System)-tracked 40 adult lesser kestrels from 15 different Spanish breeding colonies, estimating the overlap index between home ranges and the distance between their centroids. It was found that lesser kestrels from the same breeding colony placed their nonbreeding areas at 347 ± 281 km (mean ± standard deviation) away from each other (range = 23–990), and their home ranges overlapped by 38.4 ± 23.6%. No differences between intra-colony and inter-colony metrics were found, which suggests that lesser kestrels from the same breeding cluster do not overwinter together, but they spread out and mixed independently of the colony belonging throughout the nonbreeding range of the species. Ultimately, this study highlights the importance of performing connectivity studies using fine-scale approaches. [ABSTRACT FROM AUTHOR]

Parasites comprise a substantial portion of global biodiversity and play critical roles in shaping ecosystems by modulating trophic networks and affecting their hosts' abundance and distribution. The dynamics of host migration introduce new complexity to these relationships. From the host perspective, migratory behavior can either act as a defense mechanism or augment exposure to a broader spectrum of pathogens. Conversely, for parasites, host migration represents a mechanism for their dispersion and an opportunity to infect new host species. This study investigates the complex interplay between migration and parasite–host interactions, focusing on the interaction between hosts and avian malaria and malaria-like parasites in the Brazilian Atlantic Rain Forest. We captured 1466 birds representing 70 different species, uncovering 322 infections with Plasmodium/Haemoproteus parasites. We observed variations in migration timing and fluctuations in host abundance across months. By comparing the observed patterns of interaction of migratory and non-migratory birds to patterns of interaction expected at random, we show that migration affects the roles hosts take in the parasite–host network. Interestingly, despite the fact migratory species hosted more exclusive and distinct parasites, migrants did not occupy central network positions, which are mostly occupied by resident birds. Overall, we highlight the role of resident birds as a key species within parasite-host communities and the high specialization among avian haemosporidians and their hosts. [ABSTRACT FROM AUTHOR]

Mandothi Wetlands located in district Jhajjar of Haryana, India is about 1000 acres of farmland, serves as a crucial habitat for numerous species of winter migratory birds. From December 2021 to March 2023, fortnightly periodic visits were made to the area by using scan sampling and point-cum-line transect methods. A total of 54 winter migratory birds' species were recorded including 33 genera, 19 families, and 8 orders. Order Charadriiformes was highly diverse with the presence of 17 species in the study area. Feeding guild analysis expressed that Insectivores were the dominant ones among all guilds. As per the IUCN Red List criteria, 48 species were classified as least concern (LC) whereas, 3 species were classified as Near Threatened (NT) i.e., Ferruginous Duck Aythya nyroca, Eurasian Curlew Numenius arquata, Curlew Sandpiper Calidris ferruginea, and 3 species were classified as Vulnerable (VU) such as Eastern Imperial Eagle Aquila heliaca, Greater Spotted Eagle Clanga clanga and Common Pochard Aythya ferina globally. Study area holds a significant role in sustaining the diversity of birds and also facing various stress factors thus it needs to be conserved. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

In migratory animals, high mobility may reduce population structure through increased dispersal and enable adaptive responses to environmental change, whereas rigid migratory routines predict low dispersal, increased structure, and limited flexibility to respond to change. We explore the global population structure and phylogeographic history of the bar‐tailed godwit, Limosa lapponica, a migratory shorebird known for making the longest non‐stop flights of any landbird. Using nextRAD sequencing of 14,318 single‐nucleotide polymorphisms and scenario‐testing in an Approximate Bayesian Computation framework, we infer that bar‐tailed godwits existed in two main lineages at the last glacial maximum, when much of their present‐day breeding range persisted in a vast, unglaciated Siberian‐Beringian refugium, followed by admixture of these lineages in the eastern Palearctic. Subsequently, population structure developed at both longitudinal extremes: in the east, a genetic cline exists across latitude in the Alaska breeding range of subspecies L. l. baueri; in the west, one lineage diversified into three extant subspecies L. l. lapponica, taymyrensis, and yamalensis, the former two of which migrate through previously glaciated western Europe. In the global range of this long‐distance migrant, we found evidence of both (1) fidelity to rigid behavioural routines promoting fine‐scale geographic population structure (in the east) and (2) flexibility to colonise recently available migratory flyways and non‐breeding areas (in the west). Our results suggest that cultural traditions in highly mobile vertebrates can override the expected effects of high dispersal ability on population structure, and provide insights for the evolution and flexibility of some of the world's longest migrations. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Aim: Seasonal migrations, such as those of ungulates, are particularly threatened by habitat transformations and fragmentation, climate and other environmental changes caused by anthropogenic activities. Mountain ungulate migrations are neglected because they are relatively short, although traversing heterogeneous altitudinal gradients particularly exposed to anthropogenic threats. Detecting migration routes of these species and understanding their drivers are therefore of primary importance to predict connectivity and preserve ecosystem functions and services. The populations of Alpine ibex Capra ibex have all been reintroduced from the last remnant source population. Despite a general increase in abundance and overall distribution range, ibex populations are mostly disconnected but display intra‐population migrations. Therefore, its conservation is strictly linked to the interplay between external threats and related behavioural responses, including space use and migration. Location: Austria, France, Italy and Switzerland. Methods: By using 337 migratory tracks from 425 GPS‐collared individuals from 15 Alpine ibex populations distributed across their entire range, we (i) identified the environmental drivers of movement corridors in both spring and autumn and (ii) compared the ability of a connectivity modelling algorithm to predict migratory movements between seasonal ranges of the 15 populations, using either population‐specific or multipopulation datasets, and three validation procedures. Results: Steep, south‐facing, snow‐free slopes were selected while high elevation changes were avoided. This revealed the importance of favourable resources and an attempt to limit energy expenditures and perceived predation risk. The abilities of the modelling methods we compared to predict migratory connectivity from the results of those movement analyses were similar. Main Conclusions: The trade‐off between energy expenditure, food and cover was the major driver of migration routes and was overall consistent among populations. Based on these findings, we provided useful connectivity models to inform conservation of Alpine ibex and its habitats, and a framework for future research investigating connectivity in migratory species. [ABSTRACT FROM AUTHOR]

We comment on a recent study (Vasenkov et al. in Dokl Biol Sci 513:395–399, 2023, https://doi.org/10.1134/S0012496623700746) presenting the movement paths of three greater noctule bats (Nyctalus lasiopterus), two juveniles and an adult, tracked from Russia in September–October 2020 and 2021, with particular emphasis on the unprecedented straight-line migration of a juvenile male to Italy. Notably, the juvenile's extraordinary 2515 km migration marks the longest recorded (as the crow flies) movement in a bat species. We argue that the two juveniles may represent cases of dispersal. Despite the attention garnered by Vasenkov et al.'s findings, caution is warranted in interpreting the broader migration picture. The paper's dissemination underscores a potential oversimplification, neglecting key insights from recent work conducted in Italy that documented the year-round presence, hibernation, and parturition of N. lasiopterus in an area of the Friuli Venezia-Giulia region where the juvenile male tracked from Russia stopped over. Besides, inferring the existence of migratory routes based on small numbers of tracked bats is insufficient. The oversight of these findings may imply a misleading narrative about the species' behaviour, likely representing a case of partial migration, a pattern widespread among migratory bat species. [ABSTRACT FROM AUTHOR]

Migrating animals perform astonishing seasonal movements by orienting and navigating over thousands of kilometres with great precision. Many migratory species use cues from the sun, stars, landmarks, olfaction and the Earth's magnetic field for this task. Among vertebrates, songbirds are the most studied taxon in magnetic‐cue‐related research. Despite multiple studies, we still lack a clear understanding of when, where and how magnetic cues affect the decision‐making process of birds and hence, their realised migratory behaviour in the wild. This understanding is especially important to interpret the results of laboratory experiments in an ecologically appropriate way. In this review, we summarise the current findings about the role of magnetic cues for migratory decisions in songbirds. First, we review the methodological principles for orientation and navigation research, specifically by comparing experiments on caged birds with experiments on free‐flying birds. While cage experiments can show the sensory abilities of birds, studies with free‐flying birds can characterise the ecological roles of magnetic cues. Second, we review the migratory stages, from stopover to endurance flight, in which songbirds use magnetic cues for their migratory decisions and incorporate this into a novel conceptual framework. While we lack studies examining whether and when magnetic cues affect orientation or navigation decisions during flight, the role of magnetic cues during stopover is relatively well studied, but mostly in the laboratory. Notably, many such studies have produced contradictory results so that understanding the biological importance of magnetic cues for decisions in free‐flying songbirds is not straightforward. One potential explanation is that reproducibility of magnetic‐cue experiments is low, probably because variability in the behavioural responses of birds among experiments is high. We are convinced that parts of this variability can be explained by species‐specific and context‐dependent reactions of birds to the study conditions and by the bird's high flexibility in whether they include magnetic cues in a decision or not. Ultimately, this review should help researchers in the challenging field of magnetoreception to design experiments meticulously and interpret results of such studies carefully by considering the migration ecology of their focal species. [ABSTRACT FROM AUTHOR]

Animal migration has fascinated scientists and the public alike for centuries, yet migratory animals are facing diverse threats that could lead to their demise. The Anthropocene is characterised by the reality that humans are the dominant force on Earth, having manifold negative effects on biodiversity and ecosystem function. Considerable research focus has been given to assessing anthropogenic impacts on the numerical abundance of species/populations, whereas relatively less attention has been devoted to animal migration. However, there are clear linkages, for example, where human‐driven impacts on migration behaviour can lead to population/species declines or even extinction. Here, we explore anthropogenic threats to migratory animals (in all domains – aquatic, terrestrial, and aerial) using International Union for the Conservation of Nature (IUCN) Threat Taxonomy classifications. We reveal the diverse threats (e.g. human development, disease, invasive species, climate change, exploitation, pollution) that impact migratory wildlife in varied ways spanning taxa, life stages and type of impact (e.g. from direct mortality to changes in behaviour, health, and physiology). Notably, these threats often interact in complex and unpredictable ways to the detriment of wildlife, further complicating management. Fortunately, we are beginning to identify strategies for conserving and managing migratory animals in the Anthropocene. We provide a set of strategies that, if embraced, have the potential to ensure that migratory animals, and the important ecological functions sustained by migration, persist. [ABSTRACT FROM AUTHOR]

In migratory animals, the developmental period from inexperienced juveniles to breeding adults could be a key life stage in shaping population migration patterns. Nevertheless, the development of migration routines in early life remains underexplored. While age‐related changes in migration routes and timing have been described in obligate migrants, most investigations into the ontogeny of partial migrants only focused on age‐dependency of migration as a binary tactic (migrant or resident), and variations in routes and timing among individuals classified as ‘migrants’ is rarely considered. To fill this gap, we study the ontogeny of migration destination, route and timing in a partially migratory red kite (Milvus milvus) population. Using an extensive GPS‐tracking dataset (292 fledglings and 38 adults, with 1–5 migrations tracked per individual), we studied how nine different migration characteristics changed with age and breeding status in migrant individuals, many of which become resident later in life. Individuals departed later from and arrived earlier at the breeding areas as they aged, resulting in a gradual prolongation of stay in the breeding area by 2 months from the first to the fifth migration. Individuals delayed southward migration in the year prior to territory acquirement, and they further delayed it after occupying a territory. Migration routes became more direct with age. Individuals were highly faithful to their wintering site. Migration distance shortened only slightly with age and was more similar among siblings than among unrelated individuals. The large gradual changes in northward and southward migrations suggest a high degree of plasticity in temporal characteristics during the developmental window. However, the high wintering site fidelity points towards large benefits of site familiarity, prompting spatial migratory plasticity to be expressed through a switch to residency. The contrasting patterns of trajectories of age‐related changes between spatial and temporal migration characteristics might reflect different mechanisms underlying the expression of plasticity. Investigating such patterns among species along the entire spectrum of migration tactics would enable further understanding of the plastic responses exhibited by migratory species to rapid environmental changes. [ABSTRACT FROM AUTHOR]

In order to investigate the reproductive dynamics of the ichthyofauna in the Brazilian Pantanal, this study examines the spatial and temporal distribution of ichthyoplankton, taxonomic composition, and its correlation with environmental factors within one of the most important sub‐basins, the Taquari River. Egg and larvae collections were conducted at 11 sampling points between October and March of 2017/2018 and 2018/2019. Significant differences were observed between collection points, months, and years, with higher ichthyoplankton densities in the Coxim and Taquari rivers, particularly between November and January. Twenty‐eight genera and/or species of fish were identified, including 10 long‐distance migratory species. Egg density showed a negative correlation with water temperature and rainfall. For larvae, water transparency and rainfall were both significant, negatively influencing larval abundance. However, different species tend to occur in environments with distinct abiotic qualities. Yolk‐sac, preflexion, and flexion larval development stages were distributed throughout the sub‐basin, especially near the Pantanal. Considering the data and analyses presented in this study, the importance of connectivity between these environments, specifically between the plateau and Pantanal, is evident, highlighting the significance of the entire sub‐basin for fish reproductive processes. Therefore, research focusing on the ecological processes influencing the distribution of ichthyoplankton offers valuable insights for ecosystem conservation and aids in effective environmental management. [ABSTRACT FROM AUTHOR]

The blue shark is a highly migratory species with a worldwide distribution, making it susceptible to multiple fishing fleets across the globe. In southern Brazil, it is an important target, comprising up to 40% of the total biomass landed by the commercial surface longline fleet. This study aims to contribute to a better understanding of how the species uses the region and to update its life‐history information available for future assessments. Over five consecutive years (2018–2022) of landings and onboard monitoring, we gathered size data and vertebral samples to describe the species size composition in the region, as well as its seasonal and interannual variability and to update estimated life‐history parameters. The results showed that southern Brazil is mainly inhabited by large juvenile males that arrive during winter (July–September) and stay until spring (October–December), when their frequency decreases. Small adult males are present throughout the year but in higher frequencies during summer. A small number of adult females are present with higher frequencies during spring and summer, which decreases during the austral autumn and winter. Some variability in the presence of each life stage was observed among years. The estimated life‐history parameters were as follows: L∞: 255.02 cm fork length (FL), k: 0.20, L0:35.68 cm FL for males; L∞: 246.47 cm FL, k: 0.23, L0:36.77 cm FL for females; and L∞: 269.58 cm FL, k: 0.18, L0:36.19 cm FL for pooled sexes. However, the estimated values must be cautiously interpreted, as the obtained samples cannot be construed as representative of the entire harvested stock due to the lack of consistent presence of some life stages in the study region. [ABSTRACT FROM AUTHOR]

Knowledge of species distribution and, for migratory species, seasonal occurrence is particularly important for vulnerable and protected animals such as bats. The former European bat species Pipistrellus pipistrellus was split into two, Pipistrelus pipistrellus s.s. and Pipistrelus pygmaeus, over 20 years ago. However, their distribution, breeding and winter ranges as well as migratory status in Eastern Europe and the Caucasus remained obscure.In our study, we scrutinised records of both species and assessed the sex ratio during their breeding season in this region.We show that Pipistrellus pipistrellus s.s. has a significantly smaller range than previously assumed, being restricted to the southern part of the study area. On the contrary, Pipistrelus pygmaeus has a broader distribution, covering the Caucasus and Eastern Europe, up to ca. 59° N. Hence, all historical records and long‐distance movements of Pipistrellus pipistrellus sensu lato from Eastern Europe within the inferred allopatric occurrence of Pipistrelus pygmaeus should be attributed to Pipistrelus pygmaeus.The high portion of adult males in breeding localities, mass wintering within the breeding range and lacking evidence of long‐distance seasonal movements imply that Pipistrellus pipistrellus s.s. is a sedentary species. In Pipistrelus pygmaeus, the sex ratio among adults during the breeding season varies latitudinally. The female‐biased sex ratio, absence of mass wintering and the historical long‐distance recoveries of ringed individuals suggest that this species is migratory in Eastern Europe. The male‐biased sex ratio during the breeding season, along with late autumn records, suggests that the Caucasus represents its winter range. [ABSTRACT FROM AUTHOR]

The incidental capture (bycatch) of seabirds is a global conservation issue and a top threat to European species that demands urgent conservation and management action. Here, we present the first European review of seabird bycatch data, considering all fishing gears and data collection methods available in the region. We calculate seabird bycatch numbers per species, family, country and European marine region and assess the reliability of the data available. The cumulative bycatch estimate extracted from this review suggests that about 195,000 seabirds (ranging from around 130,000 to 380,000) are bycaught in European waters annually. The most affected seabird species is the Common Guillemot Uria aalge with over 31,000 birds killed per year. The marine region with the highest bycatch estimate is the Northeast Atlantic (over 115,000 seabirds year−1). Gillnet fisheries are responsible for the highest bycatch levels, with over 95,000 seabirds year−1, followed by longline fisheries. The families most affected by bycatch are Anatidae and Alcidae. These numbers are likely an underestimation since we were unable to find bycatch estimates, or to extrapolate estimates from available bycatch data for 12 (out of 34) European coastal states. Our assessment also identified significant data gaps in key areas such as Gran Sol (in the north‐east Atlantic), the central and Eastern Mediterranean and the Black Sea. Combining systematic data collection with immediate implementation of mitigation measures will be crucial to fill in knowledge gaps, reduce current mortality levels and meet international conservation commitments such as those of the European Union and the Convention on Migratory Species. [ABSTRACT FROM AUTHOR]

Marine heatwaves (MHWs) have measurable impacts on marine ecosystems and reliant fisheries and associated communities. However, how MHWs translate to changes in fishing opportunities and the displacement of fishing fleets remains poorly understood. Using fishing vessel tracking data from the automatic identification system (AIS), we developed vessel distribution models for two pelagic fisheries targeting highly migratory species, the U.S. Atlantic longline and Pacific troll fleets, to understand how MHW properties (intensity, size, and duration) influence core fishing grounds and fleet displacement. For both fleets, MHW size had the largest influence on fishing ground area with northern fishing grounds gaining and southern fishing grounds decreasing in area. However, fleet displacement in response to MHWs varied between coasts, as the Atlantic longline fleet displaced farther in southern regions whereas the most northern and southern regions of the Pacific troll fleet shifted farther. Characterizing fishing fleet responses to these anomalous conditions can help identify regional vulnerabilities under future extreme events and aid in supporting climate‐readiness and resilience in pelagic fisheries. [ABSTRACT FROM AUTHOR]

Migratory movement shapes infectious disease dynamics within migratory populations, but also impacts the disease dynamics of resident (non-migratory) species by transporting pathogens along migratory routes. Migratory animals often dominate local animal biomass and exert strong trophic effects on the resident species that they encounter. Many of these trophic effects could impact infectious disease transmission, yet very little is known about the role of migrant trophic effects in shaping resident disease dynamics. We propose mechanisms via which migrant trophic effects change the local infection risk for resident animals. We then describe a framework that captures the role of migration intensity and duration in modifying migrant transport and trophic effects that can be used to investigate the complex ecological interactions that determine resident parasite dynamics in nature. Migratory animals can bring parasites into resident animal (i.e., non-migratory) home ranges (transport effects) and exert trophic effects that either promote or reduce parasite exposure to resident hosts. Here, we examine the importance of these transport and trophic effects and their interactions for resident parasite dynamics. We propose that migrant transport and trophic effects are impacted by the number of migratory animals entering a resident's home range (migration intensity), the amount of time that migrants spend within a resident's home range (migration duration), and the timing of migrant–resident interactions. We then incorporate migration intensity, duration, and timing into a framework for exploring the net impact of migrant trophic and transport effects on resident animal parasite prevalence. [ABSTRACT FROM AUTHOR]

Alternative reproductive tactics enable individuals to choose a reproductive tactic relative to their status and prevailing environmental conditions in a way that increases their fitness. For example, females in many avian species show phenotypic plasticity and employ alternative reproductive tactics to cope with changes in predation risk and climate. Conspecific brood parasitism (CBP), in which females lay eggs in nests of conspecifics, is one example of such behaviour. It has been proposed that when prospects for successful nesting are low and/or costs of reproduction are high, females employ tactics of low effort such as non‐breeding and parasitic laying. When environmental conditions are ideal and prospects for success high, females can increase their reproductive effort above typical nesting by laying parasitic eggs prior to initiating their own nest. Here, I used this flexible life‐history strategy concept and long‐term (1994‒2022) population level data of the common goldeneye Bucephala clangula to study how the rate of parasitic laying varies in relation to variation in nest predation risk and in the timing and length of the breeding season, the latter being measured by the timing of ice breakup. Nest predation rate in the previous year and timing of ice breakup interactively affected parasitic laying, the rate of parasitic laying being particularly high in years with late ice breakup and high nest predation rate in the previous year. Furthermore, the proportion of predated eggs was lower in parasitized nests than in non‐parasitized nests, while the opposite was true for the proportion of eggs that failed in other way. As a consequence, the final number of young produced per nest was higher for parasitized nests. The findings of this study show that changes in environmental conditions affect the dynamics of alternative reproductive tactics in goldeneyes, with consequences to population level reproductive output. [ABSTRACT FROM AUTHOR]

Southern flounder are an iconic coastal finfish through the Southeast U.S. Atlantic and Gulf of Mexico. Southern flounder spend the early part of their lives in coastal and estuarine habitats, later moving offshore to spawn. Several decades of research have provided much clarity to the biology, life history, and aquaculture aspects of southern flounder—this information is summarized and reviewed in this study. Despite substantial improvement in understanding the species, major questions remain about their recruitment, offshore behaviors, captive rearing, and management. Recently, southern flounder have also been in focus because of substantial synchronous population declines throughout their range with specific concerns that recruitment failure and possibly climate change may be implicated. Management of southern flounder has thus far taken place within individual states, but coming into focus is the possibility that larger coastwide management approaches may need to be considered due to both the migratory nature of the species and the possibility of population stressors acting at regional scales. Many states have already begun aquaculture and enhancement efforts, with an eye toward supplementing wild populations. Large group efforts, like the symposium that led to this study, will likely be needed to tackle the complex challenges confronting southern flounder. [ABSTRACT FROM AUTHOR]

Biodiversity intactness index (BII) was applied to monitor the deuteriation of diversity status of East Hammar marsh (EHM). Proposed bench mark list of 30 fish species existed in EHM after inundation in 2003 was initiated. Number of fish species recorded by previous authors varied between 22 to 44. In total, 35 non-native out of 52 total fish species recorded in EHM represent 67.1% of fish assemblage. Values of Shannon and wiener biodiversity index fluctuated between 1.89 & 2.9 and were positively related to an increase in salinity of EHM. As result of the increased salinity in EHM, a rise was detected in migratory marine species and an absence of freshwater native ones. Salinity fluctuation plays a major role in altering the composition of fish assemblage in EHM.The highest BII value observed at EHM was 103.57, and the lowest score was 52.07. The highest salinity value recorded was 16.1psu in EHM in August 2018. Salinity fluctuations in EHM play a major role in increasing or decreasing BII values through migration or immigration of marine fish species to or from the marsh to the Shatt al-Arab estuary. Consequently, an opposite relationship existed between BII values and marsh salinity. The fluctuation of freshwater discharge from the Shatt al-Arab River plays a major role in salinity changes in EHM. An indirect relation exists between the BII of EHM and discharge of the Shatt al-Arab River. Nonnative species tend to increase diversity value accompanied with an increase in the number of marine species. Negative relation existed between BII values and non-native species ratio in EHM. Establishing baseline BII data for fish assemblages in EHM is a vital step to create an intact reference mark. [ABSTRACT FROM AUTHOR]

Despite the benefits that can come from coordinated movement, many diadromous fishes have evolved partial migration strategies, where a portion of a population does not migrate. Co‐occurring life‐history variants might nonetheless gain some advantage by exhibiting congruent phenologies, with key events timed to follow the same cue. Here, we assess this possibility by examining otolith microchemistry and structure to quantify the lunar periodicity of hatching and metamorphosis according to migration strategy in a facultative amphidromous goby endemic to Hawai'i. Our analyses corroborated prior evidence that Awaous stamineus exhibits partial migration and that residential A. stamineus are often proportionately more abundant than the migratory form. Contrary to expectation, we found a significant difference in hatching time between migratory and residential A. stamineus. A higher proportion of A. stamineus migrants hatched at the full moon and metamorphosed at the new moon, whereas residents exhibited the opposite phenology. Comparisons to Sicyopterus stimpsoni intended to provide a broader context revealed that the obligately amphidromous species tends to hatch at the new moon and metamorphose at the full moon, mirroring the phenology of residential A. stamineus. Evidence of convergent lunar phenologies suggests that synchronising life‐history events can confer benefits that extend beyond species boundaries. Notably, phenological discordance could be acting as a prezygotic isolating barrier between sympatric life‐history variants, pointing to the presence of heretofore unrecognised evolutionary diversity within partially migratory species like A. stamineus. [ABSTRACT FROM AUTHOR]

The use of barriers in freshwater systems to mitigate invasions, known as isolation management, has been increasingly implemented as a protection strategy for native fish. Barriers are crucial for securing vulnerable populations, but much remains to be learnt about the drivers of success and the implications of deliberate fragmentation.In Aotearoa‐New Zealand, henceforth Aotearoa, native non‐migratory galaxiid (NMG) fishes are characterized by a disproportionate number of threatened species with introduced salmonids (trout) identified as a key driver of NMG declines.We conducted a qualitative review of barriers protecting NMG in Aotearoa, illustrating varying outcomes and current knowledge gaps with case studies. Barrier types ranged from natural bedrock waterfalls, shallow velocity chutes and drying reaches to deliberately engineered structures (known commonly as exclusion barriers). Barriers were typically located in headwater streams or spring systems. NMG species secured by fragmentation often have high conservation value and barriers are essential for their protection.Despite the critical role of these barriers, the isolated NMG populations above them are at risk of stochastic extirpation, invasion, or re‐invasion. Exclusion barriers may restrict access to habitat for native migratory fish species and can sometimes alter or remove ideal mesohabitat from protected populations.Overall, when using exclusion barriers, managers must assess extinction risk for individual populations by isolation or invasion, balancing benefits and consequences. However, these assessments are frequently based on incomplete data and hindered by lack of general understanding of the underpinning processes. Despite well‐documented benefits to NMG population survival, key knowledge gaps such as long‐term viability of isolated populations, combinations of physical barrier parameters conferring exclusion under all flow regimes and extent of habitat loss to other native species still exist. [ABSTRACT FROM AUTHOR]

As seasonal migratory animals, reindeer inhabit the natural habitats in Arctic regions and have evolved their hindlimb joints to adapt to the complex ground conditions there. Inverse dynamics of the joints is an important tool to study foot functions. Herein, with a motion tracking system and plantar pressure data based on kinematics and inverse dynamics of hindlimbs, we investigated the changes in joint angles, net joint moments, net joint powers, and work of reindeer at different speeds. Reindeer may adopt different movement patterns to efficiently utilize energy and adapt to the demands of different gaits and speeds. The joint ranges of motion (ROM) of the ankle joint (αb), metatarsophalangeal (MTP) joint (αc), and interphalangeal joint (αd) of the hindlimbs were about 20.73°–28.87°, 40.37°–47.69°, and 24.47°–26.18°, respectively. The ankle joint produced positive work to provide propulsion. The positive work done at the ankle joint during walking, slow trotting, and fast trotting was 8.61 × 10–2, 9.25 × 10–2, and 15.44 × 10–2 J·kg−1, respectively. The MTP and interphalangeal joints both absorbed energy during walking, slow trotting, and fast trotting. The energy absorption at the respective speeds was 12.53 × 10–2, 13.57 × 10–2, and 19.90 × 10–2 J·kg−1, respectively, by the MTP joint and was 9.49 × 10–2, 7.71 × 10–2, and 10.26 × 10–2 J·kg−1, respectively, by the interphalangeal joint. The MTP joint and interphalangeal joint of the hindlimbs serve as the primary sites for energy storage and release, functioning as an elastic system. This study contributes to a deeper understanding about the biomechanical properties of hindlimb joints and provides a theoretical basis for designing extremity robots in extreme environments through analyzing the functional characteristics of reindeer foot joints. [ABSTRACT FROM AUTHOR]

Populations of long-distance migratory species may exhibit dissimilarities in the leeway of scheduled annual migration programs, the routes they follow and their convergence at ecological barriers. The aim of this study was to fill the current geographical gap, spanning over 1,100 km longitudinally between southern France and eastern Austria, in the pan-European assessment of the migration ecology of the European Roller Coracias garrulus, and contribute to completing the puzzle of spatio-temporal patterns of migration, stopover and wintering at the Western-Palearctic scale for this species. We utilized high-resolution GPS tracking data from adult Rollers breeding in Italy and Croatia, tracked on their intercontinental seasonal journeys between 2018 and 2022 and modelled the variation of migratory components both at individual and population levels. Rollers from the Central Mediterranean exhibited a clockwise spring migration loop, following a Central African migration route and wintering across a wide longitudinal belt spanning from Namibia to Mozambique. Northern savannah zones were used as long stopovers, both in autumn (Chad/Sudan) and spring (Central African Republic/Cameroon). The probability of movement was significantly higher during the night and in spring. Migration speed varied according to season (> in spring) and the habitat crossed (sea > desert > rainforest > savannah). Individuals tracked in successive years showed high consistency of key migratory parameters and partial winter home ranges overlap, in contrast with the large variability of migratory parameters at the population level. This work bridges the current geographical gap of Roller migration ecology at the European level and helps meet conservation needs at the scale of the species' flyway, with new ecological information valuable for the implementation of International Single Species Action Plans (ISSAP) dedicated to the Roller. Significance statement: Tracking studies help to disentangle intraspecific variation in migratory strategies and wintering destinations among populations, as well as investigate individual-level decisions taken en route across seasonal journeys. By GPS tracking the intercontinental migration of adult Rollers we found that spatio-temporal components of migratory and flight strategy largely depend on extrinsic factors such as daytime, season and the habitat they traversed, and vary at population level. In contrast, within-individual consistency in migratory and wintering patterns emerged across years. Our findings emphasize the need for effective conservation strategies at the flyway scale. [ABSTRACT FROM AUTHOR]

In spring, many migrating songbirds exhibit protandry (the phenomenon whereby males precede females in arrival at breeding sites). The reed bunting (Emberiza schoeniclus) is a short-distance European migrant which expresses a high degree of protandry and combines both nocturnal and diurnal movements during migrations. In experimental conditions, we studied the proximate mechanisms of protandry and compared locomotor behavior between spring and autumn migrations. We assumed that captive behavior is a proxy for the behavior that birds demonstrate in the wild. Combined, the analysis of seasonal patterns and circadian dynamics of locomotor activity suggested that male reed buntings depart from wintering grounds by daytime flights approximately two weeks earlier than females. Later, they develop nocturnal activity, take off shortly before dawn and continue their flight for several hours in the morning. We argue that such behavior allows males to benefit from both the advantage of nocturnal flight and an efficient start of foraging, thereby reducing the stopover duration (by minimizing search/settling costs) and increasing the total migration speed. In contrast, females express predominantly nocturnal migratory activity in spring. We observed that in spring males had lower fat reserves compared to females. We suggest that males can forage during diurnal movements and therefore do not need to store large energetic reserves. In contrast, in autumn, both sexes display similar patterns of locomotor activity and fat reserves. Overall, our results describe unique sex-specific migratory behaviour and physiology in reed buntings in spring, which, we assume, contribute to spring arrival protandry in this species. Significance statement: To reach their destinations, migratory bird species adopt specific strategies reflected in behavior and/or physiology. In many species, males arrive earlier to the breeding grounds (a phenomenon called protandry). Knowledge of migratory strategies in species that experience both nocturnal and diurnal flights is scarce. To study the mechanisms that lead to protandry in nocturnal/diurnal migrant, we kept reed buntings (Emberiza schoeniclus) under experimental conditions that mimicked changes in photoperiod experienced by free-living birds from autumn migration through wintering to spring migration and recorded the dynamics of their locomotor activity and fat reserves. In spring, we observed sex differences in the seasonal patterns and circadian dynamics of locomotor activity and in the levels of fat reserves. We argue that such sex-related variation in behavior and physiology likely serves as proximate mechanisms for spring arrival protandry in reed buntings. [ABSTRACT FROM AUTHOR]

Social information is predicted to enhance the quality of animals' migratory decisions in dynamic ecosystems, but the relative benefits of social information in the long-range movements of marine megafauna are unknown. In particular, whether and how migrants use nonlocal information gained through social communication at the large spatial scale of oceanic ecosystems remains unclear. Here we test hypotheses about the cues underlying timing of blue whales' breeding migration in the Northeast Pacific via individual-based models parameterized by empirical behavioral data. Comparing emergent patterns from individual-based models to individual and population-level empirical metrics of migration timing, we find that individual whales likely rely on both personal and social sources of information about forage availability in deciding when to depart from their vast and dynamic foraging habitat and initiate breeding migration. Empirical patterns of migratory phenology can only be reproduced by models in which individuals use long-distance social information about conspecifics' behavioral state, which is known to be encoded in the patterning of their widely propagating songs. Further, social communication improves pre-migration seasonal foraging performance by over 60% relative to asocial movement mechanisms. Our results suggest that long-range communication enhances the perceptual ranges of migrating whales beyond that of any individual, resulting in increased foraging performance and more collective migration timing. These findings indicate the value of nonlocal social information in an oceanic migrant and suggest the importance of long-distance acoustic communication in the collective migration of wide-ranging marine megafauna. [ABSTRACT FROM AUTHOR]

Simple Summary: Feathers are essential for a bird's flight, insulation, communication, and camouflage. They degrade over time, so birds must moult regularly. This study examined how avian haemosporidian infection and the size of the uropygial gland affect feather quality and growth rate in two migratory bird species in southwestern Spain—the house martin (Delichon urbicum) and the sand martin (Riparia riparia). We found that house martins had the highest haemosporidian infection rates, likely due to their large colony size. Infection only decreased feather quality in house martins and did not affect the feather growth rate in any of the two hirundinids. Additionally, feather growth rate was positively linked to feather quality, but only in house martins. Finally, we found no connection between the uropygial gland size and feather quality or feather growth rate. These results show, for the first time, that avian haemosporidian parasites can negatively impact the feather quality of migratory birds, thus potentially affecting their flight and survival. Further research is needed to fully understand these relationships. Bird feathers have several functions, including flight, insulation, communication, and camouflage. Since feathers degrade over time, birds need to moult regularly to maintain these functions. However, environmental factors like food scarcity, stress, and parasite infections can affect feather quality and moult speed. This study examined the impact of avian haemosporidian infection and uropygial gland volume, as well as feather quality and feather growth rate in two migratory hirundine species captured in southwestern Spain—the house martin (Delichon urbicum) and sand martin (Riparia riparia). Our findings showed that the prevalence of infection varied among species, with house martins having the highest rates, possibly due to their larger colony size. Moreover, haemosporidian infection had a different impact on each species; infected house martins exhibited lower feather quality than healthy individuals, although this outcome was not observed in sand martins. Furthermore, no effect of infection on feather growth rate was observed in both hirundinids. Additionally, feather growth rate only correlated positively with feather quality in house martins. Finally, no link was observed between uropygial gland volume and feather quality or feather growth rate in any of the species in this study. These findings highlight the effect of haemosporidian infections on the plumage of migratory birds, marking, for the first time, how avian haemosporidian infection is shown to adversely impact feather quality. Even so, further research is needed to explore these relationships more deeply. [ABSTRACT FROM AUTHOR]

Simple Summary: We conducted the first extensive review of shorebird species in Mongolia, examining their ecological status, population trends, threats, and conservation efforts. Mongolia is home to 62 shorebird species, including 6 globally threatened ones like the Sociable Lapwing and Siberian Sandplover. The country plays a crucial role in the breeding and migration of these birds, especially those at risk. While northern regions boast higher species diversity, threats like habitat loss and pollution endanger many species. Despite these challenges, Mongolia has general conservation measures in place and participates in international conventions. However, specific conservation plans for shorebirds are lacking, highlighting the need for more targeted efforts to protect these vulnerable species. We present the first comprehensive review of 62 migratory shorebird species in Mongolia, covering their ecological status, IUCN assessments at regional or national levels, population trends, threats, and conservation measures. Mongolia hosts a total of 62 shorebird species from twenty-two genera and seven families, with six species classified as globally threatened: the Critically Endangered Sociable Lapwing, the Endangered Siberian Sandplover, the Far Eastern Curlew, the Great Knot, and the Vulnerable Sharp-Tailed Sandpiper. Both national and global IUCN Red List assessments highlight Mongolia's significance as a breeding and passage migrating site for globally threatened and Near-Threatened shorebirds. Species richness is higher in northern regions compared to the south, with the highest diversity found in areas with complex aquatic ecosystems. Global population trends indicate a decline in 61% of species, with 18% remaining stable, 16% of unknown status, and 5% increasing. At the national level, most species are stable (61%), 34% status is unknown, and 5% are decreasing. Anthropogenic-induced threats, including habitat loss and degradation, pollution, disturbance, and harvesting, pose significant risks to 69% of species, while natural disasters affect 11%. Additionally, 8% of species are impacted by accidental mortality and intrinsic factors, and 5% by changes in native species. Despite these threats, no specific conservation action plans exist for shorebirds in Mongolia. However, general conservation measures are in place, such as environmental and fauna protection laws, regulations on foreign trade in endangered species, and the establishment of protected areas under governmental resolutions. Mongolia also participates in international conventions like the Convention on Biological Diversity (CBD), Ramsar, and Migratory Species (CMS), and has developed national red lists, red books, and publications such as "A Summary Conservation Action Plan for Mongolian Birds", "Important Bird Areas" to support conservation efforts. [ABSTRACT FROM AUTHOR]

The accelerated pace of climate-driven shifts is surpassing the temporal scope of conventional field research, potentially leading to a disconnect between ecosystem changes and scientific data collection. Climate change is producing rapid transformations within dynamic marine ecosystems, with a pronounced effect on high trophic-level species such as loggerhead sea turtles (Caretta caretta). We present a new model for data collection using ethnobiological methods, emphasizing how local community members can contribute to expanding scientific knowledge via context-informed observations, to document species occurrences beyond their anticipated habitats during climatic anomalies. In rapidly changing conditions, local expert knowledge can complement conventional scientific methods, providing high-quality data with extensive coverage--especially for elusive species--and yielding insight into potential emerging phenomena that may otherwise go unnoticed. Conventional methods for predicting distribution shifts in rare species are vulnerable to spatial biases, favoring predictions based on the most probable habitats. We present the case study of a live sea turtle sighting by a local expert in Monterey Bay, California, USA, identified post hoc as a loggerhead, to illustrate methods which can be transferred and applied to other rare and highly migratory marine species such as marine mammals, sharks, and seabirds. This emerging framework incorporates diverse knowledge sources and methodologies in monitoring climate-driven ecological shifts, enriching conservation strategies, enhancing our understanding of complex ecosystems, and contributing to robust evidentiary standards for rare species observations. [ABSTRACT FROM AUTHOR]

We evaluated the impact of a philanthropic program investing in the conservation of sites along the Pacific Americas Flyway, which spans >16,000 km of coastline and is used by millions of shorebirds. Using a quasi‐experimental, mixed methods approach, we estimated what would have happened to shorebird populations at 17 wintering sites without the sustained and additional investment they received. We modeled shorebird populations across the entire flyway and at sites with and without investment. Combining shorebird abundance estimates with a land‐cover classification model, we used the synthetic control method to create counterfactuals for shorebird trends at the treatment sites. We found no evidence of an overall effect across three outcome variables. Species‐ and site‐level treatment effects were heterogeneous, with a few cases showing evidence of a positive effect, including a site with a high level of overall investment. Results suggest six shorebirds declined across the entire flyway, including at many Latin American sites. However, the percentage of flyway populations present at the sites remained stable, and the percentage at the treatment sites was higher (i.e., investment sites) than at control sites. Multiple mechanisms behind our results are possible, including that investments have yet to mitigate impacts and negative impacts at other sites are driving declines at the treatment sites. A limitation of our evaluation is the sole focus on shorebird abundance and the lack of data that prohibits the inclusion of other outcome variables. Monitoring infrastructure is now in place to design a more robust and a priori shorebird evaluation framework across the entire flyway. With this framework, it will prove easier to prioritize limited dollars to result in the most positive conservation outcomes. [ABSTRACT FROM AUTHOR]

Many threatened species require ongoing management, which is often funded through short project cycles. Evaluating whether the management is effective in protecting a species is important to inform future management investments. For migratory species, management may affect only part of a species' annual cycle, and reversing a population decline is challenging to achieve and demonstrate. Here, we evaluate whether conservation management projects funded by the European LIFE programme to safeguard a migratory vulture population achieved their major objective of stabilizing the target breeding population. Between 2012 and 2022, an international alliance of conservation organizations implemented multiple actions to reduce poisoning, direct persecution, and electrocution and collision with power lines along the Eastern Mediterranean flyway. We monitored breeding territories of the Balkan population of the globally endangered Egyptian Vulture Neophron percnopterus between 2006 and 2022, and tracked 60 young birds with GPS transmitters since 2010. We used these data to examine whether population growth rate and survival probability had increased since project implementation. The mean annual survival probability of adult territorial birds increased by 1.9% since 2014 from 0.937 to 0.955, and the monthly survival probability of wild juvenile birds increased by 9.7% from 0.833 to 0.914 since 2018. The population growth rate across the Balkans increased by 6.9% from 0.939 before 2018 to 1.005 since 2018. This indicates that the Egyptian Vulture population has remained stable for the past 5 years (2018–2022), but at a population size that is only half (105 adult territorial birds in 2022) than at the beginning of the time series (204 in 2006). We caution that ongoing management along the flyway and reinforcement are required to ensure that the Egyptian Vulture population on the Balkans can recover, but we show that flyway‐scale collaboration of direct conservation actions can have lasting benefits for migratory species. [ABSTRACT FROM AUTHOR]

The effects of recent climate change on the phenology of avian breeding and migration, geographical range shifts, and decreasing migration distances are well documented. Only a few studies have focused on the long-term influence of these changes on the body condition of migrants, which is important as it is likely to affect the fitness of the whole population. Eurasian blackcaps have adapted their migratory behaviour to changing ecological factors. These changes seem to favour the species and its migratory populations have increased over the last decades in Europe. In the present study, we analysed the body condition index of juvenile blackcaps at their stop-over site in the southern Baltic region during autumn migration from 1967 to 2006. This index was distinctly higher since the 1990s than in the middle of the 1960s, when the number of migrating blackcaps was at least twofold lower. Moreover, there was a reduction in recapture rates of blackcaps from 14% to 6% during these periods which may imply that warblers were staying for a shorter time at the stop-over site as their body condition was higher. We hypothesized that higher berry crop availability resulted in the higher condition of migrating blackcaps. Body condition index also reflecting fuel load in migrants was higher in long-distance blackcaps compared to the short-distance ones. As the former are time-minimizing migrants, their higher body condition/fuel load may allow them to migrate faster to wintering grounds in sub-Saharan Africa. [ABSTRACT FROM AUTHOR]

Simple Summary: Understanding avian migratory routes is crucial for identifying important stopover sites during migration and for implementing targeted conservation efforts at these key locations. The Black-faced Spoonbill (Platalea minor) is a Class I protected species in China; however, research on it has been extremely limited to date. This study reconstructs the population-level migratory trajectories of the Black-faced Spoonbill based on citizen science data. The results indicate that Wenzhou, Xiamen, Shantou, Shanwei, Hsinchu, Chiayi, and Tainan are significant stopovers for this species. There are multiple migratory pathways for the Black-faced Spoonbill across the southeastern coastal region of China. This study also validates the application of citizen science data in restoring species migration trajectories. The findings enhance our understanding of the migratory patterns of the Black-faced Spoonbill and provide valuable insights for its conservation. Migration is a critical ecological process for birds. Understanding avian migratory routes is essential for identifying important stopover sites and key foraging areas to ensure high-quality stopovers for birds. The Black-faced Spoonbill (Platalea minor), a national Grade I protected wild animal in China, is classified as endangered on the IUCN Red List of Threatened Species. Studying the migratory routes of the Black-faced Spoonbill and identifying critical stopover sites across different life histories is vital for its conservation. However, research on the migratory routes of this species has been very limited. This study, utilizing citizen science data and the Level-order-Minimum-cost-Traversal (LoMcT) algorithm, reconstructs the migratory trajectories of the Black-faced Spoonbill from 2018 to 2022. The results show that Wenzhou, Xiamen, Shantou, Shanwei, Hsinchu, Chiayi, and Tainan are significant stopovers for this species. The Black-faced Spoonbill is actively migratory during the migration season across the southeastern coastal region of China. The simulation results of this study reveal the migratory routes and activity patterns of the Black-faced Spoonbill, providing critical support for its conservation. [ABSTRACT FROM AUTHOR]

This investigation holds significant merit due to its execution within a region characterized by depauperate avifaunal assemblages in the Western Desert of Egypt. Notably, the study highlights the presence of wild bird populations within petroleum industry worker camps situated in the Marsa Matrouh Governorate. The results show that the bird community recorded in the study area was rich in bird species and numerous (8425 individuals), these birds belonged to 16 species, grouped in 16 families and 6 orders. The dominant bird species were western yellow wagtail, house sparrow, rock pigeon, hooded crow, red-backed shrike and Eurasian collared dove. The highest number of bird species was recorded during autumn and then winter season according to the existence of migratory bird species, while the lowest was recorded during spring due to the return of migratory species and bird dispersal for nesting. The bird's members for the order Passeriformes were the most existence than other different orders according to its global distribution, followed by the order Columbiformes in the second rank, then Pterocliformes, Ciconiiformes, Bucerotiformes and finally Falconiformes. Autumn season led the other seasons with its highest value for bird richness and Shannon-Wiener diversity index, followed by winter for species richness and spring for Shannon-Wiener diversity index. Spring recorded the lowest value of species richness and summer recorded the lowest value for both Shannon-Wiener diversity index & species evenness. [ABSTRACT FROM AUTHOR]

Understanding of a migratory bird species' movements and winter fidelity provides insights to various population and genetic parameters that may support conservation efforts. Trumpeter Swans (Cygnus buccinator) were reintroduced into the Nebraska Sandhills beginning in the 1960s but knowledge of the ecology of these birds is limited. We examined the winter movements, home range, and fidelity of swans in the Nebraska Sandhills, 2014–2020. We captured and fitted solar-powered GPS transmitters via neck collars to swans during the summer molting period. We used movement patterns and weather data to define timing of transitions from breeding and post-breeding areas to wintering areas. The research findings showed that only one swan made a long-distance movement out of Nebraska during the winter. Mean distance (±SD) moved from breeding or post-breeding areas to their initial wintering complex was 53.4 (±52.7) km. Swans spent most (77.2%) of their time on one wintering complex and 75% of their time at one wintering site. Swans used an average of 2.7 different wintering complexes and moved among complexes 6.4 (±3.6) times. Swans in our sample used an average of 1.5 wintering sites within complexes and moved 3.1 (±3.6) times among wintering sites. Swan fidelity (proportion returning) to wintering complexes was 0.72 and to wintering sites was 0.69. Return rate to their primary wintering complex and site was 100%. Fidelity rates to wintering complexes of swans with cygnets at time of capture and those without were 0.79 and 0.55, respectively. Swan movements in the Nebraska Sandhills indicate that they are willing to move among areas but tend to show fidelity to wintering areas. Changes in wintering habitat may alter patterns of fidelity, but swans may be able to adapt and move to alternative areas. Rivers, creeks, and other areas are important to wintering swans breeding in the Nebraska Sandhills and contribute to the sustainable conservation of swans. [ABSTRACT FROM AUTHOR]

Objective: Understanding the spatial connectivity of elasmobranch populations is critical for regional fisheries management. The Blacktip Shark Carcharhinus limbatus is abundant in coastal waters of the Gulf of Mexico (GoM) and important in recreational and commercial fisheries. Based on genetic and tagging studies, GoM Blacktip Sharks are currently managed under separate quotas between the eastern and western GoM (divided at 88°W), but no studies have used vertebral chemistry to assess the population structure of adult Blacktip Sharks. Methods: We compared vertebral elemental signatures (barium [Ba], magnesium [Mg], manganese [Mn], strontium [Sr], and zinc [Zn]) for the first year of life with last occupied habitats (vertebral edges) in Blacktip Sharks collected from the western (Texas and Louisiana) and eastern (Alabama and Florida) coastal waters of the northern GoM. Result: We found significant regional differences in Ba, Mg, Mn, and Sr vertebral edge signatures, suggesting ecological separation of Blacktip Sharks. Significant correlation between first‐year and edge signatures suggested a high degree of residency between life stages. Cross‐validated discriminant function analyses yielded highest regional classification accuracies when Florida sharks were grouped separately west of 88°W (90%), demonstrating the unique elemental signatures of eastern versus western GoM Blacktip Sharks under current management delineations. Conclusion: Combined, these findings demonstrate that trace element markers can distinguish regional populations of Blacktip Sharks and provide a complimentary approach in addition to genetics and physical tagging to support current stock management efforts. Impact statementStocks of Blacktip Sharks are managed under separate quotas in the eastern and western Gulf of Mexico. In this study, elemental signatures in mineralized vertebral cartilage of Blacktip Sharks confirm ecological population separation. Natural chemical tags in shark vertebrae offer an additional tool to characterize population connectivity and stock delineation for highly migratory shark species. [ABSTRACT FROM AUTHOR]

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Urbanization involves changes in landscape terrain, hydrology, and vegetation. These changes allow some wildlife species to thrive in cities while inhibiting others. We analyzed how an urbanization gradient (i.e., percentage of impervious surface) in Xalapa, Mexico, affects raptors habitat associations and at what percentage of impervious surface these effects are the most pronounced. We also characterized the spatial distribution of species along this gradient and quantified seasonal effects. We conducted intensive area searches along an urban-to-conserved gradient inside 20, 500-m radius circular plots. Through direct observations and call-broadcast surveys, we estimated relative abundance, richness, and Shannon diversity index of diurnal and nocturnal raptors. From June 2019–February 2020, we visited each site during three seasons (breeding, fall migration, and winter), during two daily cycle periods, from 07:00–12:00 h and 19:00–00:00 h. We obtained 201 individual records of 14 species. Species abundance ranged from 1–45 individuals from 1–10 species (gradient richness), and the Shannon diversity index varied from 1–7.02 along the urban gradient. As expected, better conserved sites along the gradient held the highest diversity. Our results indicate that the transition from the intermediate to the most urbanized sites (> 70% impervious surface) is where the most abrupt filtering occurs, and we observed only four species in the most urbanized areas. According to Detrended Correspondence Analyses and two-way PERMANOVAs, the spatial distribution of the raptor community in Xalapa is significantly affected by the degree of urbanization, with some resident species using urban areas and migratory species using the intermediate and conserved areas. Our findings expand our understanding on how urbanization influences raptor communities in Neotropical cities. However, more research is needed to determine how urbanization filters raptor assemblages in cities worldwide. [ABSTRACT FROM AUTHOR]

The diel vertical migration of mesopelagic fishes in the southern (S-May station and S-Nov station) and central (C-Jun station and C-Dec station) South China Sea was investigated through a series of continuous field surveys conducted in May, June, November, and December 2017. These surveys employed a combination of mid-water trawl and acoustics techniques. The diel migration process, vertical distribution, acoustic migration proportion, and migration pattern of mesopelagic fishes were analyzed. The results revealed that mesopelagic fishes initiated an upward migration before sunset, with the process concluding within 30–120 min after dark. Subsequently, they commenced a downward migration before dawn, which terminated within 10–50 min after sunrise. The mesopelagic deep-sea layers of mesopelagic fishes at the S-May, S-Nov, C-Jun, and C-Dec stations ranged from 360 to 700 m, 350 to 680 m, 350 to 520 m, and 300 to 700 m, respectively. The acoustic migration proportions of mesopelagic fishes at the corresponding stations were found to be approximately 44.5%, 25.7%, 29.8%, and 58.0%, respectively. There were seasonal and regional differences in the vertical migration and distribution patterns of mesopelagic fishes in the South China Sea. A total of 228 species were identified, including 203 fish species, 23 cephalopod species, and 2 shark species. Among these, a subset of 43 fish and cephalopod species exhibited extensive diel vertical migrating behavior. Specifically, this subset comprised 23 lanternfish species, 8 cephalopod species, and 12 other fish species. Lanternfishes were the predominant diel vertical migratory species, while cephalopods also played a significant role in diel vertical migration. The diel migration behavior was found to be slight for Diaphus lucidus, Melamphaes microps, Argyropelecus affinis, and six other fish species. Non-migratory behavior was observed in Sternoptyx obscura, Argyropelecus sladeni, Sternoptyx diaphana, and 13 other fish species. The diel migration habits of 178 additional species of fish, cephalopods, and sharks could not be definitively determined. [ABSTRACT FROM AUTHOR]

Migration is a life-history trait that shapes individual-by-environment interactions, affecting fitness. Currently, many species are changing their migration strategies, stressing the need to identify and better understand the behavioral correlates of migration. As a partial migrant, the noctule bat, Nyctalus noctula, allows for rare intra-specific investigations of the potential behavioral causes (or consequences) of variation in migration. Here, we combined in-situ behavioral assays with stable isotope analyses to investigate whether spatial and acoustic responses to a roost-like novel environment correlate with migration strategy (local or distant). Given a migrant's more frequent exposure to novel environments, we predicted migrants would enter a novel environment more quickly and show stronger spatial and acoustic exploration activity. However, individuals of local and distant origin did not differ in acoustic exploration (call activity per unit space), nor, contrasting to several bird studies, in spatial activity (number of chambers visited). Surprisingly, local individuals were more likely than migrants to enter the novel environment. Our findings suggest that small-scale exploration does not vary with migration, potentially because of similar selection pressures across migration strategies on small-scale exploration (e.g., exploration of roosts) as opposed to large-scale. Yet, our findings on the likelihood of entering a novel environment suggest that locals may be more risk-taking. Repeated measures would be necessary to determine if personality differences are underlying these responses. Our unique approach, combining behavioral assays with isotopic geolocation, gave us novel insight into an elusive taxon, highlighting the importance of studying behavioral correlates of migration across various taxa. Significance Statement: The decision to migrate impacts both individual fitness and ecosystem connectivity, yet we know very little about the behavioral correlates of migration strategies. Studying such correlates is the first step to identifying the behavioral causes and consequences of migration. Here, we took advantage of a partially migratory species, the common noctule bat, and a unique measure of acoustic exploration, to test potential correlations between migration strategy and small-scale emergence and exploration. We found local individuals more likely to enter a novel environment than migrants and that migration strategy did not predict acoustic exploration. This is the first study examining novel environment responses and migration in bats and reveals contrasting behavioral correlates of migration compared to other taxa. Our research, therefore, highlights the importance of including more non-model species in the study of the causes and consequences of animal migration. [ABSTRACT FROM AUTHOR]

The Korean Demilitarized Zone (DMZ) is one of the world's most preserved habitats for wild animals and migratory birds. The area also plays a major role in the spread of infectious animal diseases, in particular, African swine fever (ASF) and highly pathogenic avian influenza (HPAI). These outbreaks threaten the livelihood of local livestock farms, not infrequently. In this paper, we explore these relatively under-researched diseases by modeling and mapping ASF and HPAI risks in tandem using MaxEnt, a machine-learning algorithm. The results show robust predictive power with high area under the curve values, of 0.92 and 0.99, respectively. We found that precipitation from spring to early summer and solar radiation in winter were essential in explaining the potential distribution of ASF, but land use contributed little. Thus, understanding only wild boars' habitat preferences may not be sufficient in preventing ASF epidemics. HPAI risks were shaped by precipitation and mean temperature from winter to spring and land use. Areas with high ASF and HPAI risks were primarily found in forest and agricultural lands, respectively. The DMZ included many high-risk areas, indicating that the DMZ could lead to a broader regional spread of ASF and HPAI in the peninsula. Thus, our results highlight the essential role of cross-border collaboration and the combination of environmental and epidemiological insights in strategies to control ASF and HPAI risks within and surrounding the DMZ. [ABSTRACT FROM AUTHOR]

Tidal flats provide critical habitat for migratory waterbird species; however, populations of migratory waterbirds have significantly declined due to tidal flat loss and degradation caused by human activities, particularly in Asia. Gochang getbol is one of tidal flats located on the southwest coast of South Korea and a center of clam production. Using bird monitoring data collected at five zones (zone1 to zone5) established across Gochang getbol and near coastal area, we examined distribution patterns of migratory bird diversity and conservation-related species along the coast of Gochang getbol. The intensity of human activity ‒ mudflat culture (mostly bivalve) and aquaculture was relatively high at zone2 and zone3, occupying > 30% of 2km circular area surrounding most sample points of these zones. Zone1 and particularly zone4 contained more natural/semi-natural habitats (less disturbed mudflats and wetlands) and zone5 had smallest mudflat than others. Shannon diversity, species richness, and abundance of migratory birds differed between zones (Anova test, P ≤ 0.02) except Shannon diversity in winter. In fall, all values were higher at zone4 than zone3 and zone5. In winter, zone1 showed greatest species richness and higher abundance than zone2, zone3, and zone5. In spring, while most differences were found between zone4 and zone5, abundance at zone4 was somewhat higher than zone2. The results from the fourth corner analysis indicated that abundance of species foraging at mudflat level was positively associated with zone1 (winter) but negatively with zone3 (fall). Sandpipers were positively associated with zone4. Abundance distribution maps of conservation-related species, created by inverse distance-weighted interpolation modeling, also showed high abundance of most conservation-related species at zone4 and 1. The findings of our study suggest the importance of natural/semi-natural habitat, and the possible link between human activity and distribution patterns of migratory birds in Gochang getbol. While we need further investigation on direct response of migratory birds to human activity, areas with low human activity with more natural/semi-natural habitat, e.g., zone4 and zone1 may be crucial for the conservation of migratory birds. [ABSTRACT FROM AUTHOR]