Long-distance Migration Research Articles

‘Away From Home’ - A Systematic Literature Review of the Factors and Challenges of Women Migration

Feminization of Migration refers to the increasing participation of women in long-distance migration, a trend driven by the evolving gender dynamics in the workforce. This shift is characterized by the engagement of women in occupations traditionally perceived as feminine, demanding the presence of women in these sectors. Consequently, the concept of the "Feminization of Migration" has prompted a gender-focused perspective on migration, redirecting attention towards the rights and interests of women within migration streams. Global patterns of women's migration have undergone a transformation, moving beyond the traditional role of women migrating as dependents with their families. Instead, there is a notable trend of women migrating independently, driven by economic motives and assuming the role of primary breadwinners for their families. This shift has not only altered the landscape of migration but has also amplified the presence of women in migration literature and practical policies designed with a gender-responsive approach. In light of these developments, this paper aims to conduct a systematic literature review that explores the factors and challenges associated with women's migration.

Migratory birds are able to choose the appropriate migratory direction under dim yellow narrowband light.

Currently, it is generally assumed that migratory birds are oriented in the appropriate migratory direction under UV, blue and green light (short-wavelength) and are unable to use their magnetic compass in total darkness and under yellow and red light (long-wavelength). However, it has also been suggested that the magnetic compass has two sensitivity peaks: in the short and long wavelengths, but with different intensities. In this project, we aimed to study the orientation of long-distance migrants, pied flycatchers (Ficedula hypoleuca), under different narrowband light conditions during autumn and spring migrations. The birds were tested in the natural magnetic field (NMF) and a changed magnetic field (CMF) rotated counterclockwise by 120° under dim green (autumn) and yellow (spring and autumn) light, which are on the 'threshold' between the short-wavelength and long-wavelength light. We showed that pied flycatchers (i) were completely disoriented under green light both in the NMF and CMF but (ii) showed the migratory direction in the NMF and the appropriate response to CMF under yellow light. Our data contradict the results of previous experiments under narrowband green and yellow light and raise doubts about the existence of only short-wavelength magnetoreception. The parameters of natural light change dramatically in spectral composition and intensity after local sunset, and the avian magnetic compass should be adapted to function properly under such constantly changing light conditions.

Timing, reproduction and biometrics of a long-distance passerine migrant in a core and a peripheral population

Understanding the mechanisms and the factors influencing the phenology, reproduction and biometrics of long-distance migrants are extremely important as global climate warming has induced changes in the locations of geographic ranges and dates of migration and reproduction. In this article, we compare phenology, reproductive parameters and adult biometrics of core and peripheral populations of a rare and endangered bird—the barred warbler Curruca nisoria—that inhabits the farming landscapes and makes long-distance trans-continental migrations. We predicted that: (i) individuals nesting in the core population would be larger than in the peripheral population; (ii) the reproductive parameters of the Barred Warblers in the core population would be higher than in the peripheral population. The Barred Warblers nesting in the centre of the range laid larger clutches and were clearly larger than individuals from the small, peripheral population. However, no differences in egg size and productivity were observed between the analysed populations. The Barred Warblers synchronised their breeding dates over a large geographical area as they had only a short time window for reproduction and had to lay their eggs as soon as possible. Individuals arriving earlier on the breeding grounds had larger clutches, longer wings and produced more nestlings. The pressure of the passage of time during the breeding season was a more important factor than the geographical location affecting the breeding characteristics in these populations.

Long-distance migration and venting of methane from the base of the hydrate stability zone

Marine methane hydrate is an ice-like substance that is stable in sediment around marine continental margins where water depths are greater than ~450–700 m. The release of methane due to melting of hydrates is considered to be a mechanism for past global carbon-cycle perturbations and could exacerbate ongoing anthropogenic climate change. Increases in bottom-water temperature at the landward limit of marine hydrate around continental margins, where vulnerable hydrate exists at or below the seabed, cause methane to vent into the ocean. However, this setting represents only ~3.5% of the global hydrate reservoir. The potential for methane from hydrate in deeper water to reach the atmosphere was considered negligible. Here we use three-dimensional (3D) seismic imagery to show that, on the Mauritanian margin, methane migrated at least 40 km below the base of the hydrate stability zone and vented through 23 pockmarks at the shelf break, probably during warmer Quaternary interglacials. We demonstrate that, under suitable circumstances, some of the 96.5% of methane bound in deeper water distal hydrates can reach the seafloor and vent into the ocean beyond the landward limit of marine hydrate. This reservoir should therefore be considered for estimating climate change-induced methane release during a warming world.

Climate Change Habitat Model Forecasts for Eight Owl Species in the Southwestern US.

The high-resolution forecasting of vegetation type shifts may prove essential in anticipating and mitigating the impacts of future climate change on bird populations. Here, we used the US Forest Service Ecological Response Unit (ERU) classification to develop and assess vegetation-based breeding habitat profiles for eight owl species occurring in the foothills and mountains of the Southwestern US. Shifts in mapped habitat were forecast using an ecosystem vulnerability model based on the pre-1990 climate envelopes of ERUs and the Intergovernmental Panel on Climate Change's (IPCC) A1B moderate-emission scenario for the future climate. For five of the eight owl species, the regional breeding habitat extent was projected to decline by at least 60% by 2090. Three species, the boreal owl (Aegolius funereus; at the trailing edge of its distribution), flammulated owl (Psiloscops flammeolus), and northern pygmy-owl (Glaucidium gnoma), were projected to experience the steepest habitat loss rates of 85%, 85%, and 76%, respectively. Projected vegetation shifts overlaid with well-documented flammulated owl breeding populations showed the complete or near complete loss of habitat by 2090 in areas of montane forest currently supporting dense aggregations of owl territories. Generalist or lower-elevation owl species were predicted to be less impacted, while, for the whiskered screech-owl (Megascops trichopsis), the contraction of the current habitat was nearly offset by a projected northward expansion. In general, the results of this study suggest high exposure to climate change impacts for the upper-elevation forest owls of semi-arid Southwestern North America. Long-distance migration and low natal philopatry may prove important to some montane owl populations in adapting to the regional loss of habitat.

Rectorite in flow-electrode capacitive deionization with three-dimensional current collector to achieve cost-effective desalination

The innovative design of collector is a top priority to drive the advancement of flow electrode capacitive deionization (FCDI) technology. Currently, the majority of FCDI research has concentrated on the implementation and modification of carbon-based flow electrode materials, while ignoring the effect of the current collector in FCDI. In this study, a 3D-FCDI configuration with porous titanium foam as the collector is designed, and rectorite (Rec) is used as the flow electrode in 3D-FCDI. Thanks to the porous structure of the 3D current collector, the collision opportunities of electrons with the Rec particles are increased and the long-distance migration of electrons in the conventional graphite collector is overcome, thus improving the system conductivity. The Rec exhibits good electrode dispersion, desalination rate, and energy consumption at low cost. In addition, the ASAR of Rec can be achieved by adjusting the electrode concentration (5 wt%), electrode flow rate (25 mL min−1) and operating voltage (1.8 V) to 11.43 μg cm−2 min−1. This study demonstrates the capability of 3D-FCDI configuration to advance the creation and implementation of FCDI.

Intermarriage and ancient polity alliances: isotopic evidence of cross-regional female exogamy during the Longshan period (2500–1900 BC)

The late third-millennium BC Longshan period was a crucial time for state formation in central China. During these centuries, long-distance networks expanded and shared material culture and then cultural practices spread across wider areas precipitating social and ideological developments that presaged the rise of states and cities on the Central Plain. In this research, the authors use multiple (strontium, oxygen and carbon) isotope analyses from the dental enamel of 67 individuals buried at the Xiajin cemetery, Shanxi Province. The results indicate significant long-distance migration among females during the Longshan period, which the authors interpret as evidence of exogamous marriage for political alliance-building—a phenomenon found more widely across Eurasia at the start of the Bronze Age.

Debate on Climate Induced Labour Migration

This work presents a comprehensive analysis of literature using a conceptual framework that explains how climate shocks—such as droughts, floods, or extreme temperature swings—affect two aspects of households' lives: (a) their ability to migrate, as they reduce the resources needed to do so, and (b) their vulnerability while remaining in their current location, as they raise the likelihood that they will fall (deeper) into poverty. When combined, these elements aid in the explanation of four major trends observed in the empirical literature: (1) There is no guarantee that climate-induced migration is more common in households with lower incomes; (2) Long-distance domestic migration is more common than local or international migration; (3) Slow-onset climate changes (like droughts) are more likely to cause increased migration than rapid-onset changes (like floods); and (4) The severity of climate shocks affects migration in a nonlinear way, depending on whether the capability or vulnerability channel predominates.

Feeding rates of raptors during autumn migration in the Central Appalachians 1987–2022

Migratory raptors can fuel their journeys by feeding along the way. To maximize migration success, raptors are suspected to time their movements with the availability of their prey. Feeding rates can vary among species depending on migration distance (long vs. short distance), flight strategies (flapping vs. soaring), and within species according to individual timing (early vs. late migrants). We assessed the feeding rate of four eastern North American migratory raptors over a period of 35 years. Using visual observations collected during autumn migration in the Central Appalachians, we assessed the presence/absence of distended crops of migrants. We quantified the feeding rates of species with different migration ecologies (migration distance, flight strategies), compared within-season (timing) species, and assessed if feeding rates varied over the last 35 years. We found a higher feeding rate in short-distance than in long-distance migrants and in power-flapping vs soaring migrants. We detected a long-term significant increase in feeding rate for most species, more evident in early migratory individuals coupled with a decrease in the feeding rate of late migrants. Understanding how feeding rates vary according to migratory behavior and how the migration ecology of raptors is changing under a scenario of global environmental change is important for their conservation.

Cyclic and linear siloxane contamination in sediment and invertebrates around a thermal power plant in Korea: Source impact, distribution, seasonal variation, and potential for bioaccumulation

Siloxanes have been commonly used as additives in a variety of industrial and consumer products. Media and government investigations have revealed that defoamers containing siloxanes are used in the effluent of thermal power plants in Korea. However, investigations of the source impact of siloxane contamination from the discharge of thermal power plants into coastal environments are scarce. In this study, sediment and invertebrates were collected around a thermal power plant to assess source impact, seasonal variation, and a potential for bioaccumulation. Although siloxanes were detectable in sediment and invertebrates, the spatial distribution and composition (which differed between the siloxanes found in sediment and invertebrates and those in defoamer used in the plant) suggest they were likely transported by long-distance migration as well as the discharge of thermal power plant. Seasonal differences might affect sedimentary contamination and the bioaccumulation potential of siloxanes. Specifically, octamethylcyclotetrasiloxane (D4) may have limited adsorption capacity and potential for long-distance migration, as its contribution in sediment far from the coastline was greater than that of decamethylcyclopentasiloxane (D5) and dodecamethylcyclohexasiloxane (D6). However, higher D5 accumulation in invertebrates, and D5 has a potential bioaccumulation. A molecular docking analysis showed that the binding affinity between D5 and the cytochrome enzyme in invertebrates was weaker than that with other siloxanes, which could lead to higher D5 accumulation in invertebrates.

More losses than gains? Distribution models predict species-specific shifts in climatic suitability for European beech forest herbs under climate change

IntroductionHerbaceous plant species constitute an essential element of the flora of European beech (Fagus sylvatica) forests. There is increasing evidence that rapidly changing climate is likely to modify the spatial distribution of plant species. However, we lack understanding of the impact that climate change might have on beech forest herbs across the European continent. We investigated the possible effects of predicted increasing rates of global warming and altered precipitation regimes on 71 forest herbs closely associated with beech forests, but with varying biogeographic and climatic niche attributes.MethodsBy using a total of 394,502 occurrence records and an ensemble of species distribution models (SDMs), we quantified the potential current distribution and future (2061-2080) range shifts in climatic suitability (expressed as occurrence probability, OP) according to two climate change scenarios (moderate SSP2-4.5 and severe SSP5-8.5).ResultsOverall, precipitation of the warmest quarter and temperature seasonality were the most influential predictors in shaping current distribution patterns. For SSP5-8.5 scenario, all studied species experienced significant reductions (52.9% on average) in the total size of highly suitable areas (OP >0.75). However, the magnitude and directions of changes in the climatic suitability were highly species-specific; few species might even increase OP in the future, particularly in case of SSP2-4.5 scenario. The SDMs revealed the most substantial decline of climatic suitability at the trailing edges in southern Europe. We found that climatic suitability is predicted to show unidirectional northward shift and to move toward higher elevations. The gain/loss ratio was generally higher for narrow-ranged species compared to widespread taxa.DiscussionOur findings are contextualized with regards to potential confounding factors (dispersal limitation, microclimatic buffering) that may mitigate or accelerate climate change impacts. Given the low long-distance migration ability, many beech forest herbs are unlikely to track the velocity with which macroclimatic isotherms are moving toward higher latitudes, making this species group particularly vulnerable to climate change.

Revision of <em>Sinomesuropetala daohugensis</em> Boudet, Nel & Huang, 2023 (Odonata: Aeshnoptera: Mesuropetalidae).

The mesuropetalid dragonfly Sinomesuropetala daohugensis Boudet, Nel & Huang, 2023, is here revised based on a new well-preserved dragonfly from the Haifanggou Formation of Inner Mongolia, northeastern China. The new specimen allows us to complete the forewing characters of this species, showing the close relationship of Sinomesuropetala Boudet, Nel & Huang, 2023 with Mesuropetala Handlirsch, 1906. The mesuropetalid dragonflies are currently recorded from the Late Jurassic and Lower Cretaceous deposits of east Asia, East Central South Europe, and southern America, indicating the wide distribution and the possible long-distance migration ability of some basal aeshnopteran dragonflies during these epochs.

Got milkweed? Genetic assimilation as potential source for the evolution of nonmigratory monarch butterfly wing shape.

Monarch butterflies (Danaus plexippus) are well studied for their annual long-distance migration from as far north as Canada to their overwintering grounds in Central Mexico. At the end of the cold season, monarchs start to repopulate North America through short-distance migration over the course of multiple generations. Interestingly, some populations in various tropical and subtropical islands do not migrate and exhibit heritable differences in wing shape and size, most likely an adaptation to island life. Less is known about forewing differences between long- and short-distance migrants in relation to island populations. Given their different migratory behaviors, we hypothesized that these differences would be reflected in wing morphology. To test this, we analyzed forewing shape and size of three different groups: nonmigratory, lesser migratory (migrate short-distances), and migratory (migrate long-distances) individuals. Significant differences in shape appear in all groups using geometric morphometrics. As variation found between migratory and lesser migrants has been shown to be caused by phenotypic plasticity, and lesser migrants develop intermediate forewing shapes between migratory and nonmigratory individuals, we suggest that genetic assimilation might be an important mechanism to explain the heritable variation found between migratory and nonmigratory populations. Additionally, our research confirms previous studies which show that forewing size is significantly smaller in nonmigratory populations when compared to both migratory phenotypes. Finally, we found sexual dimorphism in forewing shape in all three groups, but for size in nonmigratory populations only. This might have been caused by reduced constraints on forewing size in nonmigratory populations.

Habitat Suitability Evaluation and Environmental Factor Identification for Spatial Distribution of Urban Birds: A Case Study of Hongshan District, Wuhan City, China

The article takes 11 species of birds in Hongshan District as the research object based on the bird observation data 2020 and then identifies the spatial distribution of their habitats through the MaxEnt model. According to the results, we analyze the distribution characteristics and problems of bird habitats in Hongshan District and finally put forward the optimization suggestions according to the cohort groups. We conclude that water habitats and urban forest parks have higher suitability for bird spatial distribution and that the influence of various environmental factors on different types of birds is somewhat different. Based on the data analysis results, we provide references for the conservation of bird diversity and habitat restoration in Hongshan District: (1) Control the area of construction land and the number of high-rise buildings to make room for bird migration, enhance gene exchange among birds in different patches, and enrich species diversity. (2) Increase the number of bird migration “stations” between long-distance habitat patches to provide resting points for birds during long-distance migration. (3) Increase the number of bird migration "stations" between long-distance habitat patches to provide resting points for birds in the urban forest park. (4) Adopt tree-shrub-grass planting to provide more living space for birds. (5) Reserve a green corridor around urban roads and water systems to reduce the impact of urban roads on the distribution pattern of bird suitability.

Diadromy Drives Elevated Rates of Trait Evolution and Ecomorphological Convergence in Clupeiformes (Herring, Shad, and Anchovies).

AbstractMigration can have a profound influence on rates and patterns of phenotypic evolution. Diadromy is the migration between marine and freshwater habitats for feeding and reproduction that can require individuals to travel tens to thousands of kilometers. The high energetic demands of diadromy are predicted to select for ecomorphological traits that maximize swimming and locomotor efficiency. Intraspecific studies have shown repeated instances of divergence among diadromous and nondiadromous populations in locomotor and foraging traits, which suggests that at a macroevolutionary scale diadromous lineages may experience convergent evolution onto one or multiple adaptive optima. We tested for differences in rates and patterns of phenotypic evolution among diadromous and nondiadromous lineages in Clupeiformes, a clade that has evolved diadromy more than 10 times. Our results show that diadromous clupeiforms show convergent evolution for some locomotor traits and faster rates of evolution, which we propose are adaptive responses to the locomotor demands of migration. We also find evidence that diadromous lineages show convergence into multiple regions of multivariate trait space and suggest that these respective trait spaces are associated with differences in migration and trophic ecology. However, not all locomotor traits and no trophic traits show evidence of convergence or elevated rates of evolution associated with diadromy. Our results show that long-distance migration influences the tempo and patterns of phenotypic evolution at macroevolutionary scales, but there is not a single diadromous syndrome.

The pace of mitochondrial molecular evolution varies with seasonal migration distance.

Animals that engage in long-distance seasonal migration experience strong selective pressures on their metabolic performance and life history, with potential consequences for molecular evolution. Species with slow life histories typically show lower rates of synonymous substitution (dS) than "fast" species. Previous research suggests long-distance seasonal migrants have a slower life history strategy than short-distance migrants, raising the possibility that rates of molecular evolution may covary with migration distance. Additionally, long-distance migrants may face strong selection on metabolically-important mitochondrial genes due to their long-distance flights. Using over 1,000 mitochondrial genomes, we assessed the relationship between migration distance and mitochondrial molecular evolution in 39 boreal-breeding migratory bird species. We show that migration distance correlates negatively with dS, suggesting that the slow life history associated with long-distance migration is reflected in rates of molecular evolution. Mitochondrial genes in every study species exhibited evidence of purifying selection, but the strength of selection was greater in short-distance migrants, contrary to our predictions. This result may indicate effects of selection for cold tolerance on mitochondrial evolution among species overwintering at high latitudes. Our study demonstrates that the pervasive correlation between life history and molecular evolutionary rates exists in the context of differential adaptations to seasonality.

Improving the language of migratory bird science in North America

Abstract Several long-accepted terms are widely misused in ornithology and have led to a misperception of important concepts in the ecology of Nearctic–Neotropical migratory birds. The term “North America” (and its ancillary terms “North American species,” “North American habitats,” etc.) is widely used to refer to the United States and Canada, when in fact it should include all of the continent from the Arctic through Panama. In a similar vein, the terms “wintering” and “over-wintering” (whether used to describe the status of individual birds or species, or as a modifier for terms like habitats, ecology, or behavior), “spring migration” and “fall migration” are inappropriate for Nearctic–Neotropical migrants because they explicitly reference conditions in the temperate zone of the continent, even as most such species spend the majority of their annual cycle elsewhere, where these terms are inaccurate and unhelpful. We discuss the pitfalls of using these terms and suggest several alternatives and replacements. In particular, we urge more precision in the use of the term “North America”; for Nearctic–Neotropical migratory species (especially long-distance migrants), we suggest retiring the terms “wintering” and “over-wintering” in favor of “nonbreeding”; and for the same group of species we suggest retiring the terms “spring migration” and “fall migration” in favor of “pre-breeding,” “post-breeding,” or “post-natal” migration.

Development of a novel molecular tool to study molecular ecology of Ornithomya (Hippoboscidae) avian louse flies

Louse flies (Diptera: Hippoboscidae) are obligatory hematophagous ectoparasites of birds and mammals. These widely distributed parasitic flies may have a significant impact on wild and farm animals by feeding on their blood and transmitting bloodborne pathogens. However, despite their ecological importance, louse flies are clearly underrepresented in host-parasite research and implementation of genetic approaches in this group is generally hampered by lacking molecular tools. In addition, louse flies that parasitize long-distance migrants can travel long distances with their avian hosts, facilitating the large-scale spread of pathogens across landscapes and geographic regions. Given the wide diversity of louse flies that parasitize a variety of avian hosts, their direct negative impact on host survival, and their high potential to transmit bloodborne pathogens even along avian migration routes, it is surprising that our knowledge of louse fly ecology is rather modest and incomplete. Here, we aimed to develop a novel molecular tool for polyxenous avian louse flies from the genus Ornithomya, which are among the most common and widely distributed representatives of Hippoboscidae family, to improve research of their genetic population structure and molecular ecology.Using the Illumina Mi-seq sequencing, we conducted a genome-wide scan in Ornithomya avicularia to identify putative microsatellite markers. A panel of 26 markers was selected to develop amplification protocols and assess polymorphism in the Central European population of O. avicularia, as well as to test for cross-amplification in a congeneric species (O. chloropus).A genome-scan in O. avicularia identified over 12 thousand putative microsatellite markers. Among 26 markers selected for a population-wide screening; one did not amplify successfully and three were monomorphic. 22 markers were polymorphic with at least two alleles detected. Two markers showed presence of null alleles. A cross-amplification of microsatellite markers in O. chloropus revealed allelic polymorphism at 14 loci, with the mean allelic richness of 3.78 alleles per locus (range: 2–8).Our genome-wide scan in O. avicularia provides a novel and powerful tool for molecular research in Ornithomya louse flies. Our panel of polymorphic microsatellite loci should allow genotyping of louse flies from geographically distinct populations and from a wide spectrum of avian hosts, enhancing population genetic and phylogeographic research in Ornithomya.

Differential larval growth strategies and trophodynamics of larval Atlantic bluefin tuna (Thunnus thynnus) from two discrete spawning grounds

Atlantic bluefin tuna (ABT), Thunnus thynnus, is a globally important fishery resource. This oceanic top predator undertakes long-distance migrations from its nutrient-rich feeding grounds in the north Atlantic to oligotrophic spawning grounds. Larvae are born mainly in the corresponding ecosystems of its two well-established spawning areas: the Gulf of Mexico (GoM) and the Mediterranean Sea (MED). Stable isotopes analyses (SIA) of δ15N and δ13C have proven useful for understanding marine food webs and have evaluated larval ABT signatures in their respective spawning areas. This study is among the first to use larvae collected during the same spawning season (2014) from the GoM and one of the main spawning areas within the MED (the Balearic Sea) to standardize methodologies, compare larval growth, and relate SIA with larval postflexion growth using GAMs for the two spawning areas. The main findings identify significant population differences, with comparatively faster growth in GoM larvae. The GoM population had larger otoliths with wider increments, as well as higher δ15N values and higher trophic position for postflexion stages. Collectively, these findings highlight the importance of not only developing well-calibrated growth curves, but also integrating the distinct early life history dynamics for each spawning area to properly support ABT’s ongoing management efforts.

Cross-Regional Pollination Behavior of Trichoplusia ni between China and the Indo-China Peninsula.

Noctuid moths, a group of "non-bee" pollinators, are essential but frequently underappreciated. To elucidate their roles in cross-regional pollination, this study selected the agriculturally significant species, cabbage looper (CL) Trichoplusia ni, as a representative model. From 2017 to 2021, this study was conducted on Yongxing Island, situated at the center of the South China Sea. We investigated the flower-visiting activities of CL, including its occurrence, potential host species, and geographic distribution in the surrounding areas of the South China Sea. First, the potential transoceanic migratory behavior and regional distribution of CL were systematically monitored through a comprehensive integration of the data obtained from a searchlight trap. The transoceanic migratory behavior of CL was characterized by intermittent occurrence, with the major migratory periods and the peak outbreak yearly. Furthermore, trajectory analysis confirmed the ability of CL to engage in periodic, round-trip, migratory flights between Southeast Asian countries and China. More importantly, an observation of pollen on the body surface demonstrated that 95.59% (130/136) of the migrating individuals carried pollen. The proboscis and compound eyes were identified as the primary pollen-carrying parts, with no observable gender-based differences in pollen-carrying rates. Further, identifying the pollen carried by CL using morphological and molecular methods revealed a diverse range of pollen types from at least 17 plant families and 31 species. Notably, CL predominantly visited eudicot and herbaceous plants. In conclusion, this pioneering study has not only revealed the long-distance migration activities of these noctuid moths in the East Asian region but also provided direct evidence supporting their role as potential pollinators. These findings offer a critical theoretical basis to guide the development of scientific management strategies.