Differences In Migration Patterns Research Articles

Immune Cell Migration to Cancer.

Immune cell migration is required for the development of an effective and robust immune response. This elegant process is regulated by both cellular and environmental factors, with variables such as immune cell state, anatomical location, and disease state that govern differences in migration patterns. In all cases, a major factor is the expression of cell surface receptors and their cognate ligands. Rapid adaptation to environmental conditions partly depends on intrinsic cellular immune factors that affect a cell's ability to adjust to new environment. In this review, we discuss both myeloid and lymphoid cells and outline key determinants that govern immune cell migration, including molecules required for immune cell adhesion, modes of migration, chemotaxis, and specific chemokine signaling. Furthermore, we summarize tumor-specific elements that contribute to immune cell trafficking to cancer, while also exploring microenvironment factors that can alter these cellular dynamics within the tumor in both a pro and antitumor fashion. Specifically, we highlight the importance of the secretome in these later aspects. This review considers a myriad of factors that impact immune cell trajectory in cancer. We aim to highlight the immunotherapeutic targets that can be harnessed to achieve controlled immune trafficking to and within tumors.

Time of year and weather influence departure decisions of sandhill cranes at a primary stopover

The Rocky Mountain Population (RMP) of greater sandhill cranes uses a key stopover area, the San Luis Valley (SLV) in Colorado. Parameters of migration phenology can differ between autumn and spring and are affected by weather and environmental factors. We hypothesized that sandhill cranes in the SLV would have a longer stopover duration in autumn than in spring, and that wind assistance, crosswinds, temperature change, barometric air pressure, and surface water area would influence persistence probability. We used data from sandhill cranes fitted with transmitters that spanned autumn and spring, 2015-2022. We used an open robust design mark-recapture model to estimate stopover duration, arrival probability, and persistence probability. We examined the effects of weather and surface water on the persistence probability for 106 sandhill cranes in the SLV. Stopover duration was longer in autumn than in spring and had higher variability across years. Arrival probability to the SLV peaked on 13 October in autumn and 21 February in spring. Persistence probability declined around mid-December in autumn and mid-March in spring. We found that several weather covariates influenced persistence in both seasons. In autumn, sandhill cranes departed the SLV with higher tailwinds, lower crosswinds, and higher surface water availability. In spring, sandhill cranes departed the SLV with lower crosswinds and higher barometric air pressure at the surface and higher wind speeds at altitudes of about 3,000 m. The effect of wind speed was stronger later in the spring. Given the lower variability of arrival and persistence probability and shorter stopover duration in spring compared to autumn, we suspect that RMP sandhill cranes are using a time-minimization strategy during spring. However, given the use of supportive winds and weather conditions ideal for soaring, RMP sandhill cranes appear to be using strategies that save energy in both seasons. Our study identifies the optimal timing of water management and surveys for RMP sandhill cranes and confirms that weather influences their persistence. Understanding differences in migration patterns between seasons and the factors that influence persistence at stopover sites will also be important for anticipating phenological impacts from climate change and land use alterations.

Spatial and temporal patterns of gonadal maturation and spawning in European flounder Platichthys flesus at its southern continental edge

The European flounder (Platichthys flesus) is a marine flatfish with high plasticity in several life-history traits, including spawning sites and habitat use patterns. With the overarching goal of understanding the use of estuaries in connection with maturation and reproduction in adult flounder, this study investigates its reproductive cycle in the Douro Estuary (NW Portugal), at the southern edge of its geographical distribution. Adults were caught by monthly trawling from November 2016 to November 2017. Sex ratio and length-weight relationships were determined. The annual reproductive cycle was described using a combination of gonadosomatic (GSI), hepatosomatic (HSI), and general fish condition (Kn) indices, seasonal gonad development staging (macroscopic and histological), and quantification of plasma sexual steroids. Total sex ratio was 1 M:3 F, and females presented negative allometric growth, while males’ growth was isometric. The various indices consistently indicated that the greatest reproductive activity occurred between January and March, peaking in February. However, some females at advanced reproductive stages (late vitellogenesis), high GSI values and steroid hormone (E2) levels were observed as late as May. Females in spawning condition, i.e., undergoing full oocyte maturation and ovulation, were never found, unlike males who exhibited spermiation within the estuary. Sexual differences in migration patterns were also suggested: males seem to leave earlier and stay longer in offshore spawning grounds, while females return to the estuary shortly after spawning. Overall, there was a good correlation between GSI, seasonal hormone cycling, and sexual maturity of female and male flounder, supporting the use of circulating sex steroids as a less invasive tool to assess maturity status.

Blind shots: non‐natural mortality counteracts conservation efforts of a threatened waterbird

AbstractWaterbirds are particularly affected by the high hunting pressure they face in many regions, which in some cases is compromising conservation actions for threatened species. The marbled teal Marmaronetta angustirostris is one of the most endangered waterbirds in Europe. In order to restore its population, several conservation actions have recently been undertaken, including a population reinforcement programme in Spain using captive‐bred birds. With the aim of assessing the success of the reinforcement programme to establish a long‐term self‐sustaining population, we identified mortality causes of marbled teal, evaluated the survival of individual birds of the reinforcement programme and estimated the viability of the population under different management scenarios. We used data from wild and captive‐bred individuals tracked by GPS since 2018 (n = 42) and from a mark–recapture programme initiated in 2015 (n = 297). We recovered 15 dead birds or transmitters: 20% died of natural causes, 60% of non‐natural causes (including all anthropic causes) and 20% of unknown causes. Furthermore, the GPS tags of 24 birds unexpectedly stopped transmitting without any indication of malfunction, and for 66.7% of these disappeared birds, the cessation was suspected to be caused by illegal shooting. Survival during the hunting season was higher for males (31.3%) than for females (12.5%), and for the wild (50%) than for the captive‐bred birds (9.4%), probably due to differences in migration patterns to North Africa. Population viability models revealed that maintaining the breeding population at the current mortality rates is only possible with a permanent release programme of captive‐bred individuals, and that in order to establish a self‐sustaining population, non‐natural mortality would have to be reduced by at least 40%. We recommend management measures to reduce marbled teal mortality, such as limiting legal hunting to hours with clear visibility, prosecuting illegal shootings, controlling exotic predators and improving water management to reduce disease outbreaks. Some improvements can be implemented in captive‐breeding programmes, such as earlier release times and incorporating anti‐predator training.

P-486 Alterations in endometrial programming lead to recurrent in vitro fertilization failures

Abstract Study question Could patients with recurrent implantation failures (RIF) display alterations on the decidualization program conditioning decidual cells’ functions and the inflammatory response during peri-implantation period? Summary answer Endometrium from RIF-patients displays alterations into the decidualization program and into the induction of a physiological inflammation preventing the attachment and cell-migration for embryo implantation What is known already The decidualization program starts on each menstrual cycle and implies not only phenotypical changes on the endometrial stromal cells, but also in their secretory profile. Moreover, this process induces a physiological and sterile inflammatory response associated with inflammatory mediators production, such as IL-1β. At the same time, several molecules associated with receptivity are modulated; increasing the expression of adhesion molecules and metalloproteinases, while decreasing MUC-1 to allow embryo attachment and implantation. Even nowadays with different techniques that can identify a competent embryo and the implantation window, RIF-patients cannot reach implantation and the mechanisms involved have not been elucidated yet. Study design, size, duration First, a bioinformatic analysis was performed using standardized pathways involved in angiogenesis, placentation, decidualization, inflammation and immune regulation from public databases (Reactome, Gene Ontology Biological Process, WikiPathways, KEGG). Based on arrays that compare gene expression in endometrial biopsies from RIF or fertile women, we selected those that connect two or more processes and we validated their modulation in endometrial samples. Functional processes, such as migration and inflammatory production were also evaluated in primary cultures. Participants/materials, setting, methods Endometrial samples were obtained from fertile and RIF patients during the secretory phase. The Investigation and Ethics Committee from San Isidro, Argentina approved this study. RT-qPCR was performed to test decidualization markers: IGFBP1, PRL, PGR; inflammation: IL-1β, NLRP3, PTGS1; angiogenesis balance : CXCL14, ARG2, VEGFA; adhesion molecules: ITGA8 and MUC1. IL-1β production was quantified by Flow Cytometry. Wound healing assay was performed in human endometrial stromal cells derived from cell line and RIF patient’s biopsy Main results and the role of chance First, we performed bioinformatic analysis based on standardized pathways in public databases. We focused on genes that connected and were modulated in processes involved in implantation, angiogenesis, placentation, decidualization, inflammation and immune regulation. Then, we validated the expression of 15 genes with the highest score in biopsies from RIF or fertile women taken on LH + 7. We found decreased IGFBP1 expression, an early decidualization marker, and the progesterone receptor (p < 0.0001), suggesting alterations in the decidualization program. Since inflammation is associated with decidualization, we evaluated the IL-1β pathway. RIF biopsies had reduced expression of NLRP3, associated with inflammasome assembly, accompanied by a reduction in PTGS1 and IL-1β production in comparison with endometrial samples from fertile women. Moreover, when we evaluated genes involved in processes regulated by inflammation, we observed increased expression of MUC1, avoiding blastocyst adhesion, and decreased ITGA8 preventing its attachment accompanied by decreased MMP9 levels (p < 0.005). Also, we observed an imbalance between pro and anti-angiogenic factors (VEGFA vs CXCL14). Finally, we isolated and cultivated stromal cells from RIF samples to analyze migration ability, a process that mediates blastocyst inclusion into the decidua, by wound healing assay. These primary cultures showed a differential migration pattern compared with decidualized stromal cells. Limitations, reasons for caution The present results were obtained using endometrial samples from RIF patients and fertile women obtained during the secretory phase of the menstrual cycle. Even though the samples represent the endometrium after in vivo decidualization, further studies are necessary to elucidate whether these mechanisms operate similarly in vivo. Wider implications of the findings Decidualization process induces a physiological and sterile inflammatory response associated with the modulation of several adhesion molecules and MMP to allow the attachment and embryo implantation. However, this initial inflammatory response is differentially induced in RIF patients in comparison with fertile women, suggesting its relevance as a potential pharmacological target. Trial registration number This work was funded by the National Agency of Sciences and Technology ANPCyT (PICT 2018-4715 and PICT 2028-2461 to RR) and University of Buenos Aires (UBACyT UBACyT 20020090200034 to RR).

Country differences and determinants of yield in programmatic migrant TB screening in four European countries.

INTRODUCTION The WHO End TB Strategy emphasises early diagnosis and screening of TB in high-risk groups, including migrants. We analysed TB yield data from four large migrant TB screening programmes to inform TB policy.METHODS We pooled routinely collected individual TB screening episode data from Italy, the Netherlands, Sweden and the United Kingdom under the European Union Commission E-DETECT.TB grant, described characteristics of the screened population, and analysed TB case yield.RESULTS We collected data on 2,302,260 screening episodes among 2,107,016 migrants, mostly young adults aged 18-44 years (77.8%) from Asia (78%) and Africa (18%). There were 1,658 TB cases detected through screening, with substantial yield variation (per 100,000): 201.1 for Sweden (95% confidence intervals CI 111.4-362.7), 68.9 (95% CI 65.4-72.7) for the United Kingdom, 83.2 (95% CI 73.3-94.4) for the Netherlands and 653.6 (95% CI 445.4-958.2) in Italy. Most TB cases were notified among migrants from Asia (n = 1,206, 75/100,000) or Africa (n = 370, 76.4/100,000), and among asylum seekers (n = 174, 131.5/100,000), migrants to the Netherlands (n = 101, 61.9/100,000) and settlement visa migrants to the United Kingdom (n = 590, 120.3/100,000).CONCLUSIONS We found considerable variations in yield across programmes, types of migrants and country of origin. These variations may be partly explained by differences in migration patterns and programmatic characteristics.

Intraparticle Macromolecular Migration Alters the Structure and Function of Proteins Reversibly Immobilized on Porous Microbeads

AbstractWhile migration of reversibly immobilized proteins across the volume of supports is investigated in conditions where an external force is applied or under fluid flow conditions, their passive migration upon sample storage and its effect on the protein functionality remain unexplored. Understanding such intraparticle macromolecular migration is essential to develop protein functionalized biomaterials with a longer life span. This work investigates the spatiotemporal migration of His‐tagged immobilized fluorescent proteins inside porous agarose microbeads under different storage conditions. A tool that assesses the intraparticle protein migration across the surface of the porous supports is developed. Differences in migration patterns between different proteins suggest that binding dynamics between proteins and their supports play a key role in their migration. The effect of macromolecular migration on the functional and structural properties of bound proteins and enzymes is also explored. Therefore, single‐particle measurements to understand how the migration process affects the functionality of immobilized enzymes are performed. Evaluating protein migration and understanding the reason behind such phenomena allows gaining control over immobilization processes and design immobilization chemistries that either prevent or promote intraparticle macromolecular diffusion upon storage, depending on the desired final application.

Relating wing morphology and immune function to patterns of partial and differential bat migration using stable isotopes.

Migration is energetically expensive and is predicted to drive similar morphological adaptations and physiological trade-offs in migratory bats and birds. Previous studies suggest that fixed traits like wing morphology vary among species and individuals according to selective pressures on flight, while immune defences can vary flexibly within individuals as energy is variably reallocated throughout the year. We assessed intraspecific variation in wing morphology and immune function in silver-haired bats Lasionycteris noctivagans, a species that follows both partial and differential migration patterns. We hypothesized that if bats experience energy constraints associated with migration, then wing morphology and immune function should vary based on migratory tendency (sedentary or migratory) and migration distance. We predicted that long-distance migrants would have reduced immune function and more migration-adapted wing shapes compared to resident or short-distance migrating bats. We estimated breeding latitude of spring migrants using stable hydrogen isotope techniques. Our sample consisted primarily of male bats, which we categorized as residents, long-distance northern migrants, short-distance northern migrants and southern migrants (apparent breeding location south of capture site). Controlling for individual condition and capture date, we related wing characteristics and immune indices among groups. Some, but not all, aspects of wing form and immune function varied between migrants and residents. Long-distance northern migrants had larger wings than short-distance northern migrants and lower wing loading than southern migrants. Compared with resident bats, short-distance northern migrants had reduced IgG while southern migrants had heightened neutrophils and neutrophil-to-lymphocyte ratios. Body fat, aspect ratio, wing tip shape and bacteria killing ability did not vary with migration status or distance. In general, male silver-haired bats do not appear to mediate migration costs by substantially downregulating immune defences or to be under stronger selection for wing forms adapted for fast, energy-efficient flight. Such phenotypic changes may be more adaptive for female silver-haired bats, which migrate farther and are more constrained by time in spring than males. Adaptations for aerial hawking and the use of heterothermy by migrating bats may also reduce the energetic cost of migration and the need for more substantial morphological and physiological trade-offs.

Short communication: Amphidromous goby postlarvae (penja) migration seasons and fisheries in West Sulawesi, Indonesia

Abstract. Nurjirana, Burhanuddin AI, Keith P, Haris A, Afrisal M. 2021. Short communication: Amphidromous goby postlarvae (penja) migration seasons and fisheries in West Sulawesi, Indonesia. Biodiversitas 23: 375-380. Several gobioid species have amphidromous migration patterns; adult gobies spawn in their freshwater habitat, embryos are carried by river currents to reach the sea where they undergo a planktonic phase lasting several months before migrating to estuarine and then freshwater (predominantly riverine) environments to grow and breed. Around the island of Sulawesi in Indonesia, these migrating postlarvae have various local names; in West Sulawesi they are collectively known as penja, a popular fisheries commodity, but data on their migration patterns are limited. This study aimed to determine penja migration seasons and document some aspects of the penja fisheries in West Sulawesi. The research was conducted in the lower reaches of five rivers: the Mapilli, Mandar, Teppo, Palipi, and Lariang rivers. Penja samples were collected from fishermen's catches using several types of fishing gear such as seser (scoop nets), dariq or bunde (push nets), panesser (casting net) and other traditional or artisanal fishing equipment. Samples were also collected from traditional markets. The postlarvae were measured and grouped based on morphological characters. The results showed temporal differences in migration patterns between the five study sites, while external morphology indicated the presence of several species in migrating penja schools. During the rainy season, populations with a more diverse morphology were found than during the dry season.

Differing migration patterns and year-round habitat-use of allopatric nesting Eastern Tundra Bean Geese (Anser fabalis serrirostris) in East Asia

Sympatric Chinese-wintering Eastern Tundra Bean Geese (Anser fabalis serrirostris, ETBG) breed in two widely separated Arctic areas (Central Russian Arctic and Anadyr region); South Korean-wintering birds (Chaun-South Korea) breed in a third discrete area between these two. Such winter/summer segregation likely structures the population, potentially resulting in distinct migration patterns and habitat-use throughout the annual cycle. We tracked individuals using GPS-GSM transmitters from all three of these geographically discrete ETBG subpopulations to see whether this was the case, testing for differences in migration patterns, seasonal and diurnal habitat-use using remotely sensed land-cover mapping. Mean migration distance of Central Arctic-China and Chaun-South Korea individuals did not differ significantly, but Anadyr-China birds travelled 15–24% further (mean: 1140 ​km, P ​< ​0.001). Despite this, mean spring migration durations were longest among Central Arctic-China ETBG, significantly longer than Anadyr-China geese, due to significantly longer stopovers, which were significantly longer than Chaun-South Korea birds. Autumn migration duration of Central Arctic-China and Chaun-South Korea individuals was significantly shorter than in spring, with fewer, shorter stopovers. Lack of significant differences in migration and stopover duration or numbers of stopovers between spring and autumn among Anadyr-China ETBG confirms this is a plastic trait, differing between subpopulations responding to prevailing conditions. Migration patterns and habitat-use differed significantly between all three ETBG subpopulations, although all tended to use wetlands more at night and croplands more in daytime in winter, suggesting specific adaptations and responses to differing conditions encountered along their different migration routes. Although untestable, we speculate that differences in habitat-use may affect fitness levels and genetic exchange between subpopulations, but based on our observations, conclude clear differences in migration and foraging ecology between these elements of the same subspecies, even in winter sympatry.

How does light affect the distribution of Euglena sp. and Tetrahymena pyriformis

The broad range of energy sources utilized by organisms to obtain organic molecules from their environment include plants, animals, and sunlight. Differences in migration patterns and anatomy can often be attributed to these differing energy sources across organisms. To evaluate the distribution patterns of organisms Euglena sp. (Euglena) and Tetrahymena pyriformis (T. pyriformis) both organisms were treated with light. Euglena is a genus of more than 1,000 species consisting of single-celled flagellates that primarily live in freshwater and saltwater, and T. pyriformis is a single-celled, ciliated eukaryote that typically inhabits fresh water. Tubes filled with either T. pyriformis or Euglena were exposed to three different treatments: entirely to light, entirely to darkness, or exposed on one half to light and the other half to darkness. Results show that Euglena exhibited a phototactic response to light, as there was a statistically significant 17 organism increase on the side exposed to light and an 8 organism decrease on the side exposed to darkness after the 30-minute period. T. pyriformis did not show any significant redistribution after exposure to any of the treatments. Due to T. pyriformis’s heterotrophic nature and Euglena’s autotrophic nature, these findings were most likely the result of characteristics that aid Euglena as autotrophs and are absent in T. pyriformis. Specifically, Euglena have a red eyespot that locates areas of light and chloroplasts. Red eyespots and chloroplasts are two of the many photosynthetic organelles that facilitate the process of photosynthesis in areas of light, making lighted areas optimal for the survival of Euglena in comparison to areas of darkness.

The Role of Race, Sex, and Age in Circadian Disruption and Metabolic Disorders

The Role of Race, Sex, and Age in Circadian Disruption and Metabolic Disorders

Ontogenetic shifts from social to experiential learning drive avian migration timing

Migrating animals may benefit from social or experiential learning, yet whether and how these learning processes interact or change over time to produce observed migration patterns remains unexplored. Using 16 years of satellite-tracking data from 105 reintroduced whooping cranes, we reveal an interplay between social and experiential learning in migration timing. Both processes dramatically improved individuals’ abilities to dynamically adjust their timing to track environmental conditions along the migration path. However, results revealed an ontogenetic shift in the dominant learning process, whereby subadult birds relied on social information, while mature birds primarily relied on experiential information. These results indicate that the adjustment of migration phenology in response to the environment is a learned skill that depends on both social context and individual age. Assessing how animals successfully learn to time migrations as environmental conditions change is critical for understanding intraspecific differences in migration patterns and for anticipating responses to global change.

Seasonal and regional differences in migration patterns and conservation status of Swan Geese (Anser cygnoides) in the East Asian Flyway

BackgroundThe Swan Goose (Anser cygnoides) breeds across Mongolia and adjacent China and Russia and winters exclusively in China. It is globally threatened, showing long-term major range contractions and declining abundance, linked to habitat loss and degradation. We remain ignorant about the biogeographical subpopulation structure of the species and potential differences in their migration timing, stopovers and schedules, information that could be vital to effective conservation of different elements of the species population, which we address here with results from a telemetry study.MethodsIn 2017–2018, we attached GPS/GSM telemetry devices to 238 Swan Geese on moulting sites in three discrete parts of their summering area (Dauria International Protected Area, Central Mongolia and Western Mongolia), generating 104 complete spring and autumn migration episodes to compare migration speed and nature between birds of different summer provenances.ResultsBirds from all three breeding areas used almost completely separate migration routes to winter sympatrically in the Yangtze River floodplain. Although many features of the spring and autumn migrations of the three groups were similar, despite the significantly longer migration routes taken by Western Mongolian tagged birds, birds from Dauria Region arrived significantly later in winter due to prolonged staging in coastal areas and took longer to reach their breeding areas in spring. Among birds of all breeding provenances, spring migration was approximately twice as fast as autumn migration. Areas used by staging Swan Geese (mainly wetlands) in autumn and spring almost never fell within national level protected areas, suggesting major site safeguard is necessary to protect these critical areas.ConclusionsThis study showed the discreteness of migration routes taken by birds of different summer provenances and differences in their migratory patterns, highlighting key staging areas (Yalu River Estuary in China/North Korea for Dauria Region breeding birds, Daihai Lake for Central Mongolian and Ordos Basin for Western Mongolian birds). Based on this new knowledge of the biogeographical subpopulation structure of the Swan Goose, we need to combine data on subpopulation size, their distribution throughout the annual life cycle and conservation status, to develop more effective conservation strategies and measures to reverse population decline throughout the range.

Obesity Prolongs the Inflammatory Response in Mice After Severe Trauma and Attenuates the Splenic Response to the Inflammatory Reflex.

Thoracic traumas with extra-thoracic injuries result in an immediate, complex host response. The immune response requires tight regulation and can be influenced by additional risk factors such as obesity, which is considered a state of chronic inflammation. Utilizing high-dimensional mass and regular flow cytometry, we define key signatures of obesity-related alterations of the immune system during the response to the trauma. In this context, we report a modification in important components of the splenic response to the inflammatory reflex in obese mice. Furthermore, during the response to trauma, obese mice exhibit a prolonged increase of neutrophils and an early accumulation of inflammation associated CCR2+CD62L+Ly6Chi monocytes in the blood, contributing to a persistent inflammatory phase. Moreover, these mice exhibit differences in migration patterns of monocytes to the traumatized lung, resulting in decreased numbers of regenerative macrophages and an impaired M1/M2 switch in traumatized lungs. The findings presented in this study reveal an attenuation of the inflammatory reflex in obese mice, as well as a disturbance of the monocytic compartment contributing to a prolonged inflammation phase resulting in fewer phenotypically regenerative macrophages in the lung of obese mice.

Differential horizontal migration patterns of two male salmon sharks (Lamna ditropis) tagged in the Bering Sea

BackgroundThe salmon shark (Lamna ditropis) is a widely distributed apex predator in the North Pacific Ocean. Many salmon sharks from the eastern North Pacific, specifically Prince William Sound, Alaska, have been satellite tagged and tracked, but due to the sexual segregation present in salmon sharks, most of these tagged sharks were female. Consequently, little information exists regarding the migration patterns of male salmon sharks. To better understand the migration and distribution of this species, information on the male component of the population as well as from sharks outside of Prince William Sound, Alaska, is needed. In this study, we deployed satellite transmitters on two mature male salmon sharks caught in the Bering Sea.ResultsThe two mature male salmon sharks tagged in the Bering Sea exhibited distinct migration patterns. The first male, tagged in August 2017, traveled to southern California where it remained from January to April after which it traveled north along the United States’ coast and returned to the Bering Sea in August 2018. The second male, tagged in September 2019, remained in the North Pacific between 38° N and 50° N before returning to the Bering Sea in July of year one and as of its last known location in year two. The straight-line distance traveled by the 2017 and 2019 sharks during their 12 and 22 months at liberty was 18,775 km and 27,100 km, respectively.ConclusionsBefore this study, our understanding of salmon shark migration was limited to female salmon sharks satellite tagged in the eastern North Pacific. The 2017 male salmon shark undertook a similar, but longer, north–south migration as tagged female sharks whereas the 2019 shark showed little overlap with previously tagged females. The different migration patterns between the two male sharks suggest distinct areas exist for foraging across the North Pacific. The return of both sharks to the Bering Sea suggests some fidelity to the region. Continued tagging efforts are necessary to understand the population structure of salmon sharks in the North Pacific. This tagging study highlights the importance of opportunistic efforts for obtaining information on species and sex with limited distribution data.

Recent Dimensions of Regional Migration

Abstract Objective: The purpose of this article is to make an analysis of the size and structure of migratory flows at regional and sub-regional level. Methodology: Descriptive statistical analysis was mainly used to visualize and synthesize information about the evolution of the structure and size of migratory flows in major regions of the world. Findings: The importance of contemporary migration is related not only to the number of migrants, but also to the fact that the migratory phenomenon has become global and takes on more and more diverse forms. People travel for various periods of time, but shorter. They adopt a pattern of circulatory migration, continue to maintain strong connections with where they left from or practice unregulated migration. Migration has become a defining feature of the modern global economy, and the main factors underlying its expansion are the processes of globalization, technical progress, the new economic order, etc. In 2019, the number of l migrants at world level reached 271.6 million, well above the values forecast by international bodies in recent years. In the last three decades, more developed regions have received 69 million international migrants, while less developed regions have received only 50 million. The highest migratory flows were recorded in high-income countries (98 million persons), and middle and low-income countries added only about 20 million persons to migrants’ stock (17 million and 3 million, respectively). Value Added: The paper presents an analysis of the size and structure of migratory flows at the regional level, providing a more detailed picture of migration, and presenting a different but complementary perspective of migrants and movements from different parts of the world. A comparative analysis of migrant flows at regional level and on large migration corridors is performed, but also of the structure by age groups and gender of regional migrants. Recommendations: The analysis of data on regional migration shows significant differences in migration patterns between regions. Greater recognition of regional migration patterns, variations and complexities can help shape strategic and sustainable responses of the migration policies. It is also necessary to pay attention to the regional dimensions and variations of international migration that may have critical implications for debates and regulations, especially (but not only) globally.

Linking Peregrine Falcons' (Falco peregrinus) Wintering Areas in Peru with Their North American Natal and Breeding Grounds

Identifying migratory raptors' wintering areas and migration routes is an essential part of predicting their responses to habitat and climate change throughout their annual cycles, and therefore important for their conservation. Among the world's most widespread migratory species, the Peregrine Falcon (Falco peregrinus) has been the subject of intensive study on its breeding grounds and at some migratory stopover sites, but the links between its breeding, stopover, and wintering areas remain poorly known. In particular, few empirical data are available on migratory F. p. tundrius and F. p. anatum (hereafter, Nearctic peregrines) wintering in South America during the austral spring and summer. Here, we present evidence connecting Nearctic peregrines wintering in Peru with their natal and breeding territories in North America using mark-recapture data collected between 1963 and 2019. We documented eight encounters of banded wintering Nearctic peregrines, whose natal origins or breeding regions included the Northwest Territories, Nunavut, and Yukon Territory in Canada, and Alaska, Minnesota, and Nebraska in the USA. Our findings indicate that both tundrius and anatum peregrines winter in Peru and originate from a widespread geographic breeding range, corroborating other research suggesting that Nearctic peregrine migration is highly dispersive. Peregrines exhibit sex-related differential migration patterns in which males tend to migrate farther than females, and our data from the capture of 208 Nearctic peregrines suggest that the majority of wintering birds in Peru are males (n =150; 72%). We also report new records of Nearctic peregrine arrivals in Peru that represent advances of approximately 2–3 wk compared to the earliest previously published reports. The variability of peregrines' migratory movements may be related to the behavioral plasticity that facilitated their successful recovery following their catastrophic declines in much of North America. As peregrines remain vulnerable to human impacts including habitat and climate change, continuing to fill gaps in our knowledge of Nearctic peregrines' migratory connectivity will enable continuing conservation measures for these spectacular birds.

Understanding migration motives and its impact on household welfare: evidence from rural–urban migration in Indonesia

ABSTRACT Rural–urban migration is a common demographic phenomenon in developing countries. Over the last four decades, Indonesia has had the highest rate of urbanization among Asian countries, which has been driven primarily by rural–urban migration. This type of migration has strong economic and social impacts on individuals at both the origins and the destinations. The study analyses the patterns and impacts of rural–urban migration based on the migration motives of rural households. The difference-in-differences approach is applied to identify migration’s impact on the welfare of migrant households in rural areas based on migration motives. The study uses Indonesian Family Life Survey (IFLS) data from 2007 and 2014, which consists of 2007 household samples spread over 13 provinces. Migration is found to have a positive and significant impact on migrant household welfare based on investment motives, but an insignificant result regarding the impact of migration based on risk-coping motives. Also found is the difference in migration patterns between the two migration motives.

Linking Peregrine Falcons' (Falco peregrinus) Wintering Areas in Peru with Their North American Natal and Breeding Grounds

Identifying migratory raptors' wintering areas and migration routes is an essential part of predicting their responses to habitat and climate change throughout their annual cycles, and therefore important for their conservation. Among the world's most widespread migratory species, the Peregrine Falcon (Falco peregrinus) has been the subject of intensive study on its breeding grounds and at some migratory stopover sites, but the links between its breeding, stopover, and wintering areas remain poorly known. In particular, few empirical data are available on migratory F. p. tundrius and F. p. anatum (hereafter, Nearctic peregrines) wintering in South America during the austral spring and summer. Here, we present evidence connecting Nearctic peregrines wintering in Peru with their natal and breeding territories in North America using mark-recapture data collected between 1963 and 2019. We documented eight encounters of banded wintering Nearctic peregrines, whose natal origins or breeding regions included the Northwest Territories, Nunavut, and Yukon Territory in Canada, and Alaska, Minnesota, and Nebraska in the USA. Our findings indicate that both tundrius and anatum peregrines winter in Peru and originate from a widespread geographic breeding range, corroborating other research suggesting that Nearctic peregrine migration is highly dispersive. Peregrines exhibit sex-related differential migration patterns in which males tend to migrate farther than females, and our data from the capture of 208 Nearctic peregrines suggest that the majority of wintering birds in Peru are males (n =150; 72%). We also report new records of Nearctic peregrine arrivals in Peru that represent advances of approximately 2–3 wk compared to the earliest previously published reports. The variability of peregrines' migratory movements may be related to the behavioral plasticity that facilitated their successful recovery following their catastrophic declines in much of North America. As peregrines remain vulnerable to human impacts including habitat and climate change, continuing to fill gaps in our knowledge of Nearctic peregrines' migratory connectivity will enable continuing conservation measures for these spectacular birds.