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Journal articles on the topic 'Migratory Journeys'
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1
Howard, Christine, Philip A. Stephens, Joseph A. Tobias, Catherine Sheard, Stuart H. M. Butchart, and Stephen G. Willis. "Flight range, fuel load and the impact of climate change on the journeys of migrant birds." Proceedings of the Royal Society B: Biological Sciences 285, no. 1873 (2018): 20172329. http://dx.doi.org/10.1098/rspb.2017.2329.
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Climate change is predicted to increase migration distances for many migratory species, but the physiological and temporal implications of longer migratory journeys have not been explored. Here, we combine information about species' flight range potential and migratory refuelling requirements to simulate the number of stopovers required and the duration of current migratory journeys for 77 bird species breeding in Europe. Using tracking data, we show that our estimates accord with recorded journey times and stopovers for most species. We then combine projections of altered migratory distances under climate change with models of avian flight to predict future migratory journeys. We find that 37% of migratory journeys undertaken by long-distance migrants will necessitate an additional stopover in future. These greater distances and the increased number of stops will substantially increase overall journey durations of many long-distance migratory species, a factor not currently considered in climate impact studies.
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Ho, Ming-Jung. "Migratory Journeys and Tuberculosis Risk." Medical Anthropology Quarterly 17, no. 4 (2003): 442–58. http://dx.doi.org/10.1525/maq.2003.17.4.442.
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LØnning, Moa Nyamwathi. "Layered journeys: Experiences of fragmented journeys among young Afghans in Greece and Norway." Journal of Refugee Studies 33, no. 2 (2020): 316–35. http://dx.doi.org/10.1093/jrs/feaa032.
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Abstract This article focuses on the fragmented journeys towards and within Europe among a group of young people originating from a country marked by war and conflict. It explores how the journey towards Europe may be part of a complex migration history that leads to layered journeys. I use the term ‘layered journeys’ to refer to multidimensional and multi-experiential journeys in which past, present and future experiences of mobility are intertwined. They may include multiple stages and various statuses. The article is based on ethnographic fieldwork, creative methods and life-history interviews. It focuses on a case study of a group of young Afghan males who arrived in Greece and Norway between 2008 and 2015, looking at their journeys in the context of mobility, undocumentedness and return. Young Afghans have represented the largest group of unaccompanied minor asylum seekers arriving in Europe between 2008 and 2018. While the last decade saw a considerable increase in the number of young Afghans arriving in Europe, migration itself is not a new phenomenon in the Afghan context. Afghanistan has a long history of migratory movements as part of livelihood and survival strategies, of which the past four decades of war and conflict in Afghanistan and its resulting millions of refugees are part.
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Nourani, Elham, Noriyuki M. Yamaguchi, and Hiroyoshi Higuchi. "Climate change alters the optimal wind-dependent flight routes of an avian migrant." Proceedings of the Royal Society B: Biological Sciences 284, no. 1854 (2017): 20170149. http://dx.doi.org/10.1098/rspb.2017.0149.
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Migratory birds can be adversely affected by climate change as they encounter its geographically uneven impacts in various stages of their life cycle. While a wealth of research is devoted to the impacts of climate change on distribution range and phenology of migratory birds, the indirect effects of climate change on optimal migratory routes and flyways, through changes in air movements, are poorly understood. Here, we predict the influence of climate change on the migratory route of a long-distant migrant using an ensemble of correlative modelling approaches, and present and future atmospheric data obtained from a regional climate model. We show that changes in wind conditions by mid-century will result in a slight shift and reduction in the suitable areas for migration of the study species, the Oriental honey-buzzard, over a critical section of its autumn journey, followed by a complete loss of this section of the traditional route by late century. Our results highlight the need for investigating the consequences of climate change-induced disturbance in wind support for long-distance migratory birds, particularly species that depend on the wind to cross ecological barriers, and those that will be exposed to longer journeys due to future range shifts.
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Stutchbury, Bridget J. M. "Songbird Journeys. Four Seasons in the Lives of Migratory Birds." Journal of Field Ornithology 77, no. 3 (2006): 346. http://dx.doi.org/10.1111/j.1557-9263.2006.00065_4.x.
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Alerstam, Thomas, Mikael Hake, and Nils Kjellén. "Temporal and spatial patterns of repeated migratory journeys by ospreys." Animal Behaviour 71, no. 3 (2006): 555–66. http://dx.doi.org/10.1016/j.anbehav.2005.05.016.
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Satterfield, Dara A., John C. Maerz, and Sonia Altizer. "Loss of migratory behaviour increases infection risk for a butterfly host." Proceedings of the Royal Society B: Biological Sciences 282, no. 1801 (2015): 20141734. http://dx.doi.org/10.1098/rspb.2014.1734.
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Long-distance animal migrations have important consequences for infectious disease dynamics. In some cases, migration lowers pathogen transmission by removing infected individuals during strenuous journeys and allowing animals to periodically escape contaminated habitats. Human activities are now causing some migratory animals to travel shorter distances or form sedentary (non-migratory) populations. We focused on North American monarch butterflies and a specialist protozoan parasite to investigate how the loss of migratory behaviours affects pathogen spread and evolution. Each autumn, monarchs migrate from breeding grounds in the eastern US and Canada to wintering sites in central Mexico. However, some monarchs have become non-migratory and breed year-round on exotic milkweed in the southern US. We used field sampling, citizen science data and experimental inoculations to quantify infection prevalence and parasite virulence among migratory and sedentary populations. Infection prevalence was markedly higher among sedentary monarchs compared with migratory monarchs, indicating that diminished migration increases infection risk. Virulence differed among parasite strains but was similar between migratory and sedentary populations, potentially owing to high gene flow or insufficient time for evolutionary divergence. More broadly, our findings suggest that human activities that alter animal migrations can influence pathogen dynamics, with implications for wildlife conservation and future disease risks.
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Ramji, Hasmita. "Journeys of difference: The use of migratory narratives among British Hindu Gujaratis." Ethnic and Racial Studies 29, no. 4 (2006): 702–24. http://dx.doi.org/10.1080/01419870600665441.
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Bauer, S., and B. J. Hoye. "Migratory Animals Couple Biodiversity and Ecosystem Functioning Worldwide." Science 344, no. 6179 (2014): 1242552. http://dx.doi.org/10.1126/science.1242552.
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Animal migrations span the globe, involving immense numbers of individuals from a wide range of taxa. Migrants transport nutrients, energy, and other organisms as they forage and are preyed upon throughout their journeys. These highly predictable, pulsed movements across large spatial scales render migration a potentially powerful yet underappreciated dimension of biodiversity that is intimately embedded within resident communities. We review examples from across the animal kingdom to distill fundamental processes by which migratory animals influence communities and ecosystems, demonstrating that they can uniquely alter energy flow, food-web topology and stability, trophic cascades, and the structure of metacommunities. Given the potential for migration to alter ecological networks worldwide, we suggest an integrative framework through which community dynamics and ecosystem functioning may explicitly consider animal migrations.
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Wong, Siu Ying, Anders Frederiksen, Maja Hanić, et al. "Navigation of migratory songbirds: a quantum magnetic compass sensor." Neuroforum 27, no. 3 (2021): 141–50. http://dx.doi.org/10.1515/nf-2021-0005.
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Abstract The remarkable ability of migratory birds to navigate accurately using the geomagnetic field for journeys of thousands of kilometres is currently thought to arise from radical pair reactions inside a protein called cryptochrome. In this article, we explain the quantum mechanical basis of the radical pair mechanism and why it is currently the dominant theory of compass magnetoreception. We also provide a brief account of two important computational simulation techniques that are used to study the mechanism in cryptochrome: spin dynamics and molecular dynamics. At the end, we provide an overview of current research on quantum mechanical processes in avian cryptochromes and the computational models for describing them.
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Sharma, Aakansha, Devraj Singh, Shalie Malik, Neelu Jain Gupta, Sangeeta Rani, and Vinod Kumar. "Difference in control between spring and autumn migration in birds: insight from seasonal changes in hypothalamic gene expression in captive buntings." Proceedings of the Royal Society B: Biological Sciences 285, no. 1885 (2018): 20181531. http://dx.doi.org/10.1098/rspb.2018.1531.
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We hypothesized differences in molecular strategies for similar journeys that migrants undertake to reproduce in spring and to overwinter in autumn. We tested this in redheaded buntings ( Emberiza bruniceps ) photoinduced into spring and autumn migratory states, with winter and summer non-migratory states as controls. Compared with controls, buntings fattened, gained weight and showed Zugunruhe (nocturnal migratory restlessness) in the migratory state. Spring migration was associated with greater fat and body mass, and higher intensity of Zugunruhe , compared with autumn migration. Circulating corticosterone levels were higher in spring, while T3 levels were higher in autumn. Hypothalamic expression of thyroid hormone-responsive ( dio2 , dio3 ), light-responsive ( per2 , cry1 , adcyap1 ) and th (tyrosine hydroxylase, involved in dopamine biosynthesis) genes showed significant changes with transition from non-migratory to the migratory state. There were significantly higher mRNA expressions in autumn, except for higher th levels in the spring. Furthermore, the expression patterns of dnmt3a (not dnmt3b ) and tet2 genes suggested an epigenetic difference between the non-migrant and migrant periods, and the spring and autumn migrant periods. These results demonstrate for the first time seasonal transition in hypothalamic gene expressions, and suggest differences in regulatory strategies at the transcriptional level for spring and autumn migrations in songbirds.
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Satterfield, Dara A., Peter P. Marra, T. Scott Sillett, and Sonia Altizer. "Responses of migratory species and their pathogens to supplemental feeding." Philosophical Transactions of the Royal Society B: Biological Sciences 373, no. 1745 (2018): 20170094. http://dx.doi.org/10.1098/rstb.2017.0094.
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Migratory animals undergo seasonal and often spectacular movements and perform crucial ecosystem services. In response to anthropogenic changes, including food subsidies, some migratory animals are now migrating shorter distances or halting migration altogether and forming resident populations. Recent studies suggest that shifts in migratory behaviour can alter the risk of infection for wildlife. Although migration is commonly assumed to enhance pathogen spread, for many species, migration has the opposite effect of lowering infection risk, if animals escape from habitats where pathogen stages have accumulated or if strenuous journeys cull infected hosts. Here, we summarize responses of migratory species to supplemental feeding and review modelling and empirical work that provides support for mechanisms through which resource-induced changes in migration can alter pathogen transmission. In particular, we focus on the well-studied example of monarch butterflies and their protozoan parasites in North America. We also identify areas for future research, including combining new technologies for tracking animal movements with pathogen surveillance and exploring potential evolutionary responses of hosts and pathogens to changing movement patterns. Given that many migratory animals harbour pathogens of conservation concern and zoonotic potential, studies that document ongoing shifts in migratory behaviour and infection risk are vitally needed. This article is part of the theme issue ‘Anthropogenic resource subsidies and host–parasite dynamics in wildlife’.
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Vardanis, Yannis, Raymond H. G. Klaassen, Roine Strandberg, and Thomas Alerstam. "Individuality in bird migration: routes and timing." Biology Letters 7, no. 4 (2011): 502–5. http://dx.doi.org/10.1098/rsbl.2010.1180.
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The exploration of animal migration has entered a new era with individual-based tracking during multiple years. Here, we investigated repeated migratory journeys of a long-distance migrating bird, the marsh harrier Circus aeruginosus , in order to analyse the variation within and between individuals with respect to routes and timing. We found that there was a stronger individual repeatability in time than in space. Thus, the annual timing of migration varied much less between repeated journeys of the same individual than between different individuals, while there was considerable variation in the routes of the same individual on repeated journeys. The overall contrast in repeatability between time and space was unexpected and may be owing to strong endogenous control of timing, while short-term variation in environmental conditions (weather and habitat) might promote route flexibility. The individual variation in migration routes indicates that the birds navigate mainly by other means than detailed route recapitulation based on landmark recognition.
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Kleist, Nauja. "Mobility." African Diaspora 11, no. 1-2 (2019): 71–86. http://dx.doi.org/10.1163/18725465-01101009.
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Abstract In this keyword, I reflect upon African diaspora in a mobilities perspective, exploring analytical and empirical resonance and tensions. Despite the boom of diaspora and mobilities studies in the last decades, research explicitly linking these two literatures is still nascent. Exploring diaspora through a mobilities perspective, I suggest that attention to regimes of mobilities and migratory trajectories can yield important insights. The first perspective highlights how mobility and immobility is governed, facilitated or constrained historically and today, shedding light on the unequal distribution of safe, legal and free (im)mobility for African diaspora groups, whether ‘old’ or ‘new’; the second illuminates the twists and turns of migratory journeys or displacement, bringing attention beyond the host land – homeland axis found in some diaspora studies. Finally, turning the analytical lens around, I dwell upon temporality and belonging in diaspora studies and how they link to mobility, with emphasis on potentiality and elusiveness rather than fixity and stability.
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Vansteelant, W. M. G., J. Kekkonen, and P. Byholm. "Wind conditions and geography shape the first outbound migration of juvenile honey buzzards and their distribution across sub-Saharan Africa." Proceedings of the Royal Society B: Biological Sciences 284, no. 1855 (2017): 20170387. http://dx.doi.org/10.1098/rspb.2017.0387.
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Contemporary tracking studies reveal that low migratory connectivity between breeding and non-breeding ranges is common in migrant landbirds. It is unclear, however, how internal factors and early-life experiences of individual migrants shape the development of their migration routes and concomitant population-level non-breeding distributions. Stochastic wind conditions and geography may determine whether and where migrants end up by the end of their journey. We tested this hypothesis by satellite-tagging 31 fledgling honey buzzards Pernis apivorus from southern Finland and used a global atmospheric reanalysis model to estimate the wind conditions they encountered on their first outbound migration. Migration routes diverged rapidly upon departure and the birds eventually spread out across 3340 km of longitude. Using linear regression models, we show that the birds' longitudinal speeds were strongly affected by zonal wind speed, and negatively affected by latitudinal wind, with significant but minor differences between individuals. Eventually, 49% of variability in the birds' total longitudinal displacements was accounted for by wind conditions on migration. Some birds circumvented the Baltic Sea via Scandinavia or engaged in unusual downwind movements over the Mediterranean, which also affected the longitude at which these individuals arrived in sub-Saharan Africa. To understand why adult migrants use the migration routes and non-breeding sites they use, we must take into account the way in which wind conditions moulded their very first journeys. Our results present some of the first evidence into the mechanisms through which low migratory connectivity emerges.
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Houston, C. Stuart. ""Songbird Journeys: Four Seasons in the Lives of Migratory Birds" by Miyoko Chu. 2006. [book review]." Canadian Field-Naturalist 120, no. 3 (2006): 385. http://dx.doi.org/10.22621/cfn.v120i3.341.
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Martins Junior, Angelo. "Jornadas Diferenciadas." Plural 27, no. 1 (2020): 114–44. http://dx.doi.org/10.11606/issn.2176-8099.pcso.2020.171532.
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This article question generic homogenising representations of ‘the migrant’ by providing an examination of the multivalent ways in which social differences contours migration processes. Migration scholars often reproduce generic homogenising typologies of ‘migrants’, such as the two opposing migrant analogies ‘from the Global South’ (‘the transnational migrant’, who flows through social networks from the Global South to the developed North, seeking economic gains) and ‘from the Global North’ (‘the lifestyle migrant’, who chooses to migrate from developed countries to places they believe offers them the potential of a better quality of life). Through the examination of the journeys of Brazilians in London, this article draws attention to the connections and contexts of both sending and receiving societies, as well as the diversity existing within the Brazilian population abroad. As is argued within this paper, such an analysis allows for better understanding of how the experiences of Brazilians in London are directly shaped by the intersection of multiple social markers, resulting in what I call ‘differentiated journeys’. Brazilians navigate different levels of constraints and constantly re-formulate their journeys due to their class, gender, nationality and documental status. This allow us to frame migratory experiences beyond generalizing and homogenising representations. The empirical research combines an 18-month ethnography in places of leisure with 33 in-depth interviews with Brazilians in London.
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Hermansson, Joakim. "Characters as fictional migrants: Atonement, adaptation and the screenplay process." Journal of Screenwriting 11, no. 1 (2020): 81–97. http://dx.doi.org/10.1386/josc_00014_1.
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The migration metaphor has been widely used in connection with media adaptions, but the metaphor has remained an abstract figure of speech. Yet, to understand characters as migrants who go through journeys of acculturation when they are adapted for the screen may enhance understanding of both the characters’ potential and problems that may arise during the development process. This article proposes that the development of characters and their processes ‐ as fictional beings ‐ can be understood through the use of models that describe real migrants’ adaptation processes. Using Christopher Hampton’s screenplay drafts for the film Atonement (2001), it outlines how such migratory journeys go hand in hand with screenwriters’ problem-solving processes. The article thus develops the idea that migrating characters, in their capacity as fictional beings and the thematic issues that they represent, both adapt to and appropriate their new media environments; simultaneously, they are appropriated by new creative forces and by the conventions of those new media environments, who in turn must adapt to the characters in this process of bi-directional acculturation.
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Kilinc, Deniz. "Crossing Borders: Turkish Asylum Policies and Displaced Syrians’ Journeys in and away from Turkey." Bibliotekarz Podlaski Ogólnopolskie Naukowe Pismo Bibliotekoznawcze i Bibliologiczne 47, no. 2 (2020): 111–23. http://dx.doi.org/10.36770/bp.472.
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In recent years, economic, political and ecological crises throughout the world have created a monumental human flux, forming new migratory routes, spaces and challenges. As a result of these movements, distinct geographical, political, and social borders are formed and crossed, giving life to unique journeys with distinct stories. The current paper presents observations from field research and a creative expression intervention (conducted in 2015–2016) with Syrian displaced people in Turkey to illustrate the mutual relationship between Turkish asylum policies and the movements of Syrian migrants in and away from Turkey. It unpacks three different routes to contextualize the ways in which the availability and the characteristics of labour shape the mobility of displaced Syrians in Turkey. In examining the movements of people and communities through the lens of political and economic dynamics, the paper argues that displaced Syrians’ mobility is largely shaped by Turkish refugee policies, which deny migrants access to legal work and condemn them to vulnerability and destitution.
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Nourani, Elham, Gil Bohrer, Paolo Becciu, et al. "The interplay of wind and uplift facilitates over-water flight in facultative soaring birds." Proceedings of the Royal Society B: Biological Sciences 288, no. 1958 (2021): 20211603. http://dx.doi.org/10.1098/rspb.2021.1603.
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Flying over the open sea is energetically costly for terrestrial birds. Despite this, over-water journeys of many birds, sometimes hundreds of kilometres long, are uncovered by bio-logging technology. To understand how these birds afford their flights over the open sea, we investigated the role of atmospheric conditions, specifically wind and uplift, in subsidizing over-water flight at a global scale. We first established that Δ T , the temperature difference between sea surface and air, is a meaningful proxy for uplift over water. Using this proxy, we showed that the spatio-temporal patterns of sea-crossing in terrestrial migratory birds are associated with favourable uplift conditions. We then analysed route selection over the open sea for five facultative soaring species, representative of all major migratory flyways. The birds maximized wind support when selecting their sea-crossing routes and selected greater uplift when suitable wind support was available. They also preferred routes with low long-term uncertainty in wind conditions. Our findings suggest that, in addition to wind, uplift may play a key role in the energy seascape for bird migration that in turn determines strategies and associated costs for birds crossing ecological barriers such as the open sea.
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Lam, Lawrence, Emily A. McKinnon, James D. Ray, et al. "The influence of morphological variation on migration performance in a trans-hemispheric migratory songbird." Animal Migration 2, no. 1 (2015): 86–95. http://dx.doi.org/10.1515/ami-2015-0005.
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AbstractFor long-distance migratory songbirds, morphological traits such as longer wings and a smaller body size are predicted to increase migration efficiency. Due to previous limitations in our ability to track the long-distance journeys of small-bodied birds, the relationship between morphology and start-to-finish migration performance has never been fully tested in free-living songbirds. Using direct-tracking data obtained from light-level geolocators, we examined the effects of morphological factors (wing and body size) on spring and fall migration performance (flight speed, duration of stopovers, total stopovers taken) of a widely distributed, trans-hemispheric migratory songbird, the purple martin (Progne subis) (n = 120). We found that smaller-bodied birds spent fewer days at stopovers along fall migration, but larger-bodied birds spent fewer days at stopover and took fewer stopovers during spring migration. More of the variation in fall migration performance was explained by morphology, as compared to spring migration, possibly indicating a larger influence of environmental conditions on spring performance. Overall, our results partially support long-standing and previously untested predictions regarding the influence of intrinsic factors on migration performance. Future research should examine the influence of environmental variation on migration performance as well as additional morphological traits that may contribute to migration performance.
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La Sorte, Frank A., Daniel Fink, Wesley M. Hochachka, and Steve Kelling. "Convergence of broad-scale migration strategies in terrestrial birds." Proceedings of the Royal Society B: Biological Sciences 283, no. 1823 (2016): 20152588. http://dx.doi.org/10.1098/rspb.2015.2588.
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Migration is a common strategy used by birds that breed in seasonal environments. Selection for greater migration efficiency is likely to be stronger for terrestrial species whose migration strategies require non-stop transoceanic crossings. If multiple species use the same transoceanic flyway, then we expect the migration strategies of these species to converge geographically towards the most optimal solution. We test this by examining population-level migration trajectories within the Western Hemisphere for 118 migratory species using occurrence information from eBird. Geographical convergence of migration strategies was evident within specific terrestrial regions where geomorphological features such as mountains or isthmuses constrained overland migration. Convergence was also evident for transoceanic migrants that crossed the Gulf of Mexico or Atlantic Ocean. Here, annual population-level movements were characterized by clockwise looped trajectories, which resulted in faster but more circuitous journeys in the spring and more direct journeys in the autumn. These findings suggest that the unique constraints and requirements associated with transoceanic migration have promoted the spatial convergence of migration strategies. The combination of seasonal atmospheric and environmental conditions that has facilitated the use of similar broad-scale migration strategies may be especially prone to disruption under climate and land-use change.
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Brönmark, C., K. Hulthén, P. A. Nilsson, et al. "There and back again: migration in freshwater fishes." Canadian Journal of Zoology 92, no. 6 (2014): 467–79. http://dx.doi.org/10.1139/cjz-2012-0277.
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Animal migration is an amazing phenomenon that has fascinated humans for long. Many freshwater fishes also show remarkable migrations, whereof the spectacular mass migrations of salmonids from the spawning streams are the most well known and well studied. However, recent studies have shown that migration occurs in a range of freshwater fish taxa from many different habitats. In this review we focus on the causes and consequences of migration in freshwater fishes. We start with an introduction of concepts and categories of migration, and then address the evolutionary causes that drive individuals to make these migratory journeys. The basis for the decision of an individual fish to migrate or stay resident is an evaluation of the costs and benefits of different strategies to maximize its lifetime reproductive effort. We provide examples by discussing our own work on the causes behind seasonal migration in a cyprinid fish, roach (Rutilus rutilus (L., 1758)), within this framework. We then highlight different adaptations that allow fish to migrate over sometimes vast journeys across space, including capacity for orientation, osmoregulation, and efficient energy expenditure. Following this we consider the consequences of migration in freshwater fish from ecological, evolutionary, and conservation perspectives, and finally, we detail some of the recent developments in the methodologies used to collect data on fish migration and how these could be used in future research.
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Ferenc, Tomasz. "Coercion, Compulsion, Forced Emigrations. Experiences of Polish Artists during the Martial Law in Poland." Studia Migracyjne – Przegląd Polonijny 46, no. 3 (177) (2020): 33–50. http://dx.doi.org/10.4467/25444972smpp.20.029.12593.
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A sociological look at artists’ biographies makes one reflect on their increased mobility. Purposes and reasons of the artists’ migratory journeys are various, they have a different character and their effects also vary. The article based on the narratives of the Polish artists shows three variants of making decisions to emigrate from Poland following the imposition of the martial law in December of 1981. The purpose of the article is also an attempt to modify the dominant definitions of forced emigration by extending it to the aspect of internal coercion generating a strong push impulse. This internal factor seems to be very important in the cases analysed in the article. The biographical interview method allows to indicate that, apart from external coercion, various entanglements of circumstances and trajectories are revealed, which in some cases lead to the decision to leave the home country.
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Strandberg, Roine, Raymond H. G. Klaassen, Mikael Hake, and Thomas Alerstam. "How hazardous is the Sahara Desert crossing for migratory birds? Indications from satellite tracking of raptors." Biology Letters 6, no. 3 (2009): 297–300. http://dx.doi.org/10.1098/rsbl.2009.0785.
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We investigated the risk associated with crossing the Sahara Desert for migrating birds by evaluating more than 90 journeys across this desert by four species of raptors (osprey Pandion haliaetus , honey buzzard Pernis apivorus , marsh harrier Circus aeruginosus and Eurasian hobby Falco subbuteo ) recorded by satellite telemetry. Forty per cent of the crossings included events of aberrant behaviours, such as abrupt course changes, slow travel speeds, interruptions, aborted crossings followed by retreats from the desert and failed crossings due to death, indicating difficulties for the migrants. The mortality during the Sahara crossing was 31 per cent per crossing attempt for juveniles (first autumn migration), compared with only 2 per cent for adults (autumn and spring combined). Mortality associated with the Sahara passage made up a substantial fraction (up to about half for juveniles) of the total annual mortality, demonstrating that this passage has a profound influence on survival and fitness of migrants. Aberrant behaviours resulted in late arrival at the breeding grounds and an increased probability of breeding failure (carry-over effects). This study also demonstrates that satellite tracking can be a powerful method to reveal when and where birds are exposed to enhanced risk and mortality during their annual cycles.
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Price, Gilbert J., Kyle J. Ferguson, Gregory E. Webb, et al. "Seasonal migration of marsupial megafauna in Pleistocene Sahul (Australia–New Guinea)." Proceedings of the Royal Society B: Biological Sciences 284, no. 1863 (2017): 20170785. http://dx.doi.org/10.1098/rspb.2017.0785.
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Seasonal two-way migration is an ecological phenomenon observed in a wide range of large-bodied placental mammals, but is conspicuously absent in all modern marsupials. Most extant marsupials are typically smaller in body size in comparison to their migratory placental cousins, possibly limiting their potential to undertake long-distance seasonal migrations. But what about earlier, now-extinct giant marsupial megafauna? Here we present new geochemical analyses which show that the largest of the extinct marsupial herbivores, the enormous wombat-like Diprotodon optatum , undertook seasonal, two-way latitudinal migration in eastern Sahul (Pleistocene Australia–New Guinea). Our data infer that this giant marsupial had the potential to perform round-trip journeys of as much as 200 km annually, which is reminiscent of modern East African mammal migrations. These findings provide, to our knowledge, the first evidence for repetitive seasonal migration in any metatherian (including marsupials), living or extinct, and point to an ecological phenomenon absent from the continent since the Late Pleistocene.
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Müller, Martina S., Bruno Massa, Richard A. Phillips, and Giacomo Dell’omo. "Individual consistency and sex differences in migration strategies of Scopoli’s shearwaters Calonectris diomedea despite year differences." Current Zoology 60, no. 5 (2014): 631–41. http://dx.doi.org/10.1093/czoolo/60.5.631.
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Abstract Recently-developed capabilities for tracking the movements of individual birds over the course of a year or longer has provided increasing evidence for consistent individual differences in migration schedules and destinations. This raises questions about the relative importance of individual consistency versus flexibility in the evolution of migration strategies, and has implications for the ability of populations to respond to climatic change. Using geolocators, we tracked the migrations of Scopoli’s shearwaters Calonectris diomedea breeding in Linosa (Italy) across three years, and analysed timing and spatial aspects of their movements. Birds showed remarkable variation in their main wintering destination along the western coast of Africa. We found significant individual consistency in the total distance traveled, time spent in transit, and time that individuals spent in the wintering areas. We found extensive sex differences in scheduling, duration, distances and destinations of migratory journeys. We also found sex differences in the degree of individual consistency in aspects of migration behaviour. Despite strong evidence for individual consistency, which indicates that migration journeys from the same bird tended to be more similar than those of different birds, there remained substantial intra-individual variation between years. Indeed, we also found clear annual differences in departure dates, return dates, wintering period, the total distance traveled and return routes from wintering grounds back to the colony. These findings show that this population flexibly shifts migration schedules as well as routes between years in response to direct or indirect effects of heterogeneity in the environment, while maintaining consistent individual migration strategies.
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Nguyen, Kieu Nga, and Helen Jaqueline McLaren. "Female Student Migration: A Brief Opportunity for Freedom from Religio-Philosophical Obedience." Religions 11, no. 11 (2020): 556. http://dx.doi.org/10.3390/rel11110556.
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Vietnamese Confucian religio-philosophical ideals regulate social order in the family, community, and nation state. As a result, women’s duties to their husbands, fathers, ancestors, and Vietnam powerfully permeate all aspects of gendered life. This study of 20 Vietnamese women explored their experiences as international students in Australia. Primary focus was on how their gendered Confucian histories compelled their migratory journeys, influenced changes to their intimate partner experiences while in Australia, and the reimagining of identity, hopes and dreams on looking forward at their future returns to gendered life in Vietnam. The application of Janus Head phenomenology enabled understanding of how the women’s temporality became influenced by fascinations of future change, mixed with feelings of uncertainty and limbo that arose when forward facing hopes were thwarted by their looking back realities. There was an intense sense of unresolve as time drew closer to the end of their studies, in which the women associated feelings related to returning to Vietnam’s strict Confucian informed gender order as a “living Hell.”
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Peck, Gunther. "Migrant Labor and Global Commons: Transnational Subjects, Visions, and Methods." International Labor and Working-Class History 85 (2014): 118–37. http://dx.doi.org/10.1017/s0147547913000501.
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AbstractDespite the prominence of both migrant workers and “global commons” as protagonists in recent meetings of the World Social Forum, few activists or scholars have successfully linked their historical agency or significance. In the following essay, I locate conceptual starting points for linking migrant workers and global commons by analyzing the work of the transnational and the commons in political conversation at the WSF and in the historiographies of immigration and the environment in North America. I argue that the transnational and global commons are best understood as analytical vantages rather than as utopian visions of nation-state transcendence. Using research into the history of human trafficking, I explore the analytical advantages of linking migrant workers to global commons. As inevitable trespassers of both national sovereignty and property claims, migrant workers' journeys help reveal a global commons that is, like them, migratory, fleeting, and often illegible to the state authorities. Such commons are not pristine wildernesses, but polyglots of weedy hybrids. Migrant workers' transnational vantages illuminate the limits of enclosure and the enduring adaptability of nonhuman nature across national boundaries.
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Väli, Ülo, Paweł Mirski, Urmas Sellis, Mindaugas Dagys, and Grzegorz Maciorowski. "Genetic determination of migration strategies in large soaring birds: evidence from hybrid eagles." Proceedings of the Royal Society B: Biological Sciences 285, no. 1884 (2018): 20180855. http://dx.doi.org/10.1098/rspb.2018.0855.
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The relative contributions of genetic and social factors in shaping the living world are a crucial question in ecology. The annual migration of birds to their wintering grounds and back provides significant knowledge in this field of research. Migratory movements are predominantly genetically determined in passerine birds, while in large soaring birds, it is presumed that social (cultural) factors play the largest role. In this study, we show that genetic factors in soaring birds are more important than previously assumed. We used global positioning system (GPS)-telemetry to compare the autumn journeys and wintering ranges of two closely related large raptorial bird species, the greater spotted eagle Clanga clanga and the lesser spotted eagle Clanga pomarina , and hybrids between them. The timing of migration in hybrids was similar to that of one parental species, but the wintering distributions and home range sizes were similar to those of the other. Tracking data were supported by habitat suitability modelling, based on GPS fixes and ring recoveries. These results suggest a strong genetic influence on migration strategy via a trait-dependent dominance effect, although we cannot rule out the contribution of social interactions.
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Luschi, Paolo. "Long-Distance Animal Migrations in the Oceanic Environment: Orientation and Navigation Correlates." ISRN Zoology 2013 (January 14, 2013): 1–23. http://dx.doi.org/10.1155/2013/631839.
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A large variety of marine animals migrate in the oceanic environment, sometimes aiming at specific targets such as oceanic islands or offshore productive areas. Thanks to recent technological developments, various techniques are available to track marine migrants, even when they move in remote or inhospitable areas. The paper reviews the main findings obtained by tracking marine animals during migratory travels extending over large distances, with a special attention to the orientation and navigation aspects of these phenomena. Long-distance movements have now been recorded in many marine vertebrates, revealing astonishing performances such as individual fidelity to specific sites and basin-wide movements directed towards these locations. Seabirds cover the longest distances, sometimes undertaking interhemispheric flights, but transoceanic migrations are also the rule in pelagic fish, turtles, pinnipeds, and whales. Some features of these journeys call for the involvement of efficient orientation and navigational abilities, but little evidence is available in this respect. Oceanic migrants most likely rely on biological compasses to maintain a direction in the open sea, and displacement experiments have provided evidence for an ability of seabirds and turtles to rely on position-fixing mechanisms, possibly involving magnetic and/or olfactory cues, although simpler navigational systems are not to be excluded.
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Bairlein, Franz, D. Ryan Norris, Rolf Nagel, et al. "Cross-hemisphere migration of a 25 g songbird." Biology Letters 8, no. 4 (2012): 505–7. http://dx.doi.org/10.1098/rsbl.2011.1223.
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The northern wheatear ( Oenanthe oenanthe ) is a small (approx. 25 g), insectivorous migrant with one of the largest ranges of any songbird in the world, breeding from the eastern Canadian Arctic across Greenland, Eurasia and into Alaska (AK). However, there is no evidence that breeding populations in the New World have established overwintering sites in the Western Hemisphere. Using light-level geolocators, we demonstrate that individuals from these New World regions overwinter in northern sub-Sahara Africa, with Alaskan birds travelling approximately 14 500 km each way and an eastern Canadian Arctic bird crossing a wide stretch of the North Atlantic (approx. 3500 km). These remarkable journeys, particularly for a bird of this size, last between one to three months depending on breeding location and season (autumn/spring) and result in mean overall migration speeds of up to 290 km d −1 . Stable-hydrogen isotope analysis of winter-grown feathers sampled from breeding birds generally support the notion that Alaskan birds overwinter primarily in eastern Africa and eastern Canadian Arctic birds overwinter mainly in western Africa. Our results provide the first evidence of a migratory songbird capable of linking African ecosystems of the Old World with Arctic regions of the New World.
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Buehler, Deborah M., and Theunis Piersma. "Travelling on a budget: predictions and ecological evidence for bottlenecks in the annual cycle of long-distance migrants." Philosophical Transactions of the Royal Society B: Biological Sciences 363, no. 1490 (2007): 247–66. http://dx.doi.org/10.1098/rstb.2007.2138.
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Long-distance migration, and the study of the migrants who undertake these journeys, has fascinated generations of biologists. However, many aspects of the annual cycles of these migrants remain a mystery as do many of the driving forces behind the evolution and maintenance of the migrations themselves. In this article we discuss nutritional, energetic, temporal and disease - risk bottlenecks in the annual cycle of long-distance migrants, taking a sandpiper, the red knot Calidris canutus , as a focal species. Red knots have six recognized subspecies each with different migratory routes, well-known patterns of connectivity and contrasting annual cycles. The diversity of red knot annual cycles allows us to discuss the existence and the effects of bottlenecks in a comparative framework. We examine the evidence for bottlenecks focusing on the quality of breeding plumage and the timing of moult as indicators in the six subspecies. In terms of breeding plumage coloration, quality and timing of prealternate body moult (from non-breeding into breeding plumage), the longest migrating knot subspecies, Calidris canutus rogersi and Calidris canutus rufa , show the greatest impact of bottlenecking. The same is true in terms of prebasic body moult (from breeding into non-breeding plumage) which in case of both C. c. rogersi and C. c. rufa overlaps with southward migration and may even commence in the breeding grounds. To close our discussion of bottlenecks in long-distance migrants, we make predictions about how migrants might be impacted via physiological ‘trade-offs’ throughout the annual cycle, using investment in immune function as an example. We also predict how bottlenecks may affect the distribution of mortality throughout the annual cycle. We hope that this framework will be applicable to other species and types of migrants, thus expanding the comparative database for the future evaluation of seasonal selection pressures and the evolution of annual cycles in long-distance migrants. Furthermore, we hope that this synthesis of recent advancements in the knowledge of red knot annual cycles will prove useful in the ongoing attempts to model annual cycles in migratory birds.
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Harvey, A. C., M. Quintela, K. A. Glover, et al. "Inferring Atlantic salmon post-smolt migration patterns using genetic assignment." Royal Society Open Science 6, no. 10 (2019): 190426. http://dx.doi.org/10.1098/rsos.190426.
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Understanding migratory patterns is important for predicting and mitigating unwanted consequences of environmental change or anthropogenic challenges on vulnerable species. Wild Atlantic salmon undergo challenging migrations between freshwater and marine environments, and the numbers of salmon returning to their natal rivers to reproduce have declined over several decades. Mortality from sea lice linked to fish farms within their seaward migration routes is proposed as a contributing factor to these declines. Here, we used 31 microsatellite markers to establish a genetic baseline for the main rivers in the Hardangerfjord, western Norway. Mixed stock analysis was used to assign Atlantic salmon post-smolts caught in trawls in 2013–2017 back to regional reporting units. Analyses demonstrated that individuals originating from rivers located in the inner region of the fjord arrived at the outer fjord later than individuals from middle and outer fjord rivers. Therefore, as post-smolts originating from inner rivers also have to migrate longer distances to exit the fjord, these data suggest that inner fjord populations are more likely to be at risk of mortality through aquaculture-produced sea lice, and other natural factors such as predation, than middle or outer fjord populations with earlier exit times and shorter journeys. These results will be used to calibrate models estimating mortality from sea lice on wild salmon for the regulation of the Norwegian aquaculture industry.
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Best-Cummings, Christiana, and Margery A. Gildner. "Caribbean Women's Migratory Journey." Journal of Immigrant & Refugee Services 2, no. 3-4 (2004): 83–101. http://dx.doi.org/10.1300/j191v02n03_06.
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Diaz, Joseph O. Prewitt. "The Migratory Journey of Unaccompanied Children." Journal of Psychology & Behavior Research 3, no. 2 (2021): p21. http://dx.doi.org/10.22158/jpbr.v3n2p21.
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This article provides a brief discussion on the psychosocial needs of unaccompanied minors crossing the southern border of the United States. It highlights various aspects of migration, and the resulting emotional and psychological impact on unaccompanied minors; it subsequently proposes a resilience approach, in terms of protective behaviors towards increased adjustment and success in a new environment.
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Hesk, Gabrielle. "Gather in my name, my skin, my everything… (“Gather in my Name”: Maya Angelou, 1974)." Qualitative Research Journal 17, no. 3 (2017): 188–201. http://dx.doi.org/10.1108/qrj-03-2017-0007.
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Purpose Based on a performance of a conversation between my white mother and myself – her mixed race black daughter – the purpose of this paper is to deconstruct the complexity of the intersection of migration, racism, sexism, disability, and class within the space and place of the dynamics of our relationship. “Migration” and “borders” metaphors explore the “in between space that is neither here nor there” addressing key issues such as “migratory subjectivity” or, in other words, the translation of the process of inclusion and exclusion across the borders of oppressive social constructions to the lived emotional experience of being a mother and a daughter. Design/methodology/approach I explore my lived experience as black woman raised by a white Mum. My decision to use intersectionality as a tool with which to explore my personal experiences was based on me finding it enabled me to fully engage with the freedom of exploration, without feeling the need to “fit” with what was expected, in other words to be free to be able to express the “[…] lived experience of a presumed ‘Other’ and to experience it viscerally” (Orbe and Boylorn, 2014, p. 15). Findings A truthful account to aid the understanding of the complexities faced in the lived experience of a white mother and her black daughter. Research limitations/implications This piece has no limitations, and contains far reaching implications for social work practice and research methods. Practical implications This piece is embedded in social education and can be used as a research tool for best practice in anti-racist, black feminist practice. Social implications Social implications include a potential impact on diverse communities, with relevance to community engagement, social work practice placements, and critical reflection, and also education of the young to help them understand their own journeys. Originality/value This is an original report of an evidence-based lived experience, integrating theory to practice.
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González, Betsabé Román, Eduardo Carrillo Cantú, and Rubén Hernández-León. "Moving to the ‘Homeland’." Mexican Studies/Estudios Mexicanos 32, no. 2 (2016): 252–75. http://dx.doi.org/10.1525/mex.2016.32.2.252.
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A growing number of minors have become part of the return migratory flow from the United States to Mexico. Based on a longitudinal study started in 2012, this article uses life-history narratives to analyze the return experiences of three children who arrived in the state of Morelos, Mexico, between 2010 and 2012. The findings presented here focus on a specific segment of the children’s migratory journey: leaving the United States, crossing the border and arriving in Morelos. The article contributes to the scholarship on children’s narratives of migration, which has been under-emphasized in traditional studies of United States-Mexico migration. Un número creciente de menores de edad forma parte del flujo migratorio de retorno de Estados Unidos a México. Con base en un estudio longitudinal iniciado en el 2012, este artículo hace uso de las historias de vida para analizar las experiencias de retorno de tres niños que llegaron al estado de Morelos, México, entre el 2010 y el 2012. Los resultados que se presentan están centrados en un segmento específico del recorrido migratorio de estos niños: partir de los Estados Unidos, cruzar la frontera y llegar a Morelos. Este artículo contribuye a los estudios migratorios centrados en la narrativa de los niños, la cual ha sido poco valorada en los estudios de migración entre Estados Unidos y México.
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Hayes, Matthew A., Anne E. Lacy, Jeb Barzen, Sara E. Zimorski, Kristin A. L. Hall, and Koji Suzuki. "An Unusual Journey of Non-migratory Whooping Cranes." Southeastern Naturalist 6, no. 3 (2007): 551–58. http://dx.doi.org/10.1656/1528-7092(2007)6[551:aujonw]2.0.co;2.
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Toledo, Pamela, Audrey M. Darnaude, Edwin J. Niklitschek, et al. "Partial migration and early size of southern hake Merluccius australis: a journey between estuarine and oceanic habitats off Northwest Patagonia." ICES Journal of Marine Science 76, no. 4 (2018): 1094–106. http://dx.doi.org/10.1093/icesjms/fsy170.
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Abstract Partial migration is a key adaptive strategy, increasingly observed across multiple taxa. To investigate partial migration and life-cycle diversity of Merluccius australis in northwestern Patagonia, we analysed isotopic (δ13C, δ18O) and elemental (11B, 23Na, 24 Mg, 55Mn, 86Sr, 138Ba) compositions of otoliths from juveniles, sub-adults, and adults to identify nursery origins, habitats used, and migratory behaviours of multiple cohorts (1990–2005). Influence of early size upon migration was assessed by comparing back-calculated sizes at demersal recruitment between resident and migratory adults. Although partial migration occurred at both estuarine and oceanic nursery habitats, migratory behaviour was more frequent in fish of estuarine origin (59%) than in fish of oceanic origin (17%). Adults of estuarine origin dominated both estuarine (92%) and oceanic (77%) sampling areas. Although we found no significant differences in size at demersal recruitment between oceanic-resident and oceanic-migratory fish, a strong relationship between size at demersal recruitment and migratory behaviour appeared in fish of estuarine origin, whose probability of migration increased from 5% to 95% as demersal recruitment size increased from 18.8 to 23.6 cm. Further research on M. australis life cycle is required to incorporate sub-population processes into the stock assessment and management models being used for this overexploited species.
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Nguyen, Tu Anh Thi, M. Jerome Beetz, Christine Merlin, and Basil el Jundi. "Sun compass neurons are tuned to migratory orientation in monarch butterflies." Proceedings of the Royal Society B: Biological Sciences 288, no. 1945 (2021): 20202988. http://dx.doi.org/10.1098/rspb.2020.2988.
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Every autumn, monarch butterflies migrate from North America to their overwintering sites in Central Mexico. To maintain their southward direction, these butterflies rely on celestial cues as orientation references. The position of the sun combined with additional skylight cues are integrated in the central complex, a region in the butterfly's brain that acts as an internal compass. However, the central complex does not solely guide the butterflies on their migration but also helps monarchs in their non-migratory form manoeuvre on foraging trips through their habitat. By comparing the activity of input neurons of the central complex between migratory and non-migratory butterflies, we investigated how a different lifestyle affects the coding of orientation information in the brain. During recording, we presented the animals with different simulated celestial cues and found that the encoding of the sun was narrower in migratory compared to non-migratory butterflies. This feature might reflect the need of the migratory monarchs to rely on a precise sun compass to keep their direction during their journey. Taken together, our study sheds light on the neural coding of celestial cues and provides insights into how a compass is adapted in migratory animals to successfully steer them to their destination.
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Ponce-Blandón, José Antonio, Rocío Romero-Castillo, Nerea Jiménez-Picón, Juan Carlos Palomo-Lara, Aurora Castro-Méndez, and Manuel Pabón-Carrasco. "Lived Experiences of African Migrants Crossing the Strait of Gibraltar to Europe: A Cross-Cultural Approach to Healthcare from a Qualitative Methodology." International Journal of Environmental Research and Public Health 18, no. 17 (2021): 9379. http://dx.doi.org/10.3390/ijerph18179379.
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Background: The migratory flow from the African continent to Europe is intense and the European countries should apply a humanitarian, health and social response to this emerging problem. Migrants coming from Africa to Europe are a very vulnerable population. Healthcare professionals should be prepared for answering their needs from a transcultural approach, which requires a better understanding of this phenomenon. Thus, the aim of this study was to improve nursing and healthcare professionals’ awareness and better understanding of migrant life experiences during the migration journey. An exploratory descriptive qualitative research was conducted. In-depth interviews were conducted involving four key informants and content analysis were performed with the transcriptions. Results: Three themes merged: life situations in their countries of origin; motivations that led them to undertake the migratory journey; and experiences they lived during the migratory journey. The results described the dramatic experience and motivations for crossing the strait of Gibraltar from Africa to Europe, including feelings, fears, hopes and lived experiences. The determination of immigrants to fight for a better life opportunity and the physical damage and psychological consequences they suffer were revealed. Conclusions: This study would help healthcare professionals to better understand this complex reality and deliver culturally adapted care. Knowledge of the starting reality of these populations can help health professionals to incorporate a cross-cultural approach that improves the relational, ethical and affective competences to provide quality care to the migrant population, as well as the development of health measures to fight against inequalities suffered by these population groups.
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Kullberg, Cecilia, Ian Henshaw, Sven Jakobsson, Patrik Johansson, and Thord Fransson. "Fuelling decisions in migratory birds: geomagnetic cues override the seasonal effect." Proceedings of the Royal Society B: Biological Sciences 274, no. 1622 (2007): 2145–51. http://dx.doi.org/10.1098/rspb.2007.0554.
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Recent evaluations of both temporal and spatial precision in bird migration have called for external cues in addition to the inherited programme defining the migratory journey in terms of direction, distance and fuelling behaviour along the route. We used juvenile European robins ( Erithacus rubecula ) to study whether geomagnetic cues affect fuel deposition in a medium-distance migrant by simulating a migratory journey from southeast Sweden to the wintering area in southern Spain. In the late phase of the onset of autumn migration, robins exposed to the magnetic treatment attained a lower fuel load than control birds exposed to the ambient magnetic field of southeast Sweden. In contrast, robins captured in the early phase of the onset of autumn migration all showed low fuel deposition irrespective of experimental treatment. These results are, as expected, the inverse of what we have found in similar studies in a long-distance migrant, the thrush nightingale ( Luscinia luscinia ), indicating that the reaction in terms of fuelling behaviour to a simulated southward migration varies depending on the relevance for the species. Furthermore, we suggest that information from the geomagnetic field act as an important external cue overriding the seasonal effect on fuelling behaviour in migratory birds.
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Hamman, Evan. "Bilateral agreements for the protection of migratory birdlife: the implementation of the China-Australia Migratory Bird Agreement (CAMBA)." Asia Pacific Journal of Environmental Law 22, no. 1 (2019): 137–59. http://dx.doi.org/10.4337/apjel.2019.01.07.
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Every year, millions of migratory birds journey along the East Asian-Australasian Flyway (EAAF). The scope of the EAAF encompasses Asia Pacific nations like Australia, New Zealand, China, Japan, South Korea, Vietnam, Malaysia and Indonesia. The effective conservation of these birds rests upon the implementation of bilateral legal agreements as well as non-binding regional initiatives along this North-South nexus. This article evaluates the implementation of one of the most important bilateral bird agreements in the region – the China-Australia Migratory Bird Agreement (CAMBA). The main obligations in CAMBA are identified; as are the legal initiatives adopted by both China and Australia which reflect CAMBA's obligations. Whilst Australian law makes specific reference to CAMBA, Chinese law is far less direct, though perhaps no less effective. The argument is made that the findings in this article have relevance for an improved understanding of the mechanisms for transboundary governance of migratory birdlife, especially in the Asia Pacific.
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Flack, Andrea, Wolfgang Fiedler, Julio Blas, et al. "Costs of migratory decisions: A comparison across eight white stork populations." Science Advances 2, no. 1 (2016): e1500931. http://dx.doi.org/10.1126/sciadv.1500931.
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Annual migratory movements can range from a few tens to thousands of kilometers, creating unique energetic requirements for each specific species and journey. Even within the same species, migration costs can vary largely because of flexible, opportunistic life history strategies. We uncover the large extent of variation in the lifetime migratory decisions of young white storks originating from eight populations. Not only did juvenile storks differ in their geographically distinct wintering locations, their diverse migration patterns also affected the amount of energy individuals invested for locomotion during the first months of their life. Overwintering in areas with higher human population reduced the stork’s overall energy expenditure because of shorter daily foraging trips, closer wintering grounds, or a complete suppression of migration. Because migrants can change ecological processes in several distinct communities simultaneously, understanding their life history decisions helps not only to protect migratory species but also to conserve stable ecosystems.
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Eikenaar, Cas, Florian Müller, Clara Leutgeb, et al. "Corticosterone and timing of migratory departure in a songbird." Proceedings of the Royal Society B: Biological Sciences 284, no. 1846 (2017): 20162300. http://dx.doi.org/10.1098/rspb.2016.2300.
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Bird migration entails replenishing fuel stores at stopover sites. There, individuals make daily decisions whether to resume migration, and must also decide their time of departure. Variation in departure timing affects the total time required to complete a migratory journey, which in turn affects fitness through arrival time at the breeding and wintering grounds. It is well established that stopover departure decisions are based on cues from innate rhythms, intrinsic factors and extrinsic factors. Yet, virtually nothing is known about the physiological mechanism(s) linking these cues to departure decisions. Here, we show for a nocturnal migratory songbird, the northern wheatear ( Oenanthe oenanthe ), that baseline corticosterone levels of birds at stopover increased both over the migratory season and with wind assistance towards the migratory destination. Corticosterone in turn predicted departure probability; individuals with high baseline corticosterone levels were more likely to resume migration on a given night. Corticosterone further predicted the departure time within the night, with high baseline levels being associated with early departures. These novel findings indicate that corticosterone may be mediating between departure cues and the timing of departure from a stopover site, which is a major step towards understanding the hormonal control of animal migration.
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Coppack, Timothy, Simon F. Becker, and Philipp J. J. Becker. "Circadian flight schedules in night-migrating birds caught on migration." Biology Letters 4, no. 6 (2008): 619–22. http://dx.doi.org/10.1098/rsbl.2008.0388.
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Many species of migratory birds migrate in a series of solitary nocturnal flights. Between flights, they stop to rest and refuel for the next segment of their journey. The mechanism controlling this behaviour has long remained elusive. Here, we show that wild-caught migratory redstarts ( Phoenicurus phoenicurus ) are consistent in their flight scheduling. An advanced videographic system enabled us to determine the precise timing of flight activity in redstarts caught at a northern European stopover site during their return trip from Africa. Birds were held captive for three days in the absence of photoperiodic cues (constant dim light) and under permanent food availability. Despite the absence of external temporal cues, birds showed clear bimodal activity patterns: intense nocturnal activity alternating with diurnal foraging and resting periods. The onset of their migratory activity coincided with the time of local sunset and was individually consistent on consecutive nights. The data demonstrate that night-migrating birds are driven by autonomous circadian clocks entrained by sunset cues. This timekeeping system is probably the key factor in the overall control of nocturnal songbird migration.
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Lindecke, Oliver, Christian C. Voigt, Gunārs Pētersons, and Richard A. Holland. "Polarized skylight does not calibrate the compass system of a migratory bat." Biology Letters 11, no. 9 (2015): 20150525. http://dx.doi.org/10.1098/rsbl.2015.0525.
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In a recent study, Greif et al. (Greif et al. Nat Commun 5, 4488. ( doi:10.1038/ncomms5488 )) demonstrated a functional role of polarized light for a bat species confronted with a homing task. These non-migratory bats appeared to calibrate their magnetic compass by using polarized skylight at dusk, yet it is unknown if migratory bats also use these cues for calibration. During autumn migration, we equipped Nathusius' bats, Pipistrellus nathusii , with radio transmitters and tested if experimental animals exposed during dusk to a 90° rotated band of polarized light would head in a different direction compared with control animals. After release, bats of both groups continued their journey in the same direction. This observation argues against the use of a polarization-calibrated magnetic compass by this migratory bat and questions that the ability of using polarized light for navigation is a consistent feature in bats. This finding matches with observations in some passerine birds that used polarized light for calibration of their magnetic compass before but not during migration.
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Cariboni, Anna, Roberto Maggi, and John G. Parnavelas. "From nose to fertility: the long migratory journey of gonadotropin-releasing hormone neurons." Trends in Neurosciences 30, no. 12 (2007): 638–44. http://dx.doi.org/10.1016/j.tins.2007.09.002.
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Gervais, Christine, Isabel Côté, Andréanne Pomerleau, Kristel Tardif-Grenier, Francine de Montigny, and Renée-Pier Trottier-Cyr. "Children’s views on their migratory journey: The importance of meaning for better adaptation." Children and Youth Services Review 120 (January 2021): 105673. http://dx.doi.org/10.1016/j.childyouth.2020.105673.
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