Journal articles: 'Migratory system'

1

Handerson Joseph. "The haitian migratory system in the guianas: beyond borders." Diálogos 24, no. 2 (2020): 198–258. http://dx.doi.org/10.4025/dialogos.v24i2.54154.

Full text

Abstract:

The Guianas are an important migratory field in the Caribbean migratory system, whereby goods, objects, currencies, and populations circulate for different reasons: geographical, cultural proximity, climatic, geopolitical and socioeconomic factors. From the 1960s and 1970s, Haitian migration increased in the Guianas. Five decades later, after the January 2010 earthquake, the migratory spaces were intensified in the region, Brazil became part of them as a country of residence and transit to reach French Guiana and Suriname. In 2013, the routes were altered. Some migrants started to use the Republic of Guyana to enter Brazil through the border with Roraima, in the Amazon, or to cross the border towards Suriname and French Guiana. This article is divided into two levels. First, it describes the way in which migrants' practices and trajectories intersect national borders in the Guianas. Then, it analyzes the migratory system, documents and papers, and the problems that the different Haitian migratory generations raise in space and time. The ethnographic research is based on the Triple Border Brazil, Colombia and Peru, but also in Suriname, French Guiana and Haiti.

APA, Harvard, Vancouver, ISO, and other styles

2

Baganha, Maria I. "The Lusophone Migratory System: Patterns and Trends." International Migration 47, no. 3 (2009): 5–20. http://dx.doi.org/10.1111/j.1468-2435.2009.00522.x.

Full text

APA, Harvard, Vancouver, ISO, and other styles

3

Butler, Ann B. "Sensory system evolution at the origin of craniates." Philosophical Transactions of the Royal Society of London. Series B: Biological Sciences 355, no. 1401 (2000): 1309–13. http://dx.doi.org/10.1098/rstb.2000.0690.

Full text

Abstract:

The multiple events at the transition from non–craniate invertebrate ancestors to craniates included the gain and/or elaboration of migratory neural crest and neurogenic placodes. These tissues give rise to the peripherally located, bipolar neurons of all non–visual sensory systems. The brain was also elaborated at or about this same time. Were the peripheral and central events simultaneous or sequential? A serial transformation hypothesis postulates that paired eyes and an enlarged brain evolved before the elaboration of migratory neural crest–placodal sensory systems. Circumstantial evidence for this scenario is derived from the independent occurrence of the combination of large, paired eyes plus a large, elaborated brain in at least three taxa (cephalochordates, arthropods and craniates) and partly from the exclusivity of the diencephalon for visual system–related distal sensory components versus the restricted distribution of migratory neural crest–placodal sensory systems to the remaining parts of the neuraxis. This scenario accounts for the similarity of all central sensory system pathways due to the primary establishment of descending visual pathways via the diencephalon and midbrain tectum to brainstem motor regions and the subsequent exploitation of the same central beachhead by the migratory neural crest–placodal systems as a template for their organization.

APA, Harvard, Vancouver, ISO, and other styles

4

Kanaroglou, P., K.-L. Liaw, and Y. Y. Papageorgiou. "An Analysis of Migratory Systems: 1. Theory." Environment and Planning A: Economy and Space 18, no. 7 (1986): 913–28. http://dx.doi.org/10.1068/a180913.

Full text

Abstract:

The task of combining evolutionary migration models with stochastic utility theory is undertaken in a series of three interrelated papers. The present, first, paper deals with the evolution of migratory systems and its dynamics are drawn mainly from work by Haag and Weidlich. A migratory system is defined and then the foundations upon which the evolution of such a system is based are described, including an approximation due to Kurtz which allows the most probable state of the evolutionary model to be represented as a dynamical system. This paper closes with a discussion of disequilibrium, which is central in this series. Disequilibrium is related to the concept of a steady state, the existence of which is established for nonlinear migratory systems of the type discussed here.

APA, Harvard, Vancouver, ISO, and other styles

5

Morgan, E. R., G. F. Medley, P. R. Torgerson, B. S. Shaikenov, and E. J. Milner-Gulland. "Parasite transmission in a migratory multiple host system." Ecological Modelling 200, no. 3-4 (2007): 511–20. http://dx.doi.org/10.1016/j.ecolmodel.2006.09.002.

Full text

APA, Harvard, Vancouver, ISO, and other styles

6

Oldani, Norberto Oscar, Claudio Rafael Mariano Baigún, John Michael Nestler, and Richard Andrew Goodwin. "Is fish passage technology saving fish resources in the lower La Plata River basin?" Neotropical Ichthyology 5, no. 2 (2007): 89–102. http://dx.doi.org/10.1590/s1679-62252007000200002.

Full text

Abstract:

Over 450 dams have been constructed in the upper Paraná River basin in Brazil during the past 40 years. River regulation by these dams is considered a primary factor in the reduction of fish diversity and depletion of migratory species. In contrast to the upper Paraná Basin, only two large dams (both with upstream fish passage) have been constructed in the lower La Plata River basin. Fishery managers in the lower basin are concerned that existing and planned dams will further deplete populations of migratory fish species that constitute important recreational and commercial fisheries as has occurred in the upper basin. We assessed the sustainability of fisheries in the lower basin in the face of increased river regulation by using literature information to describe the efficiency of the fish passage systems used to mitigate river regulation impacts on fisheries. Our analysis shows that fish passage systems at both lower basin dams, Yacyreta and Salto Grande, fail to transfer sufficient numbers of upstream migrants to sustain populations of migratory species. Fish passage efficiency of target species in the fish elevators at Yacyreta is less than 2%. Fish diversity in the fish elevators is low because about 85% of the fish belong to only three non-migratory species (Pimelodus maculatus, Oxydoras kneri and Rhinodoras dorbignyi). Large migratory species targeted for passage rarely comprise even 5 % of the fish number in the passage system. The two Borland locks at Salto Grande Dam cannot dependably pass large numbers of migratory species because passage efficiency is dependent upon interactions of powerhouse and spillway operation with tailrace elevations. Most species in the Borland system were either a small catfish (Parapimelodus valenciennis) or a engraulid (Lycengraulis grossidens). Again, the targeted migratory species were not abundant in the passage system. We conclude that existing fish passage technology in the lower basin is inadequate and that improved fish passage designs are required to conserve migratory species. These designs must be based on integrated information from geomorphology (habitat), natural fish behavior, fish swimming capabilities, and detailed population studies.

APA, Harvard, Vancouver, ISO, and other styles

7

Hardesty-Moore, Molly, Stefanie Deinet, Robin Freeman, et al. "Migration in the Anthropocene: how collective navigation, environmental system and taxonomy shape the vulnerability of migratory species." Philosophical Transactions of the Royal Society B: Biological Sciences 373, no. 1746 (2018): 20170017. http://dx.doi.org/10.1098/rstb.2017.0017.

Full text

Abstract:

Recent increases in human disturbance pose significant threats to migratory species using collective movement strategies. Key threats to migrants may differ depending on behavioural traits (e.g. collective navigation), taxonomy and the environmental system (i.e. freshwater, marine or terrestrial) associated with migration. We quantitatively assess how collective navigation, taxonomic membership and environmental system impact species' vulnerability by (i) evaluating population change in migratory and non-migratory bird, mammal and fish species using the Living Planet Database (LPD), (ii) analysing the role of collective navigation and environmental system on migrant extinction risk using International Union for Conservation of Nature (IUCN) classifications and (iii) compiling literature on geographical range change of migratory species. Likelihood of population decrease differed by taxonomic group: migratory birds were more likely to experience annual declines than non-migrants, while mammals displayed the opposite pattern. Within migratory species in IUCN, we observed that collective navigation and environmental system were important predictors of extinction risk for fishes and birds, but not for mammals, which had overall higher extinction risk than other taxa. We found high phylogenetic relatedness among collectively navigating species, which could have obscured its importance in determining extinction risk. Overall, outputs from these analyses can help guide strategic interventions to conserve the most vulnerable migrations. This article is part of the theme issue ‘Collective movement ecology'.

APA, Harvard, Vancouver, ISO, and other styles

8

Rodríquez, Jorge, Daniela González, Miguel Ojeda, Maren Jiménez, and Fernanda Stang. "El sistema de ciudades chileno en la segunda mitad del siglo xx: entre la suburbanización y la desconcentración / The Chilean City System during the Second Half of the 20th Century: between Sub-Urbanization and Decentralization." Estudios Demográficos y Urbanos 24, no. 1 (2009): 7. http://dx.doi.org/10.24201/edu.v24i1.1343.

Full text

Abstract:

Desde mediados del siglo xx el sistema de ciudades de Chile se ha diversificado al ganar presencia las ciudades intermedias y se han complejizado los flujos migratorios entre sus componentes. Pese a su pertinaz importancia demográfica, la ciudad de Santiago ha registrado emigración neta en los últimos 15 años como producto de la suburbanización y de una efectiva reorientación de los flujos migratorios hacia ciudades alejadas de ella. Entre los efectos cualitativos de la migración entre ciudades sobresale la erosión de la base de recursos humanos de quienes han sufrido crisis económicas prolongadas. Este escenario migratorio emergente requiere nuevos enfoques teóricos. AbstractSince the mid-20th century, the Chilean City system has diversified, increasing its presence in intermediate cities, while its migratory flows have become more complex. Despite its continued demographic importance, Santiago has registered net emigration over the past 15 years, partly as a result of suburbanization, and partly as a result of the effective reorientation of migratory flows towards cities located some distance away. The qualitative effects of inter-city migration include the erosion of the basis of human resources of those undergoing a prolonged economic crisis. This emerging migratory scenario requires new theoretical approaches.

APA, Harvard, Vancouver, ISO, and other styles

9

Trierweiler, Christiane, Raymond H. G. Klaassen, Rudi H. Drent, et al. "Migratory connectivity and population-specific migration routes in a long-distance migratory bird." Proceedings of the Royal Society B: Biological Sciences 281, no. 1778 (2014): 20132897. http://dx.doi.org/10.1098/rspb.2013.2897.

Full text

Abstract:

Knowledge about migratory connectivity, the degree to which individuals from the same breeding site migrate to the same wintering site, is essential to understand processes affecting populations of migrants throughout the annual cycle. Here, we study the migration system of a long-distance migratory bird, the Montagu's harrier Circus pygargus , by tracking individuals from different breeding populations throughout northern Europe. We identified three main migration routes towards wintering areas in sub-Saharan Africa. Wintering areas and migration routes of different breeding populations overlapped, a pattern best described by ‘weak (diffuse) connectivity’. Migratory performance, i.e. timing, duration, distance and speed of migration, was surprisingly similar for the three routes despite differences in habitat characteristics. This study provides, to our knowledge, a first comprehensive overview of the migration system of a Palaearctic-African long-distance migrant. We emphasize the importance of spatial scale (e.g. distances between breeding populations) in defining patterns of connectivity and suggest that knowledge about fundamental aspects determining distribution patterns, such as the among-individual variation in mean migration directions, is required to ultimately understand migratory connectivity. Furthermore, we stress that for conservation purposes it is pivotal to consider wintering areas as well as migration routes and in particular stopover sites.

APA, Harvard, Vancouver, ISO, and other styles

10

Perrine-Walker, Francine. "Interactions of endoparasitic and ectoparasitic nematodes within the plant root system." Functional Plant Biology 46, no. 4 (2019): 295. http://dx.doi.org/10.1071/fp18176.

Full text

Abstract:

Root-knot and cyst nematodes have sophisticated mechanisms to invade their plant hosts to reprogram the plant developmental program to induce feeding structures essential for nematode survival and reproduction. This has a detrimental effect on the plant as this sedentary endoparasitic interaction affects the growth and yields of many crop plants. However, other migratory endoparasitic nematodes that do not establish root feeding sites are as aggressive on many crop plants. With new information gained from the genome and transcriptomes of the migratory endoparasitic nematode, Pratylenchus spp., this review compares the different lifestyles and the pathogenic interactions these nematodes have with their plant host. Pratylenchus spp. utilises a common arsenal of effectors involved in plant cell wall degradation and the manipulation of plant host innate immunity. The absence of specific cell reprogramming effector genes may explain its migratory endoparasitic lifestyle, making it relevant to pest management approaches in Australia.

APA, Harvard, Vancouver, ISO, and other styles

11

Dunn, Daniel C., Autumn-Lynn Harrison, Corrie Curtice, et al. "The importance of migratory connectivity for global ocean policy." Proceedings of the Royal Society B: Biological Sciences 286, no. 1911 (2019): 20191472. http://dx.doi.org/10.1098/rspb.2019.1472.

Full text

Abstract:

The distributions of migratory species in the ocean span local, national and international jurisdictions. Across these ecologically interconnected regions, migratory marine species interact with anthropogenic stressors throughout their lives. Migratory connectivity, the geographical linking of individuals and populations throughout their migratory cycles, influences how spatial and temporal dynamics of stressors affect migratory animals and scale up to influence population abundance, distribution and species persistence. Population declines of many migratory marine species have led to calls for connectivity knowledge, especially insights from animal tracking studies, to be more systematically and synthetically incorporated into decision-making. Inclusion of migratory connectivity in the design of conservation and management measures is critical to ensure they are appropriate for the level of risk associated with various degrees of connectivity. Three mechanisms exist to incorporate migratory connectivity into international marine policy which guides conservation implementation: site-selection criteria, network design criteria and policy recommendations. Here, we review the concept of migratory connectivity and its use in international policy, and describe the Migratory Connectivity in the Ocean system, a migratory connectivity evidence-base for the ocean. We propose that without such collaboration focused on migratory connectivity, efforts to effectively conserve these critical species across jurisdictions will have limited effect.

APA, Harvard, Vancouver, ISO, and other styles

12

Makrakis, Sérgio, Luiz Carlos Gomes, Maristela Cavicchioli Makrakis, Domingo Rodriguez Fernandez, and Carla Simone Pavanelli. "The Canal da Piracema at Itaipu Dam as a fish pass system." Neotropical Ichthyology 5, no. 2 (2007): 185–95. http://dx.doi.org/10.1590/s1679-62252007000200013.

Full text

Abstract:

The Canal da Piracema is the longest (nearly 10 km) fish pass system in the world. The construction of this fish pass was somehow controversial, because it connected two distinct ichthyofaunistic provinces. This study evaluated the ichthyofauna present in the Canal da Piracema and the abundance and distribution of long-distance migratory fish species along this fish pass system (evaluated possible selectivity). The Canal da Piracema was shown to be difficult to sample because of its environmental heterogeneity: artificial ponds, ladders and nature-like fish pass. To solve this problem, we used several fishing gears, adequate for the several biotopes present (unstructured and structured littoral were sampled with seining nets and electrofishing; lentic were sampled with gillnets and longlines (deeper areas); and rapid water areas were sampled with cast nets). The ichthyofauna of the Canal da Piracema followed the pattern for South America and the Paraná River, with a predominance of Characiformes and Siluriformes. The most representative families were Characidae, Anostomidae, Pimelodidae and Loricariidae. We captured 116 species (17 were long-distance migratory) during the period studied. Small-sized species were predominant in unstructured and structured littoral areas, especially Bryconamericus exodon and Apareiodon affinis.The most abundant species was Hypostomus spp. in lentic areas, followed by Iheringichthys labrosus. Hoplias aff. malabaricus predominated in deeper lentic areas. Long-distance migratory species were abundant in rapid waters; they were Prochilodus lineatus and Leporinus elongatus. The sharp reduction in the number of species, including migratory ones, is an indication that the Canal da Piracema is selecting the species that ascend it. Therefore, the search for information on the efficiency of the various fish passes present in the Canal da Piracema is fundamental, to facilitate upward movements of fish. If this is reached, this polemic fish pass has the potential to contribute to the conservation of fish stocks in Itaipu Reservoir and upstream stretches, because of the presence of spawning and development (nurseries) areas for migratory species.

APA, Harvard, Vancouver, ISO, and other styles

13

Popkov, Yuri S. "Soft Randomized Machine Learning Procedure for Modeling Dynamic Interaction of Regional Systems." Entropy 21, no. 4 (2019): 424. http://dx.doi.org/10.3390/e21040424.

Full text

Abstract:

The paper suggests a randomized model for dynamic migratory interaction of regional systems. The locally stationary states of migration flows in the basic and immigration systems are described by corresponding entropy operators. A soft randomization procedure that defines the optimal probability density functions of system parameters and measurement noises is developed. The advantages of soft randomization with approximate empirical data balance conditions are demonstrated, which considerably reduces algorithmic complexity and computational resources demand. An example of migratory interaction modeling and testing is given.

APA, Harvard, Vancouver, ISO, and other styles

14

Landry, Véronique. "FEMINIZACIÓN Y URBANIZACIÓN DE LA MIGRACIÓN HAITIANA EN REPÚBLICA DOMINICANA: UNA APROXIMACIÓN HACIA SU CARACTERIZACIÓN." Revista Pueblos y fronteras digital 8, no. 15 (2013): 201. http://dx.doi.org/10.22201/cimsur.18704115e.2013.15.91.

Full text

Abstract:

Inicialmente la migrante haitiana en República Dominicana era caracterizada por ser la «acompañante» del hombre dentro de los Bateyes. La urbanización de la migración le permitió introducirse en una nueva corriente compleja y heterogénea como nueva sujeta migratoria. Este artículo tiene como objetivo contextualizar las trasformaciones dentro del nuevo sistema migratorio haitiano junto con identificar a la mujer haitiana como protagonista migrante en las zonas urbanas de la República Dominicana.  FEMINIZATION AND URBANIZATION OF HAITIAN FEMALE MIGRANTS IN THE DOMINICAN REPUBLIC: APPROACHING THEIR CHARACTERIZATIONABSTRACTFemale migrants from Haiti to the Dominican Republic were initially characterized as the men’s «companions» in the rural sugar cane compounds. The urbanization of migration allowed women to join a new complex and heterogeneous stream as migrants. The aim of this article is to contextualize transformations taking place within the new migratory system in Haiti as well as to identify Haitian women as migration protagonists in the urban areas of the Dominican Republic.

APA, Harvard, Vancouver, ISO, and other styles

15

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.

Full text

Abstract:

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.

APA, Harvard, Vancouver, ISO, and other styles

16

Watts, Heather E., Jeffrey L. Rittenhouse, Kendra B. Sewall, and J. Michael Bowers. "Migratory state is not associated with differences in neural glucocorticoid or mineralocorticoid receptor expression in pine siskins." Animal Migration 6, no. 1 (2019): 19–27. http://dx.doi.org/10.1515/ami-2019-0001.

Full text

Abstract:

Abstract Although the endocrine system likely plays an important role in orchestrating the transition to a migratory state, the specific mechanisms by which this occurs remain poorly understood. Changes in glucocorticoid signaling are one proposed mechanism that may be important in migratory transitions. Although previous work has focused on the role of changes in circulating glucocorticoids, another potential mechanism is changes in the expression of its cognate receptors. Here, we test this hypothesis by comparing mRNA expression of the genes for the mineralocorticoid receptor (MR) and glucocorticoid receptor (GR) in two brain regions implicated in the regulation of migratory behavior (the hippocampus and hypothalamus) in pine siskins (Spinus pinus) sampled before or after the transition to a spring nomadic migratory state. Compared to pre-migratory birds, migratory birds had body conditions more indicative of physiological preparations for migration (e.g., larger body mass), and greater levels of nocturnal migratory restlessness. However, we found no differences between pre-migratory and migratory birds in the expression of GR or MR mRNA in either the hippocampus or hypothalamus. Thus, differences in expression of receptors for glucocorticoids do not appear to underly the observed differences in physiology and behavior across a migratory transition. Taken together with previous results showing no change in circulating corticosterone levels during this transition, our findings provide no evidence for a role of glucocorticoid signaling in the spring migratory transition of this species.

APA, Harvard, Vancouver, ISO, and other styles

17

Popkov, Yuri, and Leo Wissen. "Equilibrium and Stability of Entropy Operator Model for Migratory Interaction of Regional Systems." Mathematics 7, no. 2 (2019): 130. http://dx.doi.org/10.3390/math7020130.

Full text

Abstract:

In this paper, we develop a dynamic model for migratory interaction of regional systems that is based on an entropy operator. Next, we study the properties of this operator and establish the existence of a unique singular point in the dynamic entropy model. Here, we use monotonicity property of entropy operator on corresponding vector interval. We study Lyapunov stability of a dynamic system with entropy operator. Stability conditions have been obtained in terms of eigenvalues of linearized system’s matrix. Finally, we give an illustrative example for migratory interaction of regional systems.

APA, Harvard, Vancouver, ISO, and other styles

18

Able, Kenneth P., and Mary A. Able. "Interactions and Flexibility in the Orientation System of Migratory Birds." Journal of Navigation 46, no. 3 (1993): 353–58. http://dx.doi.org/10.1017/s0373463300011784.

Full text

Abstract:

This paper, and the following 5 papers, were presented at the RIN93 Conference on “Orientation and Navigation - Birds, Humans and other Animals.” This took place in Oxford in April, and included some 40 papers. Copies of the complete Proceedings, priced £25 for RIN members and £35 for non-members, are available from the Director.

APA, Harvard, Vancouver, ISO, and other styles

19

Tamburrini, Maurizio, Rossana D'Avino, Angela Fago, Vito Carratore, Andreas Kunzmann, and Guido di Prisco. "The Unique Hemoglobin System ofPleuragramma antarcticum, an Antarctic Migratory Teleost." Journal of Biological Chemistry 271, no. 39 (1996): 23780–85. http://dx.doi.org/10.1074/jbc.271.39.23780.

Full text

APA, Harvard, Vancouver, ISO, and other styles

20

Hagan, Jacqueline Maria, Ricardo Martinez-Schuldt, Alyssa Peavey, and Deborah M. Weissman. "Family Matters: Claiming Rights across the US-Mexico Migratory System." Journal on Migration and Human Security 6, no. 2 (2018): 167–80. http://dx.doi.org/10.1177/2331502418777456.

Full text

Abstract:

The Immigration and Nationality Act of 1952 (INA) created an immigration system favoring the immigration of spouses, children, and parents of US citizens, thereby establishing family unity as the cornerstone of US immigration policy. Despite this historical emphasis on family unity, backlogs and limited visas for non-immediate relatives of US citizens and legal permanent residents, the militarization of the US-Mexico border, punitive measures for those who enter without inspection, such as the forced separation of children from their parents at the US border, and an aggressive policy of deportation have made it more difficult for members of Mexican binational families to unify. How do members of Mexican binational families manage the hardships that result from US immigration policies that prolong and force family separation? Immigrants and return migrants alike may not be aware of their rights and the legal remedies that exist to enforce them. Structural barriers such as poverty, legal status, fear of deportation, lack of proficiency in English, and lack of familiarity with government bureaucracies no doubt prevent many migrants in the United States and return migrants in Mexico from coming forward to request legal assistance and relief in the courts. Despite these barriers, when it comes to family matters, members of some Mexican binational families can and do assert their rights. In this article, we analyze an administrative database of the Department of Legal Protection of the Mexican consular network that documents migrant legal claims resulting from family separation, along with findings from 21 interviews with consular staff and community organizations in three consular jurisdictions — El Paso, Raleigh, and San Francisco — to investigate the sociolegal processes of claims. Our investigation centers on the mediating role the Mexican state — via its consular network — has developed to assist binational families as they attempt to assert their rights and resolve child support and child custody problems resulting from prolonged and forced family separation. We find that the resolution of binational family claims in part depends on the institutional infrastructure that has developed at local, state, and federal levels, along with the commitment and capacity of the receiving and sending states and the binational structures they establish. These binational structures transcend the limitations of national legal systems to achieve and implement family rights and obligations across borders.

APA, Harvard, Vancouver, ISO, and other styles

21

Singaravadivelan, A., N. Kumaravelu, T. Sivakumar, S. M. K. Karthickeyan, D. Vinothkumar, and D. Divyalakshmi. "Facets of migratory sheep production system in southern Tamil Nadu." Indian Journal of Small Ruminants (The) 21, no. 1 (2015): 155. http://dx.doi.org/10.5958/0973-9718.2015.00004.5.

Full text

APA, Harvard, Vancouver, ISO, and other styles

22

Able, Kenneth P., and Mary A. Able. "Interactions in the flexible orientation system of a migratory bird." Nature 375, no. 6528 (1995): 230–32. http://dx.doi.org/10.1038/375230a0.

Full text

APA, Harvard, Vancouver, ISO, and other styles

23

Biebach, H., H. Wegner, and J. Habersetzer. "Measuring migratory restlessness in captive birds by an ultrasonic system." Experientia 41, no. 3 (1985): 411–12. http://dx.doi.org/10.1007/bf02004533.

Full text

APA, Harvard, Vancouver, ISO, and other styles

24

Rastogi, Ashutosh, Surbhi, Shalie Malik, Sangeeta Rani, and Vinod Kumar. "Annual life-history dependent seasonal differences in neural activity of the olfactory system between non-migratory and migratory songbirds." Behavioural Brain Research 296 (January 2016): 233–39. http://dx.doi.org/10.1016/j.bbr.2015.09.019.

Full text

APA, Harvard, Vancouver, ISO, and other styles

25

GAO, SHUJING, YUMIN DING, and JIANPING XIE. "ROLE OF DISEASE PROPAGATION IN MIGRATORY BIRD POPULATION." International Journal of Biomathematics 05, no. 03 (2012): 1260002. http://dx.doi.org/10.1142/s1793524512600029.

Full text

Abstract:

Chatterjee considered a predator–prey model with avian migration in the migration prey population [S. Chatterjee, Alternative prey source coupled with prey recovery enhance stability between migratory prey and their predator in the presence of disease, Nonlinear Anal. Real World Appl. 11 (2010) 4415–4430]. In this paper, we modify and analyze the model by taking time dependent parameters and the general functional response into consideration. The conditions for the persistence of the system and the extinction of the disease are obtained. The global attractivity of the system is also studied. By numerical simulations, we find that the qualitative behavior of the system independent on the choice of the functional response. Moreover, it is observed that the infection rate, recruitment rate and the predation rate play a vital role in predicting the behavior of the dynamics.

APA, Harvard, Vancouver, ISO, and other styles

26

Morganti, Michelangelo. "Birds facing climate change: a qualitative model for the adaptive potential of migratory behaviour." Rivista Italiana di Ornitologia 85, no. 1 (2015): 3. http://dx.doi.org/10.4081/rio.2015.197.

Full text

Abstract:

Recent climate change is altering the migratory behaviour of many bird species. An advancement in the timing of spring events and a shift in the geographical distribution have been detected for birds around the world. In particular, intra-Palearctic migratory birds have advanced arrivals in spring and shortened migratory distances by shifting northward their wintering grounds. These changes in migratory patterns are considered adaptive responses facilitating the adjustment of the life cycle to the phenological changes found in their breeding areas. However, in some cases, populations exposed to the same selective pressures do not show any appreciable adaptive change in their behaviour. Basing on the comparison of realized and non-realized adaptive changes, I propose here the formulation of a qualitative model that predicts the potential of migratory birds populations to change adaptively their migratory behaviour. The model assumes that the adaptive potential of migratory behaviour is fuelled by both genetic diversity and phenotypic plasticity. Populations of long-distance migrants are exposed to strong environmental canalization that largely eroded their phenotypic plasticity and reduced genetic variability, so that they show a very low amount of adaptive potential regarding migratory behaviour. On the contrary, partial-migrant populations have a highly varied genetic profile and are more plastic at the phenotypic level, and consequently show the highest amount of adaptive potential. Species with mainly social and mainly genetic determination of the migratory behaviour are separately treated in the model. Specific empirical models to foresee the adaptive strategies of wild bird populations that face to climate change can be derived from the general theoretical model. As example, a specific model about the shortening of migratory distances in Western European migratory bird is presented. Finally, a number of future research lines on the topic of adaptive potential of migratory behaviour are discussed, including some examples of concrete study cases. In conclusion, partial-migration emerge as the less known system and future research efforts on this topic are expected to be especially fruitful.

APA, Harvard, Vancouver, ISO, and other styles

27

Holdo, Ricardo M., Kathleen A. Galvin, Eli Knapp, Stephen Polasky, Ray Hilborn, and Robert D. Holt. "Responses to alternative rainfall regimes and antipoaching in a migratory system." Ecological Applications 20, no. 2 (2010): 381–97. http://dx.doi.org/10.1890/08-0780.1.

Full text

APA, Harvard, Vancouver, ISO, and other styles

28

Silva, Fernanda de Oliveira, Francisco Ricardo de Andrade Neto, Samara Hermes Silva, et al. "Recruitment dynamics of a migratory fish in a semiarid river system." Inland Waters 10, no. 4 (2020): 529–41. http://dx.doi.org/10.1080/20442041.2020.1805977.

Full text

APA, Harvard, Vancouver, ISO, and other styles

29

Jones, David W., and Robert J. Marmon. "Migratory tendencies for 1,5-sigmatropic shifts in the 1,3-dimethylindene system." Journal of the Chemical Society, Perkin Transactions 1, no. 6 (1993): 681. http://dx.doi.org/10.1039/p19930000681.

Full text

APA, Harvard, Vancouver, ISO, and other styles

30

Able, K., and M. Able. "The flexible migratory orientation system of the savannah sparrow (Passerculus sandwichensis)." Journal of Experimental Biology 199, no. 1 (1996): 3–8. http://dx.doi.org/10.1242/jeb.199.1.3.

Full text

Abstract:

The orientation system of the Savannah sparrow (Passerculus sandwichensis) is typical of nocturnal migrant passerine birds. It is based on a system of interacting compass senses: magnetic, star, polarized light and, perhaps, sun compasses. The magnetic compass capability develops in birds that have never seen the sky, but the preferred direction of magnetic orientation may be calibrated by celestial rotation (stars at night and polarized skylight patterns during the day). This ability to recalibrate magnetic orientation persists throughout life and enables the bird to compensate for variability in magnetic declination that may be encountered as it migrates. The polarized light compass may be manipulated by exposing young birds to altered patterns of skylight polarization. There is some evidence that the magnetic field may be involved in calibration of the polarized light compass. In short-term orientation decision-making during migration, visual information at sunset overrides both stars and magnetic cues, and polarized skylight is the relevant stimulus in dusk orientation. The star pattern compass seems to be of little importance. This extremely flexible orientation system enables the birds to respond to spatial and temporal variability in the quality and availability of orientation information.

APA, Harvard, Vancouver, ISO, and other styles

31

Kanaroglou, P., K.-L. Liaw, and Y. Y. Papageorgiou. "An Analysis of Migratory Systems: 2. Operational Framework." Environment and Planning A: Economy and Space 18, no. 8 (1986): 1039–60. http://dx.doi.org/10.1068/a181039.

Full text

Abstract:

This is the second in a series of three interrelated papers which aim to combine evolutionary migration models with stochastic utility theory. The first paper dealt with migratory dynamics. Here the details are given of a choice model, established by McFadden, which can be used in conjunction with migratory dynamics thus providing an explicit link between the macroproperties of the population system and human behaviour. First, the structure of transition probabilities is derived under a two-level decision to migrate. An argument is then given about the empirical form of these probabilities, and the discussion closes with a method which can be used for their maximum likelihood estimation.

APA, Harvard, Vancouver, ISO, and other styles

32

Miller, RL, H. Marsh, C. Benham, and M. Hamann. "Stakeholder engagement in the governance of marine migratory species: barriers and building blocks." Endangered Species Research 43 (September 3, 2020): 1–19. http://dx.doi.org/10.3354/esr01049.

Full text

Abstract:

Meaningful stakeholder engagement is important to collaborative decision-making and to effective polycentric governance, particularly when managing cross-scale environmental issues like those involving marine migratory species. In this paper, we explore the barriers to, and opportunities for, stakeholder involvement in the governance of threats to marine migratory species in eastern Australia, using semi-structured qualitative interviews and a focus group, as an example of the generic problem of managing migratory species within a large range state with multiple jurisdictions. Respondents identified several barriers to, and opportunities for, improved stakeholder involvement in the governance of marine migratory species, corresponding to 4 main themes: decision-making processes, information sharing, institutional structures, and participation processes. Respondents indicated that the governance system protecting marine turtles, dugongs, humpback whales, and non-threatened migratory shorebirds in eastern Australia would benefit from the introduction of new information pathways, reformed institutional structures (including environmental legislation), and improved participatory pathways for non-government stakeholders. Such changes could help harmonise the process of managing these species, leading to more effective conservation management throughout their range.

APA, Harvard, Vancouver, ISO, and other styles

33

Helbig, A. J. "What do we know about the Genetic Basis of Bird Orientation?" Journal of Navigation 46, no. 3 (1993): 376–82. http://dx.doi.org/10.1017/s0373463300011826.

Full text

Abstract:

Migratory directions of birds have long been assumed to be at least partly ‘innate’ that is, genetically determined. In recent years much progress has been made toward understanding the genetic basis of several components of the orientation system. An important distinction has to be made between a bird's ‘knowledge’ of which direction to migrate, and its ability to use certain compass systems to find this intended direction. Both processes, establishing an intended direction and the subsequent compass orientation, have a partly genetic basis. The present review will be concerned only with the first of these processes, and the way it allows evolutionary changes of migratory routes to occur.

APA, Harvard, Vancouver, ISO, and other styles

34

NAKAJIMA, TATSUO, and HIROYUKI AIZU. "MIDDLEWARE FOR BUILDING ADAPTIVE MIGRATORY CONTINUOUS MEDIA APPLICATIONS." International Journal of Software Engineering and Knowledge Engineering 11, no. 01 (2001): 83–107. http://dx.doi.org/10.1142/s0218194001000438.

Full text

Abstract:

In this paper, we propose a middleware system for building adaptive migratory continuous media applications. In future computing environments, a variety of objects at home and in offices will embed computers, and various applications will be moved among these computers according to the user's locations. For example, a computer that executes an application may be changed to another computer according to the location of the application's user for monitoring his behavior. However, since the computers may have dramatically different hardware and software configurations, the application cannot be moved without taking into account the configurations of the computers that the application is migrated. Therefore, migratory applications should be aware of environments where they are executed. The paper focuses on middleware for building adaptive migratory continuous media applications that are one of the most important classes of migratory applications. Our middleware consists of three components. The first component is an environment server that monitors computing environments that applications run, and it notifies the changes of the environments to the applications. The second component is a continuous media toolkit that enables us to build adaptive migratory continuous media applications easily. The toolkit enables us to build continuous media applications in a highly configurable way. This makes applications to be adapted to every computing environment by changing their configurations. The third component is a migration manager that makes applications migratory. We also show an example of a migratory application, and describe some experiences with building the application.

APA, Harvard, Vancouver, ISO, and other styles

35

Gwinner, E. "Circadian and circannual programmes in avian migration." Journal of Experimental Biology 199, no. 1 (1996): 39–48. http://dx.doi.org/10.1242/jeb.199.1.39.

Full text

Abstract:

In migratory birds, endogenous daily (circadian) and annual (circannual) rhythms serve as biological clocks that provide the major basis for their temporal orientation. Circannual rhythms are responsible for the initiation of migration both in autumn and spring. This function of timing migrations is particularly important for birds that spend the winter close to the equator where the environment is too constant or irregular to provide accurate timing cues. In addition, circannual rhythms produce programmes that determine both the temporal and the spatial course of migration. In Sylvia warblers, the time programmes controlling autumn migration are organized in a species- or population-specific manner. It has been proposed that, in first-year migrants, the time programme for autumn migration plays a major role in determining migratory distance, thus providing the vector component in a mechanism of vector navigation. It is not yet clear, however, whether this programme does indeed determine migratory distance or whether it only provides the temporal framework within which other factors determine how far a bird flies. Evidence against the first alternative comes from findings indicating that migratory activity can be drastically modified by a constellation of rather specific, but highly relevant, factors and that the resulting changes in migratory activity are not compensated by subsequent increases or decreases of migratory activity. In normally day-active but nocturnally migrating birds, circannual signals cause alterations in the circadian system leading to the development of nocturnal activity. Although the nature of these signals is unknown, there is evidence that changes in the diurnal pattern of melatonin secretion by the pineal gland are associated with, and possibly causally involved in, the waxing and waning of nocturnal activity. These changes in the melatonin pattern presumably also affect general synchronization properties of the circadian system to Zeitgebers in such a way that circadian rhythms adjust faster to new conditions after long transmeridian flights.

APA, Harvard, Vancouver, ISO, and other styles

36

Vrieze, Lance A., and Peter W. Sorensen. "Laboratory assessment of the role of a larval pheromone and natural stream odor in spawning stream localization by migratory sea lamprey (Petromyzon marinus)." Canadian Journal of Fisheries and Aquatic Sciences 58, no. 12 (2001): 2374–85. http://dx.doi.org/10.1139/f01-179.

Full text

Abstract:

This study used large laboratory mazes and natural stream waters to test the role of olfactory cues, including a pheromone released by larvae, in spawning stream localization by migratory sea lamprey (Petromyzon marinus). We found that migratory lamprey strongly prefer stream water over lake water and that this response is dependent upon a functional olfactory system. Responses persisted among migratory lamprey even after stream water was diluted a thousand times but were not seen among non-migratory lamprey. Experiments using waters from five streams demonstrated that a larval pheromone is a key determinant of stream attractiveness: water from streams with larval populations were consistently more attractive than those without, and adding larval odor to the latter reversed this relationship. Larval odor was attractive at low, realistic concentrations, especially when presented together with natural stream water, suggesting that streams contain other odors that synergize the actions of the pheromone. Some, but not all, of the activity of the larval pheromone could be explained by two bile acids released by larvae (petromyzonol sulfate and allocholic acid). Together, these results strongly suggest that migratory lamprey locate streams using a larval pheromone. This cue could be useful in lamprey control.

APA, Harvard, Vancouver, ISO, and other styles

37

Fängstam, Hasse. "Individual downstream swimming speed during the natural smolting period among young of Baltic salmon (Salmo salar)." Canadian Journal of Zoology 71, no. 9 (1993): 1782–86. http://dx.doi.org/10.1139/z93-253.

Full text

Abstract:

The individual downstream swimming behaviour of two-summer-old salmon from the Ume River hatchery stock was monitored throughout the natural smolting period in May–June. The experiment was performed in an artificial-stream tank (diameter 11 m) equipped with a passive integrated transponder (PIT) tag monitoring system. The swimming speed of individual fish in relation to water velocity and the porportion of time during which an individual fish showed active versus passive displacement were investigated using a total of 224 sexually immature fish and previously mature males, individually PIT tagged. At peak migration fish swam downstream at an average speed of about double the water velocity, indicating active downstream migration. No differences in downstream swimming speed between migratory and nonmigratory fish were observed. However, migratory and nonmigratory fish used considerably different proportions of the total time swimming faster than the water current, 10% for migratory fish but only 0.1% for nonmigratory fish. Migratory smolts covered about 25% of their total downstream displacement by means of active downstream swimming: 3.3 km out of 13.5 km in 24 h. Thus, the study clearly shows that active downstream swimming is an important part of the migratory repertoire of salmon smolts.

APA, Harvard, Vancouver, ISO, and other styles

38

Harding, D. J., R. G. Dwyer, T. M. Mullins, M. J. Kennard, R. D. Pillans, and D. T. Roberts. "Migration patterns and estuarine aggregations of a catadromous fish, Australian bass (Percalates novemaculeata) in a regulated river system." Marine and Freshwater Research 68, no. 8 (2017): 1544. http://dx.doi.org/10.1071/mf16125.

Full text

Abstract:

Catadromous fish species require adequate flows to migrate between fresh and saltwater habitats to reproduce. However, artificial barriers and flow alteration affect fish populations by reducing habitat connectivity and disrupting movement cues. In regulated rivers, it is critical that migratory flow requirements are quantified to optimise water allocation for multiple users. In the present study, we assessed the migratory timing, flow and estuarine aggregation requirements for Australian bass (Percalates novemaculeata). Over 2 years, 66 bass were tracked using an acoustic receiver array in the Logan River (Qld, Australia). Bass performed large-scale downstream movements in response to elevated winter flows (40 and 108m3 s–1), which facilitated migration to the lower estuary, where salinity conditions were appropriate for spawning. Bass migrations occurred only when gonads were mature, despite large flows providing opportunities for movement outside this period. Experimental flow releases from an impoundment (2.1m3 s–1) during winter did not elicit a migratory response. Connectivity between upstream and estuarine habitats was reduced by the presence of instream weirs, with downstream movement across weirs occurring only when sufficient flow magnitude was achieved (>76.1m3 s–1). These findings are relevant for water resource managers formulating environmental flow rules for catadromous fish species in systems with multiple instream artificial barriers.

APA, Harvard, Vancouver, ISO, and other styles

39

Sohrabi, Zeinab, and Ehsan Mousavi Khaneghah. "CHALLENGES OF USING LIVE PROCESS MIGRATION IN DISTRIBUTED EXASCALE SYSTEMS." Azerbaijan Journal of High Performance Computing 3, no. 2 (2020): 151–63. http://dx.doi.org/10.32010/26166127.2020.3.2.151.163.

Full text

Abstract:

Virtual machine-based process migrator mechanisms have the potential to be used in distributed exascale systems due to their ability to execute process execution and support environments with the heterogenous of the computational unit. The ability to reduce process suspension time and use the concept of live process migrator makes it possible to use this mechanism to transfer processes in distributed exascale systems to prevent related process activity failure. The performance function of a virtual machine-based process migrator mechanism cannot manage dynamic and interactive events and the effects of this event on the mechanism operation and the change in the basic concept of system activity from the concept of the process to the concept of global activity. This paper examines the challenges of dynamic and interactive event occurrence on virtual machine-based process migrators by analyzing VM-based migrator's performance function

APA, Harvard, Vancouver, ISO, and other styles

40

Lama, Suman. "Dwindling Social Prosperity and Migratory Youths." Himalayan Journal of Sociology and Anthropology 6 (July 7, 2014): 211–20. http://dx.doi.org/10.3126/hjsa.v6i0.10731.

Full text

Abstract:

Migratory trend in Nepalese society is an ever growing trend. Nepalese have migrated abroad through different ways in different time like recruitment in army, as cheap manpower and now to pursue the foreign degrees. Whatsoever the excuses are, country is losing the skilled youths in present context jeopardizing the socio economic development of the country. This study investigates the influencing social factors that motivate educated youth to leave their country in the name of education. Similarly this study has also sensed the integrity of youth towards their own country. It should help concerned scholars to have a bit more concern about their role to choreograph the structure and function that favour the social welfare and development. Youths attempting to enroll themselves for IELTS test in British Council were surveyed and this study adopted an exploratory and descriptive research design. It is found that youths are tempted to go abroad with the motive to settle in there as the native structural and functional aspects of the society are not found justifiable. Moreover youths have placed the foreign degrees in higher priority to access in a decent job anywhere. Lastly the study has concluded that the execution of the policies in every field should not be manipulated instead fair competition and strict bureaucracy in the system must be practiced. However the trend of employment in foreign must also be accepted with dignity. DOI: http://dx.doi.org/10.3126/hjsa.v6i0.10731 Himalayan Journal of Sociology and Anthropology Vol.6 2014: 211-220

APA, Harvard, Vancouver, ISO, and other styles

41

Miyoshi, Hiromi. "Development of Cell Culture System Utilizing Cell Migratory Response to Microstructured Surface." Proceedings of the Bioengineering Conference Annual Meeting of BED/JSME 2017.29 (2017): 1A21. http://dx.doi.org/10.1299/jsmebio.2017.29.1a21.

Full text

APA, Harvard, Vancouver, ISO, and other styles

42

Gray, G. E., S. M. Leber, and J. R. Sanes. "Migratory patterns of clonally related cells in the developing central nervous system." Experientia 46, no. 9 (1990): 929–40. http://dx.doi.org/10.1007/bf01939386.

Full text

APA, Harvard, Vancouver, ISO, and other styles

43

Acosta-Avalos, Daniel, Darci M. Esquivel, Eliane Wajnberg, Henrique G. Lins de Barros, Paulo S. Oliveira, and Inara Leal. "Seasonal patterns in the orientation system of the migratory ant Pachycondyla marginata." Naturwissenschaften 88, no. 8 (2001): 343–46. http://dx.doi.org/10.1007/s001140100245.

Full text

APA, Harvard, Vancouver, ISO, and other styles

44

Zhu, Yunlu, Samantha C. Crowley, Andrew J. Latimer, Gwendolyn M. Lewis, Rebecca Nash, and Sarah Kucenas. "Migratory Neural Crest Cells Phagocytose Dead Cells in the Developing Nervous System." Cell 179, no. 1 (2019): 74–89. http://dx.doi.org/10.1016/j.cell.2019.08.001.

Full text

APA, Harvard, Vancouver, ISO, and other styles

45

Gantz, J. D., Kristin E. Spong, Erik A. Seroogy, R. Meldrum Robertson, and Richard E. Lee. "Effects of brief chilling and desiccation on ion homeostasis in the central nervous system of the migratory locust, Locusta migratoria." Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology 249 (November 2020): 110774. http://dx.doi.org/10.1016/j.cbpa.2020.110774.

Full text

APA, Harvard, Vancouver, ISO, and other styles

46

YONG, DING LI, YANG LIU, BING WEN LOW, CARMELA P. ESPAÑOLA, CHANG-YONG CHOI, and KAZUTO KAWAKAMI. "Migratory songbirds in the East Asian-Australasian Flyway: a review from a conservation perspective." Bird Conservation International 25, no. 1 (2015): 1–37. http://dx.doi.org/10.1017/s0959270914000276.

Full text

Abstract:

SummaryThe East Asian-Australasian Flyway supports the greatest diversity and populations of migratory birds globally, as well as the highest number of threatened migratory species of any flyway, including passerines (15 species). However it is also one of the most poorly understood migration systems, and little is known about the populations and ecology of the passerine migrants that breed, stop over and winter in the habitats along this flyway. We provide the first flyway-wide review of diversity, ecology, and conservation issues relating to 170 species of long-distance and over 80 short-distance migrants from 32 families. Recent studies of songbird migration movements and ecology is limited, and is skewed towards East Asia, particularly Mainland China, Taiwan, Russia, Japan and South Korea. Strong evidence of declines exists for some species, e.g. Yellow-breasted Bunting Emberiza aureola, but tends to be fragmentary, localised or anecdotal for many others. More species have small breeding ranges (< 250,000 km2) and/or are dependent on tropical forests as wintering habitat than those in any other Eurasian migratory system, and are thus more vulnerable to habitat loss and degradation throughout their ranges. Poorly regulated hunting for food and the pet trade, invasive species and collisions with man-made structures further threaten migratory songbirds at a number of stop-over or wintering sites, while climate change and habitat loss may be of increasing concern in the breeding ranges. A key conservation priority is to carry out intensive field surveys across the region while simultaneously tapping into citizen science datasets, to identify important stop-over and wintering sites, particularly for poorly-known or globally threatened species across South-East Asia and southern China for targeted conservation actions. Additionally, the advent of miniaturised tracking technology, molecular and isotopic techniques can provide novel insights into migration connectivity, paths and ecology for species in this migration system, complementing data from banding exercises and observation-based surveys, and could prove useful in informing conservation priorities. However, until most states along the East Asian-Australasian flyway ratify the Convention on the Conservation of Migratory Species of Wild Animals (CMS) and other cross-boundary treaties, the relative lack of cross-boundary cooperation, coordination and information sharing in the region will continue to present a stumbling block for effective conservation of migratory passerines.

APA, Harvard, Vancouver, ISO, and other styles

47

Frias-Soler, Roberto Carlos, Lilian Villarín Pildaín, Agnes Hotz-Wagenblatt, Jonas Kolibius, Franz Bairlein, and Michael Wink. "De novo annotation of the transcriptome of the Northern Wheatear (Oenanthe oenanthe)." PeerJ 6 (November 20, 2018): e5860. http://dx.doi.org/10.7717/peerj.5860.

Full text

Abstract:

We have sequenced a partial transcriptome of the Northern Wheatear (Oenanthe oenanthe), a species with one of the longest migrations on Earth. The transcriptome was constructed de novo using RNA-Seq sequence data from the pooled mRNA of six different tissues: brain, muscle, intestine, liver, adipose tissue and skin. The samples came from nine captive-bred wheatears collected at three different stages of the endogenous autumn migratory period: (1) lean birds prior the onset of migration, (2) during the fattening stage and (3) individuals at their migratory body mass plateau, when they have almost doubled their lean body mass. The sample structure used to build up the transcriptome of the Northern Wheatears concerning tissue composition and time guarantees the future survey of the regulatory genes involved in the development of the migratory phenotype. Through the pre-migratory period, birds accomplish outstanding physical and behavioural changes that involve all organ systems. Nevertheless, the molecular mechanisms through which birds synchronize and control hyperphagia, fattening, restlessness increase, immunity boosting and tuning the muscles for such endurance flight are still largely unknown. The use of RNA-Seq has emerged as a powerful tool to analyse complex traits on a broad scale, and we believe it can help to characterize the migratory phenotype of wheatears at an unprecedented level. The primary challenge to conduct quantitative transcriptomic studies in non-model species is the availability of a reference transcriptome, which we have constructed and described in this paper. The cDNA was sequenced by pyrosequencing using the Genome Sequencer Roche GS FLX System; with single paired-end reads of about 400 bp. We estimate the total number of genes at 15,640, of which 67% could be annotated using Turkey and Zebra Finch genomes, or protein sequence information from SwissProt and NCBI databases. With our study, we have made a first step towards understanding the migratory phenotype regarding gene expression of a species that has become a model to study birds long-distance migrations.

APA, Harvard, Vancouver, ISO, and other styles

48

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.

Full text

Abstract:

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.

APA, Harvard, Vancouver, ISO, and other styles

49

Göler, Daniel. "Elusive Migration Systems. Lessons from Europe’s new migratory map." Glasnik Srpskog geografskog drustva 96, no. 2 (2016): 42–49. http://dx.doi.org/10.2298/gsgd1602038g.

Full text

Abstract:

Europe is facing a new era of migration. During the last decades, the European migration system underwent several shifts due to different reasons. A basic observation is that general changes, on the political map for example, do not necessarily have the same consequences in European regions, even in seemingly similar contexts. The major changes started in 1990 accelerated with the enlargement of the European Union in 2004 and found its continuation by crisis-driven migration from south European countries into Western European labour markets after 2008. All of these "migration waves" have been topped by a massive inflow of refugees in 2015 creating new migratory map of Europe. Thus, important stages of contemporary and present European migration history are interpreted as indicators for a surplus in diversity, flexibility and spontaneity and will serve for formulating the hypothesis of Elusive Migration Systems as an analytical framework and a kind of hypothesis to study new features of migrants? trajectories, which became more and more variable. Being grounded may be the wish of the majority of Europeans and, in effect, the global population, but being on the move, voluntarily or forced, is reality for a certain number of migrants inside and heading towards Europe.

APA, Harvard, Vancouver, ISO, and other styles

50

Guillaumet, Alban, Brian Dorr, Guiming Wang, et al. "Determinants of local and migratory movements of Great Lakes double-crested cormorants." Behavioral Ecology 22, no. 5 (2011): 1096–103. http://dx.doi.org/10.1093/beheco/arr096.

Full text

Abstract:

Abstract We investigated how individual strategies combine with demographic and ecological factors to determine local and migratory movements in the double-crested cormorants (Phalacrocorax auritus). One hundred and forty-five cormorants were captured from 14 nesting colonies across the Great Lakes area and fitted with satellite transmitters. We first tested the hypotheses that sexual segregation, density-dependent effects, and the intensity of management operations influenced home range size during the breeding season. The influence of these factors appeared to be limited in part due to random variability in foraging and dispersal decisions at individual and colony levels. We also designed a statistical framework to investigate the degree and determinants of migratory connectivity. Our analyses revealed a significant migratory connectivity in cormorants, although we also observed a nonnegligible amount of individual variability and flexibility. Our data were most consistent with the existence of a migratory divide across the Great Lakes, with western populations using mainly the Mississippi Flyway and eastern populations the Atlantic Flyway. Previous and current studies suggest that the divide cannot be explained by past divergence in isolation, a way to diminish travel cost, or the Appalachians constituting an ecological barrier per se but is rather the consequence of the distribution of suitable stopover and nonbreeding areas. However, a parallel migration system and no migratory divide could not be entirely ruled out with present data.

APA, Harvard, Vancouver, ISO, and other styles

Journal articles on the topic 'Migratory system'

Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles