scholarly journals Analysing the Performance of Migrating Birds Optimisation Approaches for Large Scale Continuous Problems

2016 ◽  
pp. 134-144 ◽  
Author(s):  
Eduardo Lalla-Ruiz ◽  
Eduardo Segredo ◽  
Stefan Voß ◽  
Emma Hart ◽  
Ben Paechter
Keyword(s):  
Large Scale ◽  
Continuous Problems ◽  
Migrating Birds

An Efficient Recursive Differential Grouping for Large-Scale Continuous Problems

2020 ◽  
pp. 1-1 ◽  
Author(s):  
Ming Yang ◽  
Aimin Zhou ◽  
Changhe Li ◽  
Xin Yao
Keyword(s):  
Large Scale ◽  
Continuous Problems

scholarly journals Where in the air? Aerial habitat use of nocturnally migrating birds

2016 ◽  
Vol 12 (11) ◽  
pp. 20160591 ◽  
Author(s):  
Kyle G. Horton ◽  
Benjamin M. Van Doren ◽  
Phillip M. Stepanian ◽  
Andrew Farnsworth ◽  
Jeffrey F. Kelly
Keyword(s):  
Habitat Selection ◽  
Large Scale ◽  
Migratory Birds ◽  
Lower Atmosphere ◽  
Migration Activity ◽  
Maximum Wind ◽  
Eastern Usa ◽  
Migrant Birds ◽  
Spatio Temporal ◽  
Migrating Birds

The lower atmosphere (i.e. aerosphere) is critical habitat for migrant birds. This habitat is vast and little is known about the spatio-temporal patterns of distribution and abundance of migrants in it. Increased human encroachment into the aerosphere makes understanding where and when migratory birds use this airspace a key to reducing human–wildlife conflicts. We use weather surveillance radar to describe large-scale height distributions of nocturnally migrating birds and interpret these distributions as aggregate habitat selection behaviours of individual birds. As such, we detail wind cues that influence selection of flight heights. Using six radars in the eastern USA during the spring (2013–2015) and autumn (2013 and 2014), we found migrants tended to adjust their heights according to favourable wind profit. We found that migrants' flight altitudes correlated most closely with the altitude of maximum wind profit; however, absolute differences in flight heights and height of maximum wind profit were large. Migrants tended to fly slightly higher at inland sites compared with coastal sites during spring, but not during autumn. Migration activity was greater at coastal sites during autumn, but not during spring. This characterization of bird migration represents a critical advance in our understanding of migrant distributions in flight and a new window into habitat selection behaviours.

scholarly journals Stopover behavior of Red-eyed Vireos (Vireo olivaceus) during fall migration on the coast of the Yucatan Peninsula

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Richard Evan Feldman ◽  
Antonio Celis-Murillo ◽  
Jill L. Deppe ◽  
Michael P. Ward
Keyword(s):  
Food Availability ◽  
Large Scale ◽  
Yucatan Peninsula ◽  
Activity Level ◽  
Activity Levels ◽  
Stopover Duration ◽  
Vireo Olivaceus ◽  
Migratory Flight ◽  
Yucatán Peninsula ◽  
Migrating Birds

Abstract Background For migrating birds, stopover requires spending time and energy that otherwise could be allocated to flying. Thus, birds optimally refuel their subsequent migratory flight by reducing stopover duration or foraging activity in food-rich environments. In coastal habitats, birds may forego refueling and take short stopovers irrespective of local food availability. Given the paucity of studies exploring how migrants adjust stopover behavior in response to temporal variation in food availability, especially in the Neotropics, we fixed radio tags to 51 Red-eyed Vireos (Vireo olivaceous) over two years at two sites on the coast of Mexico’s Yucatan Peninsula. Methods We applied VHF radio tags during the fall of 2016 and 2017, and tracked birds using automatic and manual receiving units. We estimated stopover duration and activity levels (one site only) for between six and fifteen birds, depending on site and year. We measured fruit availability weekly along the net lanes where we captured birds. We used a generalized linear model to estimate the relationships between stopover duration/activity level and fruit density, bird body mass and year. We interpreted relationships for the model with the lowest AICc value. Results We found that approximately half of the birds departed on the same day they were captured. For the birds that stayed longer, we could not discern whether they did so because they were light, or fruit density was high. On the other hand, lighter birds were more active than heavier birds but only in one of the two years. Conclusions Given our results, it is unlikely that Red-eyed Vireos refuel along the Yucatan coast. However, they still likely need to recuperate from crossing the Gulf of Mexico, which may necessitate foraging more often if in poor body condition. If the birds then move inland then stopover should be thought of as a large-scale phenomenon, where habitats with different functions may be spread out over a broad landscape.

scholarly journals Theoretically possible spatial accuracy of geomagnetic maps used by migrating animals

2017 ◽  
Vol 14 (128) ◽  
pp. 20161002 ◽  
Author(s):  
Andrei V. Komolkin ◽  
Pavel Kupriyanov ◽  
Andrei Chudin ◽  
Julia Bojarinova ◽  
Kirill Kavokin ◽  
...  
Keyword(s):  
Field Intensity ◽  
Geomagnetic Field ◽  
Site Fidelity ◽  
Large Scale ◽  
Migratory Birds ◽  
Time Of Day ◽  
Northern Europe ◽  
Spatial Accuracy ◽  
Total Field ◽  
Migrating Birds

Many migrating animals, belonging to different taxa, annually move across the globe and cover hundreds and thousands of kilometres. Many of them are able to show site fidelity, i.e. to return to relatively small migratory targets, from distant areas located beyond the possible range of direct sensory perception. One widely debated possibility of how they do it is the use of a magnetic map, based on the dependence of parameters of the geomagnetic field (total field intensity and inclination) on geographical coordinates. We analysed temporal fluctuations of the geomagnetic field intensity as recorded by three geomagnetic observatories located in Europe within the route of many avian migrants, to study the highest theoretically possible spatial resolution of the putative map. If migratory birds measure total field intensity perfectly and take the time of day into account, in northern Europe 81% of them may return to a strip of land of 43 km in width along one of coordinates, whereas in more southern areas such a strip may be narrower than 10 km. However, if measurements are performed with an error of 0.1%, the strip width is increased by approximately 40 km, so that in spring migrating birds are able to return to within 90 km of their intended goal. In this case, migrating birds would probably need another navigation system, e.g. an olfactory map, intermediate between the large-scale geomagnetic map and the local landscape cues, to locate their goal to within several kilometres.

scholarly journals Evaluation of Long-Distance Orientation in Birds on the Basis of Migration Routes Recorded by Radar and Satellite Tracking

2001 ◽  
Vol 54 (3) ◽  
pp. 393-403 ◽  
Author(s):  
Thomas Alerstam
Keyword(s):  
Large Scale ◽  
Satellite Tracking ◽  
Polar Regions ◽  
High Latitudes ◽  
Migration Routes ◽  
Long Distance ◽  
Sun Compass ◽  
Branta Bernicla ◽  
Migrating Birds ◽  
East West

Predicted flight trajectories differ depending on which orientation cues are used by migrating birds. Results from radar and satellite tracking of migrating birds can be used to test which of the predicted trajectories shows the best fit with observed flight routes, supporting the use of the associated orientation mechanism. Radar studies of bird migration at the Northeast Passage and the Northwest Passage support the occurrence of migration along sun compass routes in these polar regions. In contrast, satellite tracking of Brent geese (Branta bernicla) migrating from Iceland across Greenland and from Northwest Europe to Siberia show routes that conform most closely with geographic loxodromes, but which are also profoundly influenced by large-scale topography. These evaluations are discussed in relation to the adaptive values of different routes in different parts of the world. Sun compass routes are favourable mainly for east-west migration at high latitudes. For east-west migration at mid and high latitudes magnetic loxodromes are more favourable than geographic loxodromes in certain regions while the reverse holds in other regions. The geometry of migration routes, as recorded by radar and satellite tracking, may be important for understanding the evolution of the complexity of birds' orientation systems, and for providing clues about the orientation mechanisms guiding the birds on their global journeys.

Model-Based Multiobjective Optimization Methods for Efficient Management of Subsurface Flow

SPE Journal ◽  
2017 ◽  
Vol 22 (06) ◽  
pp. 1984-1998 ◽  
Author(s):  
Jianlin Fu ◽  
Xian-Huan Wen
Keyword(s):  
Multiobjective Optimization ◽  
Large Scale ◽  
Optimization Problems ◽  
Subsurface Flow ◽  
Population Based ◽  
Small Scale ◽  
Hybrid Strategy ◽  
Model Based ◽  
Continuous Problems ◽  
Oilfield Development

Summary Multiobjective optimization (MOO), which accounts for several distinct, possibly conflicting, objectives, is expected to be capable of providing improved reservoir-management (RM) solutions for efficient oilfield development because of the overall optimization of subsurface flow. Considering the complexity and diversity of MOO problems in model-based RM, we develop three MOO methods—MOAdjoint, MOGA, and MOPSO—in this work to address various oilfield-development problems. MOAdjoint combines a weighted-sum technique with a gradient-based method for solving large-scale continuous problems that have thousands of variables. An adjoint method is used to efficiently compute the derivatives of objective functions with respect to decision variables, and a sequential quadratic-programming method is used for optimization search. MOGA is a population-based method, which combines a Pareto-ranking technique with genetic algorithm (GA) to address small-scale (discrete) problems. MOPSO is another population-based method, which combines a Pareto technique with particle-swarm optimization (PSO) for a wide spectrum of optimization problems. Their advantages and disadvantages are highlighted. To take advantage of the strengths and overcome the drawbacks of these methods, a multiscale hybrid strategy is further formulated for solving complex, large-scale optimization problems by combining these methods at various scales. An example is used to compare these methods. Results show that all three methods can yield improved solutions. MOPSO seems particularly suitable for medium-scale RM problems, mainly because of its relatively fast convergence speed and efficient recovery of the Pareto front. With a proper initial guess and a set of effective weight coefficients, MOAdjoint can most efficiently solve large-scale continuous problems, particularly if model uncertainty is considered. The multiscale hybrid strategy is able to offer the best result.

The geographical scale factor in orientation of migrating birds

1996 ◽  
Vol 199 (1) ◽  
pp. 9-19 ◽  
Author(s):  
T Alerstam
Keyword(s):  
Large Scale ◽  
Position Control ◽  
The Arctic ◽  
Detailed Knowledge ◽  
Migration Routes ◽  
Continental Scale ◽  
Ice Cap ◽  
Geographical Scale ◽  
Course Changes ◽  
Migrating Birds

Migration routes of birds throw light on orientation performance at different geographic scales, over distances ranging from a few kilometres to more than 104 km. Detailed knowledge about the flight routes may be used to test predictions about optimal orientation according to theoretical principles and about the use of compasses based on celestial or magnetic cues. Ringing recoveries demonstrate that the migratory journey of many species, such as the wheatear and willow warbler, is divided into successive legs with different main orientation. Autumn and spring migration routes are often different, sometimes diverging on a continental scale. Aerial radiotracking of whooping cranes in North America and satellite tracking of brent geese migrating from Iceland across the Greenland ice cap point to the significant role of large-scale topography for the shaping of migration routes. Compass and position control are also required, e.g. during long passages across featureless sea or ice, but how these elements are integrated into the birds' orientation system remains unclear. Radar studies from the Arctic Ocean illustrate the importance of map projections for interpreting flight paths and suggest that birds accomplish approximate great circle orientation. Gradual course changes shown by migrating knots monitored by radar in Scandinavia are at variance with expected changes if the birds were to use a star, sun or magnetic compass over longer distances. Accurate recording of short flight segments shows how flying birds respond to visual, audible and electromagnetic cues, and also documents orientation precision and capacity to integrate rapidly shifting courses into a consistent resulting orientation. Analyses of flight patterns are crucial for understanding how birds find and follow their migration routes over different ranges of geographical scale.

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