Sea-crossing along migratory flyways is limited more strongly by wind than by lack of uplift

AbstractThe open sea is considered an ecological barrier to terrestrial bird movement. However, over-water journeys of many terrestrial birds, sometimes hundreds of kilometers long, are being uncovered by bio-logging technology. To understand how these birds afford their flights over the open sea, we investigated the role of atmospheric conditions in subsidizing sea-crossing behavior at the global scale. By analyzing forty years of temperature data, we show that the spatio-temporal patterns of sea-crossing in terrestrial migratory birds correspond to favorable uplift conditions. We then analyzed route selection over the open sea for four bird species with varying levels of dependence on soaring flight, representing all major migratory flyways worldwide. Our results showed that favorable uplift conditions, albeit not as common and powerful as over land, are not rare over the open seas and oceans. Moreover, wind, which is more variable than uplift in its spatio-temporal distribution, is the determining factor in the birds’ route selection over the open sea. Our findings suggest a need for revisiting how ecological barriers are defined, to reflect what we know of animal movement in the era of bio-logging.

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The interplay of wind and uplift facilitates over-water flight in facultative soaring birds

Proceedings of The Royal Society B Biological Sciences ◽

10.1098/rspb.2021.1603 ◽

2021 ◽

Vol 288 (1958) ◽

pp. 20211603

Author(s):

Elham Nourani ◽

Gil Bohrer ◽

Paolo Becciu ◽

Richard O. Bierregaard ◽

Olivier Duriez ◽

...

Keyword(s):

Migratory Birds ◽

Global Scale ◽

Atmospheric Conditions ◽

Wind Uplift ◽

Ecological Barriers ◽

Open Sea ◽

Spatio Temporal ◽

Wind Support

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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Tropospheric Ozone Assessment Report: Assessment of global-scale model performance for global and regional ozone distributions, variability, and trends

Elem Sci Anth ◽

10.1525/elementa.265 ◽

2018 ◽

Vol 6 ◽

Cited By ~ 62

Author(s):

P. J. Young ◽

V. Naik ◽

A. M. Fiore ◽

A. Gaudel ◽

J. Guo ◽

...

Keyword(s):

Atmospheric Chemistry ◽

Tropospheric Ozone ◽

Model Performance ◽

Temporal Distribution ◽

Temporal Variations ◽

Global Scale ◽

Scale Model ◽

Significant Information ◽

Assessment Report ◽

Spatio Temporal

The goal of the Tropospheric Ozone Assessment Report (TOAR) is to provide the research community with an up-to-date scientific assessment of tropospheric ozone, from the surface to the tropopause. While a suite of observations provides significant information on the spatial and temporal distribution of tropospheric ozone, observational gaps make it necessary to use global atmospheric chemistry models to synthesize our understanding of the processes and variables that control tropospheric ozone abundance and its variability. Models facilitate the interpretation of the observations and allow us to make projections of future tropospheric ozone and trace gas distributions for different anthropogenic or natural perturbations. This paper assesses the skill of current-generation global atmospheric chemistry models in simulating the observed present-day tropospheric ozone distribution, variability, and trends. Drawing upon the results of recent international multi-model intercomparisons and using a range of model evaluation techniques, we demonstrate that global chemistry models are broadly skillful in capturing the spatio-temporal variations of tropospheric ozone over the seasonal cycle, for extreme pollution episodes, and changes over interannual to decadal periods. However, models are consistently biased high in the northern hemisphere and biased low in the southern hemisphere, throughout the depth of the troposphere, and are unable to replicate particular metrics that define the longer term trends in tropospheric ozone as derived from some background sites. When the models compare unfavorably against observations, we discuss the potential causes of model biases and propose directions for future developments, including improved evaluations that may be able to better diagnose the root cause of the model-observation disparity. Overall, model results should be approached critically, including determining whether the model performance is acceptable for the problem being addressed, whether biases can be tolerated or corrected, whether the model is appropriately constituted, and whether there is a way to satisfactorily quantify the uncertainty.

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Dynamics of the energy seascape can explain intra-specific variations in sea-crossing behaviour of soaring birds

10.1101/733063 ◽

2019 ◽

Cited By ~ 1

Author(s):

E. Nourani ◽

W. M. G. Vansteelant ◽

P. Byholm ◽

K. Safi

Keyword(s):

Temporal Dynamics ◽

Low Cost ◽

Available Energy ◽

Ecological Barriers ◽

Open Sea ◽

Specific Variation ◽

Soaring Birds ◽

The Mediterranean ◽

Spatio Temporal ◽

Soaring Flight

AbstractThermal soaring birds extract energy from the atmosphere to achieve energetically low-cost movement. When encountering regions that are energetically costly to fly over, such as open seas, they attempt to adjust the spatio-temporal pattern of their passage to maximize energy extraction from the atmosphere over these ecological barriers. We apply the concept of energy landscapes to investigate the spatio-temporal dynamics of energy availability over the open sea for soaring flight. We specifically investigated how the “energy seascape” may shape age-specific sea-crossing behaviour of European honey buzzards Pernis apivorus over the Mediterranean Sea in autumn. We found uplift potential over the sea to be the main determinant of sea-crossing length, rather than wind conditions. Considering this variable as a proxy for available energy over the sea, we constructed the energy seascape for the autumn migration season using forty years of temperature data. Our results indicate that early-migrating adult buzzards are likely to encounter adverse energy subsidence over the Mediterranean, whereas late-migrating juveniles face less adverse flight conditions, and even conditions conducive to soaring flight. Our study provides evidence that the dynamics of the energy landscape can explain intra-specific variation in migratory behaviour also at sea.

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Stopover decision during migration: physiological conditions predict nocturnal restlessness in wild passerines

Biology Letters ◽

10.1098/rsbl.2008.0755 ◽

2009 ◽

Vol 5 (3) ◽

pp. 302-305 ◽

Cited By ~ 63

Author(s):

Leonida Fusani ◽

Massimiliano Cardinale ◽

Claudio Carere ◽

Wolfgang Goymann

Keyword(s):

Migratory Birds ◽

Subcutaneous Fat ◽

Bird Species ◽

Quantitative Relationship ◽

Migratory Restlessness ◽

Stopover Site ◽

Quantitative Evidence ◽

Physiological Conditions ◽

Ecological Barriers ◽

Before And After

During migration, a number of bird species rely on stopover sites for resting and feeding before and after crossing ecological barriers such as deserts or seas. The duration of a stopover depends on the combined effects of environmental factors, endogenous programmes and physiological conditions. Previous studies indicated that lean birds prolong their refuelling stopover compared with fat birds; however, the quantitative relationship between physiological conditions and stopover behaviour has not been studied yet. Here, we tested in a large sample of free-living birds of three European passerines (whinchats, Saxicola rubetra , garden warblers, Sylvia borin and whitethroats, Sylvia communis ) whether the amount of migratory restlessness (Zugunruhe) shown at a stopover site depends on physiological conditions. An integrated measure of condition based on body mass, amount of subcutaneous fat and thickness of pectoral muscles strongly predicted the intensity of Zugunruhe shown in recording cages in the night following capture. These results provide novel and robust quantitative evidence in support of the hypothesis that the amount of energy reserves plays a major role in determining the stopover duration in migratory birds.

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Dynamics of the energy seascape can explain intra-specific variations in sea-crossing behaviour of soaring birds

Biology Letters ◽

10.1098/rsbl.2019.0797 ◽

2020 ◽

Vol 16 (1) ◽

pp. 20190797 ◽

Cited By ~ 3

Author(s):

E. Nourani ◽

W. M. G. Vansteelant ◽

P. Byholm ◽

K. Safi

Keyword(s):

Temporal Dynamics ◽

Low Cost ◽

Available Energy ◽

Ecological Barriers ◽

Open Sea ◽

Specific Variation ◽

Soaring Birds ◽

The Mediterranean ◽

Spatio Temporal ◽

Soaring Flight

Thermal soaring birds extract energy from the atmosphere to achieve energetically low-cost movement. When encountering regions that are energetically costly to fly over, such as open seas, they should attempt to adjust the spatio-temporal pattern of their passage to maximize energy extraction from the atmosphere over these ecological barriers. We applied the concept of energy landscapes to investigate the spatio-temporal dynamics of energy availability over the open sea for soaring flight. We specifically investigated how the ‘energy seascape' may shape age-specific sea-crossing behaviour of European honey buzzards, Pernis apivorus , over the Mediterranean Sea in autumn. We found uplift potential over the sea to be the main determinant of sea-crossing distance, rather than wind conditions. Considering this variable as a proxy for available energy over the sea, we constructed the energy seascape for the autumn migration season using 40 years of temperature data. Our results indicate that early-migrating adult buzzards are likely to encounter adverse energy subsidence over the Mediterranean, whereas late-migrating juveniles face less adverse flight conditions, and even conditions conducive to soaring flight. Our study provides evidence that the dynamics of the energy landscape can explain intra-specific variation in migratory behaviour also at sea.

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Spatio-Temporal Distribution of Aedes Albopictus and Culex Pipiens along an Urban-Natural Gradient in the Ventotene Island, Italy

International Journal of Environmental Research and Public Health ◽

10.3390/ijerph17228300 ◽

2020 ◽

Vol 17 (22) ◽

pp. 8300

Author(s):

Mattia Manica ◽

Sara Riello ◽

Carolina Scagnolari ◽

Beniamino Caputo

Keyword(s):

Aedes Albopictus ◽

Culex Pipiens ◽

Urban Landscape ◽

Migratory Birds ◽

Temporal Distribution ◽

Pathogen Transmission ◽

Current Evidence ◽

Small Scale ◽

Stopover Site ◽

Spatio Temporal

The distribution of mosquitos and their corresponding hosts is critical in public health to determine the risk of transmission for vector-borne diseases. In this pilot study conducted in the small Mediterranean island of Ventotene, a known stopover site for migratory birds, the spatio-temporal distribution of two major mosquito vectors is analyzed from the natural to urban environment. The results show that Aedes albopictus aggregates mostly near areas with a human presence and the urban landscape, while Culex pipiens is more spatio-temporally spread, as it can also be found in wilder and less anthropized areas where the availability of human hosts is limited. Culex pipiens is also active earlier in the year. From a microgeographical perspective, our results confirm the anthropophilic spatial distribution of Ae. Albopictus, while suggesting that the circulation of bird zoonosis, such as West Nile, could be favored by the Cx. pipiens distribution. The results highlight the different ecology of the vectors and the interplay with their hosts, even at a small scale. The current evidence may help in forecasting the risk of pathogen transmission and surveillance planning.

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