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

2020 ◽  
Vol 16 (1) ◽  
pp. 20190797 ◽  
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.

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

2019 ◽  
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.

scholarly journals The shifting distribution of Mediterranean fishes: a spatio-temporal assessment based on Local Ecological Knowledge .

2019 ◽  
Author(s):  
Ernesto Azzurro ◽  
Valerio Sbragaglia ◽  
Jacopo Cerri ◽  
Michel Bariche ◽  
Luca Bolognini ◽  
...  
Keyword(s):  
Mediterranean Sea ◽  
Temporal Dynamics ◽  
Local Ecological Knowledge ◽  
Rapid Change ◽  
Species Abundance ◽  
Global Ocean ◽  
Small Scale ◽  
Ecological Knowledge ◽  
The Mediterranean ◽  
Spatio Temporal

A major problem worldwide is the rapid change in species abundance and distribution, which is rapidly restructuring the biological communities of many ecosystems under changing climates. Tracking these transformations in the marine environment is crucial but our understanding is often hampered by the absence of historical data and by the practical challenge of survey large geographical areas. Here we focus on the Mediterranean Sea, a region which is warming faster than the rest of the global ocean, tracing back the spatio-temporal dynamic of species, which are emerging the most in terms of increasing abundances and expanding distributions. To this aim, we accessed the Local Ecological Knowledge (LEK) of small-scale and recreational fishers reconstructing the dynamics of fish perceived as ‘new’ or increasing in different fishing area. Over 500 fishers across 95 locations and 9 different countries were interviewed and semi-quantitative information on yearly changes in species abundance was collected. Overall, 75 species were mentioned by the respondents, being the most frequent citations related to warm-adapted species of both, native and exotic origin. Respondents belonging to the same biogeographic sectors described coherent spatio-temporal dynamics, and gradients along latitudinal and longitudinal axes were revealed. This information provides a more complete understanding of recent bio-geographical changes in the Mediterranean Sea and it also demonstrates that adequately structured LEK methodology might be applied successfully beyond the local scale, across national borders and jurisdictions. Acknowledging this potential through macro-regional coordination, could pave the ground for future large-scale aggregations of individual observations, increasing our potential for integrated monitoring and conservation planning at the regional or even global level.

scholarly journals Static landscape features predict uplift locations for soaring birds across Europe

2019 ◽  
Vol 6 (1) ◽  
pp. 181440 ◽  
Author(s):  
Martina Scacco ◽  
Andrea Flack ◽  
Olivier Duriez ◽  
Martin Wikelski ◽  
Kamran Safi
Keyword(s):  
Energy Expenditure ◽  
Landscape Structure ◽  
Low Cost ◽  
Movement Pattern ◽  
Weather Conditions ◽  
Computationally Efficient ◽  
Landscape Features ◽  
Energy Expenditures ◽  
Soaring Birds ◽  
Soaring Flight

Soaring flight is a remarkable adaptation to reduce movement costs by taking advantage of atmospheric uplifts. The movement pattern of soaring birds is shaped by the spatial and temporal availability and intensity of uplifts, which result from an interaction of local weather conditions with the underlying landscape structure. We used soaring flight locations and vertical speeds of an obligate soaring species, the white stork ( Ciconia ciconia ), as proxies for uplift availability and intensity. We then tested if static landscape features such as topography and land cover, instead of the commonly used weather information, could predict and map the occurrence and intensity of uplifts across Europe. We found that storks encountering fewer uplifts along their routes, as determined by static landscape features, suffered higher energy expenditures, approximated by their overall body dynamic acceleration. This result validates the use of static features as uplift predictors and suggests the existence of a direct link between energy expenditure and static landscape structure, thus far largely unquantified for flying animals. Our uplift availability map represents a computationally efficient proxy of the distribution of movement costs for soaring birds across the world's landscapes. It thus provides a base to explore the effects of changes in the landscape structure on the energy expenditure of soaring birds, identify low-cost movement corridors and ultimately inform the planning of anthropogenic developments.

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

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.

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

2020 ◽  
Author(s):  
Elham Nourani ◽  
Paolo Becciu ◽  
Richard O. Bierregaard ◽  
Olivier Duriez ◽  
Sinos Giokas ◽  
...  
Keyword(s):  
Animal Movement ◽  
Migratory Birds ◽  
Bird Species ◽  
Temporal Distribution ◽  
Global Scale ◽  
Route Selection ◽  
Atmospheric Conditions ◽  
Ecological Barriers ◽  
Open Sea ◽  
Spatio Temporal

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.

Spatial and temporal dynamics of Pacific capelin Mallotus catervarius in the Gulf of Alaska: implications for ecosystem-based fisheries management

2020 ◽  
Vol 637 ◽  
pp. 117-140 ◽  
Author(s):  
DW McGowan ◽  
ED Goldstein ◽  
ML Arimitsu ◽  
AL Deary ◽  
O Ormseth ◽  
...  
Keyword(s):  
Temporal Dynamics ◽  
Marine Ecosystem ◽  
Gulf Of Alaska ◽  
Data Series ◽  
Limited Information ◽  
Important Species ◽  
Multiple Data ◽  
Spatial And Temporal Dynamics ◽  
Spawning Areas ◽  
Spatio Temporal

Pacific capelin Mallotus catervarius are planktivorous small pelagic fish that serve an intermediate trophic role in marine food webs. Due to the lack of a directed fishery or monitoring of capelin in the Northeast Pacific, limited information is available on their distribution and abundance, and how spatio-temporal fluctuations in capelin density affect their availability as prey. To provide information on life history, spatial patterns, and population dynamics of capelin in the Gulf of Alaska (GOA), we modeled distributions of spawning habitat and larval dispersal, and synthesized spatially indexed data from multiple independent sources from 1996 to 2016. Potential capelin spawning areas were broadly distributed across the GOA. Models of larval drift show the GOA’s advective circulation patterns disperse capelin larvae over the continental shelf and upper slope, indicating potential connections between spawning areas and observed offshore distributions that are influenced by the location and timing of spawning. Spatial overlap in composite distributions of larval and age-1+ fish was used to identify core areas where capelin consistently occur and concentrate. Capelin primarily occupy shelf waters near the Kodiak Archipelago, and are patchily distributed across the GOA shelf and inshore waters. Interannual variations in abundance along with spatio-temporal differences in density indicate that the availability of capelin to predators and monitoring surveys is highly variable in the GOA. We demonstrate that the limitations of individual data series can be compensated for by integrating multiple data sources to monitor fluctuations in distributions and abundance trends of an ecologically important species across a large marine ecosystem.

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