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Pekarsky S, Shohami D, Horvitz N, Bowie RCK, Kamath PL, Markin Y, Getz WM, Nathan R. Cranes soar on thermal updrafts behind cold fronts as they migrate across the sea. Proc Biol Sci 2024; 291:20231243. [PMID: 38229520 DOI: 10.1098/rspb.2023.1243] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2023] [Accepted: 12/11/2023] [Indexed: 01/18/2024] Open
Abstract
Thermal soaring conditions above the sea have long been assumed absent or too weak for terrestrial migrating birds, forcing obligate soarers to take long detours and avoid sea-crossing, and facultative soarers to cross exclusively by costly flapping flight. Thus, while atmospheric convection does develop at sea and is used by some seabirds, it has been largely ignored in avian migration research. Here, we provide direct evidence for routine thermal soaring over open sea in the common crane, the heaviest facultative soarer known among terrestrial migrating birds. Using high-resolution biologging from 44 cranes tracked across their transcontinental migration over 4 years, we show that soaring performance was no different over sea than over land in mid-latitudes. Sea-soaring occurred predominantly in autumn when large water-air temperature difference followed mid-latitude cyclones. Our findings challenge a fundamental migration research paradigm and suggest that obligate soarers avoid sea-crossing not due to the absence or weakness of thermals but due to their low frequency, for which they cannot compensate with prolonged flapping. Conversely, facultative soarers other than cranes should also be able to use thermals over the sea. Marine cold air outbreaks, imperative to global energy budget and climate, may also be important for bird migration.
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Affiliation(s)
- Sasha Pekarsky
- Movement Ecology Laboratory, Department of Ecology, Evolution and Behavior, Alexander Silberman Institute of Life Sciences, The Hebrew University of Jerusalem, Jerusalem 91904, Israel
| | - David Shohami
- Movement Ecology Laboratory, Department of Ecology, Evolution and Behavior, Alexander Silberman Institute of Life Sciences, The Hebrew University of Jerusalem, Jerusalem 91904, Israel
| | - Nir Horvitz
- Movement Ecology Laboratory, Department of Ecology, Evolution and Behavior, Alexander Silberman Institute of Life Sciences, The Hebrew University of Jerusalem, Jerusalem 91904, Israel
| | - Rauri C K Bowie
- Museum of Vertebrate Zoology, University of California, Berkeley, CA 94720, USA
- Department of Integrative Biology, University of California, Berkeley, CA 94720-3114, USA
| | - Pauline L Kamath
- School of Food and Agriculture, University of Maine, Orono, ME 04469, USA
| | - Yuri Markin
- Oksky State Reserve, pos. Brykin Bor, Spassky raion, Ryazanskaya oblast 391072, Russia
| | - Wayne M Getz
- School Mathematical Sciences, University of KwaZulu-Natal, Durban, South Africa
| | - Ran Nathan
- Movement Ecology Laboratory, Department of Ecology, Evolution and Behavior, Alexander Silberman Institute of Life Sciences, The Hebrew University of Jerusalem, Jerusalem 91904, Israel
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Becciu P, Troupin D, Dinevich L, Leshem Y, Sapir N. Soaring migrants flexibly respond to sea-breeze in a migratory bottleneck: using first derivatives to identify behavioural adjustments over time. MOVEMENT ECOLOGY 2023; 11:44. [PMID: 37501209 PMCID: PMC10375660 DOI: 10.1186/s40462-023-00402-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/19/2022] [Accepted: 06/22/2023] [Indexed: 07/29/2023]
Abstract
BACKGROUND Millions of birds travel every year between Europe and Africa detouring ecological barriers and funnelling through migratory corridors where they face variable weather conditions. Little is known regarding the response of migrating birds to mesoscale meteorological processes during flight. Specifically, sea-breeze has a daily cycle that may directly influence the flight of diurnal migrants. METHODS We collected radar tracks of soaring migrants using modified weather radar in Latrun, central Israel, in 7 autumns between 2005 and 2016. We investigated how migrating soaring birds adjusted their flight speed and direction under the effects of daily sea-breeze circulation. We analysed the effects of wind on bird groundspeed, airspeed and the lateral component of the airspeed as a function of time of day using Generalized Additive Mixed Models. To identify when birds adjusted their response to the wind over time, we estimated first derivatives. RESULTS Using data collected during a total of 148 days, we characterised the diel dynamics of horizontal wind flow relative to the migration goal, finding a consistent rotational movement of the wind blowing towards the East (morning) and to the South-East (late afternoon), with highest crosswind speed around mid-day and increasing tailwinds towards late afternoon. Airspeed of radar detected birds decreased consistently with increasing tailwind and decreasing crosswinds from early afternoon, resulting in rather stable groundspeed of 16-17 m/s. In addition, birds fully compensated for lateral drift when crosswinds were at their maximum and slightly drifted with the wind when crosswinds decreased and tailwinds became more intense. CONCLUSIONS Using a simple and broadly applicable statistical method, we studied how wind influences bird flight through speed adjustments over time, providing new insights regarding the flexible behavioural responses of soaring birds to wind conditions. These adjustments allowed the birds to compensate for lateral drift under crosswind and reduced their airspeed under tailwind. Our work enhances our understanding of how migrating birds respond to changing wind conditions during their long-distance journeys through migratory corridors.
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Affiliation(s)
- Paolo Becciu
- Animal Flight Laboratory, Department of Evolutionary and Environmental Biology and Institute of Evolution, University of Haifa, 199 Aba Khoushy Ave. Mount Carmel, 3498838, Haifa, Israel.
- Department of Ecology and Evolution, University of Lausanne, Lausanne, Switzerland.
| | - David Troupin
- Animal Flight Laboratory, Department of Evolutionary and Environmental Biology and Institute of Evolution, University of Haifa, 199 Aba Khoushy Ave. Mount Carmel, 3498838, Haifa, Israel
| | - Leonid Dinevich
- Department of Zoology, George S. Wise Faculty of Life Sciences, University of Tel Aviv, 69978, Ramat Aviv, Tel Aviv, Israel
| | - Yossi Leshem
- Department of Zoology, George S. Wise Faculty of Life Sciences, University of Tel Aviv, 69978, Ramat Aviv, Tel Aviv, Israel
| | - Nir Sapir
- Animal Flight Laboratory, Department of Evolutionary and Environmental Biology and Institute of Evolution, University of Haifa, 199 Aba Khoushy Ave. Mount Carmel, 3498838, Haifa, Israel
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Becciu P, Séchaud R, Schalcher K, Plancherel C, Roulin A. Prospecting movements link phenotypic traits to female annual potential fitness in a nocturnal predator. Sci Rep 2023; 13:5071. [PMID: 36977731 PMCID: PMC10050157 DOI: 10.1038/s41598-023-32255-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2022] [Accepted: 03/24/2023] [Indexed: 03/30/2023] Open
Abstract
Recent biologging technology reveals hidden life and breeding strategies of nocturnal animals. Combining animal movement patterns with individual characteristics and landscape features can uncover meaningful behaviours that directly influence fitness. Consequently, defining the proximate mechanisms and adaptive value of the identified behaviours is of paramount importance. Breeding female barn owls (Tyto alba), a colour-polymorphic species, recurrently visit other nest boxes at night. We described and quantified this behaviour for the first time, linking it with possible drivers, and individual fitness. We GPS-equipped 178 female barn owls and 122 male partners from 2016 to 2020 in western Switzerland during the chick rearing phase. We observed that 111 (65%) of the tracked breeding females were (re)visiting nest boxes while still carrying out their first brood. We modelled their prospecting parameters as a function of brood-, individual- and partner-related variables and found that female feather eumelanism predicted the emergence of prospecting behaviour (less melanic females are usually prospecting). More importantly we found that increasing male parental investment (e.g., feeding rate) increased female prospecting efforts. Ultimately, females would (re)visit a nest more often if they had used it in the past and were more likely to lay a second clutch afterwards, consequently having higher annual fecundity than non-prospecting females. Despite these apparent immediate benefits, they did not fledge more chicks. Through biologging and long-term field monitoring, we highlight how phenotypic traits (melanism and parental investment) can be related to movement patterns and the annual potential reproductive output (fecundity) of female barn owls.
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Affiliation(s)
- Paolo Becciu
- Department of Ecology and Evolution, University of Lausanne, Lausanne, Switzerland.
| | - Robin Séchaud
- Department of Ecology and Evolution, University of Lausanne, Lausanne, Switzerland
- Agroecology and Environment, Agroscope, Reckenholzstrasse 191, 8046, Zurich, Switzerland
| | - Kim Schalcher
- Department of Ecology and Evolution, University of Lausanne, Lausanne, Switzerland
| | - Céline Plancherel
- Department of Ecology and Evolution, University of Lausanne, Lausanne, Switzerland
| | - Alexandre Roulin
- Department of Ecology and Evolution, University of Lausanne, Lausanne, Switzerland
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4
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Nadal J, Sáez D, Margalida A. Crossing artificial obstacles during migration: The relative global ecological risks and interdependencies illustrated by the migration of common quail Coturnix coturnix. THE SCIENCE OF THE TOTAL ENVIRONMENT 2022; 808:152173. [PMID: 34875331 DOI: 10.1016/j.scitotenv.2021.152173] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/08/2021] [Revised: 11/29/2021] [Accepted: 11/30/2021] [Indexed: 06/13/2023]
Abstract
The increase of urban expansion, whereby soils become altered or filled with buildings through human action, presents a global threat to biodiversity and the spread of disease. Many of the factors determining bird migration routes and disease spread are poorly understood. We studied the migration routes of common quail Coturnix coturnix in western Europe. We examined the recoveries of ringed birds to characterize their migration trajectories to understand how this nocturnal migrant crosses artificial areas and predict the risk of migration collapse and disease transmission. We evaluated the possible consequences of quail collisions with human infrastructure elements (i.e., buildings, cranes, overhead cables and wires, and wind farm structures) to assess disease transmission in relation to the amount of urban soil. Our results show that variations in the amount of artificialized soil in central Europe are correlated with the relative absence of quail migratory routes. Conceptual models incorporating environmental ecology showed the relationships between climate warming, agroecosystems, and urban ecosystems as well as human health and economic growth. We predict a drastic loss of biodiversity and spread of disease if we do not curb the spread of land consumption. Taking a broad view of the interrelations discussed here allows predictions of global vulnerability and increased risks to health due to losses of biodiversity and ecosystem services. Lessons drawn from migration route maps of quail in relation to the distribution of urbanized soils provide tools for global conservation political decision making.
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Affiliation(s)
- Jesús Nadal
- Department of Animal Science, Division of Wildlife, Faculty of Life Sciences and Engineering, University of Lleida, Lleida, Spain.
| | - David Sáez
- Department of Animal Science, Division of Wildlife, Faculty of Life Sciences and Engineering, University of Lleida, Lleida, Spain
| | - Antoni Margalida
- Institute for Game and Wildlife Research, IREC (CSIC-UCLM-JCCM), 13005 Ciudad Real, Spain; Division of Conservation Biology, Institute of Ecology and Evolution, University of Bern, Bern, Switzerland.
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Schmaljohann H, Eikenaar C, Sapir N. Understanding the ecological and evolutionary function of stopover in migrating birds. Biol Rev Camb Philos Soc 2022; 97:1231-1252. [PMID: 35137518 DOI: 10.1111/brv.12839] [Citation(s) in RCA: 38] [Impact Index Per Article: 19.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2021] [Revised: 01/31/2022] [Accepted: 02/01/2022] [Indexed: 12/14/2022]
Abstract
Global movement patterns of migratory birds illustrate their fascinating physical and physiological abilities to cross continents and oceans. During their voyages, most birds land multiple times to make so-called 'stopovers'. Our current knowledge on the functions of stopover is mainly based on the proximate study of departure decisions. However, such studies are insufficient to gauge fully the ecological and evolutionary functions of stopover. If we study how a focal trait, e.g. changes in energy stores, affects the decision to depart from a stopover without considering the trait(s) that actually caused the bird to land, e.g. unfavourable environmental conditions for flight, we misinterpret the function of the stopover. It is thus important to realise and acknowledge that stopovers have many different functions, and that not every migrant has the same (set of) reasons to stop-over. Additionally, we may obtain contradictory results because the significance of different traits to a migrant is context dependent. For instance, late spring migrants may be more prone to risk-taking and depart from a stopover with lower energy stores than early spring migrants. Thus, we neglect that departure decisions are subject to selection to minimise immediate (mortality risk) and/or delayed (low future reproductive output) fitness costs. To alleviate these issues, we first define stopover as an interruption of migratory endurance flight to minimise immediate and/or delayed fitness costs. Second, we review all probable functions of stopover, which include accumulating energy, various forms of physiological recovery and avoiding adverse environmental conditions for flight, and list potential other functions that are less well studied, such as minimising predation, recovery from physical exhaustion and spatiotemporal adjustments to migration. Third, derived from these aspects, we argue for a paradigm shift in stopover ecology research. This includes focusing on why an individual interrupts its migratory flight, which is more likely to identify the individual-specific function(s) of the stopover correctly than departure-decision studies. Moreover, we highlight that the selective forces acting on stopover decisions are context dependent and are expected to differ between, e.g. K-/r-selected species, the sexes and migration strategies. For example, all else being equal, r-selected species (low survival rate, high reproductive rate) should have a stronger urge to continue the migratory endurance flight or resume migration from a stopover because the potential increase in immediate fitness costs suffered from a flight is offset by the expected higher reproductive success in the subsequent breeding season. Finally, we propose to focus less on proximate mechanisms controlling landing and departure decisions, and more on ultimate mechanisms to identify the selective forces shaping stopover decisions. Our ideas are not limited to birds but can be applied to any migratory species. Our revised definition of stopover and the proposed paradigm shift has the potential to stimulate a fruitful discussion towards a better evolutionary ecological understanding of the functions of stopover. Furthermore, identifying the functions of stopover will support targeted measures to conserve and restore the functionality of stopover sites threatened by anthropogenic environmental changes. This is especially important for long-distance migrants, which currently are in alarming decline.
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Affiliation(s)
- Heiko Schmaljohann
- Institute for Biology and Environmental Sciences (IBU), Carl von Ossietzky University of Oldenburg, Carl-von-Ossietzky-Straße 9-11, Oldenburg, 26129, Germany.,Institute of Avian Research, An der Vogelwarte 21, Wilhelmshaven, 26386, Germany
| | - Cas Eikenaar
- Institute of Avian Research, An der Vogelwarte 21, Wilhelmshaven, 26386, Germany
| | - Nir Sapir
- Department of Evolutionary and Environmental Biology and the Institute of Evolution, University of Haifa, 199 Aba Khoushy Ave, Haifa, 3498838, Israel
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Becciu P, Panuccio M, Dell’Omo G, Sapir N. Groping in the Fog: Soaring Migrants Exhibit Wider Scatter in Flight Directions and Respond Differently to Wind Under Low Visibility Conditions. Front Ecol Evol 2021. [DOI: 10.3389/fevo.2021.745002] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Atmospheric conditions are known to affect flight propensity, behaviour during flight, and migration route in birds. Yet, the effects of fog have only rarely been studied although they could disrupt orientation and hamper flight. Fog could limit the visibility of migrating birds such that they might not be able to detect landmarks that guide them during their journey. Soaring migrants modulate their flight speed and direction in relation to the wind vector to optimise the cost of transport. Consequently, landmark-based orientation, as well as adjustments of flight speed and direction in relation to wind conditions, could be jeopardised when flying in fog. Using a radar system operated in a migration bottleneck (Strait of Messina, Italy), we studied the behaviour of soaring birds under variable wind and fog conditions over two consecutive springs (2016 and 2017), discovering that migrating birds exhibited a wider scatter of flight directions and responded differently to wind under fog conditions. Birds flying through fog deviated more from the mean migration direction and increased their speed with increasing crosswinds. In addition, airspeed and groundspeed increased in the direction of the crosswind, causing the individuals to drift laterally. Our findings represent the first quantitative empirical evidence of flight behaviour changes when birds migrate through fog and explain why low visibility conditions could risk their migration journey.
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7
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Nourani E, Bohrer G, Becciu P, Bierregaard RO, Duriez O, Figuerola J, Gangoso L, Giokas S, Higuchi H, Kassara C, Kulikova O, Lecomte N, Monti F, Pokrovsky I, Sforzi A, Therrien JF, Tsiopelas N, Vansteelant WMG, Viana DS, Yamaguchi NM, Wikelski M, Safi K. The interplay of wind and uplift facilitates over-water flight in facultative soaring birds. Proc Biol Sci 2021; 288:20211603. [PMID: 34493076 PMCID: PMC8424339 DOI: 10.1098/rspb.2021.1603] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2021] [Accepted: 08/16/2021] [Indexed: 11/25/2022] Open
Abstract
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 ΔT, 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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Affiliation(s)
- Elham Nourani
- Department of Migration, Max Planck Institute of Animal Behavior, Germany
- Department of Biology, University of Konstanz, Germany
| | - Gil Bohrer
- Department of Civil, Environmental and Geodetic Engineering, The Ohio State University, USA
| | - Paolo Becciu
- Department of Migration, Max Planck Institute of Animal Behavior, Germany
- Department of Biology, University of Konstanz, Germany
- Department of Evolutionary and Environmental Biology, and Institute of Evolution, University of Haifa, Israel
- Department of Ecology and Evolution, University of Lausanne, Switzerland
| | | | - Olivier Duriez
- Centre for Evolutionary and Functional Ecology, Montpellier University-CNRS, France
| | - Jordi Figuerola
- Department of Wetland Ecology, Estación Biológica de Doñana, Spain
| | - Laura Gangoso
- Department of Wetland Ecology, Estación Biológica de Doñana, Spain
- Department of Biodiversity, Ecology and Evolution, Faculty of Biology, Complutense University of Madrid, Spain
- Institute for Biodiversity and Ecosystem Dynamics (IBED), University of Amsterdam, The Netherlands
| | - Sinos Giokas
- Department of Biology, University of Patras, Greece
| | - Hiroyoshi Higuchi
- Research and Education Centre for Natural Sciences, Keio University, Japan
| | | | - Olga Kulikova
- Department of Biology, University of Konstanz, Germany
- Russian Academy of Sciences, Institute of the Biological Problems of the North, Russia
| | - Nicolas Lecomte
- Canada Research Chair in Polar and Boreal Ecology, Department of Biology, University of Moncton, Canada
| | - Flavio Monti
- Department of Physical Sciences, Earth and Environment, University of Siena, Italy
| | - Ivan Pokrovsky
- Department of Migration, Max Planck Institute of Animal Behavior, Germany
- Russian Academy of Sciences, Institute of the Biological Problems of the North, Russia
- Institute of Plant and Animal Ecology, Russian Academy of Sciences, Russia
| | | | | | | | - Wouter M. G. Vansteelant
- Department of Wetland Ecology, Estación Biológica de Doñana, Spain
- Institute for Biodiversity and Ecosystem Dynamics (IBED), University of Amsterdam, The Netherlands
| | - Duarte S. Viana
- German Center for Integrative Biodiversity Research (iDiv) Halle-Jena-Leipzig, Germany
- Leipzig University, Germany
| | - Noriyuki M. Yamaguchi
- Graduate School of Fisheries and Environmental Sciences, Nagasaki University, Japan
- Organization for Marine Science and Technology, Nagasaki University, Japan
| | - Martin Wikelski
- Department of Migration, Max Planck Institute of Animal Behavior, Germany
- Department of Biology, University of Konstanz, Germany
- Centre for the Advanced Study of Collective Behaviour, University of Konstanz, Germany
| | - Kamran Safi
- Department of Migration, Max Planck Institute of Animal Behavior, Germany
- Department of Biology, University of Konstanz, Germany
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8
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Mallon JM, Bildstein KL, Fagan WF. Inclement weather forces stopovers and prevents migratory progress for obligate soaring migrants. MOVEMENT ECOLOGY 2021; 9:39. [PMID: 34246320 PMCID: PMC8272267 DOI: 10.1186/s40462-021-00274-6] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 04/08/2021] [Accepted: 06/27/2021] [Indexed: 06/13/2023]
Abstract
BACKGROUND Migrating birds experience weather conditions that change with time, which affect their decision to stop or resume migration. Soaring migrants are especially sensitive to changing weather conditions because they rely on the availability of environmental updrafts to subsidize flight. The timescale that local weather conditions change over is on the order of hours, while stopovers are studied at the daily scale, creating a temporal mismatch. METHODS We used GPS satellite tracking data from four migratory Turkey Vulture (Cathartes aura) populations, paired with local weather data, to determine if the decision to stopover by migrating Turkey Vultures was in response to changing local weather conditions. We analyzed 174 migrations of 34 individuals from 2006 to 2019 and identified 589 stopovers based on variance of first passage times. We also investigated if the extent of movement activity correlated with average weather conditions experienced during a stopover, and report general patterns of stopover use by Turkey Vultures between seasons and across populations. RESULTS Stopover duration ranged from 2 h to more than 11 days, with 51 % of stopovers lasting < 24 h. Turkey Vultures began stopovers immediately in response to changes in weather variables that did not favor thermal soaring (e.g., increasing precipitation fraction and decreasing thermal updraft velocity) and their departure from stopovers was associated with improvements in weather that favored thermal development. During stopovers, proportion of activity was negatively associated with precipitation but was positively associated with temperature and thermal updraft velocity. CONCLUSIONS The rapid response of migrating Turkey Vultures to changing weather conditions indicates weather-avoidance is one of the major functions of their stopover use. During stopovers, however, the positive relationship between proportion of movement activity and conditions that promote thermal development suggests not all stopovers are used for weather-avoidance. Our results show that birds are capable of responding rapidly to their environment; therefore, for studies interested in external drivers of weather-related stopovers, it is essential that stopovers be identified at fine temporal scales.
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Affiliation(s)
- Julie M Mallon
- Department of Biology, University of Maryland, College Park, MD, 20742, USA.
| | - Keith L Bildstein
- Hawk Mountain Sanctuary, Acopian Center for Conservation Learning, 410 Summer Valley Road, Orwigsburg, PA, 17961, USA
| | - William F Fagan
- Department of Biology, University of Maryland, College Park, MD, 20742, USA
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9
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Blas J, Salas R, Flack A, Torres-Medina F, Sergio F, Wikelski M, Fiedler W. Overland and oversea migration of white storks through the water barriers of the straits of Gibraltar. Sci Rep 2020; 10:20760. [PMID: 33262367 PMCID: PMC7708975 DOI: 10.1038/s41598-020-77273-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2019] [Accepted: 11/06/2020] [Indexed: 11/09/2022] Open
Abstract
Soaring landbirds typically exploit atmospheric uplift as they fly overland, displaying a highly effective energy-saving locomotion. However, large water bodies lack thermal updrafts, potentially becoming ecological barriers that hamper migration. Here we assessed the effects of a sea surface on the migratory performance of GPS-tagged white storks (Ciconia ciconia) before, during and after they crossed the straits of Gibraltar. Oversea movements involved only flapping and gliding and were faster, traversed in straighter, descending trajectories and resulted in higher movement-related energy expenditure levels than overland, supporting the water barrier hypothesis. Overland movements at both sides of the sea straits resulted in tortuous routes and ascending trajectories with pre-crossing flights showing higher elevations and more tortuous routes than post-crossing, thus supporting the barrier negotiation hypothesis. Individual positions at both ends of the sea narrow were predicted by zonal winds and storks´ location at entry in the European hinterland, and birds did not show compensational movements overland in anticipation to subsequent wind displacements oversea. The length of the water narrow at departure shore, the elevation therein and the winds on route affected major components of sea crossing performance (such as distances and times overwater, minimum elevations, climb angles, speeds and energy expenditure), supporting the departure position and oversea winds hypotheses. In summary, our study provides a prime example at high temporal resolution of how birds adjust their behavior and physiology as they interact with the changing conditions of the travelling medium, reallocating resources and modifying their movement to overcome an ecological barrier.
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Affiliation(s)
- Julio Blas
- Department of Conservation Biology. Estación Biológica de Doñana, Consejo Superior de Investigaciones Científicas CSIC, 41092, Seville, Spain.
| | - Reyes Salas
- Department of Conservation Biology. Estación Biológica de Doñana, Consejo Superior de Investigaciones Científicas CSIC, 41092, Seville, Spain.,Department of Migration, Max Planck Institute of Animal Behavior, 78315, Radolfzell, Germany
| | - Andrea Flack
- Department of Migration, Max Planck Institute of Animal Behavior, 78315, Radolfzell, Germany.,Centre for the Advanced Study of Collective Behaviour, University of Konstanz, 78457, Konstanz, Germany
| | - Fernando Torres-Medina
- Department of Conservation Biology. Estación Biológica de Doñana, Consejo Superior de Investigaciones Científicas CSIC, 41092, Seville, Spain
| | - Fabrizio Sergio
- Department of Conservation Biology. Estación Biológica de Doñana, Consejo Superior de Investigaciones Científicas CSIC, 41092, Seville, Spain
| | - Martin Wikelski
- Department of Migration, Max Planck Institute of Animal Behavior, 78315, Radolfzell, Germany.,Centre for the Advanced Study of Collective Behaviour, University of Konstanz, 78457, Konstanz, Germany
| | - Wolfgang Fiedler
- Department of Migration, Max Planck Institute of Animal Behavior, 78315, Radolfzell, Germany.,Centre for the Advanced Study of Collective Behaviour, University of Konstanz, 78457, Konstanz, Germany
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