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Romanova N, Utvenko G, Prokshina A, Cellarius F, Fedorishcheva A, Pakhomov A. Migratory birds are able to choose the appropriate migratory direction under dim yellow narrowband light. Proc Biol Sci 2023; 290:20232499. [PMID: 38113940 PMCID: PMC10730290 DOI: 10.1098/rspb.2023.2499] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2023] [Accepted: 11/21/2023] [Indexed: 12/21/2023] Open
Abstract
Currently, it is generally assumed that migratory birds are oriented in the appropriate migratory direction under UV, blue and green light (short-wavelength) and are unable to use their magnetic compass in total darkness and under yellow and red light (long-wavelength). However, it has also been suggested that the magnetic compass has two sensitivity peaks: in the short and long wavelengths, but with different intensities. In this project, we aimed to study the orientation of long-distance migrants, pied flycatchers (Ficedula hypoleuca), under different narrowband light conditions during autumn and spring migrations. The birds were tested in the natural magnetic field (NMF) and a changed magnetic field (CMF) rotated counterclockwise by 120° under dim green (autumn) and yellow (spring and autumn) light, which are on the 'threshold' between the short-wavelength and long-wavelength light. We showed that pied flycatchers (i) were completely disoriented under green light both in the NMF and CMF but (ii) showed the migratory direction in the NMF and the appropriate response to CMF under yellow light. Our data contradict the results of previous experiments under narrowband green and yellow light and raise doubts about the existence of only short-wavelength magnetoreception. The parameters of natural light change dramatically in spectral composition and intensity after local sunset, and the avian magnetic compass should be adapted to function properly under such constantly changing light conditions.
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Affiliation(s)
- Nadezhda Romanova
- Moscow State Pedagogical University, 1/1 M. Pirogovskaya St., Moscow 119991, Russia
| | - Gleb Utvenko
- Department of Vertebrate Zoology, St. Petersburg State University, 199034 St. Petersburg, Russia
- Biological Station Rybachy, Zoological Institute RAS, Kaliningrad Region, Rybachy 238535, Russia
| | - Anisia Prokshina
- Department of Vertebrate Zoology, Lomonosov Moscow State University, 119234 Moscow, Russia
| | - Fyodor Cellarius
- Department of Vertebrate Zoology, Lomonosov Moscow State University, 119234 Moscow, Russia
| | | | - Alexander Pakhomov
- Biological Station Rybachy, Zoological Institute RAS, Kaliningrad Region, Rybachy 238535, Russia
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Scridel D, Pirrello S, Imperio S, Cecere JG, Albanese G, Andreotti A, Arveda G, Borghesi F, La Gioia G, Massa L, Mengoni C, Micheloni P, Mucci N, Nardelli R, Nissardi S, Volponi S, Zucca C, Serra L. Weather, sex and body condition affect post-fledging migration behaviour of the greater flamingo Phoenicopterus roseus. MOVEMENT ECOLOGY 2023; 11:51. [PMID: 37612593 PMCID: PMC10464070 DOI: 10.1186/s40462-023-00409-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/15/2023] [Accepted: 06/29/2023] [Indexed: 08/25/2023]
Abstract
BACKGROUND Understanding which intrinsic and extrinsic factors dictate decision-making processes such as leaving the natal area or not (migratory vs resident strategy), departure time, and non-breeding destination are key-issues in movement ecology. This is particularly relevant for a partially migratory meta-population in which only some individuals migrate. METHODS We investigated these decision making-processes for 40 juvenile greater flamingos Phoenicopterus roseus fledged in three Mediterranean colonies and equipped with GPS-GSM devices. RESULTS Contrary to the body size and the dominance hypotheses, juveniles in better body condition were more likely to migrate than those in worse conditions, which opted for a residence strategy. Flamingo probability of departure was not associated with an increase in local wind intensity, but rather with the presence of tailwinds with departure limited to night-time mostly when the wind direction aligned with the migratory destination. Moreover, a positive interaction between tailwind speed and migration distance suggested that juveniles opted for stronger winds when initiating long-distance journeys. In contrast to previous studies, the prevailing seasonal winds were only partially aligned with the migratory destination, suggesting that other factors (e.g., adults experience in mix-aged flocks, availability of suitable foraging areas en route, density-dependence processes) may be responsible for the distribution observed at the end of the first migratory movement. We found potential evidence of sex-biased timing of migration with females departing on average 10 days later and flying ca. 10 km/h faster than males. Female flight speed, but not male one, was positively influenced by tailwinds, a pattern most likely explained by sexual differences in mechanical power requirements for flight (males being ca. 20% larger than females). Furthermore, juveniles considerably reduced their flight speeds after 400 km from departure, highlighting a physiological threshold, potentially linked to mortality risks when performing long-distance non-stop movements. CONCLUSION These results suggest that not only intrinsic factors such as individual conditions and sex, but also extrinsic factors like weather, play critical roles in triggering migratory behaviour in a partially migratory metapopulation. Furthermore, social factors, including conspecific experience, should be taken into consideration when evaluating the adaptive processes underlying migration phenology, flight performance, and final destination selection.
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Affiliation(s)
- Davide Scridel
- Area Avifauna Migratrice (BIO-AVM), Istituto Superiore per la Protezione e la Ricerca Ambientale (ISPRA), via Ca' Fornacetta 9, 40064, Ozzano dell'Emilia, BO, Italy.
- CNR-IRSA National Research Council-Water Research Institute, via del Mulino 19, 20861, Brugherio, MB, Italy.
- Department of Life Sciences, University of Trieste, 34127, Trieste, TS, Italy.
| | - Simone Pirrello
- Area Avifauna Migratrice (BIO-AVM), Istituto Superiore per la Protezione e la Ricerca Ambientale (ISPRA), via Ca' Fornacetta 9, 40064, Ozzano dell'Emilia, BO, Italy
| | - Simona Imperio
- Area Avifauna Migratrice (BIO-AVM), Istituto Superiore per la Protezione e la Ricerca Ambientale (ISPRA), via Ca' Fornacetta 9, 40064, Ozzano dell'Emilia, BO, Italy
| | - Jacopo G Cecere
- Area Avifauna Migratrice (BIO-AVM), Istituto Superiore per la Protezione e la Ricerca Ambientale (ISPRA), via Ca' Fornacetta 9, 40064, Ozzano dell'Emilia, BO, Italy
| | | | - Alessandro Andreotti
- Area Avifauna Migratrice (BIO-AVM), Istituto Superiore per la Protezione e la Ricerca Ambientale (ISPRA), via Ca' Fornacetta 9, 40064, Ozzano dell'Emilia, BO, Italy
| | | | - Fabrizio Borghesi
- Servizio Tutela Ambiente e Territorio, Ufficio Zone Naturali, Comune di Ravenna, via Berlinguer 30, 48121, Ravenna, RA, Italy
| | - Giuseppe La Gioia
- Associazione Ornitologia Mediterranea, via Saponaro 7, 73100, Lecce, LE, Italy
| | - Luisanna Massa
- Parco Naturale Regionale Molentargius Saline, via La Palma n 9, 09126, Cagliari, CA, Italy
| | - Chiara Mengoni
- Area per la Genetica della Conservazione (BIO-CGE), Istituto Superiore per la Protezione e la Ricerca. Ambientale (ISPRA), via Ca' Fornacetta 9, 40064, Ozzano dell'Emilia, BO, Italy
| | - Pierfrancesco Micheloni
- Area Avifauna Migratrice (BIO-AVM), Istituto Superiore per la Protezione e la Ricerca Ambientale (ISPRA), via Ca' Fornacetta 9, 40064, Ozzano dell'Emilia, BO, Italy
| | - Nadia Mucci
- Area per la Genetica della Conservazione (BIO-CGE), Istituto Superiore per la Protezione e la Ricerca. Ambientale (ISPRA), via Ca' Fornacetta 9, 40064, Ozzano dell'Emilia, BO, Italy
| | - Riccardo Nardelli
- Area Avifauna Migratrice (BIO-AVM), Istituto Superiore per la Protezione e la Ricerca Ambientale (ISPRA), via Ca' Fornacetta 9, 40064, Ozzano dell'Emilia, BO, Italy
| | - Sergio Nissardi
- Anthus s.n.c., via Luigi Canepa 22, 09129, Cagliari, CA, Italy
| | - Stefano Volponi
- Area per i pareri tecnici e per le strategie di conservazione e gestione del patrimonio faunistico nazionale (BIO-CFN), Istituto Superiore per la Protezione e la Ricerca Ambientale (ISPRA), via Ca' Fornacetta 9, 40064, Ozzano dell'Emilia, BO, Italy
| | - Carla Zucca
- Anthus s.n.c., via Luigi Canepa 22, 09129, Cagliari, CA, Italy
| | - Lorenzo Serra
- Area Avifauna Migratrice (BIO-AVM), Istituto Superiore per la Protezione e la Ricerca Ambientale (ISPRA), via Ca' Fornacetta 9, 40064, Ozzano dell'Emilia, BO, Italy
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Cooper NW, Dossman BC, Berrigan LE, Brown JM, Cormier DA, Bégin-Marchand C, Rodewald AD, Taylor PD, Tremblay JA, Marra PP. Atmospheric pressure predicts probability of departure for migratory songbirds. MOVEMENT ECOLOGY 2023; 11:23. [PMID: 37122025 PMCID: PMC10150475 DOI: 10.1186/s40462-022-00356-z] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/03/2022] [Accepted: 11/22/2022] [Indexed: 05/03/2023]
Abstract
BACKGROUND Weather can have both delayed and immediate impacts on animal populations, and species have evolved behavioral adaptions to respond to weather conditions. Weather has long been hypothesized to affect the timing and intensity of avian migration, and radar studies have demonstrated strong correlations between weather and broad-scale migration patterns. How weather affects individual decisions about the initiation of migratory flights, particularly at the beginning of migration, remains uncertain. METHODS Here, we combine automated radio telemetry data from four species of songbirds collected at five breeding and wintering sites in North America with hourly weather data from a global weather model. We use these data to determine how wind profit, atmospheric pressure, precipitation, and cloud cover affect probability of departure from breeding and wintering sites. RESULTS We found that the probability of departure was related to changes in atmospheric pressure, almost completely regardless of species, season, or location. Individuals were more likely to depart on nights when atmospheric pressure had been rising over the past 24 h, which is predictive of fair weather over the next several days. By contrast, wind profit, precipitation, and cloud cover were each only informative predictors of departure probability in a single species. CONCLUSIONS Our results suggest that individual birds actively use weather information to inform decision-making regarding the initiation of departure from the breeding and wintering grounds. We propose that birds likely choose which date to depart on migration in a hierarchical fashion with weather not influencing decision-making until after the departure window has already been narrowed down by other ultimate and proximate factors.
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Affiliation(s)
- Nathan W Cooper
- Migratory Bird Center, Smithsonian's National Zoo and Conservation Biology Institute, MRC 5503, 3001 Connecticut Ave. NW, Washington, DC, 20013, USA.
| | - Bryant C Dossman
- Department of Biology and McCourt School of Public Policy, Georgetown University, 37th and O Streets NW, Washington, DC, 20057, USA
- Cornell Lab of Ornithology and Department of Natural Resources and the Environment, Cornell University, 159 Sapsucker Woods Rd, Ithaca, NY, 14850, USA
| | - Lucas E Berrigan
- Department of Biology, Acadia University, 33 Westwood Avenue, Wolfville, NS, B4P 2R6, Canada
- Motus Wildlife Tracking System, Birds Canada, Port Rowan, ON, N0E 1M0, Canada
| | - J Morgan Brown
- Department of Biology, Acadia University, 33 Westwood Avenue, Wolfville, NS, B4P 2R6, Canada
- Wildlife Conservation Society Canada, 169 Titanium Way, Whitehorse, YT, Y1A 0E9, Canada
| | - Dominic A Cormier
- Department of Biology, Acadia University, 33 Westwood Avenue, Wolfville, NS, B4P 2R6, Canada
| | - Camille Bégin-Marchand
- Wildlife Research Division, Environment and Climate Change Canada, 1550 Av. D'Estimauville, Québec, QC, G1J 0C3, Canada
| | - Amanda D Rodewald
- Cornell Lab of Ornithology and Department of Natural Resources and the Environment, Cornell University, 159 Sapsucker Woods Rd, Ithaca, NY, 14850, USA
| | - Philip D Taylor
- Department of Biology, Acadia University, 33 Westwood Avenue, Wolfville, NS, B4P 2R6, Canada
| | - Junior A Tremblay
- Wildlife Research Division, Environment and Climate Change Canada, 1550 Av. D'Estimauville, Québec, QC, G1J 0C3, Canada
| | - Peter P Marra
- Department of Biology and McCourt School of Public Policy, Georgetown University, 37th and O Streets NW, Washington, DC, 20057, USA
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Cooper NW, Dossman BC, Berrigan LE, Brown JM, Brunner AR, Chmura HE, Cormier DA, Bégin-Marchand C, Rodewald AD, Taylor PD, Tonra CM, Tremblay JA, Marra PP. Songbirds initiate migratory flights synchronously relative to civil dusk. MOVEMENT ECOLOGY 2023; 11:24. [PMID: 37122011 PMCID: PMC10150543 DOI: 10.1186/s40462-023-00382-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/09/2022] [Accepted: 04/03/2023] [Indexed: 05/03/2023]
Abstract
BACKGROUND Each spring and fall billions of songbirds depart on nocturnal migrations across the globe. Theory suggests that songbirds should depart on migration shortly after sunset to maximize their potential for nightly flight duration or to time departure with the emergence of celestial cues needed for orientation and navigation. Although captive studies have found that songbirds depart during a narrow window of time after sunset, observational studies have found that wild birds depart later and more asynchronously relative to sunset than predicted. METHODS We used coded radio tags and automated radio-telemetry to estimate the time that nearly 400 individuals from nine songbird species departed their breeding or wintering grounds across North America. We also assessed whether each species was most likely beginning long-distance migratory flights at departure or instead first making non-migratory regional flights. We then explored variation in nocturnal departure time by post-departure movement type, species, age, sex, and season. RESULTS We found that 90% of individuals from species that were likely initiating long-distance migratory flights departed within 69 min of civil dusk, regardless of species, season, age, or sex. By contrast, species that likely first made non-migratory regional movements away from the migratory destination departed later and more asynchronously throughout the night. Regardless of post-departure movement type, 98% of individuals departed after civil dusk but otherwise showed no preference in relation to twilight phase. CONCLUSIONS Although the presence of celestial orientation cues at civil dusk may set a starting point for departure each night, the fact that species likely beginning long-distance migration departed earlier and more synchronously relative to civil dusk than those first making non-migratory regional movements is consistent with the hypothesis that departing promptly after civil dusk functions to maximize the potential for nightly flight duration and distance. By studying the onset of migration, our study provides baseline information about departure decisions that may enhance our understanding of departure timing throughout migration.
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Affiliation(s)
- Nathan W Cooper
- Migratory Bird Center, Smithsonian's National Zoo and Conservation Biology Institute, 3001 Connecticut Ave. NW - MRC 5503, Washington, DC, 20008, USA.
| | - Bryant C Dossman
- Department of Biology and McCourt School of Public Policy, Georgetown University, 37th and O Streets NW, Washington, DC, 20057, USA
- Cornell Lab of Ornithology, Department of Natural Resources and the Environment, Cornell University, 159 Sapsucker Woods Rd, Ithaca, NY, 14850, USA
| | - Lucas E Berrigan
- Department of Biology, Acadia University, 33 Westwood Avenue, Wolfville, NS, B4P 2R6, Canada
- Motus Wildlife Tracking System, N0E 1M0, Birds, Port Rowan, ON, Canada
| | - J Morgan Brown
- Department of Biology, Acadia University, 33 Westwood Avenue, Wolfville, NS, B4P 2R6, Canada
- Institute for Biodiversity and Ecosystem Dynamics, University of Amsterdam, 904 Science Park, 1098XH, Amsterdam, The Netherlands
| | - Alicia R Brunner
- Cornell Lab of Ornithology, Department of Natural Resources and the Environment, Cornell University, 159 Sapsucker Woods Rd, Ithaca, NY, 14850, USA
- School of Environment and Natural Resources, The Ohio State University, 2021 Coffey Rd, 43210, Columbus, OH, USA
| | - Helen E Chmura
- Rocky Mountain Research Station, USDA Forest Service, 800 East Beckwith Avenue, 59801, Missoula, MT, USA
| | - Dominic A Cormier
- Department of Biology, Acadia University, 33 Westwood Avenue, Wolfville, NS, B4P 2R6, Canada
| | - Camille Bégin-Marchand
- Wildlife Research Division, Environment and Climate Change Canada, 1550 Av. D'Estimauville, G1J 0C3, Québec, QC, Canada
| | - Amanda D Rodewald
- Cornell Lab of Ornithology, Department of Natural Resources and the Environment, Cornell University, 159 Sapsucker Woods Rd, Ithaca, NY, 14850, USA
| | - Philip D Taylor
- Department of Biology, Acadia University, 33 Westwood Avenue, Wolfville, NS, B4P 2R6, Canada
| | - Christopher M Tonra
- School of Environment and Natural Resources, The Ohio State University, 2021 Coffey Rd, 43210, Columbus, OH, USA
| | - Junior A Tremblay
- Wildlife Research Division, Environment and Climate Change Canada, 1550 Av. D'Estimauville, G1J 0C3, Québec, QC, Canada
| | - Peter P Marra
- Department of Biology and McCourt School of Public Policy, Georgetown University, 37th and O Streets NW, Washington, DC, 20057, USA
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Rüppel G, Hüppop O, Lagerveld S, Schmaljohann H, Brust V. Departure, routing and landing decisions of long-distance migratory songbirds in relation to weather. ROYAL SOCIETY OPEN SCIENCE 2023; 10:221420. [PMID: 36778957 PMCID: PMC9905979 DOI: 10.1098/rsos.221420] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/21/2022] [Accepted: 01/13/2023] [Indexed: 06/18/2023]
Abstract
Migrating birds flexibly adjust their individual migratory decisions, i.e. departing, routing and landing, based on intrinsic (e.g. energy stores) and extrinsic (e.g. landscape features and weather) factors modulating the endogenous stimuli. So far, these decisions have mostly been studied separately. Notably, we lack information on which factors landing decisions during active flight are based on. Therefore, we simultaneously recorded all three decisions in free-flying long-distance migratory songbirds in a coastal stopover area via regional-scale radio-telemetry and related them to the prevailing weather. Birds departed under favourable weather conditions resulting in specific nights with increased departure probability. Once departed, birds could either fly offshore or take a route along the coast, which was predicted by wind support. Radio-tracking revealed that departed individuals more likely interrupted their migratory endurance flight under overcast or headwind conditions. Studying departure, routing and landing decisions in concert, we highlight the importance of weather as a common driver across all migratory decisions. By radio-tracking individuals between stopovers, we provide evidence that avoidance of adverse weather conditions is an important function of stopover. Understanding how birds adjust migratory decisions and how they affect the timing of migration and survival is key to link migration performance to individual fitness.
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Affiliation(s)
- Georg Rüppel
- Institute of Avian Research ‘Vogelwarte Helgoland’, 26386 Wilhelmshaven, Germany
| | - Ommo Hüppop
- Institute of Avian Research ‘Vogelwarte Helgoland’, 26386 Wilhelmshaven, Germany
| | | | - Heiko Schmaljohann
- Institute of Avian Research ‘Vogelwarte Helgoland’, 26386 Wilhelmshaven, Germany
- Institute for Biology and Environmental Sciences, Carl von Ossietzky University Oldenburg, 26129 Oldenburg, Germany
| | - Vera Brust
- Institute of Avian Research ‘Vogelwarte Helgoland’, 26386 Wilhelmshaven, Germany
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Zinßmeister D, Troupin D, Sapir N. Autumn migrating passerines at a desert edge: Do birds depart for migration after reaching a threshold fuel load or vary it according to the rate of fuel deposition? Front Ecol Evol 2022. [DOI: 10.3389/fevo.2022.874923] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Fuel deposition rate is predicted to determine departure fuel load during stopover in two models of optimal behavior of migrating birds. Yet, near ecological barriers, such as wide deserts, birds may switch to a different strategy of departing with just enough fuel to enable the long cross-barrier flight, thus reaching a threshold of fuel load regardless of the rate of fuel deposition. To test these predictions we studied autumn migrating Red-backed Shrikes (Lanius collurio) before they departed for a ∼2,000 km journey across the Sahara Desert. The body mass of fourteen individuals was measured on a daily basis throughout their stopover using field-deployed scales while being tracked by the ATLAS biotelemetry system in the Hula Valley, Israel. Statistical analysis found that the natural log of departure fuel load was positively related to both the capture fuel load and the fuel deposition rate. Hence, the results of this analysis suggest that bird condition at departure depended on the rate of fuel deposition, as predicted by models of time-minimization migration and the minimization of the total energy cost of migration. Departure fuel load and stopover duration were negatively related to each other as birds that remained for a long time in stopover departed with relatively low fuel loads. These findings suggest that even near a wide ecological barrier, departure fuel load is sensitive to the rate of fuel deposition, especially at lower values of fuel deposition rate. Birds that were able to accumulate fuel at higher rates showed a nearly constant departure fuel load and as such we could not exclude the possibility that the birds were trying to reach a certain threshold of fuel stores. Randomized 1,000 repeats of the aforementioned correlation suggest that the correlation between fuel deposition rate and the log of departure fuel load is valid and does not represent a spurious result. Following bird migration simulation using the program Flight, we conclude that fuel loads allowed most individual to accomplish the journey across the desert. Our findings suggest high between-individual variation in stopover parameters with likely consequences for bird migration performance and survival.
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Cooper-Mullin C, McWilliams SR. Fat Stores and Antioxidant Capacity Affect Stopover Decisions in Three of Four Species of Migratory Passerines With Different Migration Strategies: An Experimental Approach. Front Ecol Evol 2022. [DOI: 10.3389/fevo.2022.762146] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
During migratory stopovers, birds must make decisions about when and where to travel and these decisions are likely contingent on their fuel stores, food availability, and antioxidant capacity as well as seasonal changes in key environmental factors. We conducted a field experiment on an offshore stopover site (Block Island, Rhode Island, United States: 41°130N, 71°330W) during autumn migration to test the hypothesis that birds with greater fuel stores and non-enzymatic antioxidant capacity have shorter stopovers than lean birds with low antioxidant capacity, and to determine the extent to which this depends on migration strategy. We used a 2 × 2 factorial field experiment (two levels each of available food and dietary polyphenols) with four species of songbirds kept in captivity for 3–5 days to produce experimental groups with different fuel stores and antioxidant capacity. We attached digital VHF transmitters to assess stopover duration and departure direction using automated telemetry. Non-enzymatic antioxidant capacity increased during refueling for Red-eyed Vireos (Vireo olivaceus) and Blackpoll Warblers (Setophaga striata) fed ad lib diets, and for ad lib fed Hermit Thrushes (Catharus guttatus) supplemented with polyphenols, but not for Yellow-rumped Warblers (Setophaga coronata coronata). Glutathione peroxidase (GPx) decreased during captivity and was influenced by dietary treatment only in Red-eyed Vireos. Oxidative damage decreased during captivity for all species except Yellow-rumped Warblers. Stopover duration was shorter for Vireos and Blackpolls fed ad lib as compared to those fed maintenance. Ad lib fed Hermit Thrushes supplemented with polyphenols had shorter stopovers than those fed ad lib, as did thrushes fed at maintenance and supplemented with polyphenols compared with those fed at maintenance alone. There was no influence of condition on stopover duration for Yellow-rumped Warblers. Departure direction was not strongly related to condition, and birds primarily reoriented north when departing Block Island. Thus, fat stores and oxidative status interacted to influence the time passerines spent on stopover, and condition-dependent departure decisions were related to a bird’s migration strategy. Therefore, seasonal variation in macro- and micro-nutrient resources available for refueling at stopover sites can affect body condition and antioxidant capacity and in turn influence the timing and success of migration.
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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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Kelsey NA, Hüppop O, Bairlein F. Days to visit an offshore island: effect of weather conditions on arrival fuel load and potential flight range for common blackbirds Turdus merula migrating over the North Sea. MOVEMENT ECOLOGY 2021; 9:53. [PMID: 34674773 PMCID: PMC8529821 DOI: 10.1186/s40462-021-00290-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/07/2021] [Accepted: 10/13/2021] [Indexed: 06/13/2023]
Abstract
BACKGROUND Crossing open water instead of following the coast(line) is one way for landbirds to continue migration. However, depending on prevailing weather and the birds' physiological conditions, it is also a risky choice. To date, the question remains as to which interplay between environmental and physiological conditions force landbirds to stop on remote islands. We hypothesise that unfavourable winds affect lean birds with low energy resources, while poor visibility affects all birds regardless of their fuel loads. METHODS To test this hypothesis, we caught 1312 common blackbirds Turdus merula stopping over on Helgoland during autumn and spring migration. Arrival fuel load was measured using quantitative magnetic resonance technology. Weather parameters (wind and relative humidity as a proxy for visibility) were interpolated for the night before arrival. Further, we calculated whether caught individuals would have successfully crossed the North Sea instead of landing on Helgoland, depending on wind conditions. RESULTS Both wind and relative humidity the night before arrival were correlated with arrival fuel load. After nights with strong headwinds, birds caught the following day were mostly lean, most of which would not have managed to cross the sea if they had not stopped on Helgoland. In contrast, fat birds that could have successfully travelled on were caught mainly after nights with high relative humidity (≥ 80%). Furthermore, the rate of presumably successful flights was lower due to wind: although only 9% of all blackbirds captured on Helgoland had insufficient fuel loads to allow safe onward migration in still air, real wind conditions would have prevented 30% of birds from successfully crossing the sea during autumn and 21% during spring migration. CONCLUSIONS We were able to decipher how physiological condition, wind and relative humidity partially force blackbirds to stop on a remote island. Adverse winds tend to affect lean birds with low energy resources, while poor visibility can affect blackbirds, regardless of whether the arrival fuel load was sufficient for onward flight. Our findings will help to understand different migratory strategies and explain further questions like migration timing.
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Affiliation(s)
- Natalie A Kelsey
- Institute of Avian Research 'Vogelwarte Helgoland', An der Vogelwarte 21, 26386, Wilhelmshaven, Germany.
| | - Ommo Hüppop
- Institute of Avian Research 'Vogelwarte Helgoland', An der Vogelwarte 21, 26386, Wilhelmshaven, Germany
| | - Franz Bairlein
- Institute of Avian Research 'Vogelwarte Helgoland', An der Vogelwarte 21, 26386, Wilhelmshaven, Germany
- Max Planck Institute of Animal Behavior, Am Obstberg 1, 78315, Radolfzell, Germany
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Ferretti A, Maggini I, Fusani L. How to recover after sea crossing: the importance of small islands for passerines during spring migration. ETHOL ECOL EVOL 2021. [DOI: 10.1080/03949370.2021.1886181] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
Affiliation(s)
- Andrea Ferretti
- Department of Behavioural and Cognitive Biology, University of Vienna, Althanstr. 14, Vienna 1090, Austria
- Konrad-Lorenz Institute of Ethology, University of Veterinary Medicine, Vienna, Savoyenstr. 1, Vienna 1160, Austria
| | - Ivan Maggini
- Konrad-Lorenz Institute of Ethology, University of Veterinary Medicine, Vienna, Savoyenstr. 1, Vienna 1160, Austria
| | - Leonida Fusani
- Department of Behavioural and Cognitive Biology, University of Vienna, Althanstr. 14, Vienna 1090, Austria
- Konrad-Lorenz Institute of Ethology, University of Veterinary Medicine, Vienna, Savoyenstr. 1, Vienna 1160, Austria
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11
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Klinner T, Schmaljohann H. Temperature change is an important departure cue in nocturnal migrants: controlled experiments with wild-caught birds in a proof-of-concept study. Proc Biol Sci 2020; 287:20201650. [PMID: 33023413 DOI: 10.1098/rspb.2020.1650] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
The decision-making process of migrating birds at stopover sites is a complex interplay of the innate migration program and both intrinsic and extrinsic factors. While it is well studied how variation in precipitation, wind and air pressure influence this process, there is less evidence of the effects of temperature changes on the departure decision. Thus, we lack knowledge on how the predicted changes due to global climate change in temperature alone may affect the decision-making process during migration. Aiming to fill parts of this gap, we conducted a proof-of-concept study by manipulating the ambient temperature of temporarily confined wild-caught migrant songbirds under constant feeding conditions. In spring, departure probability increased with a 20°C rise in temperature for both a medium-distance migrant (European robin, Erithacus rubecula) and a long-distance migrant (northern wheatear, Oenanthe oenanthe), and in autumn, departure probabilities of the long-distance migrant both decreased with a 20°C rise and increased with a 20°C drop. Consequently, the temperature is an important departure cue influencing the decision-making process of migrating songbirds. Incorporating causal relationships between changes in temperature and departure probability in migration models could substantially improve our ability to predict the effects of climate change on the phenology of migratory birds.
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Affiliation(s)
- Thomas Klinner
- Institute of Avian Research, An der Vogelwarte 21, 26386 Wilhelmshaven, Germany
| | - Heiko Schmaljohann
- Institute of Avian Research, An der Vogelwarte 21, 26386 Wilhelmshaven, Germany.,Institute for Biology and Environmental Sciences (IBU), Carl von Ossietzky University of Oldenburg, Carl-von-Ossietzky-Straße 9-11, 26129 Oldenburg, Germany
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12
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Michalik B, Brust V, Hüppop O. Are movements of daytime and nighttime passerine migrants as different as day and night? Ecol Evol 2020; 10:11031-11042. [PMID: 33144946 PMCID: PMC7593151 DOI: 10.1002/ece3.6704] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2019] [Revised: 07/29/2020] [Accepted: 07/30/2020] [Indexed: 11/11/2022] Open
Abstract
Even after decades of research, the migration of songbirds still holds numerous secrets. Distinct stopover and routing behavior of diurnally and nocturnally migrating songbirds has been stated in the 1960s, but empirical confirmation is yet lacking widely. We studied the behavior of individual diurnally migrating dunnocks and nocturnally migrating blackcaps by means of large-scale automated radio-telemetry. Birds were radio-tagged during their stopover at the German North Sea coast. Our data indicate longer initial stopover duration in the diurnally migrating dunnocks, opposing the hypothesis of nocturnal migrants needing more time to recover due to their longer migratory flights. Nonetheless, dunnocks stopped over more often along their tracks as when compared to the nocturnally migrating blackcaps. Behavior en route did not differ as clearly between species challenging the general view of contrasting routings of diurnal and nocturnal migrants with regard to landscape and open water. Our results imply additional factors of relevance other than differences in species or daily migration timing per se. We discuss and highlight the need of detailed and individual based data to better understand stopover and routing behavior of songbirds in the environmental context.
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Affiliation(s)
- Bianca Michalik
- Institute of Avian Research “Vogelwarte Helgoland”WilhelmshavenGermany
| | - Vera Brust
- Institute of Avian Research “Vogelwarte Helgoland”WilhelmshavenGermany
| | - Ommo Hüppop
- Institute of Avian Research “Vogelwarte Helgoland”WilhelmshavenGermany
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13
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Schmaljohann H, Klinner T. A quasi-experimental approach using telemetry to assess migration-strategy-specific differences in the decision-making processes at stopover. BMC Ecol 2020; 20:36. [PMID: 32641125 PMCID: PMC7346510 DOI: 10.1186/s12898-020-00307-5] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2020] [Accepted: 06/30/2020] [Indexed: 12/03/2022] Open
Abstract
Background Migrant birds travel between their breeding areas and wintering grounds by alternating energetically and physiologically demanding flights with periods of rest and fuelling, so-called stopovers. An important intrinsic factor influencing the decision to resume migration is the amount of energy stores available for the next flight. Correlative studies with free-flying birds and experimental studies with caged birds have shown that the amount of energy stores affects the day-to-day, within-day and the directional decision of departure. The methodological advantages of both the correlative and experimental approach are combined when radio-tagging many individuals on the same day and subsequently determining the departure decisions at a high spatiotemporal resolution. Making use of such a quasi-experimental approach with an automated radio-tracking system at stopover, we studied the effect of energy stores on departure decisions and whether they vary between species of different migration strategies experiencing contrasting time constraints. For this, we chose a long-distance migrant, the common redstart (Phoenicurus phoenicurus), and a medium-distance migrant, the European robin (Erithacus rubecula), because the former has to travel at relatively higher speed to reach its wintering ground in a reasonable time at the expense of relatively higher energetic costs for travelling than the latter. Results Common redstarts with higher energy stores were more likely to resume migration than their conspecifics with lower energy stores, whereas this pattern was absent in the European robins. The amount of energy stores significantly affected the timing of departure within the day, with large energy stores yielding early departures in both species. Departure directions from the stopover site during the first night after capture were oriented towards the seasonally appropriate direction but were not affected by variation in energy stores. Conclusions We demonstrate the importance of variation in energy stores on the departure decisions and that it may affect species with different migration strategies dissimilarly in autumn. Nevertheless, knowledge of other intrinsic factors, such as feeding conditions, health status and physiological consequences of previous flights, is additionally required to better understand the departure decisions of migrants, as this is the key to providing an overall assessment of the decision-making process.
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Affiliation(s)
- Heiko Schmaljohann
- Institute for Biology und Environmental Sciences (IBU), Carl von Ossietzky University of Oldenburg, Carl-von-Ossietzky-Straße 9-11, 26129, Oldenburg, Germany. .,Institute of Avian Research, An der Vogelwarte 21, 26386, Wilhelmshaven, Germany.
| | - Thomas Klinner
- Institute of Avian Research, An der Vogelwarte 21, 26386, Wilhelmshaven, Germany
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14
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Carneiro C, Gunnarsson TG, Alves JA. Linking Weather and Phenology to Stopover Dynamics of a Long-Distance Migrant. Front Ecol Evol 2020. [DOI: 10.3389/fevo.2020.00145] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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15
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Klinner T, Buddemeier J, Bairlein F, Schmaljohann H. Decision-making in migratory birds at stopover: an interplay of energy stores and feeding conditions. Behav Ecol Sociobiol 2020. [DOI: 10.1007/s00265-019-2784-7] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
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16
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Packmor F, Klinner T, Woodworth BK, Eikenaar C, Schmaljohann H. Stopover departure decisions in songbirds: do long-distance migrants depart earlier and more independently of weather conditions than medium-distance migrants? MOVEMENT ECOLOGY 2020; 8:6. [PMID: 32047634 PMCID: PMC7006082 DOI: 10.1186/s40462-020-0193-1] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/18/2019] [Accepted: 01/16/2020] [Indexed: 05/16/2023]
Abstract
BACKGROUND Songbirds following distinct migration strategies (e.g. long- vs. short- to medium-distance migrants) often differ in their speed of migration during autumn and, thus, are assumed to face different time constraints. During migration, most songbird species alternate migratory flights with stopover periods. Many of them restrict these migratory flights to the night, i.e., they are nocturnal migrants. At stopover, nocturnal migrants need to select a specific night (night-to-night decision) and time of night (within-night decision) to resume migration. These departure decisions, which largely determine the speed of migration, are jointly affected by a set of intrinsic and extrinsic factors, i.e., departure cues. Here we aim to assess whether the set of intrinsic and extrinsic factors and the magnitude of their respective effects on stopover departure decisions differs between nocturnally migrating songbird species, depending on their migration strategy and associated time constraints. METHODS We radio-tracked migrating Northern Wheatears (Oenanthe oenanthe; long-distance migrant), European robins (Erithacus rubecula) and Common Blackbirds (Turdus merula; both medium-distance migrants) during autumn stopover and analysed their night-to-night and within-night departure timing in relation to intrinsic and extrinsic factors. RESULTS Species generally differed in their departure timing on both temporal scales, with shortest stopovers and earliest nocturnal departures in the long-distance migrant. Some factors, such as day of year, fuel load, cloud cover and crosswind, had consistent effects on stopover departure decisions in all three species. However, species differed in the effects of tailwind assistance, change in atmospheric pressure and air temperature on their stopover departure decisions. Whereas night-to-night decisions were affected by these extrinsic factors in either both or one of the medium-distance migrants, such effects were not found in the long-distance migrant. CONCLUSIONS Our results suggest that the general timing of departures in songbirds is affected by the species-specific migration strategy and associated time constraints. Further, they imply that the assessment and usage of specific extrinsic factors, i.e., weather conditions, as departure cues is adjusted based on this migration strategy, with the long-distance migrants being least selective at departure. Other intrinsic and extrinsic factors, however, seem to be used as departure cues independent of migration strategy.
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Affiliation(s)
- Florian Packmor
- Institute of Avian Research “Vogelwarte Helgoland”, An der Vogelwarte 21, 26386 Wilhelmshaven, Germany
- School of Natural Sciences, Bangor University, Deiniol Road, Bangor, LL57 2UW UK
| | - Thomas Klinner
- Institute of Avian Research “Vogelwarte Helgoland”, An der Vogelwarte 21, 26386 Wilhelmshaven, Germany
| | - Bradley K. Woodworth
- School of Biological Sciences, The University of Queensland, Brisbane, Queensland 4072 Australia
| | - Cas Eikenaar
- Institute of Avian Research “Vogelwarte Helgoland”, An der Vogelwarte 21, 26386 Wilhelmshaven, Germany
| | - Heiko Schmaljohann
- Institute of Avian Research “Vogelwarte Helgoland”, An der Vogelwarte 21, 26386 Wilhelmshaven, Germany
- Institute for Biology und Environmental Sciences, Carl von Ossietzky University of Oldenburg, Carl-von-Ossietzky-Straße, 26129 Oldenburg, Germany
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17
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Brust V, Michalik B, Hüppop O. To cross or not to cross - thrushes at the German North Sea coast adapt flight and routing to wind conditions in autumn. MOVEMENT ECOLOGY 2019; 7:32. [PMID: 31695918 PMCID: PMC6824093 DOI: 10.1186/s40462-019-0173-5] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 05/22/2019] [Accepted: 08/29/2019] [Indexed: 06/10/2023]
Abstract
BACKGROUND Although many aspects of passerine migration are genetically determined, routing appears to be flexibly adjusted to the conditions experienced on each individual journey. This holds especially true for routing decisions taken when confronted with large bodies of water. Once taken, these decisions can be hardly altered or revised. In this paper, we analysed stopover and routing decisions taken by three species of thrushes, blackbirds, redwings and song thrushes, at the German North Sea coast. METHODS Birds were equipped with radio-telemetry tags at stopover sites along the coast during autumn migration and subsequently tracked by an automated receiver network covering the coastline and islands of the German Bight. RESULTS The thrushes resumed migration in nights with a favourable northward wind component and clear skies. About 40% of the tagged individuals have taken an offshore instead of an alongshore oriented flight route. Routing decisions were influenced by the strength of the eastward wind component with offshore oriented flights taking place primarily under weak winds or winds blowing towards the west. Thrushes that took an offshore oriented route stopped over at the coast longer than those flying alongshore. Interestingly, offshore as well as alongshore oriented flights co-occurred within single nights and under comparable weather conditions. CONCLUSIONS Migratory flight and routing decisions of thrushes at the German North Sea coast are highly dependent on weather, in particular wind. Still, we found evidence that weather may not be the sole reason for individual routes taken. Physical condition, morphology or animal personality lend themselves as possible additional factors of influence. Enabling a more detailed understanding of thrush migration over and along the German North Sea, our data help to better judge risks that migratory birds are facing when en route conditions are altered, for example by artificial obstacles such as offshore wind turbines.
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Affiliation(s)
- Vera Brust
- Institute of Avian Research, An der Vogelwarte 21, 26386 Wilhelmshaven, Germany
| | - Bianca Michalik
- Institute of Avian Research, An der Vogelwarte 21, 26386 Wilhelmshaven, Germany
| | - Ommo Hüppop
- Institute of Avian Research, An der Vogelwarte 21, 26386 Wilhelmshaven, Germany
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18
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Eikenaar C, Hegemann A, Packmor F, Kleudgen I, Isaksson C. Not just fuel: energy stores are correlated with immune function and oxidative damage in a long-distance migrant. Curr Zool 2019; 66:21-28. [PMID: 32467701 PMCID: PMC7245008 DOI: 10.1093/cz/zoz009] [Citation(s) in RCA: 28] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2018] [Accepted: 02/25/2019] [Indexed: 02/04/2023] Open
Abstract
In many animals, catabolic and anabolic periods are temporally separated. Migratory birds alternate energy expenditure during flight with energy accumulation during stopover. The size of the energy stores at stopover affects the decision to resume migration and thus the temporal organization of migration. We now provide data suggesting that it is not only the size of the energy stores per se that may influence migration scheduling, but also the physiological consequences of flying. In two subspecies of the northern wheatear Oenanthe oenanthe, a long-distance migrant, estimated energy stores at a stopover during autumn migration were positively related with both constitutive innate and acquired immune function, and negatively related with oxidative damage to lipids. In other words, migrants' physiological condition was associated with their energetic condition. Although time spent at stopover before sampling may have contributed to this relationship, our results suggest that migrants have to trade-off the depletion of energy stores during flight with incurring physiological costs. This will affect migrants' decisions when to start and when to terminate a migratory flight. The physiological costs associated with the depletion of energy stores may also help explaining why migrants often arrive at and depart from stopover sites with larger energy stores than expected. We propose that studies on the role of energy stores as drivers of the temporal organization of (avian) migration need to consider physiological condition, such as immunological and oxidative states.
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Affiliation(s)
- Cas Eikenaar
- Institute of Avian Research, 26386 Wilhelmshaven, Germany
| | - Arne Hegemann
- Department of Biology, Lund University, Lund, SE-223 62, Sweden
| | - Florian Packmor
- Institute of Avian Research, 26386 Wilhelmshaven, Germany.,School of Natural Sciences, Bangor University, Deiniol Road, Bangor, LL57 2DG, UK
| | - Iris Kleudgen
- Institute of Avian Research, 26386 Wilhelmshaven, Germany
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19
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20
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Müller F, Eikenaar C, Crysler ZJ, Taylor PD, Schmaljohann H. Nocturnal departure timing in songbirds facing distinct migratory challenges. J Anim Ecol 2018; 87:1102-1115. [PMID: 29504627 DOI: 10.1111/1365-2656.12821] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2017] [Accepted: 02/14/2018] [Indexed: 11/30/2022]
Abstract
Most migratory songbirds travel between their breeding areas and wintering grounds through a series of nocturnal flights. The timing of their departures defines the potential flight duration and thus the distance covered during a migratory night. Yet, migratory songbirds show substantial variation in their nocturnal departure timing. With this study, we aim to assess whether the respective challenges of the migration route, namely its distance and nature, help to explain this variation. At a stopover site, we caught Northern Wheatears (Oenanthe oenanthe) of two subspecies that differ in distance and nature of their onward migration route in spring, but not in autumn. We determined the start of their nocturnal migratory restlessness during short-term captivity, and radiotracked their nocturnal departure timing after release in both migration seasons. Northern Wheatears started their nocturnal migratory restlessness earlier when facing a long remaining migration distance and an extended sea barrier in spring. Individual departure directions generally affected the nocturnal departure timing with early departures being directed towards the respective migratory destination. In spring, this pattern was predominantly found in birds carrying relatively large fuel stores, but was absent in lean birds. At the same time, birds facing a short remaining migration distance and no extended sea barrier strongly reacted to relatively large fuel stores by an early start of nocturnal migratory behaviour (migratory restlessness and departure timing), whereas this reaction was not found in birds facing a long remaining migration distance and sea barrier. These results suggest that the basic diel schedule of birds' migratory activity is adapted to the onward migration route. Further, they suggest that birds adjust their behavioural response, that is start of nocturnal migratory behaviour, to fuel stores in relation to their impending migratory challenges. This is a substantial step in understanding variation of nocturnal departure timing and its adjustments in migratory songbirds. Further, it emphasizes the importance of interpreting birds' nocturnal migratory behaviour in the respective ecological context.
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Affiliation(s)
- Florian Müller
- Institute of Avian Research "Vogelwarte Helgoland", Wilhelmshaven, Germany
| | - Cas Eikenaar
- Institute of Avian Research "Vogelwarte Helgoland", Wilhelmshaven, Germany
| | - Zoe J Crysler
- Department of Biology, Acadia University, Wolfville, NS, Canada.,Bird Studies Canada, Port Rowan, ON, Canada
| | - Philip D Taylor
- Department of Biology, Acadia University, Wolfville, NS, Canada.,Bird Studies Canada, Port Rowan, ON, Canada
| | - Heiko Schmaljohann
- Institute of Avian Research "Vogelwarte Helgoland", Wilhelmshaven, Germany.,Institute for Biology and Environmental Sciences (IBU), Carl von Ossietzky University of Oldenburg, Oldenburg, Germany
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Eikenaar C, Müller F, Leutgeb C, Hessler S, Lebus K, Taylor PD, Schmaljohann H. Corticosterone and timing of migratory departure in a songbird. Proc Biol Sci 2018; 284:rspb.2016.2300. [PMID: 28077768 DOI: 10.1098/rspb.2016.2300] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2016] [Accepted: 11/24/2016] [Indexed: 11/12/2022] Open
Abstract
Bird migration entails replenishing fuel stores at stopover sites. There, individuals make daily decisions whether to resume migration, and must also decide their time of departure. Variation in departure timing affects the total time required to complete a migratory journey, which in turn affects fitness through arrival time at the breeding and wintering grounds. It is well established that stopover departure decisions are based on cues from innate rhythms, intrinsic factors and extrinsic factors. Yet, virtually nothing is known about the physiological mechanism(s) linking these cues to departure decisions. Here, we show for a nocturnal migratory songbird, the northern wheatear (Oenanthe oenanthe), that baseline corticosterone levels of birds at stopover increased both over the migratory season and with wind assistance towards the migratory destination. Corticosterone in turn predicted departure probability; individuals with high baseline corticosterone levels were more likely to resume migration on a given night. Corticosterone further predicted the departure time within the night, with high baseline levels being associated with early departures. These novel findings indicate that corticosterone may be mediating between departure cues and the timing of departure from a stopover site, which is a major step towards understanding the hormonal control of animal migration.
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Affiliation(s)
- Cas Eikenaar
- Institute of Avian Research, An der Vogelwarte 21, 26386 Wilhelmshaven, Germany
| | - Florian Müller
- Institute of Avian Research, An der Vogelwarte 21, 26386 Wilhelmshaven, Germany
| | - Clara Leutgeb
- Institute of Avian Research, An der Vogelwarte 21, 26386 Wilhelmshaven, Germany
| | - Sven Hessler
- Institute of Avian Research, An der Vogelwarte 21, 26386 Wilhelmshaven, Germany
| | - Konstantin Lebus
- Institute of Avian Research, An der Vogelwarte 21, 26386 Wilhelmshaven, Germany
| | - Philip D Taylor
- Bird Studies Canada Chair of Ornithology, Acadia University, Wolfville, Nova Scotia, Canada
| | - Heiko Schmaljohann
- Institute of Avian Research, An der Vogelwarte 21, 26386 Wilhelmshaven, Germany
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Åkesson S, Bianco G. Route simulations, compass mechanisms and long-distance migration flights in birds. J Comp Physiol A Neuroethol Sens Neural Behav Physiol 2017; 203:475-490. [PMID: 28500441 PMCID: PMC5522512 DOI: 10.1007/s00359-017-1171-y] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2016] [Revised: 03/28/2017] [Accepted: 04/04/2017] [Indexed: 11/29/2022]
Abstract
Bird migration has fascinated humans for centuries and routes crossing the globe are now starting to be revealed by advanced tracking technology. A central question is what compass mechanism, celestial or geomagnetic, is activated during these long flights. Different approaches based on the geometry of flight routes across the globe and route simulations based on predictions from compass mechanisms with or without including the effect of winds have been used to try to answer this question with varying results. A major focus has been use of orthodromic (great circle) and loxodromic (rhumbline) routes using celestial information, while geomagnetic information has been proposed for both a magnetic loxodromic route and a magnetoclinic route. Here, we review previous results and evaluate if one or several alternative compass mechanisms can explain migration routes in birds. We found that most cases could be explained by magnetoclinic routes (up to 73% of the cases), while the sun compas s could explain only 50%. Both magnetic and geographic loxodromes could explain <25% of the routes. The magnetoclinic route functioned across latitudes (1°S-74°N), while the sun compass only worked in the high Arctic (61-69°N). We discuss the results with respect to orientation challenges and availability of orientation cues.
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Affiliation(s)
- Susanne Åkesson
- Centre for Animal Movement Research, Department of Biology, Lund University, Ecology Building, 223 62, Lund, Sweden.
| | - Giuseppe Bianco
- Centre for Animal Movement Research, Department of Biology, Lund University, Ecology Building, 223 62, Lund, Sweden
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23
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Sjöberg S, Alerstam T, Åkesson S, Muheim R. Ecological factors influence timing of departures in nocturnally migrating songbirds at Falsterbo, Sweden. Anim Behav 2017. [DOI: 10.1016/j.anbehav.2017.03.007] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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Actogram analysis of free-flying migratory birds: new perspectives based on acceleration logging. J Comp Physiol A Neuroethol Sens Neural Behav Physiol 2017; 203:543-564. [PMID: 28343237 PMCID: PMC5522517 DOI: 10.1007/s00359-017-1165-9] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2016] [Revised: 03/06/2017] [Accepted: 03/07/2017] [Indexed: 11/24/2022]
Abstract
The use of accelerometers has become an important part of biologging techniques for large-sized birds with accelerometer data providing information about flight mode, wing-beat pattern, behaviour and energy expenditure. Such data show that birds using much energy-saving soaring/gliding flight like frigatebirds and swifts can stay airborne without landing for several months. Successful accelerometer studies have recently been conducted also for free-flying small songbirds during their entire annual cycle. Here we review the principles and possibilities for accelerometer studies in bird migration. We use the first annual actograms (for red-backed shrike Lanius collurio) to explore new analyses and insights that become possible with accelerometer data. Actogram data allow precise estimates of numbers of flights, flight durations as well as departure/landing times during the annual cycle. Annual and diurnal rhythms of migratory flights, as well as prolonged nocturnal flights across desert barriers are illustrated. The shifting balance between flight, rest and different intensities of activity throughout the year as revealed by actogram data can be used to analyse exertion levels during different phases of the life cycle. Accelerometer recording of the annual activity patterns of individual birds will open up a new dimension in bird migration research.
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Schmaljohann H, Eikenaar C. How do energy stores and changes in these affect departure decisions by migratory birds? A critical view on stopover ecology studies and some future perspectives. J Comp Physiol A Neuroethol Sens Neural Behav Physiol 2017; 203:411-429. [PMID: 28332031 DOI: 10.1007/s00359-017-1166-8] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2016] [Revised: 03/08/2017] [Accepted: 03/08/2017] [Indexed: 12/01/2022]
Abstract
In birds, accumulating energy is far slower than spending energy during flight. During migration, birds spend, therefore, most of the time at stopover refueling energy used during the previous flight. This elucidates why current energy stores and actual rate of accumulating energy are likely crucial factors influencing bird's decision when to resume migration in addition to other intrinsic (sex, age) and extrinsic (predation, weather) factors modulating the decision within the innate migration program. After first summarizing how energy stores and stopover durations are generally determined, we critically review that high-energy stores and low rates of accumulating energy were significantly related to high departure probabilities in several bird groups. There are, however, also many studies showing no effect at all. Recent radio-tracking studies highlighted that migrants leave a site either to resume migration or to search for a better stopover location, so-called "landscape movements". Erroneously treating such movements as departures increases the likelihood of type II errors which might mistakenly suggest no effect of either trait on departure. Furthermore, we propose that energy loss during the previous migratory flight in relation to bird's current energy stores and migration strategy significantly affects its urge to refuel and hence its departure decision.
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Affiliation(s)
- Heiko Schmaljohann
- Institute of Avian Research "Vogelwarte Helgoland", An der Vogelwarte 21, 26386, Wilhelmshaven, Germany.
| | - Cas Eikenaar
- Institute of Avian Research "Vogelwarte Helgoland", An der Vogelwarte 21, 26386, Wilhelmshaven, Germany
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Schmaljohann H, Lisovski S, Bairlein F. Flexible reaction norms to environmental variables along the migration route and the significance of stopover duration for total speed of migration in a songbird migrant. Front Zool 2017; 14:17. [PMID: 28344630 PMCID: PMC5360013 DOI: 10.1186/s12983-017-0203-3] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2016] [Accepted: 03/07/2017] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Predicting the consequences of continuing anthropogenic changes in the environment for migratory behaviours such as phenology remains a major challenge. Predictions remain particularly difficult, because our knowledge is based on studies from single-snapshot observations at specific stopover sites along birds' migration routes. However, a general understanding on how birds react to prevailing environmental conditions, e.g. their 'phenotypic reaction norm', throughout the annual cycle and along their entire migration routes is required to fully understand how migratory birds respond to rapid environmental change. RESULTS Here, we provide direct evidence that northern wheatears (Oenanthe oenanthe) from a breeding population in Alaska adjusted their probability to resume migration as well as the distance covered per night, i.e. travel speed, to large-scale environmental conditions experienced along their 15,000 km migratory route on both northwards and southwards migrations. These adjustments were found to be flexible in space and time. At the beginning of autumn migration, northern wheatears showed high departure probabilities and high travel speeds at low surface air temperatures, while far away from Alaska both traits decreased with increasing air temperatures. In spring, northern wheatears increasingly exploited flow assistance with season, which is likely a behavioural adjustment to speed up migration by increasing the distance travelled per night. Furthermore, the variation in total stopover duration but not in travel speed had a significant effect on the total speed of migration, indicating the prime importance of total stopover duration in the overall phenology of bird migration. CONCLUSION Northern wheatears from Alaska provide evidence that the phenotypic reaction norm to a set of environmental conditions cannot be generalized to universal and persistent behavioural reaction pattern across entire migratory pathways. This highlights the importance of full annual-cycle studies on migratory birds to better understand their response to the environment. Understanding the mechanisms behind phenotypic plasticity during migration is particularly important in the assessment of whether birds can keep pace with the potentially increasing phenological mismatches observed on the breeding grounds.
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Affiliation(s)
- Heiko Schmaljohann
- Institute of Avian Research "Vogelwarte Helgoland", An der Vogelwarte 21, Wilhelmshaven, 26836 Germany.,University of Alaska, Fairbanks, AK USA
| | - Simeon Lisovski
- Centre for Integrative Ecology, Deakin University, Geelong, VIC 3220 Australia.,Department of Neurobiology, Physiology, and Behavior, University of California, Davis, CA 95616 USA
| | - Franz Bairlein
- Institute of Avian Research "Vogelwarte Helgoland", An der Vogelwarte 21, Wilhelmshaven, 26836 Germany
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Eikenaar C, Müller F, Kämpfer S, Schmaljohann H. Fuel accumulation advances nocturnal departure: a migratory restlessness study on northern wheatears at stopover. Anim Behav 2016. [DOI: 10.1016/j.anbehav.2016.04.017] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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Eikenaar C, Fritzsch A, Kämpfer S, Schmaljohann H. Migratory restlessness increases and refuelling rate decreases over the spring migration season in northern wheatears. Anim Behav 2016. [DOI: 10.1016/j.anbehav.2015.11.021] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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Crysler ZJ, Ronconi RA, Taylor PD. Differential fall migratory routes of adult and juvenile Ipswich Sparrows (Passerculus sandwichensis princeps). MOVEMENT ECOLOGY 2016; 4:3. [PMID: 26819707 PMCID: PMC4729120 DOI: 10.1186/s40462-016-0067-8] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/16/2015] [Accepted: 01/06/2016] [Indexed: 05/26/2023]
Abstract
BACKGROUND Island breeding birds present an ideal system for studying migratory movements in passerines because their populations are clearly demarcated, and individuals must depart on migration from a single location. The Ipswich Sparrow (Paserculus sandwichensis princeps) is a subspecies of the Savannah Sparrow that breeds exclusively on Sable Island, Nova Scotia, Canada and winters along the Atlantic coast of North America. We used a network of 34 automated VHF telemetry receivers to track radio-tagged adult and juvenile Ipswich Sparrows from their breeding island southward through the first half of their fall migratory journey. RESULTS We compared adult to juvenile timing and routes. We show that juveniles leave the island approximately 24 days prior to adults and remain temporally separated from them during migration through Nova Scotia. Juveniles have different overwater orientations that result in migratory routes with shorter ocean crossings and a longer overall distance travelled compared to adults. Juveniles also have more frequent and longer stopovers, and displayed some reverse migration. CONCLUSION We demonstrate that migratory routes differ between adults and juveniles, suggesting that routes change as individuals age, possibly through learning or social interactions. These differential routes also suggest that sparrows experience risk in different ways with juveniles selecting shorter overwater flights with less navigational risk at the cost of increased time spent in migration.
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Affiliation(s)
- Zoe J. Crysler
- />Department of Biology, Acadia University, Wolfville, B4P 2R6, NS Canada
| | - Robert A. Ronconi
- />Department of Biology, Acadia University, Wolfville, B4P 2R6, NS Canada
- />Canadian Wildlife Service, Environmental Stewardship Branch, Environment Canada, 45 Alderney Drive, Dartmouth, B2y 2N6, NS Canada
| | - Philip D. Taylor
- />Department of Biology, Acadia University, Wolfville, B4P 2R6, NS Canada
- />Bird Studies Canada, Port Rowan, N0E 1M0, ON Canada
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Alaei Kakhki N, Aliabadian M, Schweizer M. Out of Africa: biogeographic history of the open-habitat chats (Aves, Muscicapidae: Saxicolinae) across arid areas of the old world. ZOOL SCR 2016. [DOI: 10.1111/zsc.12151] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Affiliation(s)
- Niloofar Alaei Kakhki
- Department of Biology; Faculty of Science; Ferdowsi University of Mashhad; Mashhad Iran
| | - Mansour Aliabadian
- Department of Biology; Faculty of Science; Ferdowsi University of Mashhad; Mashhad Iran
- Research Department of Zoological Innovations; Institute of Applied Zoology; Faculty of Science; Ferdowsi University of Mashhad; Mashhad Iran
| | - Manuel Schweizer
- Naturhistorisches Museum der Burgergemeinde Bern; Bernastrasse 15 CH 3005 Bern Switzerland
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Müller F, Taylor PD, Sjöberg S, Muheim R, Tsvey A, Mackenzie SA, Schmaljohann H. Towards a conceptual framework for explaining variation in nocturnal departure time of songbird migrants. MOVEMENT ECOLOGY 2016; 4:24. [PMID: 27833750 PMCID: PMC5066284 DOI: 10.1186/s40462-016-0089-2] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/15/2016] [Accepted: 09/22/2016] [Indexed: 05/16/2023]
Abstract
Most songbird migrants travel between their breeding areas and wintering grounds by a series of nocturnal flights. The exact nocturnal departure time for these flights varies considerably between individuals even of the same species. Although the basic circannual and circadian rhythms of songbirds, their adaptation to migration, and the factors influencing the birds' day-to-day departure decision are reasonably well studied, we do not understand how birds time their departures within the night. These decisions are crucial, because the nocturnal departure time defines the potential flight duration of the migratory night. The distances covered during the nocturnal migratory flights in the course of migration in turn directly affect the overall speed of migration. To understand the factors influencing the arrival of the birds in the breeding/wintering areas, we need to investigate the mechanisms that control nocturnal departure time. Here, we provide the first conceptual framework for explaining the variation commonly observed in this migratory trait. The basic schedule of nocturnal departure is likely regulated by both the circannual and circadian rhythms of the innate migration program. We postulate that the endogenously controlled schedule of nocturnal departures is modified by intrinsic and extrinsic factors. So far there is only correlative evidence that birds with a high fuel load or a considerable increase in fuel load and significant wind (flow) assistance towards their migratory goal depart early within the night. In contrast, birds migrating with little fuel and under unfavorable wind conditions show high variation in their nocturnal departure time. The latter may contain an unknown proportion of nocturnal movements not directly related to migratory flights. Excluding such movements is crucial to clearly identify the main drivers of the variation in nocturnal departure time. In general we assume that the observed variation in the nocturnal departure time is explained by individually different reactions norms of the innate migration program to both intrinsic and extrinsic factors.
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Affiliation(s)
- Florian Müller
- Institute of Avian Research “Vogelwarte Helgoland”, An der Vogelwarte 21, 26386 Wilhelmshaven, Germany
| | - Philip D. Taylor
- Department of Biology, Acadia University, 33 Westwood Avenue, Wolfville, NS B4P 2R6 Canada
- Bird Studies Canada, 115 Front Street, Port Rowan, ON N0E 1M0 Canada
| | - Sissel Sjöberg
- Department of Biology, Lund University, Biology Building, Sölvegatan 35, 223 62 Lund, Sweden
| | - Rachel Muheim
- Department of Biology, Lund University, Biology Building, Sölvegatan 35, 223 62 Lund, Sweden
| | - Arseny Tsvey
- Biological Station Rybachy, Zoological Institute RAS, RU-238535 Rybachy, Kaliningrad region Russia
| | | | - Heiko Schmaljohann
- Institute of Avian Research “Vogelwarte Helgoland”, An der Vogelwarte 21, 26386 Wilhelmshaven, Germany
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Dossman BC, Mitchell GW, Norris DR, Taylor PD, Guglielmo CG, Matthews SN, Rodewald PG. The effects of wind and fuel stores on stopover departure behavior across a migratory barrier. Behav Ecol 2015. [DOI: 10.1093/beheco/arv189] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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Schmaljohann H, Meier C, Arlt D, Bairlein F, van Oosten H, Morbey YE, Åkesson S, Buchmann M, Chernetsov N, Desaever R, Elliott J, Hellström M, Liechti F, López A, Middleton J, Ottosson U, Pärt T, Spina F, Eikenaar C. Proximate causes of avian protandry differ between subspecies with contrasting migration challenges. Behav Ecol 2015. [DOI: 10.1093/beheco/arv160] [Citation(s) in RCA: 48] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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Nilsson C, Bäckman J, Karlsson H, Alerstam T. Timing of nocturnal passerine migration in Arctic light conditions. Polar Biol 2015. [DOI: 10.1007/s00300-015-1708-x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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Start of nocturnal migratory restlessness in captive birds predicts nocturnal departure time in free-flying birds. Behav Ecol Sociobiol 2015. [DOI: 10.1007/s00265-015-1902-4] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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Smith AD, McWilliams SR. What to do when stopping over: behavioral decisions of a migrating songbird during stopover are dictated by initial change in their body condition and mediated by key environmental conditions. Behav Ecol 2014. [DOI: 10.1093/beheco/aru148] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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Eikenaar C, Klinner T, Stöwe M. Corticosterone predicts nocturnal restlessness in a long-distance migrant. Horm Behav 2014; 66:324-9. [PMID: 24956025 DOI: 10.1016/j.yhbeh.2014.06.013] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/31/2014] [Revised: 06/11/2014] [Accepted: 06/13/2014] [Indexed: 10/25/2022]
Abstract
The decision made by migrating birds to stop refueling and to depart from stopover depends on cues from innate rhythms, intrinsic factors such as fuel reserves, and extrinsic factors such as weather conditions. The physiological mechanism behind this decision, however, is largely unexplored. The transition from refueling to flight involves an increase in both locomotion and energetic demands. Because, at baseline levels, corticosterone stimulates locomotion and is involved in the mobilization of energy, this hormone could encourage departure of migrants. We collected field data on baseline corticosterone, migratory restlessness, and actual departure in northern wheatears at stopover. Additionally, in refueling long-term captive conspecifics, we measured migratory restlessness while simultaneously collecting droppings to determine glucocorticoid metabolite (GCM) levels. We found that migratory restlessness at stopover was positively correlated with corticosterone level. Similarly, in refueling long-term captive birds, migratory restlessness was positively correlated with concurrently measured GCM levels in droppings. To our best knowledge, our study is the first to simultaneously measure a hormonal signal and migratory restlessness. In conclusion, our results are consistent with the hypothesis that, by increasing locomotor activity, baseline corticosterone is involved in the regulation of departure of migrants at stopover. Future studies could reveal how corticosterone is up-regulated in migrants that are ready to depart.
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Affiliation(s)
- Cas Eikenaar
- Institute of Avian Research, An der Vogelwarte 21, 26386 Wilhelmshaven, Germany.
| | - Thomas Klinner
- Institute of Avian Research, An der Vogelwarte 21, 26386 Wilhelmshaven, Germany
| | - Mareike Stöwe
- Department of Biomedical Sciences/Biochemistry, University of Veterinary Medicine, Veterinärplatz 1, A-1210 Vienna, Austria
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Eikenaar C, Klinner T, Szostek KL, Bairlein F. Migratory restlessness in captive individuals predicts actual departure in the wild. Biol Lett 2014; 10:20140154. [PMID: 24718095 DOI: 10.1098/rsbl.2014.0154] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
In captivity, migratory birds show increased activity during the time that they would normally migrate. The phenology and intensity of such 'migratory restlessness' has been shown to mirror species- and population-specific migration patterns observed in the wild and has consequently been used as a proxy for the motivation to migrate. Many studies doing so, however, were aiming to explain among-individual variation in migratory behaviour or traits, and not species- or population-specific traits. These studies thus assumed that, also at the level of the individual, migratory restlessness is an accurate proxy for the motivation to migrate. We tested this assumption for the first time and found that it holds; individuals showing very little migratory restlessness remained at stopover for longer than one night, whereas most individuals showing more restlessness departed sooner. This finding validates the use of migratory restlessness as a proxy for the motivation to migrate, thereby justifying the conclusions made in a large body of research on avian migration.
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Affiliation(s)
- Cas Eikenaar
- Institute of Avian Research, , An der Vogelwarte 21, Wilhelmshaven 26386, Germany
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Corman AM, Bairlein F, Schmaljohann H. The nature of the migration route shapes physiological traits and aerodynamic properties in a migratory songbird. Behav Ecol Sociobiol 2013. [DOI: 10.1007/s00265-013-1653-z] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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