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Rüppel G, Hüppop O, Schmaljohann H, Brust V. The urge to breed early: Similar responses to environmental conditions in short- and long-distance migrants during spring migration. Ecol Evol 2023; 13:e10223. [PMID: 37408622 PMCID: PMC10318620 DOI: 10.1002/ece3.10223] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2023] [Revised: 06/07/2023] [Accepted: 06/12/2023] [Indexed: 07/07/2023] Open
Abstract
Birds migrating different distances experience different temporal, energetic, physiological, and physical constraints throughout migration, which is reflected in their migration strategy. Consequently, we predict different behavioral decisions to similar environmental cues between short- and long-distance migrants, which has been documented for autumn migration. Here, we focus on the question whether trade-off decisions regarding departure, routing, and landing when alternating between migratory endurance flights and stopovers also differ during spring migration. As early arrivals at the breeding grounds should be ultimately favored regardless of migration distance, selection may favor more similar behavioral decisions in spring than in autumn. We radio-tagged short- and long-distance migratory songbirds at stopover sites along the German North Sea coast during spring and automatically tracked their migratory behavior using a large-scale network of receiver stations. Once departed, birds could either cross the sea or detour along the coast. We corrected for spatially biased detection data, using a hierarchical multistate model to assess how birds respond to variation in environmental conditions in their day-to-day departure decisions and route selection. The day-to-day departure probability was higher in long-distance migrants independently of the routing decision. Irrespective of migration distance, all species more likely departed under light winds and rainless conditions, while the influence of air pressure change and relative humidity was species-specific. By accounting for detection probabilities, we estimated that about half of all individuals of each species crossed the sea but did not find differences between short- and long-distance migrants. Offshore flights were more likely when winds blew offshore and began earlier within the night compared with onshore flights. Our results suggest that selection more similarly affects birds of different migration distances in spring than in autumn. These findings put the focus toward how ultimate mechanisms may shape departure and routing decisions differently between migration seasons.
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Affiliation(s)
- Georg Rüppel
- Institute of Avian Research “Vogelwarte Helgoland”WilhelmshavenGermany
| | - Ommo Hüppop
- Institute of Avian Research “Vogelwarte Helgoland”WilhelmshavenGermany
| | - Heiko Schmaljohann
- Institute of Avian Research “Vogelwarte Helgoland”WilhelmshavenGermany
- Institute for Biology and Environmental SciencesCarl von Ossietzky University OldenburgOldenburgGermany
| | - Vera Brust
- Institute of Avian Research “Vogelwarte Helgoland”WilhelmshavenGermany
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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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Eikenaar C, Winslott E, Schmaljohann H, Wang HL, Isaksson C. Can differential fatty acid composition help migrating birds to limit oxidative lipid damage? Physiol Behav 2022; 249:113768. [PMID: 35247445 DOI: 10.1016/j.physbeh.2022.113768] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2021] [Revised: 01/28/2022] [Accepted: 02/28/2022] [Indexed: 01/07/2023]
Abstract
During migratory endurance flights, which are energetically very demanding, migrants have to deal with prolonged elevated generation of reactive oxygen species (ROS). To limit the damaging actions that ROS have on lipids and proteins, migrating birds are known to upregulate their antioxidant defence system. However, there may be additional ways to limit oxidative damage incurred from flying. Migratory endurance flights are fuelled mainly with fatty acids (FAs), and the risk of their peroxidation (resulting in oxidative lipid damage) increases with the number of double bonds in a FA, with polyunsaturated FAs (2 or more double bonds, PUFAs) being most peroxidation-prone. By fuelling their flights with relatively few PUFAs, migratory birds could thus limit oxidative lipid damage. Within migratory birds, there is considerable variation in the length of their flights, with nocturnal migrants making lengthier flight bouts, thus more likely to experience lengthier periods of elevated ROS production, than diurnal migrants. However, whether migrants making lengthier flights incur more oxidative lipid damage is unknown. Neither is it known whether flight length and FA composition are associated. Therefore, we determined plasmatic malondialdehyde level, a marker of oxidative lipid damage, and FA composition of three nocturnal and two diurnal migrant species caught at an autumn stopover site. We found little inter-specific variation in malondialdehyde level, indicating that the amount of oxidative lipid damage was comparable across the species. In contrast, the species strongly differed in their plasmatic FA composition. The nocturnal migrants had significantly lower relative PUFA levels than both diurnal migrants, an effect mainly attributable to linoleic acid, an essential (strictly dietary) FA. Consequently, the susceptibility of plasmatic FAs to lipid peroxidation was significantly lower in the nocturnal than diurnal migrants. Because in birds, energy expenditure during flight decreases with the degree of FA unsaturation, we interpret our observation of lower PUFA levels in nocturnal migrants as support for the idea that utilizing PUFA-poor fuel can help migrating birds to curb oxidative lipid damage.
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Affiliation(s)
- Cas Eikenaar
- Institute of Avian Research, Wilhelmshaven, 26386, Germany.
| | - Erica Winslott
- Department of Biology, Lund University, Lund, SE-223 62, Sweden
| | - Heiko Schmaljohann
- Institute of Avian Research, Wilhelmshaven, 26386, Germany; Institute for Biology and Environmental Sciences (IBU), Carl von Ossietzky University of Oldenburg,Oldenburg, 26129, Germany
| | - Hong-Lei Wang
- Department of Biology, Lund University, Lund, SE-223 62, Sweden
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Cabrera-Cruz SA, Larkin RP, Gimpel ME, Gruber JG, Zenzal TJ, Buler JJ. Potential effect of low-rise, downcast artificial lights on nocturnally migrating land birds. Integr Comp Biol 2021; 61:1216-1236. [PMID: 34240165 DOI: 10.1093/icb/icab154] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2021] [Revised: 06/22/2021] [Accepted: 06/15/2021] [Indexed: 11/14/2022] Open
Abstract
Artificial light at night (ALAN) affects the flight behavior of night-migrating birds at tall or upward-pointed lighting installations. We hypothesized that common low-rise lights pointing downwards also affect the movement of nocturnal migrants. We predicted that birds in flight will react close to low-rise lights, and be attracted and grounded near light sources, with a stronger effect on juveniles during their autumn migration. We conducted a controlled longitudinal experiment with LED floodlights and considered nearby structures that turn on lights at night. We analyzed 1501 high-resolution 3D nocturnal flight paths of free-flying migrants and diurnally captured 758-2009 birds around experimental lights during spring and autumn 2016, and spring 2017. We identified change points along flight paths where birds turned horizontally or vertically, and we considered these indicatives of reactions. Flight paths with and without reactions were generally closer to our experimental site in spring than in autumn when the lights were on. Reactions were up to 40% more likely in autumn than spring depending on threshold magnitude of turning angle. Reactions in spring were up to ∼60% more likely to occur at ∼35m from the lights than at >1.5km. In autumn, some vertical reactions were ∼40% more likely ∼50m from the lights than at >2.2km. Interactions between distance to lights and visibility or cloud cover were consistent with known effects of ALAN on nocturnal migrants. Under poor visibility, reactions were up to 50% more likely farthest from structures in spring, but up to 60% more likely closest to lights in autumn. Thus, the effects of ALAN on night-migrating land birds are not limited to bright lights pointing upwards or lights on tall structures in urban areas. Diurnal capture rates of birds were not different when lights were on or off for either season. To our knowledge, this is the first study to show that low-rise lights pointing downwards affect night-migrating birds. Although the interpreted reactions constitute subtle modifications in the linearity of flight paths, we discuss future work that could verify whether the protection of nocturnal migrants with lights-out programs would have greater impact if implemented beyond urban areas and include management of low-rise lights.
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Affiliation(s)
- Sergio A Cabrera-Cruz
- Department of Entomology and Wildlife Ecology, University of Delaware, Delaware, USA
| | - Ronald P Larkin
- Illinois Natural History Survey, Prairie Research Institute, University of Illinois, Champaign, IL, USA
| | - Maren E Gimpel
- Foreman's Branch Bird Observatory, Washington College, Chestertown, MD, USA
| | - James G Gruber
- Foreman's Branch Bird Observatory, Washington College, Chestertown, MD, USA
| | - Theodore J Zenzal
- U.S. Geological Survey, Wetland and Aquatic Research Center, Lafayette, LA, USA.,School of Biological, Environmental, and Earth Sciences, University of Southern Mississippi, Hattiesburg, MS, USA
| | - Jeffrey J Buler
- Department of Entomology and Wildlife Ecology, University of Delaware, Delaware, USA
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Åkesson S, Ilieva M, Bianco G. Flexibility and Control of Circadian Activity, Migratory Restlessness and Fueling in Two Songbird Migrants. Front Ecol Evol 2021. [DOI: 10.3389/fevo.2021.666176] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
Juvenile songbirds rely on an endogenous program, encoding direction, distance, fueling, and timing of migration. Migratory distance is species-specific, expressed as a period of migratory restlessness, for which the length is correlated with distance, while fueling is modified to meet anticipated flight distances controlled by geomagnetic cues and amount of day-light available for foraging. How daylength affect onset and level of migratory activity and fueling decisions in wild birds have so far received limited attention. Here we study how photoperiod controls onset, level and extent of autumn migratory activity and fueling in juvenile diurnally migrating dunnocks, and nocturnally migrating European robins by experimentally increasing daylength. For both species, we kept a control group indoors at the location of capture in southern Sweden exposed to the natural photoperiod, and an experimental group with increased and advanced photoperiod by 2 h in the morning. Dunnocks initiated migratory activity at sunrise (or artificial sunrise) in both groups, demonstrating a highly responsive and flexible component for the onset of migration triggered by light. Experimental robins anticipated the end of nocturnal migratory activity predicting the earlier sunrise immediately after the time-shift and expressed this behavior already under darkness, supporting a fast-resetting mechanism to the new diel period. Timing of end of morning activity was not affected by the earlier sunrise in both species, suggesting a fixed endogenous control that persisted throughout the 13-day study period. Experimental dunnocks expressed higher overall activity and lower fuel loads than controls, while robins did not change their overall activity and fuel load in response to the shifted and increased photoperiod. These results reveal important adaptations for circadian timekeeping including both a flexible onset open to fast modifications and a more rigid end, with differential effects by the treatment on migratory activity and fueling in the two species.
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