| 1. |
- Bowlin, Melissa, et al.
(författare)
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Aerodynamic costs of flying with holey wings
- 2009
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Ingår i: Comparative Biochemistry and Physiology. Part A: Molecular & Integrative Physiology. - : Elsevier BV. - 1095-6433. ; 153A:2, suppl. 1, s. 122-122
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Konferensbidrag (refereegranskat)
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| 2. |
- Bowlin, Melissa, et al.
(författare)
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Grand Challenges in Migration Biology
- 2010
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Ingår i: Integrative and Comparative Biology. - : Oxford University Press (OUP). - 1540-7063 .- 1557-7023. ; 50:3, s. 261-279
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Konferensbidrag (refereegranskat)abstract
- Billions of animals migrate each year. To successfully reach their destination, migrants must have evolved an appropriate genetic program and suitable developmental, morphological, physiological, biomechanical, behavioral, and life-history traits. Moreover, they must interact successfully with biotic and abiotic factors in their environment. Migration therefore provides an excellent model system in which to address several of the "grand challenges" in organismal biology. Previous research on migration, however, has often focused on a single aspect of the phenomenon, largely due to methodological, geographical, or financial constraints. Integrative migration biology asks 'big questions' such as how, when, where, and why animals migrate, which can be answered by examining the process from multiple ecological and evolutionary perspectives, incorporating multifaceted knowledge from various other scientific disciplines, and using new technologies and modeling approaches, all within the context of an annual cycle. Adopting an integrative research strategy will provide a better understanding of the interactions between biological levels of organization, of what role migrants play in disease transmission, and of how to conserve migrants and the habitats upon which they depend.
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| 3. |
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| 4. |
- Bowlin, Melissa, et al.
(författare)
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The effects of geolocator drag and weight on the flight ranges of small migrants
- 2010
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Ingår i: Methods in Ecology and Evolution. - 2041-210X. ; 1:4, s. 398-402
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Tidskriftsartikel (refereegranskat)abstract
- 1. Researchers are currently placing hundreds of geolocators on migratory animals. Return rates for some small birds carrying these devices have been lower than expected, potentially because geo- locators increase drag during flight. 2. We measured the drag of three different geolocators (1 2g BAS-MK10, 1 0 g SOI-GL10 09 and 0 5 g SOI-GL05 10) in backpack-style harnesses on two preserved bird bodies in a wind tunnel.We then used these measurements to estimate the effects of this drag on the flight ranges of several small migratory birds. 3. Both theBAS-MK10 and SOI-GL05 10 significantly increased drag; the drag was also consider- ably higher when a geolocator was attached between the wings (wing harness) than on the rump (leg-loop harness). 4. The effects of the increased drag of these devices on the predicted flight ranges of birds were simi- lar to the effects of their weight and may thus explain the results of previous studies that showed decreased return rateswhen using geolocators and other tracking devices. 5. We recommend that researchers and manufacturers work to minimize the drag of geolocators and other externally attached tracking or data collection devices on flying and swimming animals. This can be accomplished with geolocators by attaching devices above birds rumps instead of between their wings and flattening the devices to reduce their height.
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| 5. |
- Engel, Sophia, et al.
(författare)
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The Role of Wind-Tunnel Studies in Integrative Research on Migration Biology
- 2010
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Ingår i: Integrative and Comparative Biology. - : Oxford University Press (OUP). - 1540-7063 .- 1557-7023. ; 50:3, s. 323-335
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Konferensbidrag (refereegranskat)abstract
- Wind tunnels allow researchers to investigate animals' flight under controlled conditions, and provide easy access to the animals during flight. These increasingly popular devices can benefit integrative migration biology by allowing us to explore the links between aerodynamic theory and migration as well as the links between flight behavior and physiology. Currently, wind tunnels are being used to investigate many different migratory phenomena, including the relationship between metabolic power and flight speed and carry-over effects between different seasons. Although biotelemetry is also becoming increasingly common, it is unlikely that it will be able to completely supplant wind tunnels because of the difficulty of measuring or varying parameters such as flight speed or temperature in the wild. Wind tunnels and swim tunnels will therefore continue to be important tools we can use for studying integrative migration biology.
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| 6. |
- Muijres, Florian, et al.
(författare)
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Comparing aerodynamic efficiency in birds and bats suggests better flight performance in birds.
- 2012
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Ingår i: PLoS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 7:5
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Tidskriftsartikel (refereegranskat)abstract
- Flight is one of the energetically most costly activities in the animal kingdom, suggesting that natural selection should work to optimize flight performance. The similar size and flight speed of birds and bats may therefore suggest convergent aerodynamic performance; alternatively, flight performance could be restricted by phylogenetic constraints. We test which of these scenarios fit to two measures of aerodynamic flight efficiency in two passerine bird species and two New World leaf-nosed bat species. Using time-resolved particle image velocimetry measurements of the wake of the animals flying in a wind tunnel, we derived the span efficiency, a metric for the efficiency of generating lift, and the lift-to-drag ratio, a metric for mechanical energetic flight efficiency. We show that the birds significantly outperform the bats in both metrics, which we ascribe to variation in aerodynamic function of body and wing upstroke: Bird bodies generated relatively more lift than bat bodies, resulting in a more uniform spanwise lift distribution and higher span efficiency. A likely explanation would be that the bat ears and nose leaf, associated with echolocation, disturb the flow over the body. During the upstroke, the birds retract their wings to make them aerodynamically inactive, while the membranous bat wings generate thrust and negative lift. Despite the differences in performance, the wake morphology of both birds and bats resemble the optimal wake for their respective lift-to-drag ratio regimes. This suggests that evolution has optimized performance relative to the respective conditions of birds and bats, but that maximum performance is possibly limited by phylogenetic constraints. Although ecological differences between birds and bats are subjected to many conspiring variables, the different aerodynamic flight efficiency for the bird and bat species studied here may help explain why birds typically fly faster, migrate more frequently and migrate longer distances than bats.
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| 7. |
- Muijres, Florian, et al.
(författare)
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Vortex wake, downwash distribution, aerodynamic performance and wingbeat kinematics in slow-flying pied flycatchers.
- 2012
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Ingår i: Journal of the Royal Society Interface. - : The Royal Society. - 1742-5662 .- 1742-5689. ; 9, s. 292-303
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Tidskriftsartikel (refereegranskat)abstract
- Many small passerines regularly fly slowly when catching prey, flying in cluttered environments or landing on a perch or nest. While flying slowly, passerines generate most of the flight forces during the downstroke, and have a 'feathered upstroke' during which they make their wing inactive by retracting it close to the body and by spreading the primary wing feathers. How this flight mode relates aerodynamically to the cruising flight and so-called 'normal hovering' as used in hummingbirds is not yet known. Here, we present time-resolved fluid dynamics data in combination with wingbeat kinematics data for three pied flycatchers flying across a range of speeds from near hovering to their calculated minimum power speed. Flycatchers are adapted to low speed flight, which they habitually use when catching insects on the wing. From the wake dynamics data, we constructed average wingbeat wakes and determined the time-resolved flight forces, the time-resolved downwash distributions and the resulting lift-to-drag ratios, span efficiencies and flap efficiencies. During the downstroke, slow-flying flycatchers generate a single-vortex loop wake, which is much more similar to that generated by birds at cruising flight speeds than it is to the double loop vortex wake in hovering hummingbirds. This wake structure results in a relatively high downwash behind the body, which can be explained by the relatively active tail in flycatchers. As a result of this, slow-flying flycatchers have a span efficiency which is similar to that of the birds in cruising flight and which can be assumed to be higher than in hovering hummingbirds. During the upstroke, the wings of slowly flying flycatchers generated no significant forces, but the body-tail configuration added 23 per cent to weight support. This is strikingly similar to the 25 per cent weight support generated by the wing upstroke in hovering hummingbirds. Thus, for slow-flying passerines, the upstroke cannot be regarded as inactive, and the tail may be of importance for flight efficiency and possibly manoeuvrability.
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| 8. |
- Robinson, W. Douglas, et al.
(författare)
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Integrating concepts and technologies to advance the study of bird migration
- 2010
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Ingår i: Frontiers in Ecology and the Environment. - : Wiley. - 1540-9309 .- 1540-9295. ; 8:7, s. 354-361
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Forskningsöversikt (refereegranskat)abstract
- Recent technological innovation has opened new avenues in migration research - for instance, by allowing individual migratory animals to be followed over great distances and long periods of time, as well as by recording physiological information. Here, we focus on how technology - specifically applied to bird migration - has advanced our knowledge of migratory connectivity, and the behavior, demography, ecology, and physiology of migrants. Anticipating the invention of new and smaller tracking devices, in addition to the ways that technologies may be combined to measure and record the behavior of migratory animals, we also summarize major conceptual questions that can only be addressed once innovative, cutting-edge instrumentation becomes available.
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