Orographic lift shapes flight routes of gulls in virtually flat landscapes

Sage, Elspeth; Bouten, W.; Hoekstra, Bart; Camphuysen, C.J.; Shamoun‐Baranes, Judy

doi:10.1038/s41598-019-46017-x

Cited by 19 publications

(22 citation statements)

References 44 publications

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“…Relative to small-scale turbulence, large-scale atmospheric flows have well-known effects on flight. Examples include orographic updrafts produced by topography (17)(18)(19), thermal updrafts (20)(21)(22), internal waves (23), and fronts, which all tend to subsidize flight. These interactions are easier to observe, in part, due to the fact that the flows are slowly evolving and in an approximate steady state relative to the time it takes for a bird or aircraft to fly through them.…”

mentioning

confidence: 99%

Turbulence explains the accelerations of an eagle in natural flight

Laurent

Fogg²,

Ginsburg

et al. 2021

Proc. Natl. Acad. Sci. U.S.A.

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Turbulent winds and gusts fluctuate on a wide range of timescales from milliseconds to minutes and longer, a range that overlaps the timescales of avian flight behavior, yet the importance of turbulence to avian behavior is unclear. By combining wind speed data with the measured accelerations of a golden eagle (Aquila chrysaetos) flying in the wild, we find evidence in favor of a linear relationship between the eagle’s accelerations and atmospheric turbulence for timescales between about 1/2 and 10 s. These timescales are comparable to those of typical eagle behaviors, corresponding to between about 1 and 25 wingbeats, and to those of turbulent gusts both larger than the eagle’s wingspan and smaller than large-scale atmospheric phenomena such as convection cells. The eagle’s accelerations exhibit power spectra and intermittent activity characteristic of turbulence and increase in proportion to the turbulence intensity. Intermittency results in accelerations that are occasionally several times stronger than gravity, which the eagle works against to stay aloft. These imprints of turbulence on the bird’s movements need to be further explored to understand the energetics of birds and other volant life-forms, to improve our own methods of flying through ceaselessly turbulent environments, and to engage airborne wildlife as distributed probes of the changing conditions in the atmosphere.

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mentioning

confidence: 99%

Turbulence explains the accelerations of an eagle in natural flight

Laurent

Fogg²,

Ginsburg

et al. 2021

Proc. Natl. Acad. Sci. U.S.A.

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“…2016, Sage et al . 2019). This would also reveal the degree to which juveniles from the same colony associate during the migration and wintering periods (Flack et al .…”

Section: Discussionmentioning

confidence: 99%

“…Whether the same foraging sites are used consistently throughout ontogeny and into adulthood remains to be tested. Future work could focus on the development of fine-scale foraging and flight strategies, and energetic consequences, potentially using GPS and accelerometer data from a larger cohort of individuals (Shamoun- , Sage et al 2019. This would also reveal the degree to which juveniles from the same colony associate during the migration and wintering periods (Flack et al 2018).…”

Section: Wintering Behaviour and Habitat Usementioning

confidence: 99%

Post‐fledging migration and wintering strategies of individual juvenile Lesser Black‐backed Gulls (Larus fuscus)

Borrmann

Phillips

Clay

et al. 2021

Ibis

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Research into the patterns and drivers of juvenile migration is important for understanding the development of individual migration strategies. Although several recent studies have tracked adult large gulls throughout the annual cycle, the movements of juveniles remain poorly understood. We fitted Global Positioning System (GPS) devices that transmit locations through the Global System for Mobile Communications (GSM) to ten juvenile Lesser Black‐backed Gulls Larus fuscus prior to fledging on the island of Spiekeroog, Germany, to study their first autumn migration and wintering behaviour. The tracked birds initially departed on similar compass bearings south to south‐west, after which migration routes diverged. Individuals took 38–107 days to reach their wintering sites in Algeria, Morocco or Spain. Birds visited 6.7 ± 3.7 (mean ± sd) stopover sites en route and spent substantial time in northern Europe, with some individuals converging at the same sites over small spatial scales (<1 km), but not over the same time periods. Birds increased travel speeds in the second half of their migration. They showed relatively high site‐fidelity after arrival at wintering sites, and there was no evidence that the size of foraging areas increased over time, suggesting limited exploratory behaviour. Individuals used the same predominant habitats – cropland, open water and built‐up areas – to varying degrees, but showed limited variation in habitat use over time. Overall, the migration routes and timings of juveniles broadly resembled those of previously tracked adults. Given their similar initial bearings and abundance of large gulls on the flyway, we suggest that social learning is likely to be an important process shaping the individual migration and wintering strategies of juvenile gulls.

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“…This may suggest that there is high selection pressure for moving along coastlines in this species, implying an advantage to foraging or roosting in coastal habitats while migrating. Coastal areas may also represent energy efficient pathways, as the dunes and cliffs typical of these areas can generate orographic lift enabling gulls to switch from flapping flight to energetically cheap soaring flight (Sage et al, 2019).…”

Section: Accepted Articlementioning

confidence: 99%