Upwash exploitation and downwash avoidance by flap phasing in ibis formation flight

Portugal, Steven J.; Hubel, Tatjana Y.; Fritz, Johannes; Heese, Stefanie; Trobe, Daniela; Voelkl, Bernhard; Hailes, Stephen; Wilson, Alan M.; Usherwood, James R.

doi:10.1038/nature12939

Cited by 280 publications

(212 citation statements)

References 37 publications

(42 reference statements)

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“…This could be interpreted as a sort of collective intelligence at the population level, but at the individual level due to the signal being asymmetric, it would bestow greater benefit on later migrating individuals. Salmon likely experiences selective pressure to group for a variety of reasons, including protection from predation (Handegard et al 2012;Marras et al 2012) from larger fish, birds, marine mam mals, and sharks, for group hunting (Handegard et al 2012), hydrodynamic benefits (Ross et al 1992;Herskin and Steffensen 1998;Portugal et al 2014), and tracking gradients associated with appropriate living conditions or patchily distrib uted prey (Couzin 2007;Torney et al 2009Torney et al , 2011Berdahl et al 2013). Such coordinated group living may confer benefits of collective navi gation during migrations, even if the grouping originally evolved for other reasons.…”

Section: Salmon Schoolingmentioning

confidence: 99%

A collective navigation hypothesis for homeward migration in anadromous salmonids

et al. 2014

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Anadromous salmon (genera Oncorhynchus and Salmo) spend much of their lives feeding in productive northern oceans and then return home to natal sites for reproduction with remarkable accuracy. The mechanisms used for navigation by individuals during migrations are thought to include geomagnetic, celestial and olfactory cues, but rarely are social interactions between individuals considered. Mounting evidence from other taxa indicates that individuals in larger groups can better sense and respond to environmental cues, thus potentially increasing their ability to navigate. Here, we propose that salmon might similarly benefit from col lective navigation on their homeward journey. To explore this, we compiled data from multiple studies and found strong evidence that rates of successful homing increase with population abundance, consistent with collective navigation. We then discuss how collective navigation could benefit salmon during each stage of their seaward and homeward migrations, and complement this with a review of salmon sociality. Next, we analyse historic high seas catch records and provide new insight into schooling structure of salmon in the marine environment. We argue that collective navigation likely represents a presently under appreciated Fish and Fisheries ; 17 (2016), 2. -S. 525-542 https://dx.doi.org/10.1111 mechanism enhancing the navigational ability of salmon as well as other migra tory species, and outline critical tests of our hypothesis.

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Section: Salmon Schoolingmentioning

confidence: 99%

A collective navigation hypothesis for homeward migration in anadromous salmonids

et al. 2014

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“…Finally, in birds that fly in groups, the flight formation may also influence whether sleep is possible in flight. For example, if flapping in V-formations requires full attention to maximize the aerodynamic benefits [87] and avoid collisions, then even USWS might not be possible in birds that rely on this flight strategy.…”

Section: Rsfsroyalsocietypublishingorg Interface Focus 7: 20160082mentioning

confidence: 99%

Sleeping on the wing

Rattenborg¹

2017

Interface Focus.

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Wakefulness enables animals to interface adaptively with the environment. Paradoxically, in insects to humans, the efficacy of wakefulness depends on daily sleep, a mysterious, usually quiescent state of reduced environmental awareness. However, several birds fly non-stop for days, weeks or months without landing, questioning whether and how they sleep. It is commonly assumed that such birds sleep with one cerebral hemisphere at a time (i.e. unihemispherically) and with only the corresponding eye closed, as observed in swimming dolphins. However, the discovery that birds on land can perform adaptively despite sleeping very little raised the possibility that birds forgo sleep during long flights. In the first study to measure the brain state of birds during long flights, great frigatebirds ( Fregata minor ) slept, but only during soaring and gliding flight. Although sleep was more unihemispheric in flight than on land, sleep also occurred with both brain hemispheres, indicating that having at least one hemisphere awake is not required to maintain the aerodynamic control of flight. Nonetheless, soaring frigatebirds appeared to use unihemispheric sleep to watch where they were going while circling in rising air currents. Despite being able to engage in all types of sleep in flight, the birds only slept for 0.7 h d −1 during flights lasting up to 10 days. By contrast, once back on land they slept 12.8 h d −1 . This suggests that the ecological demands for attention usually exceeded that afforded by sleeping unihemispherically. The ability to interface adaptively with the environment despite sleeping very little challenges commonly held views regarding sleep, and therefore serves as a powerful system for examining the functions of sleep and the consequences of its loss.

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“…The observed effect of flock size was, however, opposite to the prediction from energy saving in formation flight. Even if large species may obtain aerodynamic benefit from formation flight [18,46], such a benefit is unlikely in our terns that most often formed quite loose flocks with large inter-individual distances, although tight formations did also occur on migration. A potential mechanistic explanation for the observed effect of flock size on airspeed could result from the increased likelihood of inclusion of heavy individuals in flocks of increasing numbers from random sampling from a source population.…”

Section: (C) Airspeedmentioning

confidence: 99%

“…Flight in flock formation is expected to alleviate flight cost by reducing the induced drag of individual birds [17,18], which should reduce the characteristic flight speeds U mr and U mt , respectively [19]. However, the few observations available where flight speed was measured in relation to flock size suggest that airspeed increases with increasing flock size [20].…”

Section: Introductionmentioning

confidence: 99%

Ecology of tern flight in relation to wind, topography and aerodynamic theory

Hedenström

Åkesson

2016

Phil. Trans. R. Soc. B

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One contribution of 17 to a theme issue 'Moving in a moving medium: new perspectives on flight'. Flight is an economical mode of locomotion, because it is both fast and relatively cheap per unit of distance, enabling birds to migrate long distances and obtain food over large areas. The power required to fly follows a U-shaped function in relation to airspeed, from which context dependent 'optimal' flight speeds can be derived. Crosswinds will displace birds away from their intended track unless they make compensatory adjustments of heading and airspeed. We report on flight track measurements in five geometrically similar tern species ranging one magnitude in body mass, from both migration and the breeding season at the island of Ö land in the Baltic Sea. When leaving the southern point of Ö land, migrating Arctic and common terns made a 608 shift in track direction, probably guided by a distant landmark. Terns adjusted both airspeed and heading in relation to tail and side wind, where coastlines facilitated compensation. Airspeed also depended on ecological context (searching versus not searching for food), and it increased with flock size. Species-specific maximum range speed agreed with predicted speeds from a new aerodynamic theory. Our study shows that the selection of airspeed is a behavioural trait that depended on a complex blend of internal and external factors.This article is part of the themed issue 'Moving in a moving medium: new perspectives on flight'.

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Upwash exploitation and downwash avoidance by flap phasing in ibis formation flight

Cited by 280 publications

References 37 publications

A collective navigation hypothesis for homeward migration in anadromous salmonids

A collective navigation hypothesis for homeward migration in anadromous salmonids

Sleeping on the wing

Ecology of tern flight in relation to wind, topography and aerodynamic theory

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