New modeling approach for bounding flight in birds

Sachs, Gottfried; Lenz, Jakob

doi:10.1016/j.mbs.2011.08.005

Cited by 8 publications

(4 citation statements)

References 17 publications

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“…Modelling the power costs of flap-bounding generally indicates that this flight style can offer an energetic saving compared with continuous flapping during fast flight if, as is observed, the body and tail produce lift that is sufficient to support 10-15% of weight [103][104][105]. However, using kinematics of zebra finch [103], Sachs' analysis indicates that flap-bounding only offers an energetic advantage during flight into a headwind [106,107]. By contrast, it is predicted that flap-gliding offers energetic advantages over a broad range of flight speeds [105,108].…”

Section: Scaling Of Flight Performance (A) On Being Largementioning

confidence: 99%

Evolution of avian flight: muscles and constraints on performance

Tobalske¹

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'. Competing hypotheses about evolutionary origins of flight are the 'fundamental wing-stroke' and 'directed aerial descent' hypotheses. Support for the fundamental wing-stroke hypothesis is that extant birds use flapping of their wings to climb even before they are able to fly; there are no reported examples of incrementally increasing use of wing movements in gliding transitioning to flapping. An open question is whether locomotor styles must evolve initially for efficiency or if they might instead arrive due to efficacy. The proximal muscles of the avian wing output work and power for flight, and new research is exploring functions of the distal muscles in relation to dynamic changes in wing shape. It will be useful to test the relative contributions of the muscles of the forearm compared with inertial and aerodynamic loading of the wing upon dynamic morphing. Body size has dramatic effects upon flight performance. New research has revealed that mass-specific muscle power declines with increasing body mass among species. This explains the constraints associated with being large. Hummingbirds are the only species that can sustain hovering. Their ability to generate force, work and power appears to be limited by time for activation and deactivation within their wingbeats of high frequency. Most small birds use flap-bounding flight, and this flight style may offer an energetic advantage over continuous flapping during fast flight or during flight into a headwind. The use of flap-bounding during slow flight remains enigmatic. Flap-bounding birds do not appear to be constrained to use their primary flight muscles in a fixed manner. To improve understanding of the functional significance of flap-bounding, the energetic costs and the relative use of alternative styles by a given species in nature merit study.This article is part of the themed issue 'Moving in a moving medium: new perspectives on flight'. OverviewMuscles are obviously key to the capacity of birds for flight, and the goal of this review is to explore current hypotheses of the ways muscles permit and constrain this capacity. Insight into the phylogeny of birds is improving rapidly, and this offers great promise for improving understanding of how evolution transformed ancestral theropod forms [1] into the derived, volant bird species we observe today. Genomic study [2][3][4] and the extraordinary rate of new discovery of fossil dinosaurs [5][6][7][8][9][10] have provided rich phylogenetic hypotheses from which we can begin to test patterns of historical transformation [11]. Concurrently, modern empirical and modelling techniques in comparative biomechanics offer new ways of testing hypotheses that link form and function. These include in vivo and in situ measures of the contractile behaviour of muscle [12 -14]: high-speed, three-dimensional videography that can reveal details of wing motion [15,16]; X-ray videography of skeletal kinematics [16,17]; particle ima...

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Section: Scaling Of Flight Performance (A) On Being Largementioning

confidence: 99%

Evolution of avian flight: muscles and constraints on performance

Tobalske¹

2016

Phil. Trans. R. Soc. B

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“…Flap-bounding is exhibited by diverse species of relatively small birds, including most passerines, woodpeckers and some smaller owls, yet mathematical modeling of bird flight suggests that this flight style requires a higher aerodynamic power output than continuous flapping across all conditions, except perhaps at high flights speeds ( Rayner, 1985 ; Ward-Smith, 1984a , b ), or when flying fast into a headwind ( Sachs, 2013 ; Sachs and Lenz, 2011 ). Regardless, many flap-bounding species continue to bound in slow and hovering flight.…”

Section: Introductionmentioning

confidence: 99%

“…Second, finches could opt to increase their aerodynamic efficiency (meaning that they could decrease the power output required to fly at a given speed) by increasing their flapping ratio and decreasing wingbeat amplitude. These two responses would theoretically create a steadier momentum jet with less induced power cost ( Muijres et al, 2011 ; Rayner, 1985 ; Sachs and Lenz, 2011 ; Usherwood, 2016 ; Ward-Smith, 1984b ) and the increase in flapping ratio would compensate for the added power-cost incurred by loading. This response should not be possible for finches governed by the fixed-gear hypothesis ( Rayner, 1985 ), but could occur via a reduction in activation/deactivation efficiency (because a shallower wingbeat means a shorter downstroke duration and thus less work is produced for activating that volume of muscle) for finches governed by the cost of muscle activation/deactivation.…”

Section: Introductionmentioning

confidence: 99%

Zebra finch (Taeniopygia guttata) shift toward aerodynamically efficient flight kinematics in response to an artificial load

2019

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We investigated the effect of an added mass emulating a transmitter on the flight kinematics of zebra finches ( Taeniopygia guttata ), both to identify proximal effects of loading and to test fundamental questions regarding the intermittent flight of this species. Zebra finch, along with many species of relatively small birds, exhibit flap-bounding, wherein the bird alternates periods of flapping with flexed-wing bounds. Mathematical modeling suggests that flap-bounding is less aerodynamically efficient than continuous flapping, except in limited circumstances. This has prompted the introduction of two major hypotheses for flap-bounding – the ‘fixed-gear’ and ‘cost of muscle activation/deactivation’ hypotheses – based on intrinsic properties of muscle. We equipped zebra finches flying at 10 m s −1 with a transmitter-like load to determine if their response was consistent with the predictions of these hypotheses. Loading caused finches to diverge significantly from their unloaded wingbeat kinematics. Researchers should carefully consider whether these effects impact traits of interest when planning telemetry studies to ensure that tagged individuals can reasonably be considered representative of the overall population. In response to loading, average wingbeat amplitude and angular velocity decreased, inconsistent with the predictions of the fixed-gear hypothesis. If we assume that finches maintained muscular efficiency, the reduction in amplitude is inconsistent with the cost of the muscle activation/deactivation hypothesis. However, we interpret the reduction in wingbeat amplitude and increase in the proportion of time spent flapping as evidence that loaded finches opted to increase their aerodynamic efficiency – a response which is consistent with the latter hypothesis.

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“…On the other hand, dynamical models typically couple the body dynamics with the dynamics of the surrounding fluid environment and tend to be complex, amenable only to computational analysis and specifically tailored to the case at hand. For example, in [23] a model for fish-like swimming that includes a flexible body (the fish) interacting with a viscous fluid is evaluated for the efficiency of burst-and-coast swimming, while reduced order models [24,25] have been used to numerically find optimal solutions for intermittent flight and dynamic soaring in birds. The fact that similar intermittent locomotion strategies have arisen in animals that are not closely related [2] suggests a search for basic principles that might be gleaned from a general model.…”

Section: Introductionmentioning

confidence: 99%

Intermittent locomotion as an optimal control strategy

Paoletti

Mahadevan

2014

Proc. R. Soc. A.

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Birds, fish and other animals routinely use unsteady effects to save energy by alternating between phases of active propulsion and passive coasting. Here, we construct a minimal model for such behaviour that can be couched as an optimal control problem via an analogy to travelling with a rechargeable battery. An analytical solution of the optimal control problem proves that intermittent locomotion has lower energy requirements relative to steady-state strategies. Additional realistic hypotheses, such as the assumption that metabolic cost at a given power should be minimal (the fixed gear hypothesis), a nonlinear dependence of the energy storage rate on propulsion and/or a preferred average speed, allow us to generalize the model and demonstrate the flexibility of intermittent locomotion with implications for biological and artificial systems.

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New modeling approach for bounding flight in birds

Cited by 8 publications

References 17 publications

Evolution of avian flight: muscles and constraints on performance

Evolution of avian flight: muscles and constraints on performance

Zebra finch (Taeniopygia guttata) shift toward aerodynamically efficient flight kinematics in response to an artificial load

Intermittent locomotion as an optimal control strategy

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