Fifteen Testable Predictions about Bird Flight

Pennycuick, Colin J

doi:10.2307/3543476

Cited by 175 publications

(176 citation statements)

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“…Theoretical aerodynamic literature (Table 2a) reports mass exponents for the energy expenditure of avian flight which range from 1.16 to 1.59 (Pennycuick 1975(Pennycuick , 1978Rayner 1990;Norberg 1996). We found an exponent of 0.58 (95% CI 0.19-0.97).…”

Section: Aerodynamic Theoriesmentioning

confidence: 99%

Energy expenditure and wing beat frequency in relation to body mass in free flying Barn Swallows (Hirundo rustica)

et al. 2006

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Section: Aerodynamic Theoriesmentioning

confidence: 99%

Energy expenditure and wing beat frequency in relation to body mass in free flying Barn Swallows (Hirundo rustica)

et al. 2006

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“…To test for possible changes in flight behaviour along the flight track, we made separate analyses for the first two flight segments of each flight (the first 10 min of flight), and the last two flight segments of each flight (the last 10 min of flight), to test whether wind drift occurred at the beginning of the flight while compensation for crosswind took place close to destination, as has been suggested under changing winds [3]. We additionally tested whether bats adjusted their airspeed in relation to tail-and crosswind speed [22,23] to optimize their cost of transport [17,18]. This was accomplished by regressing bat airspeed relative to the wind component in the direction between the trip's origin and destination.…”

Section: (C) Data Analysismentioning

confidence: 99%

“…We additionally report the results of the unweighted regression. E. helvum power curve [18] (electronic supplementary material, figure S2) was calculated using published morphological data [36].…”

Section: (C) Data Analysismentioning

confidence: 99%

“…Under variable winds, partial compensation with some degree of lateral drift at the start of the journey and full compensation near the destination is expected [3]. (ii) To minimize their cost of transport, bat airspeed will decrease with tailwind assistance and increase under headwinds ( [17,18]; electronic supplementary material, figure S2). (iii) Likewise, bat airspeed will increase with crosswind speed [13,22,23].…”

Section: Introductionmentioning

confidence: 99%

“…Because wind may affect not only the bat's sideways movement but also its forward speed with respect to the destination, bats are also expected to change their behaviour under tail-or headwind conditions. To minimize their cost of transport, airborne animals using flapping flight that encounter tailwinds should reduce their airspeed, and increase it under headwinds [17,18] (electronic supplementary material, figure S2). In addition, a strong effect of crosswind speed on airspeed was suggested [13], such that animals are expected to increase their airspeed with increasing crosswind speed as a way to reduce drift effect.…”

Section: Introductionmentioning

confidence: 99%

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Commuting fruit bats beneficially modulate their flight in relation to wind

et al. 2014

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When animals move, their tracks may be strongly influenced by the motion of air or water, and this may affect the speed, energetics and prospects of the journey. Flying organisms, such as bats, may thus benefit from modifying their flight in response to the wind vector. Yet, practical difficulties have so far limited the understanding of this response for free-ranging bats. We tracked nine straw-coloured fruit bats (Eidolon helvum) that flew 42.5 + 17.5 km (mean + s.d.) to and from their roost near Accra, Ghana. Following detailed atmospheric simulations, we found that bats compensated for wind drift, as predicted under constant winds, and decreased their airspeed in response to tailwind assistance such that their groundspeed remained nearly constant. In addition, bats increased their airspeed with increasing crosswind speed. Overall, bats modulated their airspeed in relation to wind speed at different wind directions in a manner predicted by a two-dimensional optimal movement model. We conclude that sophisticated behavioural mechanisms to minimize the cost of transport under various wind conditions have evolved in bats. The bats' response to the wind is similar to that reported for migratory birds and insects, suggesting convergent evolution of flight behaviours in volant organisms.

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Effects of age, sex, and ENSO phase on foraging and flight performance in Nazca boobies

Howard

Tompkins

Anderson

2021

Ecology and Evolution

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Age-related changes in survival and reproduction are common in seabirds; however, the underlying causes remain elusive. A lack of experience for young individuals, and a decline in foraging performance for old birds, could underlie age-related variation in reproduction because reproductive success is connected closely to provisioning offspring. For seabirds, flapping flight during foraging trips is physiologically costly; inexperience or senescent decline in performance of this demanding activity might cap delivery of food to the nest, providing a proximate explanation for poor breeding success in young and old age, respectively. We evaluated the hypothesis that young and old Nazca boobies (Sula granti), a Galápagos seabird, demonstrate deficits in foraging outcomes and flight performance. We tagged incubating male and female adults across the life span with both accelerometer and GPS loggers during the incubation periods of two breeding seasons (years), during the 2015 El Niño and the following weak La Niña. We tested the ability of age, sex, and environment to explain variation in foraging outcomes (e.g., mass gained) and flight variables (e.g., wingbeat frequency). Consistent with senescence, old birds gained less mass while foraging than middle-aged individuals, a marginal effect, and achieved a slower airspeed late in a foraging trip. Contrary to expectations, young birds showed no deficit in foraging outcomes or flight performance, except for airspeed (contingent on environment).Young birds flew slower than middle-aged birds in 2015, but faster than middle-aged birds in 2016. Wingbeat frequency, flap-glide ratio, and body displacement (approximating wingbeat strength) failed to predict airspeed and were unaffected by age.Sex influenced nearly all aspects of performance. Environment affected flight performance and foraging outcomes. Boobies' foraging outcomes were better during the extreme 2015 El Niño than during the 2016 weak La Niña, a surprising result given the negative effects tropical seabirds often experience during extreme El Niños.

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Fifteen Testable Predictions about Bird Flight

Cited by 175 publications

References 0 publications

Energy expenditure and wing beat frequency in relation to body mass in free flying Barn Swallows (Hirundo rustica)

Energy expenditure and wing beat frequency in relation to body mass in free flying Barn Swallows (Hirundo rustica)

Commuting fruit bats beneficially modulate their flight in relation to wind

Effects of age, sex, and ENSO phase on foraging and flight performance in Nazca boobies

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