Flight Speeds of Birds in Relation to Energetics and Wind Directions

Tucker, Vance A.; Schmidt-Koenig, Klaus

doi:10.2307/4083964

Cited by 56 publications

(34 citation statements)

References 9 publications

(1 reference statement)

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“…Although tailwinds can benefit airborne animals, power required for flight typically increase under conditions of headwinds or crosswinds (Tucker and Schmidt-Koenig 1971;Liechti et al 1994). Avoidance of colder, windier conditions minimizes energetic costs of mid-winter flights and conserves fat stores, which likely improves body condition and chance of survival upon emergence in the spring (Humphries et al 2003).…”

Section: Anderson 2002)mentioning

confidence: 99%

Environmental correlates and energetics of winter flight by bats in southern Alberta, Canada

et al. 2016

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Winter activity of bats is common, yet poorly understood. Other studies suggest a relationship between winter activity and ambient temperature, particularly temperature at sunset.We recorded echolocation calls to determine correlates of hourly bat-activity in Dinosaur Provincial Park, Alberta, Canada. We documented bat activity in temperatures as low as -10.4°C.We observed big brown bats (Eptesicus fuscus (Palisot de Beauvois, 1796)) flying at colder temperatures than species of Myotis bats (genus Myotis (Kaup 1829). We show that temperature and wind are important predictors of winter activity by E. fuscus and Myotis, and that Myotis may also use changes in barometric pressure to cue activity. In the absence of foraging opportunity, we suggest these environmental factors relate to heat loss and thus the energetic cost of flight. To understand the energetic consequences of bat flight in cold temperatures, we estimated energy expenditure during winter flights of E. fuscus and Myotis lucifugus using species-specific parameters. We estimated that winter flight uses considerable fat stores and that flight thermogenesis could mitigate energetic costs by 20% or more. We also show that temperature-dependent interspecific differences in winter activity likely stem from differences between species in heat loss and potential for activity-thermoregulatory heat substitution. IntroductionDuring hibernation, metabolic rate (MR) and body temperature (T b ), are decreased for days to weeks (Ruf and Geiser 2015). Hibernating animals save considerable energy and can survive on limited resources (i.e., body fat or cached food) for extended periods, up to months at a time (Humphries et al. 2003). Benefits of hibernation are obvious (Geiser 2004;Geiser and Brigham 2012) but there are associated costs, such as suppressed molecular synthesis (Lillegraven et al. 1987), ceased or delayed reproduction (Racey 1969; Barnes et al. 1986), and immunosuppression (Bouma et al. 2010). For these reasons and likely others, nearly all hibernating mammals arouse periodically (Willis 1982; French 1985), ostensibly to excrete metabolic wastes (Baumber et al. 1971), mount immune responses (Burton and Reichman 1999), mate (Thomas et al. 1979), eat (Humphries et al. 2001), and possibly drink (Thomas and Cloutier 1992;Thomas and Geiser 1997; Ben-Hamo et al. 2013).Much of what we know about arousals and winter activity of temperate-zone bats comes from research on caverniculous species. In eastern North America, bats often roost in large groups in sizeable, humid, thermally-stable hibernacula (Webb et al. 1996;Perry 2012). Most activities typical of arousals occur within the hibernacula; caves and mines allow flight within hibernacula and may contain open water sources and hibernating insects that can be consumed (Swanson and Evans 1936;Rysgaard 1942). Opportunistic mating is also possible with mixedsex groups typically found in cave hibernacula (Thomas et al. 1979).Bats are also active outside of hibernacula for reasons poorly understood. Early ...

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Section: Anderson 2002)mentioning

confidence: 99%

Environmental correlates and energetics of winter flight by bats in southern Alberta, Canada

et al. 2016

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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%

“…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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“…The requirement for dual operators is a downside and implies synchronization issues, but this system potentially offers low uncertainty at long distances, and behavioural records. Tucker and Schmidt-Koenig (1971) had used a similar dual-theodolite system, without the video record.…”

Section: Comparison With Existing Tracking Methodsmentioning

confidence: 99%

3D tracking of animals in the field, using rotational stereo videography

Margerie

Simonneau

Caudal

et al. 2015

Journal of Experimental Biology

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We describe a method for tracking the path of animals in the field, based on stereo videography and aiming-angle measurements, combined in a single, rotational device. In open environments, this technique has the potential to extract multiple 3D positions per second, with a spatial uncertainty of <1 m (rms) within 300 m of the observer, and <0.1 m (rms) within 100 m of the observer, in all directions. The tracking device is transportable and operated by a single observer, and does not involve any animal tagging. As a video of the moving animal is recorded, track data can easily be completed with behavioural data. We present a prototype device based on accessible components that achieves about 70% of the theoretical maximal range. We show examples of bird ground and flight tracks, and discuss the strengths and limits of the method, compared with existing fine-scale (e.g. fixed-camera stereo videography) and largescale tracking methods (e.g. GPS tracking).

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Flight Speeds of Birds in Relation to Energetics and Wind Directions

Cited by 56 publications

References 9 publications

Environmental correlates and energetics of winter flight by bats in southern Alberta, Canada

Environmental correlates and energetics of winter flight by bats in southern Alberta, Canada

Commuting fruit bats beneficially modulate their flight in relation to wind

3D tracking of animals in the field, using rotational stereo videography

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