Flight Performance Of Birds Research Articles

Designing and producing a bird-inspired unmanned sailplane

PurposeIncreasing endurance was a very appropriate subject for the biomimetic approach. The study aims to design and manufacture a long-lasting mini unmanned aerial vehicle (UAV) using active gliding and soaring.Design/methodology/approachThe endurance of mini UAVs is limited by battery or fuel capacity, and it is not always possible to increase these energy sources due to the fuselage size. Long endurance aircraft are required in various areas such as silent environment and traffic monitoring or search and rescue. Literature research on bird flight performance conducted to determine design parameters. These parameters are used in the theoretical design of the UAV for optimization. Computational fluid dynamics simulation and flight tests of the UAV performed to figure out the success of the design.FindingsFor a mini UAV to be produced in this class, it has been observed that it is more accurate to examine birds instead of gliders due to the size similarity. The UAV design reaches a 27.5 L/D (Glide ratio) ratio in the theoretical approach. However, flight results approved max L/D ratio is around 25 at the sea level. This flight performance is enough to outperform in glide ratio of Wandering albatrosses.Practical implicationsSailplanes are known as sport aircraft. However, recent projects focus on glider designs due to fuel efficiency and silent tracking. Stemme S-14 that carries a high-resolution camera is one of the examples of these projects. The unmanned glider design can lead to these implications in the UAVs at least during the stand-by period in the air. Thanks to low weight, UAVs do not require strong thermals, which allows flying almost all over the world.Originality/valueResearchers generally focus on increasing the battery capacity or the performance of the UAV. However, this study’s concentration is to increase the flight duration of the UAV by using geographical currents. For this purpose, taking advantage of bird morphology is quite a new topic. Also, glider type designs are rarely found in the field.

Colin James Pennycuick (1933–2019)

Colin James Pennycuick (1933–2019)

Limits to load-lifting performance in a passerine bird: the effects of intraspecific variation in morphological and kinematic parameters.

Although more massive flight muscles along with larger wings, higher wingbeat frequencies and greater stroke amplitudes enhance force and power production in flapping flight, the extent to which these parameters may be correlated with other morphological features relevant to flight physiology and biomechanics remains unclear. Intraspecifically, we hypothesized that greater vertical load-lifting capacity would correlate with higher wingbeat frequencies and relatively more massive flight muscles, along with relatively bigger hearts, lungs, and stomachs to enhance metabolic capacity and energy supply, but also with smaller body size given the overall negative allometric dependence of maximum flight performance in volant taxa. To explore intraspecific correlates of flight performance, we assembled a large dataset that included 13 morphological and kinematic variables for a non-migratory passerine, the Eurasian tree sparrow (Passer montanus). We found that heavier flight muscles and larger wings, heavier stomachs and shorter bills were the most important correlates of maximum load-lifting capacity. Surprisingly, wingbeat frequency, wing stroke amplitude and masses of the heart, lungs and digestive organs (except for the stomach) were non-significant predictor variables relative to lifting capacity. The best-fit structural equation model (SEM) indicated that load-lifting capacity was positively correlated with flight muscle mass, wing area and stomach mass, but was negatively correlated with bill length. Characterization of individual variability in flight performance in a free-ranging passerine indicates the subtlety of interaction effects among morphological features, some of which differ from those that have been identified interspecifically for maximum flight performance in birds.

Feather holes and flight performance in the barn swallow Hirundo rustica

ABSTRACTFeather holes are small (0.5–1 mm in diameter) deformities that appear on the vanes of flight feathers. Such deformities were found in many bird species, including galliforms and passerines. Holey flight feathers may be more permeable to air, which could have a negative effect on their ability to generate aerodynamic forces. However, to date the effects of feather holes on flight performance in birds remained unclear. In this study we investigated the relationship between the number of feather holes occurring in the wing or tail feathers and short term flight performance traits – aerial manoeuvrability, maximum velocity and maximum acceleration – in barns swallows, which are long distance migrating aerial foragers. We measured short-term flight performance of barn swallows in a standardized manner in flight tunnels. We found that acceleration and velocity were significantly negatively associated with the number of holes in the wing flight feathers, but not with those in the tail feathers. In the case of acceleration the negative relationship was sex specific – while acceleration significantly decreased with the number of feather holes in females, there was no such significant association in males. Manoeuvrability was not significantly associated with the number of feather holes. These results are consistent with the hypothesis that feather holes are costly in terms of impaired flight. We discuss alternative scenarios that could explain the observed relationships. We also suggest directions for future studies that could investigate the exact mechanism behind the negative association between the number of feather holes and flight characteristics.

Low level exposure to crude oil impacts avian flight performance: The Deepwater Horizon oil spill effect on migratory birds

In 2010, the Deepwater Horizon oil spill released 134 million gallons of crude oil into the Gulf of Mexico making it the largest oil spill in US history. The three month oil spill left tens of thousands of birds dead; however, the fate of tens of thousands of other migratory birds that were affected but did not immediately die is unknown. We used the homing pigeon as a surrogate species for migratory birds to investigate the effects of a single external oiling event on the flight performance of birds. Data from GPS data loggers revealed that lightly oiled pigeons took significantly longer to return home and spent more time stopped en route than unoiled birds. This suggests that migratory birds affected by the oil spill could have experienced long term flight impairment and delayed arrival to breeding, wintering, or crucial stopover sites and subsequently suffered reductions in survival and reproductive success.

Wind estimation based on thermal soaring of birds.

The flight performance of birds is strongly affected by the dynamic state of the atmosphere at the birds' locations. Studies of flight and its impact on the movement ecology of birds must consider the wind to help us understand aerodynamics and bird flight strategies. Here, we introduce a systematic approach to evaluate wind speed and direction from the high‐frequency GPS recordings from bird‐borne tags during thermalling flight. Our method assumes that a fixed horizontal mean wind speed during a short (18 seconds, 19 GPS fixes) flight segment with a constant turn angle along a closed loop, characteristic of thermalling flight, will generate a fixed drift for each consequent location. We use a maximum‐likelihood approach to estimate that drift and to determine the wind and airspeeds at the birds' flight locations. We also provide error estimates for these GPS‐derived wind speed estimates. We validate our approach by comparing its wind estimates with the mid‐resolution weather reanalysis data from ECMWF, and by examining independent wind estimates from pairs of birds in a large dataset of GPS‐tagged migrating storks that were flying in close proximity. Our approach provides accurate and unbiased observations of wind speed and additional detailed information on vertical winds and uplift structure. These precise measurements are otherwise rare and hard to obtain and will broaden our understanding of atmospheric conditions, flight aerodynamics, and bird flight strategies. With an increasing number of GPS‐tracked animals, we may soon be able to use birds to inform us about the atmosphere they are flying through and thus improve future ecological and environmental studies.

An Inexpensive and Mobile See-Through Tunnel for Collecting Bird Flight Performance Data in the Field

ABSTRACT Flight performance data for flying animals are valuable for estimating energetic budgets and may be necessary for testing hypotheses of optimal foraging, predator-prey response, and physiological demand. However, measuring the flight performance of birds, particularly in the field, may be expensive and time consuming. Additionally, depending on the level of biological scale or the particular research question, apparatuses such as laboratory-bound wind tunnels may be inappropriate. We offer a see-through tent as an inexpensive alternative for certain situations where the goal is simply to constrain the flight path of a bird for videography. Data on acceleration and morphology were sampled from birds in an old-field habitat in central Pennsylvania, USA and demonstrate the utility of the apparatus.

Qualitative skeletal correlates of wing shape in extant birds (Aves: Neoaves).

BackgroundAmong living fliers (birds, bats, and insects), birds display relatively high aspect ratios, a dimensionless shape variable that distinguishes long and narrow vs. short and broad wings. Increasing aspect ratio results in a functional tradeoff between low induced drag (efficient cruise) and increased wing inertia (difficult takeoff). Given the wide scope of its functional effects, the pattern of aspect ratio evolution is an important factor that contributes to the substantial ecological and phylogenetic diversity of living birds. However, because the feathers that define the wingtip (and hence wingspan and aspect ratio) often do not fossilize, resolution in the pattern of avian wing shape evolution is obscured by missing information. Here I use a comparative approach to investigate the relationship between skeletal proxies of flight feather attachment and wing shape.ResultsAn accessory lobe of the internal index process of digit II-1, a bony correlate of distal primary attachment, shows weak but statistically significant relationships to aspect ratio and mass independent of other skeletal morphology. The dorsal phalangeal fossae of digit II-1, which house distal primaries VIII and IX, also show a trend of increased prominence with higher aspect ratio. Quill knobs on the ulna are examined concurrently, but do not show consistent signal with respect to wing shape.ConclusionsAlthough quill knobs are cited as skeletal correlates of flight performance in birds, their relationship to wing shape is inconsistent among extant taxa, and may reflect diverging selection pressures acting on a conserved architecture. In contrast, correlates of distal primary feather attachment on the major digit show convergent responses to increasing aspect ratio. In light of the diversity of musculoskeletal and integumentary mophology that underlies wing shape in different avian clades, it is unlikely that a single skeletal feature will show consistent predictive power across Neoaves. Confident inference of wing shape in basal ornithurine birds will require multiple lines of evidence, together with an understanding of clade-specific evolutionary trends within the crown.Electronic supplementary materialThe online version of this article (doi:10.1186/s12862-015-0303-7) contains supplementary material, which is available to authorized users.

Early life disadvantage strengthens flight performance trade-offs in European starlings, Sturnus vulgaris

Developmental stress has been shown to affect adult flight performance in birds, with both negative and positive effects reported in the literature. Previous studies have used developmental manipulations that had substantial effects on patterns of growth. They have also examined mean levels of flight performance per individual, rather than investigating how developmental stress might alter trade-offs between different components of flight performance. We recorded multiple components of escape flight performance in 20 adult European starlings previously subjected to a manipulation likely to have altered levels of developmental stress. Siblings had been cross-fostered to nests where they were either slightly larger (advantaged treatment) or slightly smaller (disadvantaged treatment) than their competitors. The manipulation had no detectable effect on growth. However, developmental treatment affected performance in escape flights a year later by strengthening the trade-offs between different flight parameters. Disadvantaged birds faced a steeper trade-off between take-off speed and take-off angle, and a steeper trade-off between take-off angle and total time in flight, than advantaged birds. The results suggest that even subtle early life adversity that has no obvious effect on growth or size can leave a lasting legacy in the form of constraints on locomotor performance later in life.

The mechanics and behavior of cliff swallows during tandem flights.

Cliff swallows (Petrochelidon pyrrhonota) are highly maneuverable social birds that often forage and fly in large open spaces. Here we used multi-camera videography to measure the three-dimensional kinematics of their natural flight maneuvers in the field. Specifically, we collected data on tandem flights, defined as two birds maneuvering together. These data permit us to evaluate several hypotheses on the high-speed maneuvering flight performance of birds. We found that high-speed turns are roll-based, but that the magnitude of the centripetal force created in typical maneuvers varied only slightly with flight speed, typically reaching a peak of ~2 body weights. Turning maneuvers typically involved active flapping rather than gliding. In tandem flights the following bird copied the flight path and wingbeat frequency (~12.3 Hz) of the lead bird while maintaining position slightly above the leader. The lead bird turned in a direction away from the lateral position of the following bird 65% of the time on average. Tandem flights vary widely in instantaneous speed (1.0 to 15.6 m s(-1)) and duration (0.72 to 4.71 s), and no single tracking strategy appeared to explain the course taken by the following bird.

Comparing Aerodynamic Efficiency in Birds and Bats Suggests Better Flight Performance in Birds

Flight is one of the energetically most costly activities in the animal kingdom, suggesting that natural selection should work to optimize flight performance. The similar size and flight speed of birds and bats may therefore suggest convergent aerodynamic performance; alternatively, flight performance could be restricted by phylogenetic constraints. We test which of these scenarios fit to two measures of aerodynamic flight efficiency in two passerine bird species and two New World leaf-nosed bat species. Using time-resolved particle image velocimetry measurements of the wake of the animals flying in a wind tunnel, we derived the span efficiency, a metric for the efficiency of generating lift, and the lift-to-drag ratio, a metric for mechanical energetic flight efficiency. We show that the birds significantly outperform the bats in both metrics, which we ascribe to variation in aerodynamic function of body and wing upstroke: Bird bodies generated relatively more lift than bat bodies, resulting in a more uniform spanwise lift distribution and higher span efficiency. A likely explanation would be that the bat ears and nose leaf, associated with echolocation, disturb the flow over the body. During the upstroke, the birds retract their wings to make them aerodynamically inactive, while the membranous bat wings generate thrust and negative lift. Despite the differences in performance, the wake morphology of both birds and bats resemble the optimal wake for their respective lift-to-drag ratio regimes. This suggests that evolution has optimized performance relative to the respective conditions of birds and bats, but that maximum performance is possibly limited by phylogenetic constraints. Although ecological differences between birds and bats are subjected to many conspiring variables, the different aerodynamic flight efficiency for the bird and bat species studied here may help explain why birds typically fly faster, migrate more frequently and migrate longer distances than bats.

HIGH-FLYING HUMMINGBIRDS BURST TO BEAT COMPETITORS

Locomotory behaviour and performance has long been assumed to be the key factor in determining the outcome of competition between animals for resources. However, empirical data to support this hypothesis has proved challenging to collect. In a recent publication in The American Naturalist,Douglas Altshuler sought to experimentally test the hypothesis that flight performance influences both territoriality, and success when competing for niches, by comparing the flight behaviour of several hummingbird species over a range of altitudes.Although simple measurements of wing disc loading in flying birds had previously been used to approximate the bird's flight performance, Altshuler instead used more complex aerodynamic theory to calculate more realistically the costs of flight. Altshuler also filmed the birds at different altitudes in the wild, and under low-pressure conditions in the lab, to identify their flight kinematics. Finally, Altshuler calculated the power requirements for flight, particularly in relation to maximal or `burst' power, as well as recording features of territorial behaviour during field observations.Travelling to the Andes and Colorado, Altshuler studied hummingbird flight in three experiments. First, he compared territorial behaviour of hummingbird species in the mountains from 400-3860 m and found that wing disc loading had no effect on territoriality, but burst power did. Territorial hummingbird species had higher burst aerodynamic power outputs than not-territorial species. Second, he studied two species of Selasphorus hummingbirds competing for access to nectar at 1875 and 2900 m. At the lower altitude, S. rufus males appeared to have a competitive advantage over S. platycerus males, but the roles were reversed as altitude increased. S. rufus had relatively lower burst power output and Altshuler found important difference in hovering kinematics between the two species of hummingbirds. Altshuler's measurements showed that S. rufus males used higher stroke angles when hovering and this constrained their ability to modulate aerodynamic force production when compared with S. platycerus. Tempting the hummingbirds with high-quality feeders (sucrose solutions) revealed that not only did altitude affect the way in which the hummingbirds selected feeding sites, but that the density of competitors for feeders also effected the bird's choice. The final component of the study involved laboratory studies of flight performance under high and low pressure conditions. Both species increased power output to compensate for lower air density.Altshuler's study has provided several intriguing insights into both the mechanical requirements for flight of territorial birds and the influence of environment on competitive interactions. The ability to produce bursts of power appears to be a pre-requisite for successful competitive outcomes at higher altitudes; however, at lower altitudes other flight parameters (such as manoeuvrability) can improve a hummingbird's advantage. Clearly, physiological and aerodynamic limitations become more important as oxygen availability and air density decline with increasing altitude. This study has shown how a bird's flight performance, and a bird's ability to modulate it, can affect its ability to compete with other species for resources.

Circulatory variables and the flight performance of birds

When considering the 'burst' flight performance of birds, such as during take-off, one of the most important structural variables is the ratio of the mass of the flight muscle myofibrils with respect to body mass. However, when considering 'prolonged' flight performance the variable of interest should be the body mass ratio of the mass of the flight muscle myofibrils that can be perfused sustainably with metabolites via the blood supply. The latter variable should be related to blood flow (ml min(-1)), which in turn has been shown to be a function of heart muscle mass, the value of which is more easily obtainable for different species than that for the mass of perfused muscle. The limited empirical evidence available suggests that for birds and mammals the rate of maximum oxygen consumption scales with heart mass (Mh) as Mh 0.88 and that for birds Mh scales with body mass (Mb) as Mb 0.92, leading to the conclusion that the rate of maximum oxygen consumption in birds scales with an exponent of around Mb 0.82. A similar exponent would be expected for the rate of maximum oxygen consumption with respect to the flight muscle mass of birds. This suggests that the sustainable power output from the flight muscles may ultimately be limiting the flight performance of very large flying animals, but as a result of circulatory constraints rather than biomechanical considerations of the flight muscles per se. Under the particular circumstances of sustainable flight performance, calculations of rates of metabolic energy consumed by the flight muscles can be compared directly with the estimates of biomechanical power output required, as calculated using various aerodynamic models. The difference between these calculated values for rates of energy input and output from the muscles is equivalent to the 'apparent' mechanochemical conversion efficiency. The results of one such analysis, of the maximum sustainable flight performance of migratory birds, leads to the conclusion that the efficiency of the flight muscles appears to scale as Mb 0.14. However, much of this apparent scaling may be an artefact of the application and assumptions of the models. The resolution of this issue is only likely to come from studying bird species at either extreme of the size range.

Versatility from a Single Song: The Case of the Nightingale Wren

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Gone with the Wind? A Comment on Butler et al. (1997)

Because wind speed and flight speed of migratory birds generally are of the same magnitude, wind direction has a significant effect on the ground speed of birds. Consequently, migrants should prefer days of favorable tailwinds for commencing migratory flights, or at least they should avoid strong headwinds. These predictions generally are the case as revealed by radar studies (Richardson 1990). Based on estimated flight costs of shorebirds, Butler et al. (1997) concluded that tailwinds are necessary for successful spring migration of Western Sandpipers (Calidris mauri). Butler et al. (1997) proposed that the migration strategy for Western Sandpipers consists of maintaining relatively large fuel reserves and departing on migratory flights when tailwinds are present. This strategy was put forth as an alternative to the strategy of time minimization of migration (sensu Alerstam and Lindstrom 1990). We think it is premature to reject time minimization as a migration strategy for Western Sandpiper on the basis of the data presented by Butler et al. (1997), and we outline our arguments below. First, we show that new information concerning the aerodynamic drag of bird bodies indicates that Western Sandpipers may complete their spring migration without wind assistance. Next, we provide a critical discussion of the assumptions, methods, and conclusions put forward by Butler et al. (1997). Flight costs: They can do it.-Butler et al. (1997) calculated that when using Pennycuick's (1989) model of bird flight performance, the arrival mass will be 17.5 g for a male Western Sandpiper in the absence of wind assistance. Two amendments to the theory of bird flight may change this conclusion. First, the default value for the body-drag coefficient (Cpar), which determines the magnitude of parasite drag (i.e. drag of the body), has been overestimated previously. The old default value (Cpar= 0.4) was based on measurements using frozen bird bodies in a wind tunnel (Pennycuick et al. 1988), although the experiments were suspected to overestimate Cpar. Based on new wind-tunnel experiments on live birds, Pennycuick et al. (1996) found that CP,, is much lower than previously measured on frozen birds, and they rec-

Are Rooster Crows Honest Signals of Fighting Ability?

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THE USE AND MISUSE OF MATHEMATICAL FLIGHT MODELS

ABSTRACT There are two types of mathematical flight models. A particular model is constructed by an observer or experimenter to describe observations of a particular animal in particular circumstances, and may include any amount of detail about wing kinematics, vortex wake structure, etc., provided that such details have been observed. The detailed results apply only to the particular animal observed. A general model attempts to predict certain aspects of performance for any flying animal, based on estimates of body mass, wingspan, wing area, and very little else. This calls for simplified methods of calculation. It is not possible to improve the accuracy by introducing additional details, because such details are unknown for most species. Confidence in the predictions of a general model depends on feeding back field observations, and trying to eliminate discrepancies by adjusting variables whose values are only roughly known or guessed. The computer programs by Pennycuick (1989b, Bird Flight Performance,...

Bird flight performance: a practical calculation manual

Bird flight performance: a practical calculation manual

The Taxonomic Status of the Small Ground-Finch, Geospiza (Aves: Emberizidae) of Genovesa Island, Galápagos, and Its Relevance to Interspecific Competition

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