Predator versus prey: on aerial hunting and escape strategies in birds

Predator and prey attack-escape performance is likely to bethe outcome of an evolutionary arms race. Predatory birds aretypically larger than their prey, suggesting different flightperformances. We analyze three idealized attack-escape situationsbetween predatory and prey birds: climbing flight escape, horizontalspeeding, and turning and escape by diving. Generally a smallerbird will outclimb a larger predator and hence outclimbing shouldbe a common escape strategy. However, some predators such asthe Eleonora's falcon (Falco elenorae) has a very high rateof climb for its size. Prey species with an equal or highercapacity to climb fast, such as the swift Apus apus, usuallyadopt climbing escape when attacked by Eleonora's falcons.To analyze the outcome of the turning gambit between predatorand prey we use a Howland diagram, where the relative lineartop speeds and minimum turning radii of prey and predator definethe escape and danger zones. Applied to the Eleonora's falconand some potential prey species, this analysis indicates thatthe falcon usually wins against the example prey species; thatis, the prey will be captured. Level maneuvering hunting isthe most common strategy seen in Eleonora's falcons. To avoidcapture via use of this strategy by a predator, the prey shouldbe able to initiate tight turns at high linear speed, whichis facilitated by a low wing loading (weight per unit of wingarea). High diving speed is favored by large size. If close enough to safe cover, a prey might still opt for a verticaldive to escape in spite of lower terminal diving speed thanthat of the predator. On the basis of aerodynamic considerationswe discuss escape flight strategies in birds in relation tomorphological adaptations.     

Skylark optimal flight speeds for flying nowhere and somewhere

Flight is energetically very costly. For birds the mechanicalpower in relation to airspeed is characterized by a U-shapedfunction. From this function we can derive optimal flight speedsassociated with minimum power (V_mp), minimum cost of transport(V_mr) and minimum overall time of migration (V_mt). Since flightis energetically so costly, aerial displays and song flightcan potentially serve as signals reliably indicating the individualquality or resource potential of the signaler. In order to maximizethe amount of song flight produced, we expect V_mp during songflight, while during migration we rather expect V_mr or V_mv Wecompared flight speeds of skylarks (Alauda arvensis) duringsong flight and migration flight, respectively. In this speciespredicted V_mp = 5.5 m/s, V_mr = 10.5 m/s, and V_mt = 12.1 m/s.The preferred airspeed during song flight did not differ significantlyfrom the predicted V_mp, while airspeed during migration wassignificantly higher than V_mr and Vmp indicating that flightspeed is a flexible trait that birds adjust to different situations.Why the skylarks speed up so much on migration is still unclear,but it may be that due to the shape of the predicted power curve,variation in cost of transport at high speeds is relativelysmall.     

Gravity-defying Behaviors: Identifying Models for Protoaves

Most current phylogenetic hypotheses based upon cladistic methodologyassert that birds are the direct descendants of derived maniraptorantheropod dinosaurs, and that the origin of avian flight necessarilydeveloped within a terrestrial context (i.e., from the "groundup"). Most theoretical aerodynamic and energetic models or chronologicallyappropriate fossil data do not support these hypotheses forthe evolution of powered flight. The more traditional modelfor the origin of flight derives birds from among small arborealearly Mesozoic archosaurs ("thecodonts"). According to thismodel, protoavian ancestors developed flight in the trees viaa series of intermediate stages, such as leaping, parachuting,gliding, and flapping. This model benefits from the assemblageof living and extinct arboreal vertebrates that engage in analogousnon-powered aerial activities using elevation as a source ofgravitational energy. Recent reports of "feathered theropods"notwithstanding, the evolution of birds from any known groupof maniraptoran theropods remains equivocal.     

Risk taking by singing males

The distance at which an individual flees from a potential predatorrepresents a measure of risk taking. If individuals are engagedin another activity that might affect fitness, trade-offs betweenthe fitness benefits of flight and the other activity shoulddetermine the nearest distance of approach by a predator. Ina comparative analysis of birds, flight distance representeda reliable measure of risk of predation by the sparrowhawk Accipiternisus that increased with decreasing flight distance acrossspecies. To test the hypothesis that singing males adjustedtheir risk taking to the costs and benefits of early flight,we compared the flight distance of singing and nonsinging birdsto an approaching human observing with a binocular. Singingbirds on average fled at a greater distance than nonsingingbirds, implying that singing birds took small risks. We useda standardized measure of difference in flight distance betweensinging and nonsinging individuals to investigate factors affectinginterspecific variation in risk taking. Species that used moreexposed song posts (sites used for singing) took smaller risksthan species with less exposed song posts. Species that sufferedfrom higher levels of parasitism as reflected by the prevalenceof Plasmodium, but not by 3 other genera of blood parasites,took greater risks during singing compared with nonsinging activities.Likewise, species with high circulating levels of natural antibodies,and hence a history of natural selection caused by bacteriatook relatively greater risks during singing than species withfew natural antibodies. These findings suggest that risks takenby singing birds have been molded by natural and sexual selection,and that risk taking represents a compromise between the costsand benefits of flight from a potential predator.     

Functional osteology of the avian wrist and the evolution of flapping flight

The avian wrist is extraordinarily adapted for flight. Its intricate osteology is constructed to perform four very different, but extremely important, flight-related functions. (1) Throughout the downstroke, the cuneiform transmits force from the carpometacarpus to the ulna and prevents the manus from hyperpronating. (2) While gliding or maneuvering, the scapholunar interlocks with the carpometacarpus and prevents the manus from supinating. By employing both carpal bones simultaneously birds can lock the manus into place during flight. (3) Throughout the downstroke-upstroke transition, the articular ridge on the distal extremity of the ulna, in conjuction with the cuneiform, guides the manus from the plane of the wing toward the body. (4) During take-off or landing, the upstroke of some heavy birds exhibits a pronounced flick of the manus. The backward component of this flick is produced by reversing the wrist mechanism that enables the manus to rotate toward the body during the early upstroke. The upward component of the flick is generated by mechanical interplay between the ventral ramus of the cuneiform, the ventral ridge of the carpometacarpus, and the ulnocarpo-metacarpal ligament. Without the highly specialized osteology of the wrist it is doubtful that birds would be able to carry out successfully the wing motions associated with flapping flight. Yet in Archaeopteryx, the wrist displays a very different morphology that lacks all the key features found in the modern avian wrist. Therefore, Archaeopteryx was probably incapable of executing the kinematics of modern avian powered flight.     

How Lovebirds Maneuver Rapidly Using Super-Fast Head Saccades and Image Feature Stabilization

Diurnal flying animals such as birds depend primarily on vision to coordinate their flight path during goal-directed flight tasks. To extract the spatial structure of the surrounding environment, birds are thought to use retinal image motion (optical flow) that is primarily induced by motion of their head. It is unclear what gaze behaviors birds perform to support visuomotor control during rapid maneuvering flight in which they continuously switch between flight modes. To analyze this, we measured the gaze behavior of rapidly turning lovebirds in a goal-directed task: take-off and fly away from a perch, turn on a dime, and fly back and land on the same perch. High-speed flight recordings revealed that rapidly turning lovebirds perform a remarkable stereotypical gaze behavior with peak saccadic head turns up to 2700 degrees per second, as fast as insects, enabled by fast neck muscles. In between saccades, gaze orientation is held constant. By comparing saccade and wingbeat phase, we find that these super-fast saccades are coordinated with the downstroke when the lateral visual field is occluded by the wings. Lovebirds thus maximize visual perception by overlying behaviors that impair vision, which helps coordinate maneuvers. Before the turn, lovebirds keep a high contrast edge in their visual midline. Similarly, before landing, the lovebirds stabilize the center of the perch in their visual midline. The perch on which the birds land swings, like a branch in the wind, and we find that retinal size of the perch is the most parsimonious visual cue to initiate landing. Our observations show that rapidly maneuvering birds use precisely timed stereotypic gaze behaviors consisting of rapid head turns and frontal feature stabilization, which facilitates optical flow based flight control. Similar gaze behaviors have been reported for visually navigating humans. This finding can inspire more effective vision-based autopilots for drones.     

Great tits (Parus major) reduce body mass in response to wing area reduction: a field experiment

Flight performance is crucial in determining whether a smallbird will survive an attack by a predator. Given the importanceof body mass in determining flight performance, it has beensuggested that birds should strategically regulate body massas a response to predation risk. However, all experiments upto now have been carried out with captive birds, comparing experimental to control birds. Here we present data from thefirst experiment in the field using a within-individuals experimentaldesign. The wing area of wild great tits, Parus major, wasreduced by reversibly taping primaries five to seven. Thisallowed for the same individual to alternatively act as controlor experimental bird. Great tits reduced body mass (but not pectoral muscle width) during episodes of wing area reduction,lending support to the view that the reduction in body massexperienced by birds during molt is a strategy rather thanthe result of energetic stress. Theoretical models establishingthe different trade-offs that determine optimal body mass should therefore take into account this important life-history episode.     

Aerodynamics and Energetics of Intermittent Flight in Birds

Hypotheses explaining the use of intermittent bounding and undulatingflight modes in birds are considered. Existing theoretical modelsof intermittent flight have assumed that the animal flies ata constant speed throughout. They predict that mean mechanicalpower in undulating (flap-gliding) flight is reduced comparedto steady flight over a broad range of speeds, but is reducedin bounding flight only at very high flight speeds. Lift generatedby the bird's body or tail has a small effect on power, butis insufficient to explain observations of bounding at intermediateflight speeds. Measurements on starlings Sturnus vulgaris inundulating flight in a wind tunnel show that flight speed variesby around ±1 m/sec during a flap-glide cycle. Dynamicenergy is used to quantify flight performance, and reveals thatthe geometry of the flight path depends upon wingbeat kinematics,and that neither flapping nor gliding phases are at constantspeed and angle to the horizontal. The bird gains both kineticand potential energy during the flapping phases. A new theoreticalmodel indicates that such speed variation can give significantsavings in mechanical power in both bounding and undulatingflight. Alternative hypotheses for intermittent flight includea gearing mechanism, based on duty factor, mediating musclepower or force output against aerodynamic requirements. Thiscould explain the use of bounding flight in hovering and climbingin small passerines. Both bounding and undulating confer otheradaptive benefits; undulating may be primitive in birds, butbounding may have evolved in response to flight performanceoptimization, or to factors such as unpredictability in responseto predation.     

Prognostic evaluation of spinal microlesions under exposure of longitudinal blow accelerations of prolonged action

The performed experimental investigations were aimed at qualitative and approximate quantitative estimation of parameters of cumulated microtraumatic destructions in spine, leading to its lowered bearing capabilities under prolonged loading with compressing exposures corresponding to high levelled maneuverable accelerations, which exceed 5 G and onset rates 10 G/s and more. Process of microlesions in bone tissues of vertebral bodies at this range of accelerations is not still sufficiently studied. Practical importance of these effects has close relation as to problem of high intensity flight maneuvering accelerations with onset rates up to 10 G/s and higher as well as to estimation if impact acceleration tolerance in ejection event with controllable flightpath of kicked out capatult seat. The data, received in natural experiments on spinal segments T11-L3 with fixation of acoustical emission signals (AES), suggest that stage of minor lesion of vertebral bodies (the first degree of severity), characterizing by avalanche-like increment of acoustical emission signals and starting point of specific crack in loading flow chart, may be pertained as having fragile character.     

Field Flight Dynamics of Hummingbirds during Territory Encroachment and Defense

Hummingbirds are known to defend food resources such as nectar sources from encroachment by competitors (including conspecifics). These competitive intraspecific interactions provide an opportunity to quantify the biomechanics of hummingbird flight performance during ecologically relevant natural behavior. We recorded the three-dimensional flight trajectories of Ruby-throated Hummingbirds defending, being chased from and freely departing from a feeder. These trajectories allowed us to compare natural flight performance to earlier laboratory measurements of maximum flight speed, aerodynamic force generation and power estimates. During field observation, hummingbirds rarely approached the maximal flight speeds previously reported from wind tunnel tests and never did so during level flight. However, the accelerations and rates of change in kinetic and potential energy we recorded indicate that these hummingbirds likely operated near the maximum of their flight force and metabolic power capabilities during these competitive interactions. Furthermore, although birds departing from the feeder while chased did so faster than freely-departing birds, these speed gains were accomplished by modulating kinetic and potential energy gains (or losses) rather than increasing overall power output, essentially trading altitude for speed during their evasive maneuver. Finally, the trajectories of defending birds were directed toward the position of the encroaching bird rather than the feeder.     

Energetic bottlenecks and other design constraints in avian annual cycles

The flexible phenotypes of birds and mammals often appear torepresent adjustments to alleviate some energetic bottleneckor another. By increasing the size of the organs involved indigestion and assimilation of nutrients (gut and liver), anindividual bird can increase its ability to process nutrients,for example to quickly store fuel for onward flight. Similarly,an increase in the exercise organs (pectoral muscles and heart)enables a bird to increase its metabolic power for sustainedflight or for thermoregulation. Reflecting the stationary costof organ maintenance, changes in the size of any part of the"metabolic machinery" will be reflected in Basal Metabolic Rate(BMR) unless changes in metabolic intensity also occur. Energeticbottlenecks appear to be set by the marginal value of organsize increases relative to particular peak requirements (includingsafety factors). These points are elaborated using the studieson long-distance migrating shorebirds, especially red knotsCalidris canutus. Red knots encounter energy expenditure levelssimilar to experimentally determined ceiling levels of ca. 5times BMR in other birds and mammals, both during the breedingseason on High Arctic tundra (probably mainly a function ofcosts of thermoregulation) and during winter in temperate coastalwetlands (a function of the high costs of processing mollusks,prey poor in nutrients but rich in shell material and salt water).During migration, red knots phenotypically alternate betweena "fueling [life-cycle] stage" and a "flight stage." Fuelingred knots in tropical areas may encounter heat load problemswhilst still on the ground, but high flight altitudes duringmigratory flights seem to take care of overheating and unacceptablyhigh rates of evaporative water loss. The allocation principlesfor the flexible phenotypes of red knots and other birds, thecosts of their organ flexibility and the ways in which they"organize" all the fast phenotypic changes, are yet to be discovered.     

How swift are swifts Apus apus?

Swifts Apus apus are renowned for their fast flight manner which has fascinated people in all times. However, previous studies of swifts in flight during migration and roosting flights have shown that the birds operate over a narrow range of flight speeds compared with most other birds studied. In this study we have focused on the special flight behavior often called 'screaming parties'. During these flights the birds appear to reach very high speeds and therefore we used a stereo high speed camera setup to measure the flight speeds of the birds during this behavior with high accuracy. The birds were found to fly at much higher speeds during 'screaming parties' than during migration or roosting, on average twice as fast, 20.9  ms⁻¹ (±5.1  ms⁻¹) in horizontal speed. The highest record was 31.1  ms⁻¹ which is the highest measured yet for a swift in self powered flight. Furthermore, the birds were performing steep climbing flights, on average 4.0  ms⁻¹ (±2.8  ms⁻¹) in vertical velocity. A clear trade-off between horizontal speed and vertical speed was found, suggesting that the birds are operating at their maximum.     

Optimal flight behavior of soaring migrants: a case study of migrating steppe buzzards, Buteo buteo vulpinus

This article presents tests of the theoretical predictions onoptimal soaring and gliding flight of large, diurnal migrantsusing Pennycuick's program 2 for "bird flight performance."Predictions were compared with 141 observed flight paths ofmigrating steppe buzzards, Buteo buteo vulpinus. Calculationsof cross-country speed relative to the air included bird's airspeedsand sinking rates in interthermal gliding and climbing ratesin thermal circling. Steppe buzzards adjusted interthermal glidingairspeed . according to their actual climbing rate in thermalcircling. By optimizing their gliding airspeed, the birds maximizedtheir crosscountry performance relative to the air. Despitethis general agreement with the model, there was much scatterin the data, for the model neglects horizontal winds and updraftsduring the gliding phase. Lower sinking rates due to updraftsduring the gliding phases allowed many birds to achieve highercross-country speeds than predicted. In addition, birds reactedto different wind directions and speeds: in side and opposingwinds, the steppe buzzards compensated for wind displacementduring soaring and increased their gliding airspeed with decreasingtailwind component Nevenheless, cross-country speed relativeto the ground, which is the important measure for a migratorybird, was still higher under following winds. This study showsthat Pennycuick's program 2 provides reliable predictions onoptimal soaring and gliding behavior using realistic assumptionsand constants in the model, but a great deal of variation aroundthe mean is generated by factors not included in the model     

美洲斑潜蝇在不同温度下的飞行能力

利用昆虫飞行磨测试了美洲斑潜蝇Liriomyza sativae在18℃到36℃条件下的飞行能力。结果表明：在33℃下美洲斑潜蝇的飞行能力最强,个体最大飞行距离、最高飞行速度和最长飞行时间分别为8.22 km、1.10 km/h和253.50 min,其平均飞行距离为0.95 km。其飞行的适温范围是21～36℃,18℃为其飞行的下限温度。从18～33℃,随着温度的升高平均飞行距离（0.08～0.95 km）和平均飞行时间(6.57～47.94 min)也在增加,但到36℃又开始下降;雌虫比雄虫飞行能力强。在理论上,美洲斑潜蝇能靠自身飞行扩散0.08～0.95 km。     

Sexual differences in tailwind drift compensation in Phoebis sennae butterflies (Lepidoptera: Pieridae) migrating over seas

One prediction derived from optimal migration theory is thatmigrating animals that maximize their flight distance on agiven amount of energy will decrease their airspeed in a tailwindand increase it in a headwind. To test this in a migratingbutterfly, I followed male and female cloudless sulfur butterfliesPhoebis sennae (Pieridae) migrating from Colombia toward Panamaover the Caribbean Sea. P. sennae headed westerly over the Caribbean Sea in the morning and then turned southeasterly tohead downwind in the afternoon. Changes in heading and trackdirections of P. sennae were not related to changes in theposition of the solar azimuth. As predicted from optimal migrationtheory, flight velocities of females decreased in a tailwindto minimize energy consumption. However, males did not showany compensation for tailwinds. Females are minimizing energyconsumption, whereas males may be minimizing the time to reachthe destination site in order to maximize matings with newlyarrived or newly emerged females. Orientation of females changedbefore that of males, presumably because their greater reproductiveload imposed greater flight costs and limited flight fuels.     

Butterfly contests and flight physiology: why do older males fight harder?

The males of many butterfly species compete for territoriesvia conspicuous aerial wars of attrition, in which the determinantsof persistence ability are largely unclear. Flight performancefeatures, such as stamina, acceleration, and maneuverability,are often assumed to be important in this context, yet thereis no direct evidence by which to evaluate these possibilities.Recent research has indicated that competitive ability increaseswith age in a notably territorial species, Hypolimnas bolina,which could arise from lifetime morphological or physiologicalchanges that directly affect flight performance. I evaluatedthis hypothesis by investigating how size-independent variancein body composition, energy stores, flight muscle ratio (FMR),and wing condition change with age in this species. Males infive age categories (spanning the functional life span of territorialindividuals) were sampled from encounter sites in tropicalAustralia. Analysis of body composition with respect to anestimate of eclosion mass (forewing length) indicated thattotal body mass, abdomen mass, and wing area decrease throughoutan individual's lifetime, but thorax mass remains unchanged.Wing loading (the ratio of wing area to body mass) is lowestin intermediately aged individuals, but FMR and energetic statusremain largely similar regardless of age. On average, therefore,the energetic cost of sustained flight should first decrease,then increase, with age in a male H. bolina (of standardizedbody size), while available energy reserves decline slightly. Acceleration and maneuverability should remain relatively constant.These results, coupled with the fact that body size is unrelatedto contest success in this territorial butterfly, fail to supportthe idea that age-related competitive ability is mediated simplyby energetics or flight performance.     

Maneuvering and stability performance of a robotic tuna

The Draper Laboratory Vorticity Control Unmanned Undersea Vehicle(VCUUV) is the first mission-scale, autonomous underwater vehiclethat uses vorticity control propulsion and maneuvering. Builtas a research platform with which to study the energetics andmaneuvering performance of fish-swimming propulsion, the VCUUVis a self-contained free swimming research vehicle which followsthe morphology and kinematics of a yellowfin tuna. The forwardhalf of the vehicle is comprised of a rigid hull which housesbatteries, electronics, ballast and hydraulic power unit. Theaft section is a freely flooded articulated robot tail whichis terminated with a lunate caudal fin. Utilizing experimentallyoptimized body and tail kinematics from the MIT RoboTuna, theVCUUV has demonstrated stable steady swimming speeds up to 1.2m/sec and aggressive maneuvering trajectories with turning ratesup to 75 degrees per second. This paper summarizes the vehiclemaneuvering and stability performance observed in field trialsand compares the results to predicted performance using theoreticaland empirical techniques.     

A hassle a day may keep the doctor away: stress and the augmentation of immune function

Stress may be defined as a sequence of events, that begins witha stimulus (stressor), that is recognized by the brain (stressperception), and which results in the activation of physiologicfight/flight/fright systems within the body (stress response).Many evolutionary selection pressures are stressors, and oneof the primary functions of the brain is to perceive stress,warn the body of danger, and enable an organism to respond.We hypothesized that under acute conditions, just as the stressresponse prepares the cardiovascular and musculoskeletal systemsfor fight or flight, it may also prepare the immune system forchallenges (e.g., wounding) which may be imposed by a stressor(e.g., an aggressor). Initial studies showed that acute (2h)stress induced a significant trafficking of immune cells tothe skin. Since the skin is an organism's major protective barrier,we hypothesized that this leukocyte redistribution may serveto enhance skin immunity during acute stress. We tested thishypothesis using the delayed type hypersensitivity (DTH) reaction,which mediates resistance to various infectious agents, as amodel for skin immune function. Acute stress administered immediatelybefore antigen exposure significantly enhanced skin DTH. Adrenalectomy(ADX) eliminated the stress-induced enhancement of DTH whileadministration of physiological doses of corticosterone and/orepinephrine to ADX animals enhanced skin DTH in the absenceof stress. These studies showed that changes in leukocyte distributionand circulating stress hormones are systemic mediators of theimmunoenhancing effects of acute stress. We recently identifiedgamma interferon as a local cytokine mediator of a stress-inducedimmunoenhancement. Our results suggest that during acute stressthe brain sends preparatory warning signals to the immune systemjust as it does to other fight/flight systems of the body.     

南京地区棉蚜的飞行活动节律及其飞行能力

昆虫的飞行活动规律及飞行能力是研究其能否迁飞的基础。通过采用春季到秋季20 m高空黄盆诱蚜、高空所诱蚜和春季木槿树上有翅蚜的卵巢解剖,以及春夏秋三季田间有翅蚜的吊飞试验等方法,研究了南京地区棉蚜Aphis gossypii的飞行活动节律和飞行能力。结果表明,有翅棉蚜的日羽化高峰出现在19:00～20:00。2001年南京地区棉蚜的春、秋两季迁飞高峰分别在5月8日和10月25日。5月份高空诱集的棉蚜中,95.7%个体的卵巢小管数在7条以下,而木槿上羽化后1天的有翅蚜中有35.2%个体的卵巢小管数在7条以上;高空诱蚜和木槿上蚜的平均卵巢小管数存在极显著差异,分别为3.94±1.65和5.88±1.92。8月中下旬棉田棉蚜存在低空飞行行为,并且出现飞行高峰时有翅蚜的卵巢小管数平均在6条以下,超过6条则停止飞行。羽化后1～2天有翅棉蚜吊飞个体的飞行比率和平均飞行距离表现为春、秋季显著大于夏季,三季的最长飞行距离分别为3.89 km、6.15 km和1.44 km。     

Kinematic compensation for wing loss in flying damselflies

Flying insects can tolerate substantial wing wear before their ability to fly is entirely compromised. In order to keep flying with damaged wings, the entire flight apparatus needs to adjust its action to compensate for the reduced aerodynamic force and to balance the asymmetries in area and shape of the damaged wings. While several studies have shown that damaged wings change their flapping kinematics in response to partial loss of wing area, it is unclear how, in insects with four separate wings, the remaining three wings compensate for the loss of a fourth wing. We used high-speed video of flying blue-tailed damselflies (Ischnura elegans) to identify the wingbeat kinematics of the two wing pairs and compared it to the flapping kinematics after one of the hindwings was artificially removed. The insects remained capable of flying and precise maneuvering using only three wings. To compensate for the reduction in lift, they increased flapping frequency by 18 ± 15.4% on average. To achieve steady straight flight, the remaining intact hindwing reduced its flapping amplitude while the forewings changed their stroke plane angle so that the forewing of the manipulated side flapped at a shallower stroke plane angle. In addition, the angular position of the stroke reversal points became asymmetrical. When the wingbeat amplitude and frequency of the three wings were used as input in a simple aerodynamic model, the estimation of total aerodynamic force was not significantly different (paired t-test, p = 0.73) from the force produced by the four wings during normal flight. Thus, the removal of one wing resulted in adjustments of the motions of the remaining three wings, exemplifying the precision and plasticity of coordination between the operational wings. Such coordination is vital for precise maneuvering during normal flight but it also provides the means to maintain flight when some of the wings are severely damaged.