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Plecotus auritus specimen and the completed wind-tunnel model. A: Dried P. auritus bat specimen upon which the bat model was based (Scale bar = 100 mm). B and C: Completed bat model at the extremes of the leg positions (B: Leg angle (b) = 0u, C: Leg angle (b) = 60u), showing the effect on the tail membrane angle of attack and the increased wing camber (termed leg-induced wing camber). Leg angle adjustments were made via small screw mountings hidden within the body of the model. The model was mounted upside down in the wind-tunnel to minimise the aerodynamic effect of the wake from the support, since the tail is then deflected away from the support, instead of towards. Note that the large ears of P. auritus were excluded from the model, since this investigation was primarily concerned with the aerodynamics of the tail membrane. doi:10.1371/journal.pone.0018214.g001
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Wind tunnel tests conducted on a model based on the long-eared bat Plecotus auritus indicated that the positioning of the tail membrane (uropatagium) can significantly influence flight control. Adjusting tail position by increasing the angle of the legs ventrally relative to the body has a two-fold effect; increasing leg-induced wing camber (i.e.,...
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Context 1
... the 17 families of bats [15] only one family, the old world fruit bats (Pteropodidae), have no real tail membrane. The tail membrane is an extension of the skin between the hind limbs often incorporating the tail vertebrae ( Figure 1A). This membrane is usually supported at its rear edge by a thin structure called the calcar, which extends from the ankle joint. ...
Context 2
... model for wind tunnel testing was created using detailed morphological measurements taken from a reference specimen held at the Manchester Museum (Manchester, UK) of a brown long-eared bat (P. auritus, Figure 1A). Plecotus auritus is a slow flying, highly manoeuvrable species which gleans prey from amongst vegetation [28,29]. ...
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... Vienna, Austria), was then stretched over the model frame and glued to the sheet with Cyanoacrylate. Once the glue had dried the model frame was cut out, leaving the stretched latex to form the wings and tail membrane of the bat model ( Figure 1B). Latex sheeting was used since this could be tensioned before attachment to the frame, therefore reducing the chance of the trailing edge of the wing fluttering during testing. ...
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... to the angle of the tail membrane were made by changing the leg angles via screw fittings hidden within the body of the model. Adjusting the leg positions not only repositioned the tail membrane but also locally changed the camber and angle of attack of the inner surface of the wing (the plagiopatagium) ( Figure 1C). Henceforth, we term this effect 'leg- induced wing camber'. ...
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... wind tunnel working section area of 261.5 m is significantly larger than the bat model, removing the potential for unwanted aerodynamic effects induced by the tunnel walls [31]. The bat model was mounted upside-down so that the tail was deflected away from the structural support as opposed to towards it and therefore the effect of the wake from the structural support on the tail membrane aerodynamics was minimised ( Figure 1C). The leg angle (b) was set relative to the body and the body angle (Q) was set relative to the oncoming air stream (Figure 2). ...
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The kinematics, aerodynamics, and energetics of Plecotus auritus in slow horizontal flight, 2-35 m s-1, are analysed. At this speed the inclination of the stroke path is ca. 58 degrees to the horizontal, the stroke angle ca. 91 degrees, and the stroke frequency ca. 11-9 Hz. A method, based on steady-state aerodynamic and momenthum theories, is deri...
Wings are the most obvious adaptation bats have for powered flight and differences in wing morphology are known to correlate with flight behaviour. However, the function(s) of ancillary structures such as the ears and tail, which may also play an important role during flight, are less well understood. Here we constructed a simplified model of a bat...
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Citations
... The fourth section involves a tail membrane between the hind limbs, found in various species of bat and called the uropatagium [10,11] . The bat wings have an important role in critical for powering flight, as all those sections have a function in bat flight [2,12] . However, the large and thin wing membranes make them particularly susceptible to injuries, holes, and tears [8,13] . ...
... This movement upwards would likely prevent an extreme downwards pitching moment on the body, but the extent of this effectiveness is challenging to categorize from the current measurements. The hawks tail could act similarly to bat tails or bird tails, which have been observed to act as pitch controls and pitch oscillation dampeners [29,30]. Similar gust control schemes have also been observed in Anna's hummingbirds, with a significant increase in dorsoventral deflection (body-relative tail pitch) during gust interactions [20]. ...
A limiting factor in the design of smaller size uncrewed aerial vehicles is their inability to navigate through gust-laden environments. As a result, engineers have turned towards bio-inspired engineering approaches for gust mitigation techniques. In this study, the aerodynamics of a red-tailed hawk's response to variable-magnitude discrete transverse gusts was investigated. The hawk was flown in an indoor flight arena instrumented by multiple high-speed cameras to quantify the 3D motion of the bird as it navigated through the gust. The hawk maintained its flapping motion across the gust in all runs; however, it encountered the gust at different points in the flapping pattern depending on the run and gust magnitude. The hawk responded with a downwards pitching motion of the wing, decreasing the wing pitch angle to between -20deg and -5deg, and remained in this configuration until gust exit. The wing pitch data was then applied to a lower-order aerodynamic model that estimated lift coefficients across the wing. In gusts slower than the forward flight velocity (low gust ratio), the lift coefficient increases at a low-rate, to a maximum of around 2 to 2.5. In gusts faster than the forward flight velocity (high gust ratio), the lift coefficient initially increased rapidly, before increasing at a low-rate to a value around 4 to 5. In both regimes, the hawk's observed height change due to gust interaction was similar (and small), despite larger estimated lift coefficients over the high gust regime. This suggests another mitigation factor apart from the wing response is present. One potential factor is the tail pitching response observed here, which prior work has shown serves to mitigate pitch disturbances from gusts.
... *It has also been suggested Carollia brevicaudum (Schinz, 1821). Experimental studies can be useful to unveil the relative importance of pollex in bat locomotion as has been conducted for other structures such as tail membranes (Gardiner et al., 2011b;Adams et al., 2012). When analyzing the claw length in relation to size, species that belonged to gleaning understory frugivores (CUF) such as Rhinophylla alethina Handley, 1966, Sturnira oporaphilum (Tschudi, 1844, and Sturnira aratathomasi Peterson and Tamsitt, 1968, presented the highest values, although guild mean was inferior than that of hematophagous bats (Fig. 3b, Table 1). ...
Bats have an extraordinary morphological diversity and most of the studies have focused on exploring ecomorphology of wings, ears, nostrils, tooth, and skull. However, structures like the pollex have not been assessed yet. Here, I describe pollex measurements of 97 Neotropical bat species, analyze variation among guilds, and explore correlations with wing morphology. Besides sanguinivores, frugivores that use cluttered habitats and employ gleaning strategy showed larger pollex, whereas aerial insectivores that use open spaces presented smaller pollex. I found a negative relationship between pollex size and hand-wing length, but a positive relationship between pollex size and wing width. Results suggest a potential importance of the pollex on resource exploitation, especially in guilds associated to handling objects such as large fruits. Conversely, the pollex may be useless in aerial insectivores that employ other structures like uropatagium or dactylopatagium for prey capture and manipulation. The pollex is related to wing morphology and habitat use given that species with larger pollex and wide wings obtain their resources in cluttered habitats, while species with shorter pollex and longer wings acquire their preys over open spaces. It is important to keep documenting natural history of bats by studying unexplored structures that unveil the functional importance of morphology in resource exploitation.
... On the other hand, the prediction that longrange migrant birds should have a short length of tail found no evidence. To better understand the effect of a tail, a longeared bat model was tested by [206] in a wind tunnel showing that the absence of tail significantly decreases the pitching moment but does not affect the living generation. Also, the existence of tail increased the lift, drag, and pitching moment. ...
... Also, the existence of tail increased the lift, drag, and pitching moment. From these data, Also, tails are essential in improving agility and maneuverability Gardiner et al., [206] Aerodynamics of bird feathers The major portion of the lift and drag in a bird flight is contributed by the wings. It is the wing that creates the induced drag at the tip understood by the Helmholtz hypothesis [155]. ...
This review investigates the nature-inspired techniques for the optimization of the aerodynamic forces on bluff bodies. To provide a rich understanding of these nature-inspired phenomena, three distinct zones of the species fishes (nektons), birds (avians) and the fast running land animals are considered. This allows contextualizing different capabilities of the species in different environmental necessities. The review follows a trend in which drag reduction capabilities of individual parts of these species, including body shape & size, tails, fins, surface structure, wings, and wingtips, have been explored in detail. By focusing on specific parts, the review examined the methods and physics involved, which provides space to narrate the development of ideas and our current understanding of the nature-inspired drag reduction and their application to bluff body aerodynamics. Consequently, nature-inspired promising areas for future endeavor related to the bluff body has been discussed in detail. It was found that, though, aerospace field has found several bird inspired application but the bluff body flow modification have only few. Similar is the case with fishes and land animals which have not been explored yet for aerodynamic use on the bluff bodies. The crucial importance of passive devices are also highlighted along with the review of their application on the bluff bodies inspired by nature. Furthermore, several of nature-inspired techniques are proposed and compared to facilitate the research in this direction. It provides a fundamental method to develop nature-inspired flow control devices for the bluff bodies.
... Reduced fused pygostyle of birds supports the tail feathers while allowing unrivaled levels of modification of the full tail shape and position (Gatesy and Dial 1996) allowing it to variably act as an added wing, rudder, stabilizer, and drag reducer (e.g., Sachs 2007;Usherwood et al. 2020). Bat tails, made of a membrane stretched between hind limbs and including the caudal vertebrae, also provide a flight control surface (Gardiner et al. 2011). In both cases, the added lift and reduced drag provided by the tails decrease energetic costs relative to wing-only flight. ...
Tails are a defining characteristic of chordates and show enormous diversity in function and shape. Although chordate tails share a common evolutionary and genetic-developmental origin, tails are extremely versatile in morphology and function. For example, tails can be short or long, thin or thick, feathered or spiked, and they can be used for propulsion, communication, or balancing, and they mediate in predator-prey outcomes. Depending on the species of animal the tail is attached to, it can have extraordinarily multi-functional purposes. Despite its morphological diversity and broad functional roles, tails have not received similar scientific attention as, for example, the paired appendages such as legs or fins. This forward-looking review article is a first step towards interdisciplinary scientific synthesis in tail research. We discuss the importance of tail research in relation to five topics: 1) Evolution and Development, 2) Regeneration, 3) Functional Morphology, 4) Sensorimotor Control, and 5) Computational and Physical Models. Within each of these areas, we highlight areas of research and combinations of long-standing and new experimental approaches to move the field of tail research forward. To best advance a holistic understanding of tail evolution and function, it is imperative to embrace an interdisciplinary approach, re-integrating traditionally siloed fields around discussions on tail-related research.
... Although the structures of forelimb are mainly responsible for flight performance, the structures that support the tail membrane (uropatagium) are important for aerial locomotion, especially in maneuverability and thrust during horizontal takeoffs (Gardiner et al., 2011b;Adams et al., 2012). Moreover, uropatagium performs a key role in prey capture for insectivorous bats (Webster & Griffin, 1962;Saunders & Barclay, 1992;Kalko, 1995), carrying pups during the reproductive season (Adams & Thibault, 1999), and in thermoregulation through blood perfusion (Reeder & Cowles, 1951). ...
... Tail length: the tail and the surrounding membrane (uropatagium) are involved in flight performance by providing greater maneuverability (Gardiner et al., 2011b). These structures also provide thrust and horizontal displacement during the flight (Adams et al., 2012). ...
... These structures also provide thrust and horizontal displacement during the flight (Adams et al., 2012). Species with tails and larger uropatagia have better flight control (Gardiner et al., 2011b). ...
New World bats are involved in key ecological processes and are good indicators of environmental changes. Recently, trait-based approaches have been used in several taxa to better understand mechanisms underlying species assemblages, biotic interactions, environmental relationships and ecosystem functions. However, despite the relevance of bats on ecosystem dynamics, so far, there is no conceptual framework that relies on the measurement of bat traits to address functional studies. Here, we present a set of 50 bat biological traits, which are suitable to assess environmental stressors and can potentially affect ecological processes. Several examples were provided to show the applicability of this framework in the study of Neotropical bat ecology. We suggest some considerations regarding trait-based approach including the importance of intraspecific variation, correlations between traits, response-effect framework, global dataset, and future directions to assess the reliability of functional relations across species and Neotropical regions by using traits. This could be helpful in tackling ecological questions associated with community assembly and habitat filtering, species diversity patterns along environmental gradients, and ecological processes. We envision this paper as a first step toward an integrative bat functional trait protocol held up with solid evidence.
... While collisions are probably more likely to affect the distal sections of the wing, perhaps injuries during take-off (when the wing unfurls) or grounding might be a possible cause of these tears in the P section. Certainly, this section is extended first before flight and might get caught or snagged during flight preparation(Gardiner, Dimitriadis, Codd, & Nudds, 2011). Due to its position closer to the body, the P section might also be more likely to snag on branches during hanging, or be less manoeuvrable to tuck in to escape collisions. ...
Cat predation upon bat species has been reported to have significant effects on bat populations in both rural and urban areas. The majority of research in this area has focussed on observational data from bat rehabilitators documenting injuries, and cat owners, when domestic cats present prey. However, this has the potential to under- estimate the number of bats killed or injured by cats. Here, we use forensic DNA analysis techniques to analyze swabs taken from injured bats in the United Kingdom, mainly including Pipistrellus pipistrellus (40 out of 72 specimens). Using quantitative PCR, cat DNA was found in two-thirds of samples submitted by bat rehabilitators. Of these samples, short tandem repeat analysis produced partial DNA profiles for approximately one-third of samples, which could be used to link predation events to individual cats. The use of genetic analysis can complement observational data and potentially provide additional information to give a more accurate estimation of cat predation.
... It also contains the fewest bones (Fig. 1a), which may act to stop tearing. Section P is extended first before flight and might get caught or snagged during flight preparation (see figure 1 in Gardiner et al. 2011). Our consideration of anatomical properties (fiber type and material testing data) within section P suggests it should not be more prone to tearing than sections CI and CII. ...
Bats have large, thin wings that are particularly susceptible to tearing. Anatomical specializations, such as fiber reinforcement, strengthen the wing and increase its resistance to puncture, and an extensive vasculature system across the wing also promotes healing. We investigated whether tear positioning is associated with anatomy in common pipistrelles (Pipistrellus pipistrellus). Wing anatomy was described using histological techniques, imaging, and material testing. Tear information, including type, position, time in rehabilitation, and possible causes, was collected from rehabilitators of injured bats across the United Kingdom. Results suggest that the position of the plagiopatagium (the most proximal wing section to the body), rather than its anatomy, influenced the number, location, and orientation of wing tears. While material testing did not identify the plagiopatagium as being significantly weaker than the chiropatagium (the more distal sections of the wing), the plagiopatagium tended to have the most tears. The position of the tears, close to the body and toward the trailing edge, suggests that they are caused by predator attacks, such as from a cat (Felis catus), rather than collisions. Consistent with this, 38% of P. pipistrellus individuals had confirmed wing tears caused by cats, with an additional 38% identified by rehabilitators as due to suspected cat attacks. The plagiopatagium had the lowest number of blood vessels and highest amounts of elastin fibers, suggesting that healing may take longer in this section. Further investigations into the causes of tears, and their effect on flight capabilities, will help to improve bat rehabilitation.
... It also contains the fewest bones (Fig. 1a), which may act to stop tearing. Section P is extended first before flight and might get caught or snagged during flight preparation (see figure 1 in Gardiner et al. 2011). Our consideration of anatomical properties (fiber type and material testing data) within section P suggests it should not be more prone to tearing than sections CI and CII. ...
Bats have large, thin wings that are particularly susceptible to tearing. Anatomical specializations, such as fiber reinforcement, strengthen the wing and increase its resistance to puncture, and an extensive vasculature system across the wing also promotes healing. We investigated whether tear positioning is associated with anatomy in common pipistrelles (Pipistrellus pipistrellus). Wing anatomy was described using histological techniques, imaging, and material testing. Tear information, including type, position, time in rehabilitation, and possible causes, was collected from rehabilitators of injured bats across the United Kingdom. Results suggest that the position of the plagiopatagium (the most proximal wing section to the body), rather than its anatomy, influenced the number, location, and orientation of wing tears. While material testing did not identify the plagiopatagium as being significantly weaker than the chiropatagium (the more distal sections of the wing), the plagiopatagium tended to have the most tears. The position of the tears, close to the body and toward the trailing edge, suggests that they are caused by predator attacks, such as from a cat (Felis catus), rather than collisions. Consistent with this, 38% of P. pipistrellus individuals had confirmed wing tears caused by cats, with an additional 38% identified by rehabilitators as due to suspected cat attacks. The plagiopatagium had the lowest number of blood vessels and highest amounts of elastin fibers, suggesting that healing may take longer in this section. Further investigations into the causes of tears, and their effect on flight capabilities, will help to improve bat rehabilitation.
... The brown long-eared bat has a relatively large tail membrane connecting the feet and tail and is able to control the shape of the tail to a large degree. The tail has been shown previously to significantly influence flight control, in particular through ventral movement of the feet [19]. Therefore, we predicted that the tail plays a role in executing the manoeuvres with the biggest effect from deflection of the tail by up and down movement of the legs and feet. ...
In this study, we explicitly examine the aerodynamics of manoeuvring flight in animals. We studied brown long-eared bats flying in a wind tunnel while performing basic sideways manoeuvres. We used particle image velocimetry in combination with high-speed filming to link aerodynamics and kinematics to understand the mechanistic basis of manoeuvres. We predicted that the bats would primarily use the downstroke to generate the asymmetries for the manoeuvre since it has been shown previously that the majority of forces are generated during this phase of the wingbeat. We found instead that the bats more often used the upstroke than they used the downstroke for this. We also found that the bats used both drag/thrust-based and lift-based asymmetries to perform the manoeuvre and that they even frequently switch between these within the course of a manoeuvre. We conclude that the bats used three main modes: lift asymmetries during downstroke, thrust/drag asymmetries during downstroke and thrust/drag asymmetries during upstroke. For future studies, we hypothesize that lift asymmetries are used for fast turns and thrust/drag for slow turns and that the choice between up- and downstroke depends on the timing of when the bat needs to generate asymmetries.
