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Håkansson J, Quinn BL, Shultz AL, Swartz SM, Corcoran AJ. Application of a novel deep learning-based 3D videography workflow to bat flight. Ann N Y Acad Sci 2024; 1536:92-106. [PMID: 38652595 DOI: 10.1111/nyas.15143] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/25/2024]
Abstract
Studying the detailed biomechanics of flying animals requires accurate three-dimensional coordinates for key anatomical landmarks. Traditionally, this relies on manually digitizing animal videos, a labor-intensive task that scales poorly with increasing framerates and numbers of cameras. Here, we present a workflow that combines deep learning-powered automatic digitization with filtering and correction of mislabeled points using quality metrics from deep learning and 3D reconstruction. We tested our workflow using a particularly challenging scenario: bat flight. First, we documented four bats flying steadily in a 2 m3 wind tunnel test section. Wing kinematic parameters resulting from manually digitizing bats with markers applied to anatomical landmarks were not significantly different from those resulting from applying our workflow to the same bats without markers for five out of six parameters. Second, we compared coordinates from manual digitization against those yielded via our workflow for bats flying freely in a 344 m3 enclosure. Average distance between coordinates from our workflow and those from manual digitization was less than a millimeter larger than the average human-to-human coordinate distance. The improved efficiency of our workflow has the potential to increase the scalability of studies on animal flight biomechanics.
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Affiliation(s)
- Jonas Håkansson
- Department of Biology, University of Colorado Colorado Springs, Colorado Springs, Colorado, USA
| | - Brooke L Quinn
- Department of Ecology, Evolution, and Organismal Biology, Brown University, Providence, Rhode Island, USA
| | - Abigail L Shultz
- Department of Biology, University of Colorado Colorado Springs, Colorado Springs, Colorado, USA
| | - Sharon M Swartz
- Department of Ecology, Evolution, and Organismal Biology, Brown University, Providence, Rhode Island, USA
- School of Engineering, Brown University, Providence, Rhode Island, USA
| | - Aaron J Corcoran
- Department of Biology, University of Colorado Colorado Springs, Colorado Springs, Colorado, USA
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Smirnova KP, Frill MA, Warner SE, Cheney JA. Shape change in the saddle region of the equine back during trot and walk. J R Soc Interface 2024; 21:20230644. [PMID: 38916112 DOI: 10.1098/rsif.2023.0644] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2023] [Accepted: 05/01/2024] [Indexed: 06/26/2024] Open
Abstract
Equine back pain is prevalent among ridden horses and is often attributed to poor saddle fit. An alternative explanation is that saddle fits are technically good but fit to the wrong configuration. Saddles are fit for the standing horse, but much of the time ridden is instead spent locomoting when the back experiences the greatest peak forces. We used an array of cameras to reconstruct the surface of the back and its movement during trot, walk and standing for five horses. We verified the setup's accuracy by reconstructing a laser-scanned life-sized model horse. Our reconstructions demonstrate that saddles sit within a large, relatively low-mobile region of the back. However, saddles do sit adjacent to the highly mobile withers, which demands care in positioning and design around this important region. Critically, we identified that saddle curvature between standing and moving horses is substantially different, where trotting and walking horses have flatter backs than their standing configurations. Saddles designed around the locomoting configuration of horses may improve horse welfare by being better fit and decreasing the focal pressures applied by saddles.
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Affiliation(s)
| | | | | | - Jorn A Cheney
- Royal Veterinary College , Hatfield AL9 7TA, UK
- School of Biological Sciences, University of Southampton , Southampton SO17 1BJ, UK
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Skandalis DA, Baliga VB, Goller B, Altshuler DL. The spatiotemporal richness of hummingbird wing deformations. J Exp Biol 2024; 227:jeb246223. [PMID: 38680114 PMCID: PMC11166462 DOI: 10.1242/jeb.246223] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2023] [Accepted: 04/17/2024] [Indexed: 05/01/2024]
Abstract
Animals exhibit an abundant diversity of forms, and this diversity is even more evident when considering animals that can change shape on demand. The evolution of flexibility contributes to aspects of performance from propulsive efficiency to environmental navigation. It is, however, challenging to quantify and compare body parts that, by their nature, dynamically vary in shape over many time scales. Commonly, body configurations are tracked by labelled markers and quantified parametrically through conventional measures of size and shape (descriptor approach) or non-parametrically through data-driven analyses that broadly capture spatiotemporal deformation patterns (shape variable approach). We developed a weightless marker tracking technique and combined these analytic approaches to study wing morphological flexibility in hoverfeeding Anna's hummingbirds (Calypte anna). Four shape variables explained >95% of typical stroke cycle wing shape variation and were broadly correlated with specific conventional descriptors such as wing twist and area. Moreover, shape variables decomposed wing deformations into pairs of in-plane and out-of-plane components at integer multiples of the stroke frequency. This property allowed us to identify spatiotemporal deformation profiles characteristic of hoverfeeding with experimentally imposed kinematic constraints, including through shape variables explaining <10% of typical shape variation. Hoverfeeding in front of a visual barrier restricted stroke amplitude and elicited increased stroke frequencies together with in-plane and out-of-plane deformations throughout the stroke cycle. Lifting submaximal loads increased stroke amplitudes at similar stroke frequencies together with prominent in-plane deformations during the upstroke and pronation. Our study highlights how spatially and temporally distinct changes in wing shape can contribute to agile fluidic locomotion.
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Affiliation(s)
- Dimitri A. Skandalis
- Department of Zoology, University of British Columbia, Vancouver, BC, Canada, V6T 1Z4
| | - Vikram B. Baliga
- Department of Zoology, University of British Columbia, Vancouver, BC, Canada, V6T 1Z4
| | - Benjamin Goller
- Department of Zoology, University of British Columbia, Vancouver, BC, Canada, V6T 1Z4
- College of Agriculture Data Services, Purdue University, West Lafayette, IN 47907-2053, USA
| | - Douglas L. Altshuler
- Department of Zoology, University of British Columbia, Vancouver, BC, Canada, V6T 1Z4
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Kelling M, Currie SE, Troxell SA, Reusch C, Roeleke M, Hoffmeister U, Teige T, Voigt CC. Effects of tag mass on the physiology and behaviour of common noctule bats. MOVEMENT ECOLOGY 2024; 12:38. [PMID: 38725032 PMCID: PMC11084088 DOI: 10.1186/s40462-024-00477-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/06/2024] [Accepted: 05/01/2024] [Indexed: 05/12/2024]
Abstract
BACKGROUND External tags, such as transmitters and loggers, are often used to study bat movements. However, physiological and behavioural effects on bats carrying tags have rarely been investigated, and recommendations on the maximum acceptable tag mass are rather based on rules of thumb than on rigorous scientific assessment. METHODS We conducted a comprehensive three-step assessment of the potential physiological and behavioural effects of tagging bats, using common noctules Nyctalus noctula as a model. First, we examined seasonal changes in body mass. Second, we predicted and then measured potential changes in flight metabolic rate in a wind tunnel. Third, we conducted a meta-analysis of published data to assess effects of different tag masses on the weight and behaviour of bats. RESULTS Individual body mass of common noctules varied seasonally by 7.0 ± 2.6 g (range: 0.5-11.5 g). Aerodynamic theory predicted a 26% increase in flight metabolic rate for a common noctule equipped with a 3.8 g tag, equating to 14% of body mass. In a wind tunnel experiment, we could not confirm the predicted increase for tagged bats. Our meta-analysis revealed a weak correlation between tag mass and emergence time and flight duration in wild bats. Interestingly, relative tag mass (3-19% of bat body mass) was not related to body mass loss, but bats lost more body mass the longer tags were attached. Notably, relatively heavy bats lost more mass than conspecifics with a more average body mass index. CONCLUSION Because heavy tags (> 3 g) were generally used for shorter periods of time than lighter tags (~ 1 g), the long-term effects of heavy tags on bats cannot be assessed at this time. Furthermore, the effects of disturbance and resource distribution in the landscape cannot be separated from those of tagging. We recommend that tags weighing 5-10% of a bat's mass should only be applied for a few days. For longer studies, tags weighing less than 5% of a bat's body mass should be used. To avoid adverse effects on bats, researchers should target individuals with average, rather than peak, body mass indices.
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Affiliation(s)
- Marit Kelling
- Leibniz Institute for Zoo and Wildlife Research, Alfred-Kowalke-Str. 17, 10315, Berlin, Germany.
- University of Potsdam, Plant Ecology and Nature Conservation, Potsdam, Germany.
| | - Shannon E Currie
- Leibniz Institute for Zoo and Wildlife Research, Alfred-Kowalke-Str. 17, 10315, Berlin, Germany
- School of BioSciences, University of Melbourne, Parksville, 3010, Australia
| | - Sara A Troxell
- Leibniz Institute for Zoo and Wildlife Research, Alfred-Kowalke-Str. 17, 10315, Berlin, Germany
| | - Christine Reusch
- Leibniz Institute for Zoo and Wildlife Research, Alfred-Kowalke-Str. 17, 10315, Berlin, Germany
| | - Manuel Roeleke
- University of Potsdam, Plant Ecology and Nature Conservation, Potsdam, Germany
| | - Uwe Hoffmeister
- Natura Büro für Zoologische und Botanische Fachgutachten, Leipzig, Germany
| | - Tobias Teige
- Büro für Faunististische und Ökologische Fachgutachten, Berlin, Germany
| | - Christian C Voigt
- Leibniz Institute for Zoo and Wildlife Research, Alfred-Kowalke-Str. 17, 10315, Berlin, Germany
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Smith TD, Santana SE, Eiting TP. Ecomorphology and sensory biology of bats. Anat Rec (Hoboken) 2023; 306:2660-2669. [PMID: 37656052 DOI: 10.1002/ar.25314] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2023] [Revised: 08/12/2023] [Accepted: 08/14/2023] [Indexed: 09/02/2023]
Abstract
This special issue of The Anatomical Record is inspired by and dedicated to Professor Kunwar P. Bhatnagar, whose lifelong interests in biology, and long career studying bats, inspired many and advanced our knowledge of the world's only flying mammals. The 15 articles included here represent a broad range of investigators, treading topics familiar to Prof. Bhatnagar, who was interested in seemingly every aspect of bat biology. Key topics include broad themes of bat development, sensory systems, and specializations related to flight and diet. These articles paint a complex picture of the fascinating adaptations of bats, such as rapid fore limb development, ear morphologies relating to echolocation, and other enhanced senses that allow bats to exploit niches in virtually every part of the world. In this introduction, we integrate and contextualize these articles within the broader story of bat ecomorphology, providing an overview of each of the key themes noted above. This special issue will serve as a springboard for future studies both in bat biology and in the broader world of mammalian comparative anatomy and ecomorphology.
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Affiliation(s)
- Timothy D Smith
- School of Physical Therapy, Slippery Rock University, Slippery Rock, Pennsylvania, USA
| | - Sharlene E Santana
- Department of Biology, University of Washington, Seattle, Washington, USA
| | - Thomas P Eiting
- Department of Physiology and Pathology, Burrell College of Osteopathic Medicine, Las Cruces, New Mexico, USA
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Lauber M, Weymouth GD, Limbert G. Rapid flapping and fibre-reinforced membrane wings are key to high-performance bat flight. J R Soc Interface 2023; 20:20230466. [PMID: 37963557 PMCID: PMC10645508 DOI: 10.1098/rsif.2023.0466] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2023] [Accepted: 10/20/2023] [Indexed: 11/16/2023] Open
Abstract
Bats fly using significantly different wing motions from other fliers, stemming from the complex interplay of their membrane wings' motion and structural properties. Biological studies show that many bats fly at Strouhal numbers, the ratio of flapping to flight speed, 50-150% above the range typically associated with optimal locomotion. We use high-resolution fluid-structure interaction simulations of a bat wing to independently study the role of kinematics and material/structural properties in aerodynamic performance and show that peak propulsive and lift efficiencies for a bat-like wing motion require flapping 66% faster than for a symmetric motion, agreeing with the increased flapping frequency observed in zoological studies. In addition, we find that reduced membrane stiffness is associated with improved propulsive efficiency until the membrane flutters, but that incorporating microstructural anisotropy arising from biological fibre reinforcement enables a tenfold reduction of the flutter energy while maintaining high aerodynamic efficiency. Our results indicate that animals with specialized flapping motions may have correspondingly specialized flapping speeds, in contrast to arguments for a universally efficient Strouhal range. Additionally, our study demonstrates the significant role that the microstructural constitutive properties of the membrane wing of a bat can have in its propulsive performance.
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Affiliation(s)
- Marin Lauber
- Faculty of Engineering and Physical Sciences, University of Southampton, Southampton, UK
- Faculty of Mechanical Maritime and Materials Engineering (3mE), Delft University of Technology, Delft, The Netherlands
| | - Gabriel D. Weymouth
- Faculty of Mechanical Maritime and Materials Engineering (3mE), Delft University of Technology, Delft, The Netherlands
| | - Georges Limbert
- Faculty of Engineering and Physical Sciences, University of Southampton, Southampton, UK
- Department of Human Biology, Faculty of Health Sciences, University of Cape Town, Cape Town, South Africa
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Rummel AD, Sierra MM, Quinn BL, Swartz SM. Hair, there and everywhere: A comparison of bat wing sensory hair distribution. Anat Rec (Hoboken) 2023; 306:2681-2692. [PMID: 36790015 DOI: 10.1002/ar.25176] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2022] [Revised: 01/17/2023] [Accepted: 01/27/2023] [Indexed: 02/16/2023]
Abstract
Bat wing membranes are composed of specialized skin that is covered with small sensory hairs which are likely mechanosensory and have been suggested to help bats sense airflow during flight. These sensory hairs have to date been studied in only a few of the more than 1,400 bat species around the world. Little is known about the diversity of the sensory hair network across the bat phylogeny. In this study, we use high-resolution photomicrographs of preserved bat wings from 17 species in 12 families to characterize the distribution of sensory hairs along the wing and among species. We identify general patterns of sensory hair distribution across species, including the apparent relationships of sensory hairs to intramembranous wing muscles, the network of connective tissues in the wing membrane, and the bones of the forelimb. We also describe distinctive clustering of these sensory structures in some species. We also quantified sensory hair density in several regions of interest in the propatagium, plagiopatagium, and dactylopagatia, finding that sensory hair density was higher proximally than distally. This examination of the anatomical organization of the sensory hair network in a comparative context provides a framework for existing research on sensory hair function and highlights avenues for further research.
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Affiliation(s)
- Andrea D Rummel
- Department of Ecology, Evolution, and Organismal Biology, Brown University, Providence, Rhode Island, USA
- Department of Ecology and Evolutionary Biology, Princeton University, Princeton, New Jersey, USA
| | - Melissa M Sierra
- Department of Ecology, Evolution, and Organismal Biology, Brown University, Providence, Rhode Island, USA
| | - Brooke L Quinn
- Department of Ecology, Evolution, and Organismal Biology, Brown University, Providence, Rhode Island, USA
| | - Sharon M Swartz
- Department of Ecology, Evolution, and Organismal Biology, Brown University, Providence, Rhode Island, USA
- School of Engineering, Brown University, Providence, Rhode Island, USA
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Hedenström A. Effects of wing damage and moult gaps on vertebrate flight performance. J Exp Biol 2023; 226:307304. [PMID: 37132410 DOI: 10.1242/jeb.227355] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/04/2023]
Abstract
Vertebrates capable of powered flight rely on wings, muscles that drive their flapping and sensory inputs to the brain allowing for control of the motor output. In birds, the wings are formed of arrangements of adjacent flight feathers (remiges), whereas the wings of bats consist of double-layered skin membrane stretched out between the forelimb skeleton, body and legs. Bird feathers become worn from use and brittle from UV exposure, which leads to loss of function; to compensate, they are renewed (moulted) at regular intervals. Bird feathers and the wings of bats can be damaged by accident. Wing damage and loss of wing surface due to moult almost invariably cause reduced flight performance in measures such as take-off angle and speed. During moult in birds, this is partially counteracted by concurrent mass loss and enlarged flight muscles. Bats have sensory hairs covering their wing surface that provide feedback information about flow; thus, wing damage affects flight speed and turning ability. Bats also have thin, thread-like muscles, distributed within the wing membrane and, if these are damaged, the control of wing camber is lost. Here, I review the effects of wing damage and moult on flight performance in birds, and the consequences of wing damage in bats. I also discuss studies of life-history trade-offs that make use of experimental trimming of flight feathers as a way to handicap parent birds feeding their young.
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Affiliation(s)
- Anders Hedenström
- Department of Biology, Animal Flight Lab, SE-223 62 Ecology Building, Lund University, 22362 Lund, Sweden
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Provini P, Camp AL, Crandell KE. Emerging biological insights enabled by high-resolution 3D motion data: promises, perspectives and pitfalls. J Exp Biol 2023; 226:286825. [PMID: 36752301 PMCID: PMC10038148 DOI: 10.1242/jeb.245138] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/09/2023]
Abstract
Deconstructing motion to better understand it is a key prerequisite in the field of comparative biomechanics. Since Marey and Muybridge's work, technical constraints have been the largest limitation to motion capture and analysis, which, in turn, limited what kinds of questions biologists could ask or answer. Throughout the history of our field, conceptual leaps and significant technical advances have generally worked hand in hand. Recently, high-resolution, three-dimensional (3D) motion data have become easier to acquire, providing new opportunities for comparative biomechanics. We describe how adding a third dimension of information has fuelled major paradigm shifts, not only leading to a reinterpretation of long-standing scientific questions but also allowing new questions to be asked. In this paper, we highlight recent work published in Journal of Experimental Biology and influenced by these studies, demonstrating the biological breakthroughs made with 3D data. Although amazing opportunities emerge from these technical and conceptual advances, high-resolution data often come with a price. Here, we discuss challenges of 3D data, including low-throughput methodology, costly equipment, low sample sizes, and complex analyses and presentation. Therefore, we propose guidelines for how and when to pursue 3D high-resolution data. We also suggest research areas that are poised for major new biological advances through emerging 3D data collection.
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Affiliation(s)
- Pauline Provini
- Université Paris Cité, Inserm, System Engineering and Evolution Dynamics, F-75004 Paris, France
- Learning Planet Institute, F-75004 Paris, France
- Département Adaptations du Vivant, UMR 7179 CNRS/Muséum National d'Histoire Naturelle, F-75005 Paris, France
| | - Ariel L Camp
- Department of Musculoskeletal and Ageing Science, Institute of Life Course and Medical Sciences, University of Liverpool, Liverpool L78TX, UK
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Fan X, Swartz S, Breuer K. Power requirements for bat-inspired flapping flight with heavy, highly articulated and cambered wings. J R Soc Interface 2022; 19:20220315. [PMID: 36128710 PMCID: PMC9490335 DOI: 10.1098/rsif.2022.0315] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2022] [Accepted: 08/25/2022] [Indexed: 11/12/2022] Open
Abstract
Bats fly with highly articulated and heavy wings. To understand their power requirements, we develop a three-dimensional reduced-order model, and apply it to flights of Cynopterus brachyotis, the lesser dog-faced fruit bat. Using previously measured wing kinematics, the model computes aerodynamic forces using blade element momentum theory, and incorporates inertial forces of the flapping wing using the measured mass distribution of the membrane wing and body. The two are combined into a Lagrangian equation of motion, and we performed Monte Carlo simulations to address uncertainties in measurement errors and modelling assumptions. We find that the camber of the armwing decreases with flight speed whereas the handwing camber is more independent of speed. Wing camber disproportionately impacts energetics, mainly during the downstroke, and increases the power requirement from 8% to 22% over flight speed U = 3.2-7.4 m s-1. We separate total power into aerodynamic and inertial components, and aerodynamic power into parasitic, profile and induced power, and find strong agreement with previous theoretical and experimental studies. We find that inertia of wings help to balance aerodynamic forces, alleviating the muscle power required for weight support and thrust generation. Furthermore, the model suggests aerodynamic forces assist in lifting the heavy wing during upstroke.
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Affiliation(s)
- Xiaozhou Fan
- Center for Fluid Mechanics, School of Engineering, Brown University, Providence, RI, USA
| | - Sharon Swartz
- Center for Fluid Mechanics, School of Engineering, Brown University, Providence, RI, USA
- Department of Ecology, Evolution, and Organismal Biology, Aeromechanics & Evolutionary Morphology Lab, Brown University, Providence, RI, USA
| | - Kenneth Breuer
- Center for Fluid Mechanics, School of Engineering, Brown University, Providence, RI, USA
- Department of Ecology, Evolution, and Organismal Biology, Aeromechanics & Evolutionary Morphology Lab, Brown University, Providence, RI, USA
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Knight K. Membrane muscles tension bat wings for faster flight. J Exp Biol 2022. [DOI: 10.1242/jeb.244731] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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