membranes, regardless of taxonomic affiliation, use TAFT locomotion and there may be some affiliation with TAFT in the evolutionary origin of flight in mammals. Materials and Methods Ethics statement All animal handling protocols were approved by the University of Northern Colorado Institution Animal Care and Use Committee (IACUC protocol number 0505) and field work was carried out under Colorado Division of Wildlife Permit # 11TR897 and a Boulder County Parks and Open Space research permit. All procedures for the handling of bats informed by these permits were followed. Animal captures We used a mist net to capture free-flying bats at a water source located in Boulder County, Colorado. A single mist net was erected in a known flight path. Once individuals were captured and removed, they were placed in cloth sacks to await processing. Each individual was identified to species, sex, reproductive condition and relative age. In addition, for the little brown myotis (Myotis lucifugus), we wrapped each individual in a nylon mesh cloth and weighed them to the nearest 0.01 g using a pan-scale (Acculab PP-201, 60.02; Colombia, MD, USA). High-speed videography We filmed individuals launching from the tailgate of a pickup truck on which a wooden plank was laid for traction. For positional information, we made a back-drop that consisted of 1 m61 m paper grid divided into 9610 cm squares. We saturated the filming area using six high-intensity halogen lamps providing 1,800 watts of light. As bats were released, we filmed them from a lateral position to the anticipated flight path using a single high- speed video camera [22,23,24] Casio Exilim EX-F1 Digital Camera, (Casio, Inc., Montrose, CA, USA) set at 300 frames per second from a distance of 1 m or 2 m. In some cases, individuals were filmed flying head-on into the camera or from behind, flying away from the camera. These methods were replicated using a wooden plank placed on a table for filming individuals from a captive colony of pallid bats, Antrozous pallidus, held at the University of Wyoming, Laramie, USA. The pallid bats were housed in a free-flight room approximately 6610 m in size and thus were able to maintain their flight skills and abilities. Bats were not marked because the film resolution was more than adequate to digitize motions of the wing-tip, wrist, and tail-tip throughout the takeoff events without markers and thus minimized potential impacts to wild-caught and released individuals. Markers were placed on landmarks during digitizing analyses through each video frame using analysis software provided by the Tyson Hedrick Research Laboratory at the University of North Carolina, Chapel Hill, USA [28]. Motion angles for the tail-membrane in relation to body plane were calculated using MaxTrax software provided by Innovision Systems (Columbiaville, MI, USA). Body axis was defined and marked as a line between two points, one placed at the nose-tip (as the head is held in-line with the body axis during takeoff flight) and the other placed at the point where tail- membrane connects to the body midline. Parallax error due to roll and yaw motions of individuals during takeoffs can produce digitizing inaccuracies difficult to correct A Hind-Wing in Bats from a single camera angle. To correct for this, we analyzed film from individuals that showed takeoffs nearing 90 degrees to the camera and had minimal body-axis rotations. If some roll and yaw was evident we made slight adjustment to point placement visually during digitizing by placing markers in positions that allowed for corrections and expected consistency of smooth curvilinear motions of the points through time. We are confident that any parallax errors within our data had minimal, if any, effect on the outcome of our results. We used the body-axis plane of each individual as a reference point to measure sweep angles of the tail- membrane during fanning motions. To produce oscillation graphs for wrist and tail-tip motions in relation to each other as individuals ascended and accelerated from their takeoff points, the motion of the bat’s body plane was taken into account, and positional information was adjusted if the body-axis moved when either the wing or tail-membrane were held stationary. Supporting Information Video S1 Head-on view of a fringed myotis (Myotis thysanodes) using the tail-membrane during takeoff and slow flight. Note collapsing of the tail-membrane on the upstroke and expansion during the downstroke. (MPEG) Video S2 Rear-view of a fringed myotis (Myotis thysa- nodes) using the tail-membrane during takeoff and slow flight with extensive use of tail-membrane flapping during seven wing-beat cycles. (MPEG) Video S3 Rear-view of a Townsend’s big-eared bat (Corynorhinus townsendii) during takeoff. Note the fanning motion of the tail membrane during acceleration and steep climbing. (MPEG) Video S4 Lateral view of a little brown myotis (M. lucifugus) using the tail-membrane during take-off and slow flight. Although this video was not analyzable due to parallax concerns, it illustrates a view of tail-wing use from various angles. (MPEG) Video S5 Lateral view of a long-eared myotis (Myotis evotis) using the tail-membrane during takeoff and slow flight showing a nearly 906 tail extension during the first upstroke cycle of the hind-wing. (MPEG) Acknowledgments Special thanks to Professor Thomas H. Kunz for providing feedback on an earlier draft of this manuscript. We thank Boulder County Parks and Open Space for permission to conduct research on their property. Special thanks to Professor Nick Fuzessery, University of Wyoming for allowing us to film his captive pallid bats. Author Contributions Conceived and designed the experiments: RAA. Performed the experi- ments: RAA ERS JBS. Analyzed the data: RAA. Contributed reagents/ materials/analysis tools: RAA. Wrote the paper: RAA. PLoS ONE | www.plosone.org 10 February 2012 | Volume 7 | Issue 2 | e32074