Bat trajectory data were collected for 9 seconds and 79 seconds at 131.5 frames per second as groups of 20 and 86 bats, respectively, emerged from their cave on the Bamberger Ranch in Texas. Each bat was in view for approximately 1.7 seconds with a maximum of 10 bats in view at any one time. The cave bats were filmed in low light using three mid-infra-red FLIR SC8000 cameras at a resolution of 1024 x 1024 pixels. Camera calibration was performed for both bats and swallows (see below) by passing a 1 m long reference object through the shared field of view and applying a structure-from-motion algorithm. Correspondences between the views were made using semi-automated tracking tools, and the three-dimensional trajectories were generated using least squares reconstruction. The bats were filmed by the Kunz Bat Lab, and the pre-experiment planning of the multi-camera recording and the post-processing of the three video streams was done by the Image and Video Computing Group, both at Boston University. Theriault DH, Fuller NW, Jackson BE, Bluhm E, Evangelista D, Wu Z, Betke M, Hedrick TL. 2014 A protocol and calibration method for accurate multi-camera field videography. J. Exp. Biol. 217, 1843– 1848. (doi:10.1242/jeb.100529)