ICHNOENDOSCOPY: USING BORESCOPES AND INSPECTION CAMERAS FOR NEOICHNOLOGICAL IMAGING AND PHOTOGRAMMETRY OF BURROW INTERIORS

Neoichnological observations of burrows in three dimensions traditionally rely on pouring a casting medium, e.g., plaster, resin, inside of a burrow, letting the medium cure, and excavating the cast. Such methods are extremely informative, but can be detrimental to the tracemaker by causing habitat disturbance and occasionally death if casting is performed while the burrow is still occupied. These risks greatly limit the feasibility of neoichnological studies of such animals as vertebrates and threatened and endangered species. Additionally, use of liquid casting media makes it nearly impossible to fully cast horizontal burrows because of air pockets trapped against their ceilings and flowing of the casting media out of burrow entrances. These problems may be solved through nondestructive imaging techniques using tools designed for observing narrow confined spaces. Such tools as action cameras, inspection cameras, borescopes, and otoscopes are widely available and relatively inexpensive. Many have their own light sources and connect to and record to mobile devices. This presentation will feature results of in situ internal imaging of burrows using a range of these devices, as well as recommendations and limitations. Methods include imaging mammal burrows with a 360-degree swivel lens borescope and an action camera mounted on a selfie stick. An otoscope has been found to be the appropriate size for invertebrate burrows < 1 cm in diameter. Sequences of overlapping images imported into photogrammetry software are used to generate three-dimensional (3D) point clouds with the goal of producing accurate 3D mesh models. Preliminary results show that burrow architectures are well represented by point clouds obtained from this method. Refinement of this technique promises to allow burrow characterization that is relatively rapid and nondestructive. Use of these imaging methods also has the added benefit of the potential to film the tracemaker within its burrow, allowing for identification and observations of behaviors.