A camera trapping method for the targeted capture of Eurasian beaver (Castor fiber) tails for individual scale pattern recognition

Camera traps are commonly used to monitor and study wild animals in their natural habitat, with minimal disturbance. Several investigations have shown that the natural markings of animals for some species can be used for individual recognition. However, most commercially available cameras are unable to obtain photos of sufficient quality to highlight these features. Our study further exemplifies the use of applying an external lens to a camera, to obtain higher quality images. We tested various lenses and their ability to record the scale patterns on Eurasian beaver (Castor fiber) tails, for individual identification. We tested eleven different commercially available camera trap models, across six different beaver territories in the Districts of Kleve and Wesel (North Rhine-Westphalia, Germany). The use of an external lens, attached to the camera, produced the best quality pictures for reliable identification of individual beavers based on the scale patterns on their tales. These results further exemplify the application of external lenses for improving image quality for individual recognition which has potential applications for other species.