| During a two-year drought study conducted by the California Department of Fish and Wildlife, ultrasonic recordings were collected at over 600 locations throughout the Great Valley and Mojave Desert ecoregions. These recordings targeted chiropteran species' calls ranging from 6-125 kHz, and over three terabytes of triggered, full-spectrum recordings were produced. During review of the data, many incidental recordings of potential rodent calls were also observed. Given the importance of rodent species to biological communities as low-level consumers, prey, and seed dispersers, development of techniques to discriminate these vocalizations was warranted. A representative selection of triggered recordings were analyzed using the Kaleidoscope Pro 4.3 Cluster Analysis tool, a novel technology that uses Hidden Markov Models to group similar acoustic signals. Clusters that best fit known rodent vocalizations were refined and reapplied to the entire data set. Manual analysis of the results, as well as analysis of recordings initially attributed to audible bat species, have verified rodent detections, including the genera Onychomys and Peromyscus. Further work is necessary to expand California rodent call libraries, but with the existing data available, the potential value of this emerging technique to detect ultrasonic and near-ultrasonic rodents has been demonstrated. |