Evaluation of automated radio telemetry technologies for ground-dwelling species

Abstract

The Motus Wildlife Tracking System employs automated radio telemetry towers to remotely record transmitter detections. While Motus technologies have successfully been used to study large-scale space use of migrating birds, they have not been assessed for use in evaluating fine- scale space use of ground-dwelling birds. We used GLMs to estimate the accuracy, precision, and detection probability of Motus transmitters relative to standard VHF transmitters, with a focus on assessing the technology for evaluating fine-scale space use of ground-dwelling birds. Our results supported strong effects of transmitter type on transmitter performance metrics. Triangulated estimates of Motus transmitter locations were more precise and accurate than those of VHF, particularly at short distances. However, the mean observable distance of VHF transmitters (597 + or - 69m) was nearly twice that of the Motus transmitters (264 + or - 30m). In 2023, we equipped 56 sharp-tailed grouse with Motus transmitters in areas with stationary Motus towers, but only a small fraction of grouse were detected simultaneously by enough towers to estimate their locations accurately. Only 26 grouse were detected simultaneously by at least 2 towers on fewer than 30 unique occasions, none of which occurred during the critical nesting period. Although triangulation accuracy and precision were higher for handheld Motus technology than traditional VHF, reduced detection distances and inconsistent automated detection limited the utility of Motus technology for fine-scale assessments of space use for ground-dwelling birds in western Montana.