Quantifying activity budgets and determining the accuracy of behavioral data obtained by telemetry is essential to understand the behavior of animals that are difficult to observe. We fitted 8 captive white-tailed deer (Odocoileus virginianus) with VHF or GPS collars to determine the accuracy of VHF variable-pulse sensors and GPS dual-axis sensors and validate the performance of VHF telemetry for the measurement of activity budgets. We also evaluated whether instantaneous activity counts could measure daily activity patterns of 16 free-ranging deer fitted with GPS collars on Anticosti Island (Québec, Canada). Comparison of VHF telemetry data and visual observations of active (feeding, moving, and standing) and inactive (resting) deer behaviors were correct in 74% of the scans. Using the activity values of 3 successive VHF scans, we increased accuracy to 84% of the observed behaviors and detected 87% of observed activity bouts. The accuracy of GPS activity data varied with orientation of the sensor: activity counts of vertical sensors (92% agreement) were better able to predict observed behaviors than activity counts from horizontal sensors (83% agreement). GPS activity sensors detected peaks of activity after dawn and at dusk in free-ranging deer. We conclude that dual-axis GPS motion sensors can be used to reliably record activity data and successive scans from VHF sensors can precisely detect activity bouts in large herbivores.
global positioning system