Evaluation of Automated Radio Telemetry for Quantifying Movements and Home Ranges of Snakes

—We evaluated an automated telemetry system that can dramatically increase the amount of activity and spatial data collected for snakes. We developed methods for analyzing data from single automated receiving units (ARUs) and ARU arrays, compared results from ARUs with conventional hand tracking, and assessed previously untested assumptions used in conventional telemetry, using data from ratsnakes (Pantherophis spp.) in Texas and Illinois. ARU data indicated that ratsnakes spent most of their time in small home ranges (mean = 25 ha) but engaged in forays of up to 1.5 km from their core-use areas, suggesting this species may engage in central place foraging. Forays inflated homerange sizes greatly if areas were estimated using minimum convex polygons rather than 95% kernels. Large numbers of locations generated by ARUs produce more reliable home-range estimates than those from hand tracking. ARU data indicated that snakes moved in response to observers during hand tracking. Daily hand tracking produced reliable estimates of distances moved but underestimated distances by a factor of 4 when snakes were tracked every 5 days. Drawbacks of ARUs are that the error associated with individual locations exceeds that for handtracked locations and that the costs exceed those for hand tracking. Automated receivers can increase data greatly from radio-tracked snakes, providing novel insights unavailable from conventional hand tracking. There are drawbacks to this technology, some of which will vary among study species; therefore, researchers should evaluate the appropriateness of the technology for both the study species and the questions being