Using High-Resolution Radiotracking to Improve Inference About the Spatial Ecology of Small, Slow-Moving Ectotherms

Abstract

Ornate box turtle (Terrapene ornata) and eastern box turtle (Terrapene carolina carolina) are long-lived, relatively small, and slow-moving ectotherms experiencing range-wide declines primarily due to habitat loss. Understanding home range and movement patterns of box turtles is crucial for conservation efforts in fragmented landscapes. Very High Frequency (VHF) radio transmitters are commonly used to locate box turtles, but sample size and availability of personnel can limit how often each turtle is tracked. In this study, we evaluated whether the rate of tracking events affects the estimated home range and average daily movement of T. ornata in a short-grass prairie located in Roosevelt County, New Mexico, and T. c. carolina in an urban forest located in Wake County, North Carolina, USA. We tracked three T. ornata and four T. c. carolina four to 7 days per week during their active season. Using the full dataset, we first calculated 100% Minimum Convex Polygon for each turtle. Then, we randomly sampled the full dataset, representing scenarios where turtles were tracked from one to four times per week, and recalculated home ranges. We also calculated distances between consecutive locations in the full dataset to evaluate how rates of tracking events affect estimates of mean daily movement. Mixed effect models revealed that home range size estimates significantly decreased with less frequent tracking events. Furthermore, we found that turtles occasionally moved longer distances within a single day. Our findings suggest that these rare bursts of movement are ecologically relevant but may be overlooked, and consequently home range sizes underestimated, if turtles are not tracked frequently.