Cost comparison between GPS- and VHF-based telemetry: case study of feral cats Felis catus in New Zealand

Improvements in technology now make it possible to track animals of cat size using Global Positioning System (GPS)-telemetry. GPS technology has important advantages over traditional Very High Frequency (VHF)-radio tracking, but does incur higher per-tag costs. Budget is a limiting factor in experimental research; thus, an evaluation of the costs associated with both technologies according to the targets of a project should be undertaken before making any final decisions on the purchase of units and final experimental design. We simulated and compared the relative costs associated with the use of GPS and VHF telemetry applied to the study of the spatial ecology of feral cats (Fells catus) in the Tasman Valley (South Island, New Zealand) as a test case. We assessed different project durations and location acquisition rates. Cost analysis revealed that GPS-telemetry is the less expensive method to quantify the spatial ecology of feral cats when long-term (>1-year duration) projects and/or high acquisition rates (>1 location/day) are required.