Evaluation of New Telemetry Technologies for Research on Island Foxes

Abstract

New telemetry technologies have recently become available for research on island foxes (Urocyon littoralis). These include GPS units, which collect location data, and proximity logger units, which record contacts between individuals. We evaluated these technologies on island foxes through 4 field studies. GPS collars were deployed on foxes on Santa Catalina during 2007–2008 (n = 20) and 2010–2011 (n = 5) and on Santa Rosa during 2009–2010 (n = 14). The GPS units had multiple issues including malfunctioning drop-off mechanisms, failure of some units to yield data, low location acquisition rates, improper factory programming, high rates of premature failure of VHF transmitters and GPS units, poor VHF signal strength, faulty mortality sensors, and breakage of the unit housing or antenna. Proximity loggers were deployed on foxes on San Miguel during 2009–2010 (n = 17). Performance was satis- factory and consistent with expectations. Both the GPS and proximity logger units yielded high-quality data when the units worked correctly. Some minor collar-related injuries were noted on 4 foxes with GPS units. We conclude that both technologies can potentially collect valuable data that would be more difficult and expensive to collect using conven- tional VHF methods and therefore could benefit island fox conservation. We recommend (1) using GPS units with a remote download function; (2) downloading data from both types of units as frequently as is practicable; (3) attempting GPS-unit data downloads from the air; (4) frequently monitoring foxes using the VHF transmitters to determine areas of use; and (5) rigorously pretesting all functions on both types of units prior to deployment on foxes.