title: Evaluation of micro-GPS receivers for tracking small-bodied mammals.
abstract: GPS telemetry markedly enhances the temporal and spatial resolution of animal location data, and recent advances in micro-GPS receivers permit their deployment on small mammals. One such technological advance, snapshot technology, allows for improved battery life by reducing the time to first fix via postponing recovery of satellite ephemeris (satellite location) data and processing of locations. However, no previous work has employed snapshot technology for small, terrestrial mammals. We evaluated performance of two types of micro-GPS (< 20 g) receivers (traditional and snapshot) on a small, semi-fossorial lagomorph, the pygmy rabbit (Brachylagus idahoensis), to understand how GPS errors might influence fine-scale assessments of space use and habitat selection. During stationary tests, microtopography (i.e., burrows) and satellite geometry had the largest influence on GPS fix success rate (FSR) and location error (LE). There was no difference between FSR while animals wore the GPS collars above ground (determined via light sensors) and FSR generated during stationary, above-ground trials, suggesting that animal behavior other than burrowing did not markedly influence micro-GPS errors. In our study, traditional micro-GPS receivers demonstrated similar FSR and LE to snapshot receivers, however, snapshot receivers operated inconsistently due to battery and software failures. In contrast, the initial traditional receivers deployed on animals experienced some breakages, but a modified collar design consistently functioned as expected. If such problems were resolved, snapshot technology could reduce the tradeoff between fix interval and battery life that occurs with traditional micro-GPS receivers. Our results suggest that micro-GPS receivers are capable of addressing questions about space use and resource selection by small mammals, but that additional techniques might be needed to identify use of habitat structures (e.g., burrows, tree cavities, rock crevices) that could affect micro-GPS performance and bias study results.
authors.affiliation: Department of Fish and Wildlife Sciences, University of Idaho, Moscow, Idaho, United States of America.
authors.forename: Laura A
authors.identifier: http://orcid.org/0000-0003-0521-9530
authors.initials: LA
authors.lastname: McMahon
authors.affiliation: Department of Fish and Wildlife Sciences, University of Idaho, Moscow, Idaho, United States of America.
authors.forename: Janet L
authors.initials: JL
authors.lastname: Rachlow
authors.affiliation: School of the Environment, Washington State University, Pullman, Washington, United States of America.
authors.forename: Lisa A
authors.initials: LA
authors.lastname: Shipley
authors.affiliation: Department of Biological Sciences, Boise State University, Boise, Idaho, United States of America.
authors.forename: Jennifer S
authors.initials: JS
authors.lastname: Forbey
authors.affiliation: Department of Statistical Science, University of Idaho, Moscow, Idaho, United States of America.
authors.forename: Timothy R
authors.initials: TR
authors.lastname: Johnson
authors.affiliation: School of the Environment, Washington State University, Pullman, Washington, United States of America.
authors.forename: Peter J
authors.initials: PJ
authors.lastname: Olsoy
mesh_terms: D025041:Animal Migration; D000818:Animals; D040362:Geographic Information Systems; D007061:Idaho; D007793:Lagomorpha / Q000502:physiology*