Abstract
BackgroundDespite the increasing worldwide use of global positioning system (GPS) telemetry in wildlife research, it has never been tested on any freshwater diving animal or in the peculiar conditions of the riparian habitat, despite this latter being one of the most important habitat types for many animal taxa. Moreover, in most cases, the GPS devices used have been commercial and expensive, limiting their use in low-budget projects.Methodology/Principal FindingsWe have developed a low-cost, easily constructed GPS GSM/GPRS (Global System for Mobile Communications/General Packet Radio Service) and examined its performance in stationary tests, by assessing the influence of different habitat types, including the riparian, as well as water submersion and certain climatic and environmental variables on GPS fix-success rate and accuracy. We then tested the GPS on wild diving animals, applying it, for the first time, to an otter species (Lutra lutra). The rate of locations acquired during the stationary tests reached 63.2%, with an average location error of 8.94 m (SD = 8.55). GPS performance in riparian habitats was principally affected by water submersion and secondarily by GPS inclination and position within the riverbed. Temporal and spatial correlations of location estimates accounted for some variation in the data sets. GPS-tagged otters also provided accurate locations and an even higher GPS fix-success rate (68.2%).Conclusions/SignificanceOur results suggest that GPS telemetry is reliably applicable to riparian and even diving freshwater animals. They also highlight the need, in GPS wildlife studies, for performing site-specific pilot studies on GPS functioning as well as for taking into account eventual spatial and temporal correlation of location estimates. The limited price, small dimensions, and high performance of the device presented here make it a useful and cost-effective tool for studies on otters and other aquatic or terrestrial medium-to-large-sized animals.
Highlights
Continuous improvements in component technologies, combined with price reductions for Global Positioning System (GPS) devices is resulting in their increase use for animal tracking [1,2] and often preferred to traditional very high frequency (VHF) telemetry [3]
It is surprising that, to date, the performance of global positioning system (GPS) devices used in wildlife telemetry has never been tested in a riparian habitat, despite it being one of the habitat types most commonly used by many animal taxa [11,12]
The wide applicability and benefits of GPS technologies in wildlife telemetry are increasingly cited in the literature [2,9]
Summary
Continuous improvements in component technologies, combined with price reductions for Global Positioning System (GPS) devices is resulting in their increase use for animal tracking [1,2] and often preferred to traditional very high frequency (VHF) telemetry [3]. It is surprising that, to date, the performance of GPS devices used in wildlife telemetry has never been tested in a riparian habitat, despite it being one of the habitat types most commonly used by many animal taxa [11,12] The existence of such gap is still more noticeable considering that intense canopy closure, one of the basic constituents of riparian vegetation galleries, has been identified as one of the major causes of GPS failure [4,5,13]. Inferences from studies on habitat selection by riparian animals (or animals that intensively use such a habitat type) tagged via GPS devices may yield biased results Such biases could be even more pronounced in the case of diving animals, as repeated water submersion could interfere with proper GPS functioning. In most cases, the GPS devices used have been commercial and expensive, limiting their use in low-budget projects
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