Performance of GPS units for deployment on semiaquatic animals

Abstract

Global Positioning System (GPS) technology is widely used in wildlife research to study animal movement and habitat use. In order to evaluate the quality and reliability of GPS data, the factors influencing the performance of these devices must be known, especially for semiaquatic species, because terrestrial and aquatic habitat might affect GPS performance differently. We evaluated the location error and fix success rate of three GPS receiver models in stationary tests and on a semi-aquatic mammal, the Eurasian beaver (Castor fiber). The location error during stationary tests was on average 15.7 m, and increased with increasing canopy closure, slope, and horizontal dilution of precision, potentially leading to the erroneous classification of GPS positions when studying habitat use in animals. In addition, the position of the GPS antenna (flat versus 90° tilted) affected the location error, suggesting that animal behavior affects GPS performance. The fix success rate was significantly higher during stationary tests compared to when GPS units were deployed on beavers (94% versus 86%). Further, GPS receivers did not obtain any positions underwater and underground, the latter potentially allowing the estimation of activity periods in animals that use lodges or burrows as shelter. We discuss the possibilities for data screening, the use of buffer zones along the shoreline, and combination with other data loggers to avoid the erroneous classification of GPS positions when studying habitat use.

Causes and consequences of inverse density‐dependent territorial behaviour and aggression in a monogamous mammal

“…Additionally, we used a 25‐m buffer radius around each ESM location (hereafter 'ESM area', Figure ). The buffer radius of 25 m was chosen to account for GPS inaccuracy (Schlippe Justicia, Rosell, & Mayer, ). Lastly, we calculated the straight line distance between consecutive GPS positions, defined as distance moved (m per 15 min).…”

Design of Unmaned Surfaces Vehicle System Based on Coordinates and Internet of Things for Semi Automatic Shrimp Feeding

“…Meanwhile, digital devices, such as GPS (Global Positioning System), are able to retrieve ship locations by relying on signals from satellites rotating around the earth [8]. GPS accepts data in the NMEA 0183 format, which is the standard for transmitting marine navigation data, including information such as latitude, longitude, altitude, and time [9]…”

Decision rules for determining terrestrial movement and the consequences for filtering high-resolution global positioning system tracks: a case study using the African lion (Panthera leo)

“…Many factors affect GPS performance, including habitat type and heterogeneity [30–33], topography of the terrain [34,35], clear sky availability [36], weather conditions [31], submersion in water [37,38], time of day [39], vegetation cover/type [34,40], GPS orientation [41] and fix acquisition rate [42,43], in addition to the number of available satellites and their orbiting geometry with respect to one another [44,45]. All these elements affect the propagation of signal quality and/or receiver reception capability and thus increase triangulation error (see Hofman et al [4] for review), often assessed via the dilution of precision (DOP) values [45,46].…”

“…We note that since GPS ‘jitter' (a term we use to define fixes inaccurately fluctuating around a central location) is disproportionately high during stationary periods [38,42,47] the viability of deriving accurate movement from high-resolution GPS trajectories depends on the ability to determine when an animal is moving or not in a manner that is independent of the GPS-derived movement. Studies have already used acceleration to activate GPS units only during movement, both as a means to increase battery longevity and to avoid the fix inaccuracy prevalent during periods of inactivity [53,62].…”