The accuracy of GPS for wildlife telemetry and habitat mapping

Abstract

Summary1. Decision support tools used for vegetation management require accurate information on the spatial array of different plant communities and a herbivore's grazing location. We tested the accuracy and precision of locations derived using the satellite navigation global positioning system (GPS). 2. Before May 2000, the accuracy and precision of GPS-derived locations were degraded by a process known as selective availability (SA); after May 2000, SA was disabled. In this study we investigated how to handle and improve the quality of data generated both when SA was enabled and when SA was disabled using relative GPS (rGPS). rGPS entails the post-processed correction of the roving GPS module with simultaneously acquired positional errors recorded at a known stationary reference location. 3. With SA enabled, GPS data were obtained at a fixed known location to obtain baseline information, and from a roving module that essentially mimicked surveying techniques or the movement of a free-ranging animal. The mean accuracy of GPS with SA enabled was 21 m for the fixed module and 25 m for the roving module. Use of rGPS and further manipulation of the data improved the mean accuracy of the data to 7 m for the fixed module and 10 m for the roving module. With SA disabled, data were similarly recorded from the fixed known location and resulted in a mean location accuracy of 5 m. The use of rGPS resulted in a significant improvement of this value to 3·6 m and precision measured by the 95% quantile was < 10 m. For mapping and wildlife tracking, such quality in terms of location accuracy and precision is unprecedented and demonstrates that rGPS may still be useful in many applications. 4. GPS enables the world-wide collection of accurate and precise location information at 1-second intervals. Furthermore, by programming the GPS receiver to overdetermine location by using information from all visible satellites, many of the limitations that arise in habitats or environments with a limited view of the sky may be overcome. 5. With SA now disabled, the potential use of GPS will increase. With further miniaturization, surveying of remote featureless landscapes or the tracking of crepuscular or far-ranging animals will become more accurate and more quantifiable than ever before.

Technological innovation in archival tags used in seabird research

“…Weimers kirch et al 1992, Brothers et al 1998, Wilson et al 2002b). These 2 limitations have now been largely mitigated by global positioning systems (GPS) which derive the tag position using radio-waves from orbiting satellites (von Hünerbein et al 2000, Hulbert & French 2001. Calculated bird positions are good to within a few metres (Grémillet et al 2004) and updated positions can be derived at any time, except when the bird is underwater.…”

Habitat Selection by Grazing Animals in Heterogeneous Environments: The Case of Hill Sheep In Western Ireland

“…Compared with field observations and manual mapping techniques, advantages of current GPS tracking techniques include minimizing human disturbance, higher recording frequencies and numbers of records, increased location accuracy, superior recording success rates (i.e. when study animals are obscured from surveyors' view) and absence of recorder bias (Hulbert and French 2001).…”

“…Global Positioning System (GPS) collars offer an efficient method for collecting data on resource use by animals (Hulbert and French 2001;Davidson-Watts et al 2006;Thomas et al 2008). GPS collars have recently been used to investigate habitat selection by lowland sheep on shrubby rangeland in Argentina (Bertiller and Ares 2008) and grassland in Germany (Putfarken et al 2008).…”

“…GPS collars have recently been used to investigate habitat selection by lowland sheep on shrubby rangeland in Argentina (Bertiller and Ares 2008) and grassland in Germany (Putfarken et al 2008). Locations of hill sheep have previously been tracked using GPS devices to investigate accuracy of GPS data, home ranges, circadian rhythm and bite rates and classification of behaviour categories (Roberts et al 1995;Rutter et al 1997;Hulbert et al 1998;Hulbert and French 2001;Umstätter et al 2008) but not habitat selection. Compared with field observations and manual mapping techniques, advantages of current GPS tracking techniques include minimizing human disturbance, higher recording frequencies and numbers of records, increased location accuracy, superior recording success rates (i.e.…”

An accuracy assessment of global navigation wildlife-tracking collars in the southern clilean Patagonia

“…the position, of an object of interest) in terrestrial vertebrate wildlife research is that, without human monitoring or manipulation, GNSS can provide accurate positioning information on wildlife at any time, in any weather condition, and at any place (Samuel & Fuller 1996, Spilker 1996a, Friar et al 2004. Satellite-based positioning is considered especially useful for species that are hard-to-see, nocturnal, or live in remote or rugged terrain because receivers can be programmed to automatically collect many positions over long time periods without human direction (Hulbert & French 2001). Under ideal conditions, positions should meet the + / -15-meter accuracy claims of the GNSS collar manufacturers (Samuel & Fuller 1996, Hebblewhite et al 2007, Villepique et al 2008.…”