GPS Measurement Error Gives Rise to Spurious 180° Turning Angles and Strong Directional Biases in Animal Movement Data
Open Access
- 20 May 2009
- journal article
- research article
- Published by Public Library of Science (PLoS) in PLOS ONE
- Vol. 4 (5), e5632
- https://doi.org/10.1371/journal.pone.0005632
Abstract
Movement data are frequently collected using Global Positioning System (GPS) receivers, but recorded GPS locations are subject to errors. While past studies have suggested methods to improve location accuracy, mechanistic movement models utilize distributions of turning angles and directional biases and these data present a new challenge in recognizing and reducing the effect of measurement error. I collected locations from a stationary GPS collar, analyzed a probabilistic model and used Monte Carlo simulations to understand how measurement error affects measured turning angles and directional biases. Results from each of the three methods were in complete agreement: measurement error gives rise to a systematic bias where a stationary animal is most likely to be measured as turning 180° or moving towards a fixed point in space. These spurious effects occur in GPS data when the measured distance between locations is <20 meters. Measurement error must be considered as a possible cause of 180° turning angles in GPS data. Consequences of failing to account for measurement error are predicting overly tortuous movement, numerous returns to previously visited locations, inaccurately predicting species range, core areas, and the frequency of crossing linear features. By understanding the effect of GPS measurement error, ecologists are able to disregard false signals to more accurately design conservation plans for endangered wildlife.Keywords
This publication has 35 references indexed in Scilit:
- Effects of habitat on GPS collar performance: using data screening to reduce location errorJournal of Applied Ecology, 2007
- GPS measurement error and resource selection functions in a fragmented landscapeEcography, 2006
- GPS MEASUREMENT ERROR INFLUENCES ON MOVEMENT MODEL PARAMETERIZATIONEcological Applications, 2005
- Fine-Scale Tracking of Marine Turtles Using GPS-Argos PTTsZoological Science, 2005
- The three-dimensional flight of red-footed boobies: adaptations to foraging in a tropical environment?Proceedings Of The Royal Society B-Biological Sciences, 2005
- Estimating Cougar Predation Rates from GPS Location ClustersThe Journal of Wildlife Management, 2003
- A Multicriteria Assessment of the Irreplaceability and Vulnerability of Sites in the Greater Yellowstone EcosystemConservation Biology, 2002
- Caribou movement as a correlated random walkOecologia, 2000
- A landscape simulation model of winter foraging by large ungulatesEcological Modelling, 1993
- Satellite Telemetry: Performance of Animal-Tracking SystemsThe Journal of Wildlife Management, 1991