Global positioning system (GPS) radiotelemetry has become an important wildlife research technique, but quantifying and addressing error and bias in resultant data requires additional work.
SGRC Lead Researchers: Dr. Rob D’Eon and Donna Delparte
This project addressed the effects of collar position (angle relative to the sky or horizon) and orientation (compass direction) on GPS-radiocollar performance by varying the position and orientation of five stationary GPS-radiocollars in southeast British Columbia.
The use of PDOP (positional dilution of precision) was also investigated as a method for screening data with high location errors. Orientation had no statistical effect on fix rates or location errors. The biggest source of variation was attributed to collar position which resulted in significantly lower performance at low angles. PDOP-based screening can be used to lower location error, but consideration of the trade-off between higher location accuracy and data loss (potentially leading to new bias) must be made. The research establishes the recommendation that orientation can safely be disregarded as a potential source of bias, but collar position remains one of the largest potential sources of bias and error and has large implications regarding animal activity and GPS-radiotelemetry research.
Related Publication: Effects of radio-collar position and orientation on GPS radio-collar performance, and the implications of PDOP in data screening, Journal of Applied Exology, Vol 42, 2005.