Sampling Animal Movement Paths Causes Turn Autocorrelation
- 328 Downloads
Animal movement models allow ecologists to study processes that operate over a wide range of scales. In order to study them, continuous movements of animals are translated into discrete data points, and then modelled as discrete models. This discretization can bias the representation of the movement path. This paper shows that discretizing correlated random movement paths creates a biased path by creating correlations between successive turning angles. The discretization also biases statistical tests for correlated random walks (CRW) and causes an overestimate in distances travelled; a correction is given for these biases. This effect suggests that there is a natural scale to CRWs, but that distance-discretized CRWs are in a sense, scale invariant. Perhaps a new null model for continuous movement paths is needed. Authors need to be aware of the biases caused by discretizing correlated random walks, and deal with them appropriately.
KeywordsCorrelated random walk Discretization Bias Scale-free
This research was funded by the Natural Sciences and Engineering Research Council of Canada. I thank Simon Benhamou and Alex Georgallas for useful comments.
- Edenius L (1997) Field test of a GPS location system for moose Alces alces under Scandinavian boreal conditions. Wildl Biol 3:39–43Google Scholar
- Heisswolf A, Ulmann S, Obermaier E, Mitesser O, Poethke H (2007) Host plant finding in the specialised leaf beetle Cassida canaliculata: an analysis of small-scale movement behaviour. Ecol Entomol 32:194–200Google Scholar
- Turchin P (1998) Quantitative analysis of movement. Sinauer, SunderlandGoogle Scholar
- Turchin P, Odendaal FJ, Rausher MD (1991) Quantifying insect movement in the field. Environ Entomol 20:955–963Google Scholar