EFFECTS OF SPATIOTEMPORAL SCALE ON AUTOCORRELATION AND HOME-RANGE ESTIMATORS

We compared 3 home range estimators (kernel estimator [Kernel], multip le polygons by clustering [Cluster], and minimum convex polygon [MCP]) and evaluated a measure of autocorrelation (Schoener's ratio). with r espect to the effects of sampling frequency, spatial resolution of the sampling reference grid, and sample size, We also used Schoener's rat io as a descriptor of within home range movements. An extensive datase t from radiotracking of root voles (Microtus occonomus) formed the bas is for these comparisons, The degree of autocorrelation was sex specif ic. In particular, locations of reproductive females were significantl y autocorrelated for a sampling interval equal to the period of the po pulation's ultradian activity rhythm, indicating territory patrolling behavior in this ser. We assessed the effect of spatial resolution of animal location data on home range descriptors by manipulating the cel l size of the sampling reference grids. The Kernel estimator was robus t to changes in spatial resolution of the data. In contrast, tile poly gon estimates were severely biased upwards with decreasing spatial res olution (increasing grid cell size). Therefore, comparative studies ba sed on polygon methods must use the same spatial resolution. The sampl ing frequency affected all estimators, but qualitative differences wer e found among tile specific estimators, Numerical resampling methods i ndicated that home range sizes were underestimated, and that the preci sion of the estimators was generally low.