Effects of spatiotemporal scale on autocorrelation and home range estimators

We compared 3 home range estimators (kernel estimator [Kernel], multiple polygons by clustering [Cluster], and minimum convex polygon [MCP]) and evaluated a measure of autocorrelation (Schoener's ratio). with respect to the effects of sampling frequency, spatial resolution of the sampling reference grid, and sample size, We also used Schoener's ratio as a descriptor of within home range movements. An extensive dataset from radiotracking of root voles (Microtus occonomus) formed the basis for these comparisons, The degree of autocorrelation was sex specific. In particular, locations of reproductive females were significantly autocorrelated for a sampling interval equal to the period of the population'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 cell size of the sampling reference grids. The Kernel estimator was robust to changes in spatial resolution of the data. In contrast, the polygon estimates were severely biased upwards with decreasing spatial resolution (increasing grid cell size). Therefore, comparative studies based on polygon methods must use the same spatial resolution. The sampling frequency affected all estimators, but qualitative differences were found among the specific estimators, Numerical resampling methods indicated that home range sizes were underestimated, and that the precision of the estimators was generally low.