Possible use of environmental gradients in orientation by homing wood mice, Apodemus sylvaticus.

51 wood mice, Apodemus sylvaticus, tagged with chemoluminescent bulbs, were visually tracked in a series of night homing experiments. The mice did not go straight towards home, but wandered around the release area and covered distances equal to twice the radial lengths recorded. In the course of their walk, they orientated preferentially towards landscapes which resembled their usual habitat, irrespective of where their actual homeward direction lay. In spite of the randomness of their paths, homing success was good, but detailed analysis of homing time showed that the homing performances of the mice depended on the direction in which they vanished in the course of the observation period. The good fit of observed orientations with those obtained by computer simulation of klinokinesis along an axial gradient, and field observation of a vegetational gradient in the study area, are both consistent with the hypothesis that homing may have resulted from wandering, locally biased by a klinokinetic effect.