How red backed voles find habitat patches

The purpose of this study was to discover how red-backed voles (Clethrionomys gapperi pallescens) found preferred habitat patches. Two hypotheses tested were that voles discover habitat patches by chance, and that they perceive them from a distance and travel towards them. The distance at which voles detected a wooded habitat was determined by measuring the accuracy of orientation at different distances. Animals were released in an unfamiliar grassland at one of five distances (0-20 m) from the boundary of an adjacent unfamiliar woodland and tracked using the spool and line technique. At all distances, the voles oriented towards the woods. However, their reaction was much weaker at greater distances. Thus, reaction to the woodland was not an "all or nothing response": the closer the voles came to the woods, the straighter were their paths and the more directly they oriented towards the woods. This adds to our understanding of how habitat fragmentation affects voles. A between-patch distance of 20 m does not completely isolate red-backed voles, but a distance equivalent to a home-range diameter (60-70 m) likely would.