Although it has been demonstrated that European roe deer ( Capreolus capreolus (L. 1758)) may migrate seasonally in areas with snow gradients, this behaviour remains scarcely understood. From 1999 to 2002, radio-tracking techniques in an Italian alpine area showed that 40% of the 32 monitored roe deer migrated (12.0 ± 6.2 km, mean ± SD) from the high-elevation summer ranges to the low-elevation winter ranges. Proportions of migratory deer were similar for fawns and adults and for males and females. We documented a mixed migration strategy, with most deer migrating once to the winter range in years of heavy snowfalls, but many deer migrating inconsistently or only for a short period to the winter range in one year with very scarce snowfalls. Seasonal home-range sizes were similar for migratory and stationary deer, except in a winter with very shallow snow when migrators used unusually large home ranges. In all seasons, migrators showed a lower within home range site fidelity than did stationary deer. Our results indicate that seasonal migrations may be a common strategy exhibited by roe deer living in mountain areas to avoid deep snow, and that variability in climatic conditions might be responsible for the development of variable spatial strategies.