Partial migration in roe deer

We studied partial migrations in the European roe deer (Capreolus capreolus), a species particularly suited for such a study, due to a wide distribution range and a high level of ecological plasticity and adaptation to human-induced environmental changes. We undertook a comparative analysis of a set of representative and contrasting European ecosystems (boreal, boreo-nemoral, alpine, central European and sub-Mediterranean), using a dataset of about 100 individuals tracked for at least 1 year, using GPS collars. One of the main finding was the relevance of intermediate migratory behaviour, i.e. many animals performed numerous trips back and forth between winter and summer areas before taking a final decision and stabilize their range. The migration process resulted highly inter- and intra-individually variable, where the “classic” partial migration alternatives (residents and sharp migrants) were only the extremes of a highly complex behavioural gradient. The probability of adopting a migratory strategy, and sharp migrations in particular, depended on modulation by external factors, and in particular by the presence of snow, and on costs of displacement. The behavioural migratory gradient seemed therefore an expression of ecological plasticity and quick adaptation to climatic variation. However, migration patterns differed a lot between males and females, providing evidence that sex-specific adaptations also play a role in shaping the movement tactics of roe deer