Partial Migration or Just Habitat Selection? Seasonal Movements of Roe Deer in an Alpine Population

Abstract

The European roe deer (Capreolus capreolus) responds to environmental conditions that vary in time and space across its distributional range, generating many different space use patterns. To test the expectation that variation in movement patterns should track changes in environmental conditions, we used the net squared displacement metric to identify the factors shaping observed movement patterns of roe deer in the French Alps. Based on 5 years of data from 25 radiomonitored roe deer (54 individual-years), we found that movements were longest in spring and summer when the normalized difference vegetation index (NDVI) was higher and shortest in autumn and winter when NDVI was lower and snow cover was present. Roe deer displayed long displacements toward high elevations with gentle slope when the NDVI was higher. The higher quality food resources at higher elevations may have compensated for the energy costs of those movements. Contrary to previous studies on roe deer in mountain ranges, we showed that roe deer movements in the northern French Alps should be interpreted as within home range habitat selection (48 cases; 89%) rather than as partial migration because very few deer (6 cases; 11%) stabilized their activity in distinct home ranges across seasons.