Relationship between hydrology and the activity of an endangered semi-aquatic mammal, the Pyrenean desman ( <i>Galemys pyrenaicus</i> )

Abstract This study aimed at understanding the effects of hydrology on the activity pattern of the Pyrenean desman. Fourteen individuals were monitored by radiotracking in six rivers having different hydrology. Several metrics describing aquatic activity were assessed to study variability among individuals. First, whatever hydrology, individuals had a similar average daily activity. Individuals which experienced the greatest variations in flow during monitoring and which were radiotracked in autumn tended to be more or less active depending on days. Second, several patterns of activity were observed. Individuals monitored at a flow value close to the mean annual flow in summer tended to be mainly active at night and to travel a larger distance along the river. Individuals monitored during periods of low or high flows tended to be more active during daytime and to travel smaller distance. Finally, some individuals had consistent daily activity throughout the monitoring period, while others showed some variability. These differences are not related to hydrology or other variables studied but the highest intra-individual variabilities were observed during significant flow variations. These findings provide new information on the ecology of the Pyrenean desman and will help to improve management and conservation actions.