Living on the edge - circadian habitat usage in pre-weaning European hares (Lepus europaeus) in an intensively used agricultural area

Over the last decades, the European hare (Lepus europaeus) has become the subject of many interdisciplinary studies due to the sharp Europe-wide population decline. In European hares, the first stage of life until weaning and the subsequent dispersal have been sparsely studied, in particular, habitat selection, movements and survival rate, as juveniles´ precocial lifestyle is dominated by concealment, motionlessness and inconspicuousness. In this study, free-living juvenile European hares (leverets) were detected systematically by thermography (n = 394), radio-tagged or marked (n = 122) from birth until the fifth week of life to research their habitat usage and pre-dispersal movements. The day-resting places and night locations, as well as the distance moved by leverets with aging, were evaluated by generalized linear mixed effect models. In addition, the habitat preference was assessed by a conservative use-availability analysis. Up to the fifth week of life, 30.5% of all leverets used cultivated areas in the daytime. In contrast, the remaining 69.4% animals inhabitated linear or small planar structures in the daytime, with the edges of field tracks, hedges and some ruderal structures clearly being preferred. At nighttime, 93% of all juveniles, which occupied linear structures in the daytime, used the adjoining fields up to 20 m away from the next linear structure. Nocturnal distances of more than 60 m to the next edge rarely occurred before the end of the pre-weaning phase. The time of day and age have a significant influence on the distance moved by juvenile hares. With increasing age, leverets moved less during the day and roamed further at night. The results are largely consistent with the behavioral patterns found in the few previous studies on pre-weaning European hares and show the importance of hiding places for leverets in early life stages. This study should contribute to a better understanding of behavior in juvenile life-history stages of European hares that may help to identify vulnerable phases in their lifecycle. In addition, the findings can refine existing population models and improve conservation efforts.