Seasonal and Diurnal Variation in Habitat Overlap of Roe Deer and Eurasian Lynx in a Human-Dominated Landscape
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- Institutt for biologi 
Predators affect prey directly (lethally), and indirectly (non-lethally), by altering their behaviour as they try to maximise habitat overlap with prey. Prey, on the other hand, are trying to minimise habitat overlap with predators by altering their spatial behaviour, often in a fine-scaled temporally-explicit manner. In a human-dominated world, humans also alter the landscape of fear of both predators and prey, whereas prey have to deal with predation risks from multiple sources. In southern Norway, roe deer is the main prey for lynx, and both roe deer and lynx face mortality risks from humans. Lynx are stalk-and-ambush predators that have highest activity at dusk and night, whereas mortality risks from humans and human hunters are higher by day in open areas with good visual sight. Thus, roe deer face mortality risks from multiple sources that are non-overlapping in space and time. I examined how habitat overlap between roe deer and lynx varied in seasonal and diurnal temporal scales in southern Norway. Data was collected during the period 2005-2013 from Global Positioning System (GPS)-collars of 47 roe deer (27 females and 20 males) and 18 lynx (7 females and 11 males) with overlapping home ranges. I used an ecological niche factor analytical approach to obtain four uncorrelated environmental axes that explained most of the variation in the data. These axes were used as dependent variables in linear regressions to analyse habitat use and total niche distance between species in relation to seasons, photoperiods (day, night and twilight) and sex.I found that total niche distance between roe deer and lynx was smallest by day (except in winter) and largest at twilight, in winter and between female roe deer and lynx compared to male roe deer and lynx. These findings suggests that diurnal variation in habitat overlap between roe deer and lynx seemed to be driven by predation risks as both species lowered their potential mortality risks by temporally shifting habitats with low and high risk, whereas fluctuations in high-quality food distribution seemed to drive changes in habitat overlap between seasons. These patterns were more pronounced in females compared to males, but in different ways which were dependent on the species-specific ecology. This study have documented seasonal and diurnal variation in habitat overlap of predators and prey in a human-dominated world.