Reduced human disturbance increases diurnal activity in wolves, but not Eurasian lynx

Abstract

Wildlife in the Anthropocene is increasingly spatially and temporally constrained by lethal and non-lethal human disturbance. For large carnivores with extensive space requirements, like wolves and Eurasian lynx, avoiding human disturbance in European landscapes is challenging when sufficient space with low disturbance is rarely available. Consequently, investigating behavioural adjustments to human presence is critical to understanding the capacity to adapt to human disturbance. We hypothesised that under low human disturbance conditions, large carnivores would adjust their temporal behaviours to make use of daytime, and when daytime human disturbance is high, they would opt for nocturnality. Using camera trap data from nine European study sites along a gradient in human disturbance, we analysed wolf and Eurasian lynx activity patterns. Our data spanned multiple years, 2014 – 2022, and we focused our analysis on September until April, when most large carnivore monitoring takes place. For wolves, our analysis revealed i) increased nocturnal behaviour, ii) decreased diurnal overlap with increasing human activity, and iii) a significant association between a higher probability of nocturnal activity and increasing human disturbance. For Eurasian lynx, we found iv) consistently nocturnal behaviours across all study sites, regardless of human disturbance, and v) no association between human disturbance and increased probability of being active during the night. Our results show that wolves can adjust to diurnal or cathemeral behaviours under low human disturbance, but shift to nocturnality when human disturbance increases. Eurasian lynx, however, consistently maintain their nocturnal behaviour, which we attribute to their principal hunting strategy of stalk and ambush. If human disturbance constrains large carnivore activity to nighttime, it could influence their interactions with prey, leading to cascading effects in the ecosystem. On the other hand, maintaining nocturnal behaviours in human-dominated landscapes may benefit large carnivore conservation, by decreasing negative interactions with humans thereby contributing to a landscape of coexistence.