While constrained by endogenous rhythms, morphology and ecology, animals may still exhibit flexible activity patterns in response to risk. Temporal avoidance of interspecific aggression can enable access to resources without spatial exclusion. Apex predators, including humans, can affect mesopredator activity patterns. Human context might also modify temporal interactions between predators. We explored activity patterns, nocturnality and the effects of human activity upon a guild of carnivores (grey wolf, Canis lupus; Eurasian lynx, Lynx lynx; red fox, Vulpes vulpes) using travel routes in Plitvice Lakes National Park, Croatia. Humans were diurnal, foxes nocturnal and large carnivores active during the night, immediately after sunrise and before sunset. Carnivore activity patterns overlapped greatly and to a similar extent for all pairings. Activity curves followed expectations based on interspecific killing, with activity peaks coinciding where body size differences were small (wolf and lynx) but not when they were intermediate (foxes to large carnivores). Carnivore activity, particularly fox, overlapped much less with that of diurnal humans. Foxes responded to higher large carnivore activity by being more nocturnal. Low light levels likely provide safer conditions by reducing the visual detectability of mesopredators. The nocturnal effect of large carnivores was however moderated and reduced by human activity. This could perhaps be due to temporal shielding or interference with risk cues. Subtle temporal avoidance and nocturnality may enable mesopredators to cope with interspecific aggression at shared spatial resources. Higher human activity moderated the effects of top-down temporal suppression which could consequently affect the trophic interactions of mesopredators. Temporal partitioning can provide an important mechanism for spatial resource access and species coexistence. Our findings show that carnivores partition the use of shared travel routes in time, using the cover of darkness to travel safely where their suppressors (large carnivores) are more active. We however observed fox nocturnality to be flexible, with responses depending on the activity levels but also the composition of apex predators. High human activity modified the top-down temporal suppression of mesopredators by large carnivores. The use of time by predators can have demographic and trophic consequences. Prey accessibility and susceptibility can be temporally variable. As such, the ecosystem services and the ecological roles of predators may be affected by human time use as well as that of intraguild competitors. Temporal interactions should not be overlooked when evaluating human use and conservation priorities in protected areas.

中文翻译：

---

怕黑？食肉动物通过夜间活动减轻大型食肉动物的风险，但人类会缓和互动

尽管受到内源性节律、形态和生态的限制，动物仍可能表现出灵活的活动模式以应对风险。对种间侵略的暂时避免可以在没有空间排斥的情况下访问资源。包括人类在内的顶级掠食者会影响中掠食者的活动模式。人类环境也可能会改变捕食者之间的时间相互作用。我们使用克罗地亚十六湖国家公园的旅行路线探索了活动模式、夜间活动以及人类活动对食肉动物行会（灰狼、犬狼疮；欧亚猞猁、猞猁猞猁；红狐、Vulpes vulpes）的影响。人类白天活动，狐狸夜间活动，大型食肉动物在夜间、日出后和日落前活动。食肉动物的活动模式在所有配对中都有很大的重叠和相似的程度。活动曲线遵循基于种间杀戮的预期，活动峰值与体型差异较小的地方（狼和猞猁）一致，但在中间（狐狸到大型食肉动物）时则不同。食肉动物的活动，尤其是狐狸，与昼夜活动的人类活动的重叠要少得多。狐狸通过在夜间活动来应对大型食肉动物的活动。低光照水平可能会通过降低中掠食者的视觉可探测性来提供更安全的条件。然而，大型食肉动物的夜间活动受到人类活动的影响和减弱。这可能是由于时间屏蔽或对风险提示的干扰。微妙的时间回避和夜间活动可能使 mesopredators 应对共享空间资源的种间侵略。较高的人类活动缓和了自上而下的时间抑制的影响，这可能因此影响中食肉动物的营养相互作用。时间分区可以为空间资源获取和物种共存提供重要机制。我们的研究结果表明，食肉动物会及时划分共享旅行路线的使用，利用黑暗的掩护安全地旅行到它们的抑制器（大型食肉动物）更活跃的地方。然而，我们观察到狐狸的夜间活动是灵活的，其反应取决于活动水平以及顶级捕食者的组成。高人类活动改变了大型食肉动物对食肉动物的自上而下的时间抑制。捕食者对时间的利用会产生人口和营养方面的后果。猎物的可及性和易感性可以随时间变化。因此，生态系统服务和捕食者的生态作用可能会受到人类时间使用以及行业内竞争者的影响。在评估保护区的人类利用和保护优先事项时，不应忽视时间上的相互作用。