Interactions among coexisting mesocarnivores can be influenced by different factors such as the presence of large carnivores, land-use, environmental productivity, or human disturbance. Disentangling the relative importance of bottom-up and top-down processes can be challenging, but it is important for biodiversity conservation and wildlife management. The aim of this study was to assess how the interactions among mesocarnivores (red fox Vulpes vulpes, badger Meles meles, and pine marten Martes martes) are affected by large carnivores (Eurasian lynx Lynx lynx and wolf Canis lupus), land cover variables (proportion of agricultural land and primary productivity), and human disturbance, as well as how these top-down and bottom-up mechanisms are influenced by season. We analyzed three years (2018-2020) of camera trapping data from Norway and used structural equation models to assess hypothesized networks of causal relationships. Our results show that land cover variables are stronger predictors of mesocarnivore activity than large carnivores in Norway. This might be caused by a combination of low density of large carnivores in an unproductive ecosystem with strong seasonality. Additionally, all mesocarnivores showed positive interactions among each other, which were stronger in winter. The prevalence of positive interactions among predators might indicate a tendency to use the same areas and resources combined with weak interference competition. Alternatively, it might indicate some kind of facilitative relationship among species. Human disturbance had contrasting effects for different species, benefiting the larger mesocarnivores (red fox and badger) probably through food subsidization, but negatively affecting apex predators (wolf and lynx) and smaller mesocarnivores (pine marten). In a human-dominated world, this highlights the importance of including anthropogenic influences in the study of species interactions.

Giorgia Ausilio

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Spatial patterns of human hunting and predation risk are mediated by the physical landscape, with human hunting risk often associated with habitat features contrasting those linked to risk from large carnivores. Risk patterns from hunters and large carnivores can also vary in time, which may allow prey species to adjust anti-predator strategies not only in risky places but also during risky times. We examined whether moose (Alces alces) in south-central Scandinavia adjusted diel habitat selection during and after the hunting season in response to contrasting human hunting and wolf (Canis lupus) predation risks. We found evidence for a diel and seasonal shift in habitat selection of moose consistent with a behavioural adaptation to no human hunting risk at night and after the hunting season. We found no evidence that moose responded to the spatiotemporal variation in wolf predation risk since moose selected habitats of high wolf predation risk both day and night during and after the hunting season. Human hunting risk was therefore the main driver of moose habitat selection during the hunting season while decreasing in importance during times when hunting did not occur. However, since we did not find evidence for a diel or seasonal shift in habitat selection consistent with an increase in the importance of wolf predation risk during the night and after the hunting season, our study is in line with the notion that moose in Scandinavia are currently naïve to wolves. Our findings show the importance of including the effects of humans in studies of predator-prey dynamics within anthropogenic landscapes. An increased understanding of the risk effects arising from humans and large carnivores and the responses of prey might be important for managing ungulate populations, since behaviours aimed at reducing exposure to risk may also affect crucial demographic traits like growth and reproduction.