Bottom-up rather than top-down mechanisms determine mesocarnivore interactions in Norway

Area of Science:

• Ecology
• Wildlife Conservation
• Behavioral Ecology

Background:

• Mesocarnivore interactions are shaped by factors like large carnivores, land use, and human activity.
• Understanding these dynamics is crucial for biodiversity conservation and wildlife management.
• Differentiating between bottom-up and top-down ecological processes is challenging but important.

Purpose of the Study:

• To assess how large carnivores, land cover, and human disturbance affect interactions among red foxes, badgers, and pine martens.
• To investigate the influence of season on these top-down and bottom-up ecological mechanisms.
• To analyze causal relationships using structural equation models.

Main Methods:

• Utilized 3 years (2018-2020) of camera trapping data from Norway.
• Employed structural equation modeling to analyze complex ecological interactions.
• Quantified the effects of land cover, large carnivore presence, and human disturbance on mesocarnivore detection rates.

Main Results:

• Land cover variables showed a stronger association with mesocarnivore detection than large carnivores.
• All mesocarnivore species exhibited positive detection associations, particularly during winter.
• Human disturbance had varied effects: benefiting larger mesocarnivores (red fox, badger) but negatively impacting apex predators (wolf, lynx) and smaller mesocarnivores (pine marten).

Conclusions:

• Land cover and seasonality appear to be more significant drivers of mesocarnivore interactions in this Norwegian ecosystem than large carnivore presence.
• Positive interspecific associations suggest resource overlap or facilitation rather than strong competition.
• Anthropogenic influences play a critical role in shaping species interactions, necessitating their inclusion in ecological studies.