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Data and code from: Urbanisation and human activities influence the co-occurrence of red squirrels Sciurus vulgaris and meso-carnivores in Berlin, Germany

Vergara Stuardo, Josefa12; Drenske, Sinah13; Louvrier, Julie14

Published Mar 12, 2026 on Dryad. https://doi.org/10.5061/dryad.hmgqnk9x8

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Mar 12, 2026 version files 16.33 MB

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Abstract

Urban expansion is a major driver of habitat fragmentation, shrinking wildlife habitat, and restricting wildlife movements and activity patterns. In this novel environment, species must adapt to the new composition of wildlife communities. For example, red squirrels (Sciurus vulgaris) are commonly found in urban environments, while their potential predators have also managed to accommodate and even thrive in cities. Consequently, studying species interactions in an urban landscape provides crucial insights into our understanding of species’ plasticity and behavioural adjustments to novel situations. This study aims to understand the potentially novel predator–prey interactions in private gardens of Berlin, specifically between red squirrels and red foxes Vulpes vulpes, raccoons (Procyon lotor), martens (Martes sp.), and cats (Felis catus). We hypothesized that squirrels’ occurrence would be influenced by human activity, garden characteristics, and proximity to the city centre, and that these factors would also affect co-occurrence with meso-carnivores. We used a raster of 150 camera traps per season, in total 575, located in private gardens of citizens of Berlin, which detected the species during four sampling seasons between 2019 and 2020. We first applied single occupancy models for each species separately to understand the variation in the detection and occupancy of each species at given environmental variables. We then assessed paired co-occurrence of squirrels with each meso-carnivore by applying a multi-species occupancy model framework. We found that squirrels were more likely to occur during autumn than in spring and at a higher percentage of local tree cover, which has been confirmed by previous studies. Additionally, results suggested that squirrels are more likely to occur when cats were absent, suggesting an avoidance of the latter. However, squirrels did not display clear patterns of negative or positive co-occurrence with other urban wild meso-carnivores. These results demonstrate the complexity of species interactions in urban settings.