Native and immigrant bat niches in a city agglomeration: implication for urban landscape planning

Urbanisation and climate change drive species range shifts, reshaping biodiversity in cities. In Košice, a large urban agglomeration in eastern Slovakia, Mediterranean bats, Hypsugo savii and Pipistrellus kuhlii, have colonised the region since 2016, entering ecological interactions with native Pipistrellus pipistrellus and Pipistrellus pygmaeus. We investigated their spatial distribution and foraging niche overlap across the city’s heterogeneous urban landscape to understand ecological interactions. In the period 2017–2019, we collected 4,142 acoustic recordings of bat activity across six habitat types (old town, multistorey prefabs, houses, greenery, water, and industrial area). Niche optima, breath and overlap in the p-dimensional hypervolume were quantified using species chromatograms. P. pipistrellus was the most frequent bat (69.7%), followed by P. kuhlii (21.4%), H. savii (6.3%) and P. pygmaeus (2.6%). Different breadths of foraging niches were found, P. kuhlii exhibited the broadest niche, while P. pygmaeus the narrowest. Native species showed low niche overlap (0–6.5%), indicating habitat partitioning, while P. kuhlii overlapped more with P. pipistrellus (average 21.3%), and suggesting potential competition. These findings suggest how urban landscape structure shapes bat communities. For urban planning, preserving greenery and water habitats supports specialists like P. pygmaeus, while enhancing connectivity mitigates competition for generalists.