Metabarcoding Reveals the Dietary Patterns of Bats Within a Unique European Habitat, the Pasture‐Dominated Landscapes of Ireland

Considered as keystone predators, insectivorous bats play essential roles in maintaining the functioning of ecosystems. Investigating how bat species' diets vary across landscapes is crucial for understanding bat ecology and their role in ecosystem health. Here, we characterised the predator-prey interactions of two common bat species with different foraging strategies, the Brown long-eared bat (<i>Plecotus auritus</i>) and Soprano pipistrelle (<i>Pipistrellus pygmaeus</i>), across the unique pastureland-dominated landscape of Ireland. Over 3 years (2021-2023), faecal samples (<i>n</i> = 4627 in total) were collected annually at three time points (gestation, lactation, post-lactation) from 12 maternity roosts and analysed using metabarcoding and next-generation sequencing. Both bat species showed broad diet diversity, with 392 and 350 arthropod species identified for the Brown long-eared bat and Soprano pipistrelle, respectively, primarily Lepidoptera and Diptera. The Brown long-eared bat exhibited a generalist diet, demonstrating dietary flexibility. Lepidoptera interactions were more frequent overall (62%) compared to Diptera (31%), but interactions with Diptera species increased markedly at one specific roost, suggesting that this species can opportunistically feed on available prey species. In contrast, the Soprano pipistrelle exhibited a more specialised diet, with 83% consisting of Diptera species. Both spatial and temporal factors significantly influenced dietary richness and composition in both species. Surrounding land cover, in particular, played an important role in shaping diet composition. Our findings suggest that the Brown long-eared bat exhibits a broad foraging strategy, acting as a generalist with a preference for Lepidoptera, while the Soprano pipistrelle shows a consistent reliance on Diptera. Our study provides new insights into bat diet variation in pastureland landscapes, contributing to the understanding of their ecological role.