Not all crickets are equal: selective shrike predation highlights the conservation value of diverse arthropod communities to grassland birds

Résumé fourni par la source

Understanding dietary preferences and prey selection is pivotal for interpreting the ecology and conservation needs of threatened species. We investigated the diet composition and prey selection of the Red‐backed Shrike Lanius collurio in a montane grassland of the central Italian Apennines, with special regard to sex‐related differences and the relationships between prey use and local prey availability. Using a non‐invasive camera‐trapping protocol at artificial perches, we collected high‐resolution photographic records of predation events over three breeding seasons (2021–2023). This method allowed us to identify individual shrikes through colour‐ringing and enabled prey items to be identified to fine taxonomic resolution. From 2968 recorded predation events involving 18 individually identifiable shrikes, we identified prey belonging to 12 arthropod orders, 52 families, 55 genera and 48 species. Arthropods dominated the diet, with Orthoptera accounting for the majority of prey items, followed by Hymenoptera, Coleoptera, Araneae and Lepidoptera. Multivariate analyses revealed a significant effect of sex on prey composition, whereas perch location had no detectable influence. Males disproportionately consumed large Ensiferans, bumblebees and spiders, whereas females more frequently preyed upon smaller orthopterans and solitary bees. Comparisons between prey use and availability showed clear evidence of active prey selection patterns. Shrikes consistently selected Ensiferan orthopterans and melolonthid beetles over their local availability, whereas abundant taxa such as honeybees and pierid butterflies were avoided. These patterns indicate that prey profitability, handling efficiency and risk probably play a major role in shaping foraging decisions, rather than simple opportunistic feeding. Our results highlighted the importance of diverse arthropod assemblages, particularly Ensiferan communities, in sustaining breeding populations of this declining farmland bird. Methodologically, the study confirmed the effectiveness of camera trapping at fixed perches for obtaining individual‐level dietary data in small passerines. Maintaining structurally heterogeneous grasslands and traditional low‐intensity management practices is critical for preserving key trophic resources and supporting viable Red‐backed Shrike populations in upland landscapes.

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