The early bat catches the moth –relationship between Salix flowers, Orthosia moths and the barbastelle Barbastella barbastellus (Schreber 1774)

Abstract

We present the results of a study which describes the relationship between the western barbastelle Barbastella barbastellus a highly specialised moth predator and its prey – moths of the genus Orthosia, another selective animal known to converge around a dominant producer of pollen and nectar in early spring – willow trees Salix sp.. In order to describe this trophic relationship we conducted acoustic recordings at five paired sites (willow / control tree), in proximity to known barbastelle hibernation sites (Natura 2000: PLH080003 & PLH200014) beginning mid-March 2022 after the first willow blossom sighting. Our study confirms a connection between willow trees and barbastelles during early spring as their activity around them was significantly higher than control sites. We also explore the relative abundance of barbastelles over time finding that activity levels around willows first increases, before decreasing from the night of the first recorded bat, while the activity of non-moth specialist bats remains consistent. We show decreasing importance of willows as other species blossomed attracting alternative prey. This newly described relationship should influence current conservation measures aimed at barbastelles.