A Sonic Net deters European starlings Sturnus vulgaris from maize silage stores

Deterrents against avian pest species might be more effective if they were based on some aspect of the target species' sensory salience. Sonic Nets broadcast a loud and spatially- focused pink noise that spans the frequency range of the target species' vocalizations, restricting interspecific communication so that it is costly for birds to remain in the treated area. In parts of their native and introduced ranges, European starlings (Sturnus vulgaris) impact livestock operations where they consume and contaminate animal feed, damage infrastructure, and may contribute to pathogen transmission. We evaluated Sonic Net technology to exclude starlings from outdoor maize silage stores on 10 dairy farms in Cornwall, U.K. in February-March and November-December 2019. We quantified frequency of starling presence and approximate flock size and combined these to estimate starling burden in starling-minutes before, during, and after Sonic Net treatment. During an initial proof-of-concept trial, each phase lasted 2 days, whilst in a second, longer experiment, treatment lasted 14 days. During Sonic Net treatment, frequency of starling presence was reduced, flock sizes were smaller, and starling-minutes were reduced by 94% and 89% in the 2-day and 14-day treatments, respectively. In the last 2 days of the 14-day treatment, starling-minutes remained 85% lower than before treatment, but 4 of 10 farms experienced some diminution of effects after 6 days. Sonic Nets had a significant and sustained effect, with potential for deterring avian pests from agricultural and other settings.