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

Abstract

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 spatiallyfocused 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.

Increasing perceived predation risk through playbacks reduces Red-winged Blackbird abundance in agriculture late in the breeding season

“…As such, broadcasting hawk vocalizations or the Sonic Net during the late-season when blackbirds are still residing in nesting habitat could reduce abundances and potentially mitigate crop damage (sensu Tracey et al 2007). Other studies have demonstrated that the Sonic Net can reduce problematic bird abundances in target areas (Swaddle et al 2016, Werrell et al 2021, Woods et al 2022, with similar studies in agricultural settings showing even greater reducing effects than we found (Woods et al 2022).…”

“…First, we noted if blackbirds were detected in fields or in nesting habitat, but due to low sample sizes we could not statistically evaluate if our treatments reduced numbers in agricultural fields specifically. Second, because our Sonic Net playback design was quieter than previous studies (Swaddle et al 2016, Werrell et al 2021, Woods et al 2022, our data may not be directly comparable to previous studies on the Sonic Net. However, even when broadcast at a quieter volume, the Sonic Net still reduced late-season blackbird abundances.…”

“…Blackbirds stay informed of threats with alarm call communication systems, such that acoustically “jamming” these systems should have increased actual predation and brood parasitism risk (Werrell et al 2021). Notably, unlike previous studies on the Sonic Net (Swaddle et al 2016, Werrell et al 2021, Woods et al 2022), our broadcast was at a quieter volume and included periods of silence to match the playback rate of our other treatments, which could have allowed blackbirds to simply “tolerate” the noise after establishing breeding territories.…”

“…However, even when broadcast at a quieter volume, the Sonic Net still reduced late-season blackbird abundances. Third, it is possible that our experimental design used less energy than previous studies on the Sonic Net (Werrell et al 2021, Woods et al 2022), which could potentially cost crop producers less monetarily while still reducing target bird abundances with the Sonic Net. Last, if perceived predation risk from playbacks is truly high enough to reduce blackbird abundances during the non-breeding season, then non-target species of conservation concern utilizing agricultural habitat could also be affected, such as early-autumn neotropical migrants (Hagy et al 2010).…”