Experimental Assessment of Laser Scarecrows for Reducing Avian Damage to Sweet Corn

Sean T. Manz, Kathryn E. Sieving, Rebecca N. Brown, Page E. Klug, Bryan M. Kluever


BACKGROUND: Birds damage crops, costing millions of dollars annually, and growers utilize a variety of lethal and nonlethal deterrents in an attempt to reduce crop damage by birds. We experimentally tested laser scarecrows for their effectiveness at reducing sweet corn (Zea mays) damage. We presented 18 captive flocks of free-flying European starlings (Sturnus vulgaris) with fresh sweet corn ears distributed on two plots where laser and control treatments were alternated each day and allowed each flock to forage over five days. In 16 trials, fresh sweet corn ears were mounted on wooden sticks distributed from 0-32m from laser units (Stick Trials), and in two trials birds foraged on ripe corn grown from seed in the flight pen (Natural Trials). We aimed to determine if laser-treated plots had significantly less damage overall and closer to the laser unit, and whether birds became more or less likely to forage in laser-treated plots over time.

RESULTS: Lasers reduced damage overall, marginally in Stick Trials and dramatically in Natural Trials. Damage increased during each week in both trial types. Damage increased significantly with distance from lasers, and significant treatment effects occurred up until ~20 m from lasers.

CONCLUSION: Our results concur with recent field trials demonstrating strong reductions in sweet corn damage when lasers are deployed. This study provides a first look at how birds respond to repeated laser exposure and whether damage increases with distance from lasers. Key differences between pen and field trials are discussed.

Robotic Laser Scarecrows: A Tool for Controlling Bird Damage in Sweet Corn

Rebecca NelsonBrown1David H.Brown2 


Sweet corn (Zea mays L.) is an important direct retail and local wholesale crop in the United States. Birds have long been recognized as a pest of corn, which they damage by shredding the husks and eating the kernels. This study was performed to evaluate moving green laser beams as a bird control strategy in sweet corn. A portable, battery-powered robotic scarecrow was designed to continuously move a 14 mm diameter, 532 nm wavelength beam from a 50 mW laser. The scarecrow was tested in sweet corn fields in Rhode Island, USA over three years using a split-field design where half of each field was covered by the laser and the other half served as a control. In 2017, the control sections averaged 48.4 ± 6.9 damaged ears per plot, while the sections covered by the laser averaged 14.6 ±5.5 damaged ears (P = 0.0002). In 2018, the control sections averaged 23.8% ± 4.1% damaged ears while 13.7% ±2.1% of ears were damaged in sections covered by the laser (P = 0.0046). In 2019, mean damage values across all planting blocks were 14.9% ± 4.1% for the protected plots and 20.3% ±5.8% for the unprotected plots (P = 0.0332). The results of this study show that automated laser scarecrows can reduce bird damage to sweet corn under field conditions. Further research, including aviary studies with controlled populations of individually identified birds, are needed to measure efficacy and test for habituation.

Laser Scarecrows: Gimmick or Solution? (2017)

Rebecca Brown


Laser scarecrows appear to be effective as a means of preventing starlings and blackbirds from feeding in sweet corn fields. Based on grower reports, they are more effective than scare guns at preventing damage. Commercial laser scarecrows are more expensive than scare guns, but cost less to operate, and avoid problems with noise pollution. Labor requirements are similar to scare guns. A preliminary single-site trial suggests that laser scarecrows are effective at preventing starlings, blackbirds, crows, and flickers from feeding on grapes, but are less effective against catbirds. The scarecrows also may be effective at protecting newly-seeded cover crops from Canada geese. Laser scarecrows are not effective against deer or other mammals (VerCauteren et al. 2006). We will be repeating the controlled studies on sweet corn in 2017, and will be initiating further tests of the laser scarecrows on additional crops and against additional bird species.