Abstract
The effectiveness of a visual birdscarer, the Peaceful Pyramid®, relative to a much-cheaper eye-spot balloon was investigated experimentally in two vineyards in Canterbury, New Zealand. Monitoring of bird damage to natural bunches of Riesling grapes within vineyard blocks showed that the rate of starling (Sturnus vulgaris) damage to the crop was reduced significantly by the balloon relative to pyramid and control plots. Nevertheless, after 24 days of monitoring, birds in the balloon plot had damaged 75% of the grapes, respectively (cf. 84% in the pyramid plot). In a second trial, clusters of table grapes were attached to vineyard wire at a Lincoln vineyard. The balloon and pyramid both reduced bird damage to clusters within 15 m of the device, but had no measurable effect on clusters further away. We conclude that neither device would provide growers with any economically significant reduction in grape damage. This study highlights the importance of undertaking quantitative assessments of the numerous bird-scaring technologies presently available to growers.