Monofilament Lines Fail to Protect Grapes from Bird Damage

Abstract

Birds feeding on horticultural crops may cause extensive losses, but control techniques currently available are not always practical or otherwise appropriate. Control of certain birds is attempted by placing widely spaced lines or wires over or around sites needing protection (Pochop et al., 1990). Recently, Knight (1988) reported observations that monofilament lines could be used to protect various horticultural crops, including grapes, from bird damage. However, more closely controlled research was needed to better quantify effectiveness of this technique for various bird species. The objectives of this study were to determine the effectiveness of monofilament lines in protecting ripening grapes (Vitis) from bird damage and to observe how damage-causing bird species behave in relation to the lines. We selected the vineyard at the Univ. of Nebraska horticultural garden because of its availability and its history of bird damage ranging from 30% to 100% of the crop (D.H.S., unpublished). The study was conducted from 17 July through 25 Sept. 1988, and included seven grape cultivars, each with four or more plants (Table 1). Plants of the various cultivars were distributed haphazardly throughout the vineyard. Each grape bunch on all plants was tagged and visually examined before ripening occurred. Plants were individually and randomly assigned to control (no lines) or experimental groups. Each experimental plant received, sepa-