DAMAGE BY ROBINS AND STARLINGS TO GRAPES IN ONTARIO

Abstract

Damage caused by birds feeding on ripening grapes was observed in 108 of 128 vineyards surveyed in the Niagara Peninsula during 1962 and 1963, but in only 14 vineyards was the damage moderate to severe. In general, damage was more prevalent and serious to French-hybrid cultivars than to the more common North American cultivars such as Concord. Birds began feeding on grapes as early as 4 weeks before harvest, but in some vineyards damage stopped up to 2 weeks before harvest. Robins, Turdis migratorius L., and starlings, Sturnus vulgaris L., were the only species of significance in two study vineyards; robins appeared to be responsible for most of the damage as they were not repelled by control measures in operation. All of the robins and starlings collected in vineyards were shown by examining the stomach contents to have been feeding on grapes. It was estimated that the total damage to grapes in the Niagara Peninsula in 1965 was about $24,000, or less than 0.5% of the total value of the crop.