Date of this Version
Bird damage to ripening and sprouting agricultural crops is a serious problem in many Departamentos (States) in Uruguay and a limiting factor in the production of some crops. A total of about one million hectares of wheat, corn, sunflowers, grain sorghum, rice, soybeans, barley, oats, and peanuts are grown (De Grazio and Besser, 1975). Grain sorghum and sunflower crops are damaged most seriously by birds; corn and rice, soybeans, peanuts, and fruits (such as apples and pears), to a lesser extent. Three families of birds are responsible for most of the damage: doves and pigeons, parakeets, and blackbirds. Waterfowl and fringillids also contribute to bird damage problems in the production of cereal grains. Both cereal and oil grains are attacked as they sprout but more serious losses occur as crops ripen. Damage by the Eared Dove (zenaida auriculata) to ripening grain sorghum and sunflowers and by the Monk Parakeet (Myiopsitta monachus) to ripening sunflowers and corn are the most serious problems. Eared Doves, the Spot-winged Pigeon (columba maculosa) and Picazuro Pigeons (columba picazuro) sometimes seriously damage emerging soybeans. Blackbirds, chiefly the Chestnut-capped Blackbird (Agelaius ruficapillus) and three species of cowbirds (Molothrus bonariensus, M. badius and M. rufoaxillarls), damage rice both when sprouting and ripening. Waterfowl, mostly the White-faced Tree Duck (Dendiocygna viduata), sometimes heavily damage rice seed in flooded paddies. Lesser amounts of damage are caused by parakeets to ripening wheat and grain sorghum fields and by pigeons and doves to ripening barley and oat plantings. To alleviate these losses, the Department of Plant Health of Uruguay (Direccion de Sanidad Vegetal) began organized campaigns nearly a decade ago to reduce the numbers of Monk Parakeets and Eared Doves in zones where crop damage was most severe. Some measure of success was attained in some areas by spraying the colonial nests of Monk Parakeets with contact toxicants and by baiting harvested fields with oral toxicants for Eared Doves (Martinez, 1971). In 1973, the Uruguayan Government sought the assistance of the U.S. Fish and Wildlife Service, through the U.S. Agency for International Development, Department of State, for additional methods of protecting their crops from birds. The purpose of this paper is to present the results of trials using two chemical agents: (1) a repellent, methiocarb, and (2) a frightening agent, 4-aminopyridine, for the protection of sprouting and ripening crops.