AVIAN REPELLENTS

The use of repellents to protect crops from birds has a long history. Early European settlers in eastern North America observed that native Americans used an extract of Veratrum spp. to protect corn seeds from avian depredators: ‘‘Then when the starlings, crows, or other birds, pick up or pluck out the grains of corn, their heads grow delirious, and they fall, which so frightens the rest that they never venture on the field again. When those which have tasted the grains recover, they leave the field, and are no more tempted to visit it again’’ (1). Repellents move birds from one place to the next. After successful application of a bird repellent, the overall amount damage will probably not decrease, but it will be distributed differently. Some persons are philosophically opposed to repellents because they do not reduce damage overall, but instead shift the problem to a neighbor’s field or vineyard. However, by definition, repellents are nonlethal and as such they represent a very appealing approach to the management of bird damage in crops (2). Bird damage is usually highly skewed among sites, with most producers incurring little damage and few suffering high, economically important levels of damage (3). Realistically, the goal of bird damage management is not to eliminate losses, but to reduce them to an acceptable, manageable level. To the extent that a repellent can help redistribute the economic impact among producers, and especially provide relief at the few high-damage sites, it will be a successful component of bird damage management plans