Effects of great bustards (Otis tarda) on cultivated areas in west-central Spain

Great bustard (Otis tarda) populations in Spain are located mostly in cultivated areas during winter. The birds concentrate in large flocks and feed on cultivated plants. This paper reports two types of bustard-caused damage which occur in cereal, lucerne and vetch crops in west-central Spain, as a result of grazing and other bird activities such as display. Field work was carried out between 1994 and 1995. Damage to cereal crops was caused during germination and early seedling growth or to young plants, although plants were able to recover from this by regrowth and the overall yield was not reduced. Vetch crops were damaged in localized areas, but these recovered and were useful for forage enrichment or as grain. However, the damage to lucerne plots, although local, was extensive, resulting in yield losses of 23-31% with respect to the total production.