Factors affecting the level of damage by wild boar in farmlands in north-eastern Poland

The level of damage caused by wild boar in 33 forest districts was investigated. The study area covered 2.231 million ha including 0.662 million ha of forests. In the last six years (2005-2010) the wild boar population has increased from 15,200 to 24,100 individuals and harvesting from 10,700 to 20,700. In the same period, the area of farmland damaged by these animals increased from 1,470 ha to 2,800 ha. The level of damage results primarily from 5 variables of which the most important are population density (r=0.67) and Simpson’s biodiversity index (r=0.54). The population density of wild boars, however, was affected by 5 variables. The most important was Simpson’s biodiversity index (r=0.86), proportion of oak and beech trees (r=0.80) and amount of cereal food at baiting sites (r=0.68). The highest level of wild boar-related damage was recorded in April (on meadows) and in August (in cereals). The financial performance of wild boar management indicates that the income from selling carcasses is lower than the damage compensation. The paper discusses the methods to reduce numbers of wild boars, based on reliable population census data and reproductive patterns.