In Lithuania, free-ranging European bison live sedentarily in the fragmented landscape of the central part of the country. The aim of this study was to analyze the distribution and habitat selection of European bison in a semi-isolated territory. Free-ranging European bison living sedentarily have formed six groups in the mosaic landscape of central Lithuania. A herd of 34 individuals of European bison entered into a new semi-isolated territory in 2016. During the snow-free season, we tracked the movements of the herd by fitting a global positioning system (GPS) collar to the leading cow. To evaluate the home range and habitat selection, we used ArcGIS software, Jacobs’ index, and chi-square testing to verify significant differences between proportions. The home range of European bison was largest in spring, decreased in summer, and increased again in autumn; this was associated with feeding and the food supply in agricultural lands. European bison spent more time in the forest, especially during the daytime, due to disturbance, but in summer time and at night, the bison did not avoid agricultural land. In the forests, European bison preferred clear-cut, small-leaved deciduous (aspen, grey alder) forests of middle and mature age, but they avoided broad-leaved deciduous (ash), coniferous, and young forests. The increased number of European bison caused damage to agricultural crops and increased conflict with farmers.
European bison (Bison bonasus L.) is the largest herbivore in Europe. Historically, it was distributed throughout western, central, and south-eastern Europe. Habitat degradation and fragmentation due to agricultural activity, forest loggings, and unlimited hunting were the main reasons for the decrease and extinction of European bison populations. In Lithuania, European bison were exterminated in the seventeenth century, but reintroduced in 1969. The species is still included in the country's Red Data Book. The first free ranging herd was established in 1973. Currently, the population of 186 free-ranging European bison individuals could be observed in the central part of the country -Panevezys and Kedainiai regions. European bison are spread in a highly anthropogenic agricultural landscape. Free-ranging European bison spend most of their time in forested areas, semi-open areas and forest fragments in agro-lands and agricultural fields, causing high damage rate to local farmers. They prefer young coniferous stands to mature and over-mature hardwood or softwood deciduous stands. In agricultural fields they prefer grain and corn to rape, leguminous or perennial grass. Recently, the amount of damage compensation reached 98820 euros per year. A test of a new method for evaluating the damage to agricultural fields caused by bison was successfully used by analysing orthophotoplan, obtained by using unmanned aircraft.
The paper presents experimental studies of different techniques (measurements directly in the sample plots and remote measurements, such as high-resolution satellite images or images made by a quadcopter drone) for estimation of damage, made by wild ungulates in agricultural fields. The practical experience gained during the research was analysed. It has been found that for the assessment of the damage caused by wild ungulates, the most suitable layout of sample plots is systematic, covering the whole area evenly. When the sample plots covered 0.2% of the total surveyed area, the error of the estimated wildlife damage was in a range of ±3.8%; when the sample plots covered 0.3% of the total surveyed area, the error of the estimated wildlife damage was in a range of ±2.1%. The measurements of 10 sample plots in loco took 33–40 min, with a team of three assessors. Evaluation works done with a quadcopter drone are faster (10 ha field shot in 20 min and analysis of data in 40 min) and require only one specialist to operate the drone. It was proved that high-resolution satellite images, done in Sentinel missions, are not suitable for estimation of damage, made by wild ungulates in agricultural fields.
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