Browsing by Subject "nyctereutes procyonoides"

It has been found out that the raccoon dog Nyctereutes procyonoides causes considerable damage to native species, and it has been included among one of the hundred worst invasive alien species in Europe. In June 2017 the raccoon dog was included in the list of invasive alien species of the European Union concern, the so-called black list. The diet of the raccoon dog has been dealt with in several studies, and it has been found out that it may have an effect on the density of different species. The findings of the studies, however, have varied. There is a need to study further the results of the research on the diet of the raccoon dog and its influence on other species. In this thesis master's thesis, the role of the raccoon dog was studied as a predator of ground nesting birds' nests by means of artificial nests. Although artificial nests do not fully correspond to the predation of real nests, the results can, however, be used as an index on the nest predation by the raccoon dog. The study analysed the influence of raccoon dog density (index) on the visits in the artificial nests by the raccoon dog. The data also facilitated the spatial and temporal modelling of nest predations by the raccoon dog. In this research trail cameras were used, which have made new ways possible to study the predation behaviour of game species. The data of this study was collected in 2015–2017 in Southern Finland. The data consists of data collected from altogether 168 artificial nests in 20 areas. In each area eight artificial nests were founded, in which pheasant Phasanius colchicus eggs were used. Nest predation was studied in a 400-meter zone perpendicularly to the side of the field, located 150 meters on the field side and 250 meters on the forest side. The locations of the artificial nests were chosen randomly, and the nests were founded in nesting surroundings typical of pheasants and dabbling ducks in the research zone. A trail camera was placed by each nest to photograph the visits at the nests. The cameras were photographing for eight days, after which they were taken away and the data was recorded. The modelling of the data was made by means of R-program using generalized linear mixed model. During the research 33,3 % of the artificial nests were predated. 21,4 % of the robbed nests were predated by the raccoon dog. According to the results of the study the part of nest predation by the raccoon dog varies yearly. The number of nests destroyed by the raccoon dog seems to have a positive correlation to found raccoon dog density indexes. Beside the raccoon dog corvids were remarkable nest predators. According to the results of this study the raccoon dog seems to utilize agricultural landscape in a many-sided way when predating. It robbed nests both in field and forest areas, though there was less predation in the edge zone between these areas than expected. The results support the understanding that the raccoon dog is a flexible predator. As a generalist it typically exploits various environments when looking for food and uses food in different ways, so the part of bird eggs in the diet may vary yearly.