Cereal killers, when and where do they strike? : a spatio-temporal analysis of wild boar activities in Swedish agricultural fields

Abstract: Wildlife damages to crops is one of the major factors for human-wildlife conflicts. Wild boar (Sus scrofa), has during the last decades increased greatly in numbers, both in its natural and introduced range. By eating and trampling the crop, wild boar causes huge economic losses to farmers. To reduce wild boar damages to crops and to mitigate this conflict, it is important to understand the underlying factors of high-damage risk areas. In this study, I analysed the probability and size of damage, both in relation to several landscape features and time during the vegetative season. Damage data was collected in four study areas in southcentral Sweden, at five different occasions during the summer of 2017. Landscape features of interest were; distance to forest edge, feeding stations, water resources, roads and houses. I found temporal differences in both probability and size of damage. In cereals, the damage level peaked in August, while it was slightly higher earlier in the season in ley fields. There was also a difference in damage level between crop types, with more and greater damages in cereal than in ley fields. Distances to the different landscape variables were non-consistent for probability and size of damage, as well as among the two crop types. In cereals, the damage level was highest in proximity to forest edge (probability and size) and feeding stations (only probability), and lowest close to roads (probability and size). Feeding station was the only landscape variable with a significant influnce on damage level in ley fields, showing a lower probability of damages close to feeding stations in ley. Time of season proved to contribute much more to both probability and size of damages in ley fields than distance to any landscape feature, indicating that it is a temporal matter rather than a spatial. With the differences in damage level between the two crop types, both temporally and spatially, I suggest future studies to separate different types of crops when analysing damage distribution.