Looking for a magic island in the sea of agriculture: factors affecting forest patch attractiveness for wild boar in human-dominated landscape

Abstract

Landscape fragmentation carries the risk of habitat loss for many animal species. This may include wild boars, which are one of the main culprits of conflicts with humans, while isolated patches of forest (forest islands) scattered in the agricultural landscape may affect its ecology and the pressure on the crops. This study aimed to understand the importance of small forest islands located in a human-dominated agricultural landscape in the ecology of wild boar. It explores what features, both of the interior and exterior of the islands, influence their use. The study area covered approximately 220,000 ha of northern Poland, where wild boar use of 200 islands distributed across the agricultural landscape was investigated. For this purpose, the method of counting pellet groups was applied on transects of a total length of 51.6 km. In order to compare the use of islands with compact forest complexes, 84 km of transects were made in the latter, divided into developmental stages and forest type. Among the features of the interior of the islands, increasing cover conditions and the main species of trees (pine, spruce and alder) had a positive influence on the wild boar use. The utilization also depended on the presence of human settlements, other islands, and the type of agricultural crop around the island. When comparing island use to compact forest complexes, islands were used more often than forest regeneration sites and mature stands, but less often than pre-thickets. For the 25% most frequently used by wild boar, islands were more attractive than virtually all stand development stages in compact forest complexes. Due to the cover conditions provided, the occurrence of islands in the agricultural space enables wild boars to use areas more distant from compact forest complexes. This may cause the spread of damage caused by wild boars in the fields, but on the other hand it may reduce the pressure on agricultural areas in the immediate vicinity of compact forest complexes. Intensification of hunting pressure in the vicinity of islands with specific characteristics e.g. good cover conditions, considerable distance from human settlements) will increase the effectiveness of wild boar population control in the agricultural landscape and will have a limiting effect on the damage caused by this species in the fields.