Paweł Nasiadka

Wild boars (Sus scrofa) forage on plant resources located both above and below the soil surface, but it remains unclear whether these resources are exploited simultaneously or used as complementary food pools according to season. This study examined seasonal changes in the use of understory plant resources by analyzing the stomach contents of 470 wild boars collected throughout the year in central Poland. Four dietary fractions were quantified: grass leaves, herb leaves, grass roots, and herb roots. Their frequency and proportional contribution were compared among six phenological seasons using non-parametric statistics and generalized linear models. Significant seasonal differences were found in both occurrence and dietary contribution. Aboveground plant parts, particularly grass leaves, dominated during the Greening and Flowering periods, whereas underground organs became more important in autumn and winter. Herb roots showed the strongest seasonal increase during the Shedding season, while grass roots remained uncommon throughout the year. Our findings indicate that wild boars switch between these complementary food pools according to plant phenology, tracking seasonal changes in the availability and nutritional quality of plant tissues rather than exploiting aboveground and belowground resources indiscriminately. This flexible foraging strategy provides new insight into the ecological mechanisms underlying rooting behavior.

In Kampinoski National Park (KNP), located in central Poland near the Warsaw agglomeration, the ASF epidemic lasted five years (2017–2021). The virus likely entered the park via wild boar migrating along a natural ecological corridor or through unintentional transmission by residents and tourists. Between 2014 and 2021, intensive monitoring and wild boar population reduction were implemented. The wild boar population, estimated at 11 individuals/km² in 2013, began to be reduced from 2014 onward, when ASF was first detected in Poland. In 2018, at the peak of the epidemic, the density of wild boar dropped to about 0.51 individuals/km²—the lowest in the park’s history. Between 2017 and 2021, 408 ASF cases were recorded, mainly in dead wild boar, although age and sex structure analysis suggests that the actual mortality rate could have been up to about 50% higher. The early intervention—culling—which was controversial from the National Park’s perspective, appears to have played a key role in controlling the situation and likely in limiting the epidemic. At the same time, the limited organizational resources of KNP highlighted the need for proactive management and close institutional cooperation in protected areas subject to high anthropogenic pressure.

This study analyzed 9871 cases of wild boar damage recorded over more than 20 years using a consistent methodology in a 5000-hectare area with minimal changes in crop structure. This allowed for a reliable assessment of seasonal damage dynamics. Wild boar exhibited seasonal feeding preferences: grasses in spring, cereals in summer, legumes in early autumn, and root crops in late autumn. A bimodal pattern of damage was identified, comprising three types. The rare and severe pattern occurred in spring when the wild boar population at its lowest size caused infrequent but highly damaging events, mainly in meadows. The frequent and weak pattern appeared in late summer and autumn when wild boar numbers were two to three times higher, leading to frequent but less severe damage. The indirect pattern was linked to lower field attractiveness in summer and winter. The high symmetry of damage observed suggests that an effective wild boar management strategy should account for not only damage reduction but also sanitary risks, such as ASF.

The movement of wild boars is a complex process influenced by both internal conditions and external factors. Despite their typically sedentary lifestyle, dispersion constitutes an integral element of the wild boar’s behavior. This report documents the longest observed wild boar dispersal, involving a collared two-year-old male near Warsaw, Poland. The aim of this study was to present the characteristics of movement during the “nomadic phase”, drawing comparisons with the “sedentary phase”. The other aim was to evaluate the influence of meteorological factors on the minimum daily travel distance of the wild boar. We collected data from two-year-old males. The first exhibited long-distance dispersal and the second only demonstrated local movements. We calculated the minimum daily distance of both wild boars based on collar locations and calculated basic statistics of movement. We used a generalized linear model with a gamma distribution and log link function to assess the potential impact of weather conditions on the minimum daily distance of wild boars. We tested maximum daily temperature, average daily temperature, and the sum of daily precipitation. The wild boar during a “nomadic phase” covered a total of 922 km with a mean minimum daily movement of 6 km. The dispersion distance was 307 km. The highest value of the minimum daily distance reached 31.8 km/day. The second wild boar (near Warsaw) covered a mean minimum daily distance of 1.4 km; the highest value of the minimum daily distance was 3.9 km. Both wild boars exhibited no dependence of minimum daily distance on weather conditions. However, when intensive and non-intensive dispersion were analyzed separately, it was demonstrated that the maximum daily temperature positively influenced the minimum daily distance. We speculate that the wild boar was forced to search for water sources after dark on hot days, which induced a longer traveling distance in an unfamiliar environment. This study highlights the significant spatial capabilities of wild boar in the transmission of genes or pathogens. We speculate that extended daily distances during the initial “nomadic phase” might suggest a panicked escape from a perceived threat. It is plausible that the wild boar found improved shelter within tall cereal crops in July and August, which resulted in lower daily distances.

One of the basics of effectively managing a wild boar population is knowledge of its home range, spatial patterns, and habitat use. However, little is known about the reaction of wild boar to changes in the agricultural landscape during the time of harvesting. In this study, we assessed the impact of crop harvesting on habitat selection of wild boar. For this reason, we analyzed radio-collared animals in four summer months (from June to September) in an agricultural landscape in Poland. We analyzed the habitat selection by wild boar with a generalized linear model and Jacob’s selectivity index. The wild boar preference for arable land, pastures and the “other” category showed clear monthly dynamics. In contrast, a stable preference for forests and mosaics was observed throughout all months. The preference of wild boar to arable land dropped significantly in August, which we interpret as the impact of the harvest. We conclude that intensive agriculture contributes to significant changes in the frequency of wild boar in various habitats. This, however, does not apply to all habitats, because forest habitats are constantly visited by wild boar as their main daytime refuge. Moreover, extensive farming, although less attractive for wild boar, is rather neutral and does not alter the abundance of animals in habitats.