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Wild Boar Shifted From Grass Leaves Toward Herb Roots as the Growing Season Ended in Central Poland

Wild boar among leaf litter and understory vegetation in Kraków, Poland
Research · Ecology

Wild boar (Sus scrofa) in a forest–agricultural landscape of central Poland changed which parts of understory plants they ate as the seasons progressed. Stomach contents from 470 animals showed that grass leaves were especially important during spring and early summer, while roots of herbaceous plants became more prominent toward autumn and winter. The study was published in Animals on 28 August 2026.

The animals came from the Spała Forest District in the Pilica Primeval Forest, where forest and agricultural land form a mosaic. Researchers divided the year into six periods based on plant development and separated four understory food fractions from the stomach contents: grass leaves, herb leaves, grass roots and herb roots.

Understory vegetation remained a year-round resource

Understory plants were a persistent part of the diet rather than a seasonal food used only occasionally. At least one of the four fractions occurred in 82.5% of all stomach samples, and the overall composition of grasses and herbs remained more than 80% similar between successive seasonal periods. What changed most strongly was which plant parts the boar used.

Grass leaves peaked early, herb roots later

Grass leaves were the most frequently recorded fraction. They occurred in 82.3% of samples during spring greening and 90.9% during the June–July flowering period, when young aboveground tissues were abundant. Their contribution declined later in the growing season.

Herb roots showed the opposite tendency. They occurred in 37.5% of samples during the autumn shedding period, compared with 15.2% during both greening and flowering. Grass roots remained uncommon throughout the year. The authors interpret the pattern as flexible foraging that tracks seasonal changes in plant development and food availability: aboveground tissues are especially useful while plants are actively growing, whereas underground storage organs become relatively more important as aboveground vegetation senesces.

The study covered only the understory part of the diet

Food availability in the surrounding farmland may also contribute to the autumn shift. After crops are harvested and agricultural foods become depleted, wild boar can turn more strongly toward the forest understory, where herb roots remain accessible through rooting. The study examined this understory component rather than the complete wild-boar diet, which also includes crops, tree seeds, animal food and other resources.

The result is therefore not a simple switch from plants above ground to roots below it. Understory vegetation remained a year-round food source, while wild boar adjusted the balance among leaves and roots as seasonal conditions changed. This combination of a broad diet and fine-scale seasonal flexibility helps explain how the species continues to exploit the same forest–agricultural landscape throughout the year.

Sources and image credit

  1. From Leaves to Roots: Seasonal Dynamics of Wild Boar (Sus scrofa) Use of Understory Plant Resources in a Forest–Agricultural Landscape of Central PolandOpen-access Animals study published 28 August 2026. Researchers analysed stomach contents from 470 wild boar in central Poland across six seasonal plant-development periods. Understory vegetation remained a year-round resource, while grass leaves were most important during active growth and herb roots increased toward autumn and winter.

Image: Wild boar at Czerwone Maki in Kraków, Poland, photographed on 27 November 2024. Photo: Jakub Hałun. Source: Wikimedia Commons. Representative image; not an animal from the central Poland study. · CC BY 4.0 · Source

About this content: This story was produced with AI assistance within an editorial workflow developed by Wildlife Vagabond. Editorial responsibility remains with Wildlife Vagabond.How AI is used

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