The influence of wild boar (Sus scrofa) on microhabitat quality for the endangered butterfly Pyrgus malvae in the Netherlands

Abstract

The decline of open habitats in Europe, such as semi-natural grasslands and heathlands, has caused a general decline in biodiversity, which has been well documented for butterflies. Current conservation practices often involve grazing by domestic livestock to maintain suitable butterfly habitats. The extent to which wild ungulates may play a similar role remains largely unknown. Through their rooting activity, wild boar could be effective to reduce grass encroachment and restore pioneer microhabitats that are vital to many grassland insects in temperate climates. Here, we assessed the microhabitat requirements of Pyrgus malvae, an endangered butterfly of heathland and grassland habitats in the Netherlands, with special attention for the influence of wild boar rooting. To date, oviposition site selection of this species has concentrated on calcareous grasslands, whereas we also include heathlands. Overall, larval occupancy was higher in warm, open and sparsely vegetated microhabitats, which supports earlier findings. In heathland, microhabitat occupancy was positively affected by bryophyte and litter cover. In heath-grassland mosaic, microhabitat occupancy was also influenced by bryophyte and litter cover, but in addition low grass cover increased occupancy by favouring host plants. In grassland, only low grass cover and host plant cover determined microhabitat quality. Across all habitats, occupied microhabitats were characterized by lower vegetation as well as higher average daytime temperatures than unoccupied microhabitats. We discovered that wild boar play an important role in reducing grass cover by shallow rooting in grass patches, thereby increasing host plant availability. Hence, wild boar may have an added value in maintaining and restoring P. malvae microhabitats in grassland habitats in addition to grazing by domestic livestock.

Risks and opportunities of trophic rewilding for arthropod communities

“…It also creates germination niches for plants that require disturbed soil, on which herbivorous insects may be specialized. This was exemplified by the positive effect of wild boar rooting on the grizzled skipper butterfly (Pyrgus malvae) [36].…”

The Boar War: Five Hot Factors Unleashing Boar Expansion and Related Emergency

“…Efforts could also be directed at sensitising local communities to the importance of wild boar as a part of biodiversity which, if properly managed, can represent an ecological and economic resource (i.e., [215,277,[279][280][281]); indeed, one of the main problems we have observed in our working areas is the misperception of the wild boar emergency, with consequent discomfort. This triggers a very strong frustration in human populations, which can also make the emergency more complex than it really is.…”

A Review of the Engineering Role of Burrowing Animals: Implication of Chinese Pangolin as an Ecosystem Engineer

“…Changes in plant communities usually cascade to animal communities, such as invertebrates that rely strictly on certain environmental conditions to complete their life cycle. For example, the decline of open, such as semi-natural grasslands and heathlands in Europe, has caused a general decline in biodiversity, especially for butterflies [77] . The digging activity could be effective in reducing grass encroachment and restoring pioneer microhabitats.…”