Hillside lagomorph grazing and its influence on Orthoptera

Abstract

The effects of lagomorph grazing on the Orthoptera of a small hill in Mistley (southeast England) were studied during the summer of 2020. Transect counts of Orthoptera revealed low sward height with abundant bare earth due to high wild rabbit Oryctolagus cuniculus grazing on the high slopes. This intensive grazing led to only field grasshopper Chorthippus brunneus (Thunberg, 1815) adults being found in any number on the high slopes, perhaps utilizing the short swards and bare earth as basking and egg-laying habitat. Aspect was also important, with significantly more grasshopper nymphs and C. brunneus adults on the south-facing slope than on the northern slope. Soil slippage areas seem like valuable micro-habitats on the south-facing slope, with these ‘sun traps’ providing excellent basking habitat for nymphs and C. brunneus. This study confirms that lagomorph grazing alters hill summit habitats for Orthoptera, benefiting C. brunneus and, to a lesser extent, the meadow grasshopper Pseudochorthippus parallelus (Zetterstedt, 1821). However, overgrazing of higher hill slopes can exclude tall grass species, such as long-winged conehead Conocephalus fuscus (Fabricius, 1793), and reduce assemblage diversity.