What Determines the Distribution of Forest Flightless Bush Cricket Pholidoptera griseoaptera in the Eastern Part of Its Range (The Kaluga Region, Russia)?

(1) Pholidoptera griseoaptera (De Geer, 1773) (Orthoptera, Tettigoniidae) is a common and widespread inhabitant of forest edges in Europe and may therefore serve as a suitable model species for understanding past and future changes in forest wildlife. (2) We recorded the presence or absence of the species in 189 forest and forest-edge plots within the Kaluga Region using acoustic observations and pitfall trapping, and analysed the data using logistic regression. (3) Across the region, the main positive factor affecting species presence was the dominance of nemoral herbs in the herb layer. The main negative factors were habitat isolation caused by physical barriers and location within moraine plains formed during the late stage of the Moscow glaciation. The presence of coniferous tree species and spatial autocovariation were also significant factors, although their contributions were relatively small. The abundance of Ph. griseoaptera was higher in forests located within river valleys. Within Kaluga, the long-term persistence of tree vegetation and habitat isolation were the main significant factors affecting species occurrence. The smallest urban habitat occupied by the species covered approximately 13 ha, whereas the total area of unmown patches within this habitat was only about 0.2 ha. (4) Ph. griseoaptera may be used as an indicator of the long-term persistence of broadleaved deciduous (nemoral) forests. Under conditions of high urbanization, however, the species may become threatened.