Current distribution, microhabitat requirements and vulnerability of the Keeled Plump Bush-cricket (Isophya costata) at the north-western periphery of its range

Abstract

Edge populations are of conservation importance because they typically suffer an elevated risk of extinction, possess low genetic variation and can be genetically distinct from core populations. Peripheral populations are generally characterized as being less abundant and more vulnerable to habitat change. In this study, we investigated the current distribution and microhabitat requirements of the Keeled Plump Bush-cricket (Isophya costata), a threatened species, at the north-western periphery of its range (Austrian-Slovak trans-border area, Central Europe). To clarify the current distribution pattern in relation to microhabitat requirements, we employed a comprehensive combination of microhabitat assessment and microrelief topography in a flood-plain area, which was supplemented by photo documentation created using a drone. We found that the distribution of the bush-cricket follows isolated occurrences with low densities. Regarding microhabitat requirements, we discovered a link between the distribution pattern of the bush-cricket and micro-elevations connected to dicotyledonous broadleaf plants. We assume that the novel information on species ecology found in this study could be a first step in obtaining sufficient data for further systematic monitoring. To set these findings for species conservation, it is necessary to mitigate the most serious threats, which are represented by early mowing and habitat degradation. Therefore, further detailed analysis of major threats and determination of the genetic structure of the species will be crucial to ensure appropriate conservation measures for the threatened peripheral bush-cricket metapopulation. This research provides the novel information about microhabitat requirements of the threatened bush-cricket at the north-western edge of its range. Current distribution data together with detailed knowledge of the microhabitat requirements provide important ecological information, which could have significant implications for the further systematic monitoring and species conservation.