Mobility and microhabitat utilization in a flightless wetland grasshopper, Chorthippus montanus (Charpentier, 1825)

Abstract

Wetlands are among the most threatened habitat types on our planet. Their decline will probably even intensify under climate change. Many biota are strongly dependent on wetlands, including a large number of invertebrate species. The populations of such hygrophilous species become increasingly disconnected due to the ongoing fragmentation of their habitats. This is particularly true for species with reduced dispersal capacities, such as flightless insects. We studied mobility, population size and microhabitat utilization in a population of an endangered grasshopper species, the Water-meadow Grasshopper, Chorthippus montanus. Our mark-recapture study revealed that the cumulative movement distance of the adults was on average 23.5 m with a maximum of 104 m. The microhabitat analysis showed that both sexes of C. montanus preferred warmer patches with greater radiation than measured at control sites. Niche overlap among sexes was stronger than expected by chance, while niche overlap between insects and controls showed the opposite pattern. Our results suggest that C. montanus is strongly restricted to its habitat and is probably not able to cross larger distances through unsuitable vegetation. Hence, we assume that the populations of this flightless insect species are strongly isolated. However, the effect of the rare macropterous morph of C. montanus on gene flow remains unknown. Wetland restoration is crucial to reconnect the existing wetland patches in Central Europe and thereby reduce the negative effects of habitat fragmentation on wetland species.