Co-occurrence and Microhabitat Distribution of Six Nebria Species (Coleoptera: Carabidae) in an Alpine Glacier Retreat Zone in the Alps, Austria

Abstract

The ground beetle (Carabidae) assemblage in a glacier retreat zone in the Zillertal Alps, Austria, was investigated over the course of three summers. Twenty species belonging to 10 genera were collected using pitfall traps. This study focuses on aspects of the co-existence of six species of the genus Nebria, including the spatial and temporal distribution and activities of larval stages and adults. Additionally, temperature preferences and water loss at low humidity were determined for several species. Each of the Nebria species were most active, both as adults and larval stages, in different areas within the glacier retreat zone characterized by distinct geomorphological and ecological conditions. Microhabitat conditions and habitat stability appear to be factors in habitat choice. Two ecologically distinct groups were observed: (1) N. germari, N. hellwigi, N. castanea, and N. austriaca generally inhabit stable high-altitude habitats and are nocturnal and (2) the two riparian species (N. jockischi, N. rufescens) are also diurnally active. Furthermore, the latter two species preferred significantly higher temperatures and survived low humidity conditions longer than the other investigated species and showed flight ability, in contrast with the other four wingless species.