Ecology of alpine carabid beetles ( Coleoptera , Carabidae ) in a Norwegian glacier foreland , with a special focus on claw wearing to indicate relative age

Nine species of carabid beetles (Coleoptera, Carabidae) were pitfall-trapped during two years in an alpine glacier foreland of southern Norway. A two-year (biennial) life cycle was documented for Nebria nivalis (Paykull, 1790), N. rufescens (Ström, 1768), and Patrobus septentrionis Dejean, 1828. This was based on the simultaneous hibernation of larvae and adults. In P. septentrionis, both larvae and adults showed a considerable activity beneath snow. A limited larval material of Amara alpina (Paykull, 1790) and A. quenseli (Schönherr, 1806) from the snow-free period indicated larval hibernation. A. quenseli was, however, not synchronized with respect to developmental stages, and its life cycle was difficult to interpret. Measurements of claw lengths in eight species showed a considerable wearing during adult life. The data indicated that some individuals might hibernate a second time and thus experience two egg-laying seasons. Wearing of mandible tooth was not suited as age indictor in Nebria nivalis and N. rufescens, since some individuals hatched with a small tooth. Supplied with literature data, a “niche profile” is presented for each species. The most important ecological factors that contributed to niche segregation were: preference for vegetation-free ground, occurrence along the successional and time gradient, humidity or temperature preference, nocturnal versus diurnal activity, flight ability, food habits, phenology, and the ability to be active under snow.