Microhabitat selection and seasonality of alpine invertebrates

Microhabitat selection is important for invertebrates in both summer and winter, but has not been investigated extensively in alpine terrestrial communities. We investigated the factors affecting microhabitat selection by alpine invertebrates in a system of rock slab pavement on the Rock and Pillar Range, Central Otago, New Zealand. We found fewer individuals of most groups under the 379 rocks re-examined during the winter. Logistic regression was used to model the presence of the cockroach Celatoblatta. quinquemaculata (Dictyoptera: Blattidae); the alpine weta Hemideina maori (Orthoptera: Anostostomatidae); and the spider Neoramia childi (Aranea: Agelenidae). We found that rock refuge size and season were extremely important in determining presence of all of these species, and that both abiotic and biotic aspects of rock microhabitat were necessary to describe occupancy. We also found clear evidence of biological interactions between the three species modelled. The marked decrease in under-rock occupancy by C. quinquemaculata in the winter is hypothesised to be a result of selection of alternative (non-rock) microhabitats.