BENNETT, V.A.; STEED, J.N.*; LEE, R.E.; KUKAL, O.: A description of Gynaephora groenlandica hibernacula sites and behavioral preferences for light, temperature, and soil moisture related to microhabitat selection

G. groenlandica caterpillars overwinter in hibernacula anchored at the base of rocks on the Arctic tundra. At each of two study sites on Ellesmere Island, hibernacula were consistently found on the same aspect of the rocks, possibly related to prevailing winds and/or patterns of snow accumulation. Hibernacula temperatures were slightly warmer and more buffered than ambient temperatures. How do caterpillars select suitable microhabitats for hibernacula? Laboratory experiments tested for behavioral preferences based on light, temperature, and soil moisture conditions. Both active caterpillars and those entering hibernation showed strong preference for light over dark conditions. Along a 0-25°C temperature gradient, most caterpillars settled at the warmest region (21-25°C), indicating that they may select hibernacula sites based on thermal cues. However they do not appear to select colder microhabitats, as we had hypothesized, as a means of metabolic depression for energy conservation in late sumer and fall. Active caterpillars showed no preference based on soil moisture, however most caterpillars entering hibernation preferred low soil moisture (0-10%), which may be indicative of microhabitats where snow melts earliest in Spring.