Diurnal Behavior and Habitat Preferences of Erebia aethiops, an Aberrant Lowland Species of a Mountain Butterfly Clade

Erebia aethiops is an aberrant lowland representative of a predominately arctic and alpine butterfly genus. We used behavioral records obtained during a mark-recapture study (MR) to extract information about its adult diurnal and within-season activity, and to compare its activity with previously studied mountain Erebia species. Similarly to them, maintenance activities (nectaring, basking) increased with season. Contrary to mountain relatives, E. aethiops nectars in morning hours and spends the hottest parts of the day in the shade. Therefore, high rather than low temperatures seem to be limiting E. aethiops activity. We also compared microhabitat preferences of sexes, finding that females preferred grassy patches, whereas males often entered scrub and sparse canopy forest. The study illustrates the utility of auxiliary MR data to analyze butterfly activity, and points to the necessity of finely structured habitat mosaics for E. aethiops, an open woodland species that retracted to abandoned grasslands and has become vulnerable in Central Europe.