Differing habitat affinities of four Erebia species (Lepidoptera : Nymphalidae, Satyrinae) in the Hruby Jesenik Mts, Czech Republic

An experiment with yellow pan water traps was conducted in the Hruby Jeseni k Mts in 1997. A loglinear model was constructed to evaluate the pattern of trap capture distribution. The habitat, species, time interval and sex sig - nificantly affected the distribution. The four Erebia species in the stud y area differ in habitat preferences and phenology. E. epiphron catches pea ked at the highest elevations of the study area (above and/or around the ti mberline, where the habitat is arctic-alpine tundra); E. sudetica occurred mainly in avalanche slopes of a glacial cirque (around and/or below the tim ber-line). E. euryale was found in a wide range of habitats (forests to arc tic-alpine tundra), while E. ligea was confined to forest zones. Phenologic ally, E. epiphron had maximum population density before those of the other species. Capture sex ratios of the four species were male biased, possibly due to behavioural differences between sexes. Reasons for the niche differe ntiation, e.g. the possibility of past competition resulting into character displacement, are discussed.