HABITAT ASSOCIATIONS OF SYMPATRIC VIOLET-FEEDING FRITILLARIES (EUPTOIETA, SPEYERIA, BOLORIA) (LEPIDOPTERA, NYMPHALIDAE) IN TALLGRASS PRAIRIE

At 106 tallgrass prairies in the midwestern USA, 18,055 individuals of six fritillary species (Lepidoptera: Nymphalidae) were counted in 552 .9 hr and 987.1 km of transect survey effort from 14 June to 13 Septem ber during 1988-96. The relative abundance of Euptoieta claudia, Speye ria cybele, S. aphrodite, S. idalia, Boloria selene, and B. bellona wa s analyzed for significant patterns relative to five habitat factors. Topographic diversity (i.e., whether the site was uniform or contained both uplands and lowlands) produced the most significant effects. Pra irie patch size and vegetation type (wet, mesic, dry) also produced nu merous significant patterns. When management type was significant, bur ning alone or in combination with another management was associated wi th lower densities, non-management with intermediate or higher densiti es, haying and grazing with higher densities. Vegetative quality (i.e. , degree of floristic degradation) produced the fewest significant pat terns. Three of four testable fritillary species significantly and pos itively correlated in abundance with one or more species of Viola (Vio laceae) (violets). Most correlations were with particular violet speci es, not combined violet abundance, suggesting that the fritillaries se gmented violet resources (their larval food) by species and/or habitat . The two most abundant violet species, V. pedata and V. pedatifida, a nd violets in general, occurred in more sites than any of the fritilla ry species did. The species most restricted to tallgrass prairie, S. i dalia, was relatively denser in dry prairie vegetation in larger prair ie patches with topographic diversity and management by haying or graz ing.