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Kansas Cooperative Fish and Wildlife Research Unit

Nervalis Medina-Echevarria (2012)

Nervalis Medina-Echevarria (2012)- Adult Regal Fritillary (Speyeria idalia) density among fire and grazing regimes at Konza Prairie with notes on the occurrence patterns of its host plant, Prairie Violet (Viola pedatifida). (Mentors: Gene Albanese, and David Haukos)

The Regal Fritillary (Speyeria idalia) is a North American butterfly of remnant native prairie maintained by disturbance. The range of this species once extended from the border of Canada south to Oklahoma and east to the Atlantic coast. However, populations have declined dramatically (? 99 %) across most of its former range. The causes for decline remain largely undetermined but habitat loss is generally suspected. We surveyed areas managed with different grazing and fire regimes within the Konza Prairie Biological Station (KPBS) in northeastern Kansas, USA for adult Regal Fritillaries. Among the areas surveyed, fire regimes included 20 year (low), 3-5 year (moderate) and 1 year (high) fire return intervals and grazing regimes of cattle, Bison (Bison bison), and ungrazed. Additionally, we surveyed these areas for the Regal Fritillary's sole known host plant, Prairie Violet (Viola pedatifida), to develop a map of potential host plant occurrence throughout the KPBS. We used a factorial ANOVA to examine the response of adult Regal Fritillary density to different fire and grazing treatments. The density of adult Regal Fritillary differed significantly among grazing (P = 0.007) and fire (P = 0.003) treatments. Adult Regal Fritillary density was greatest in areas grazed by cattle and bison and lowest in areas that were ungrazed. Among fire treatments, adult Regal Fritillary density was greatest in areas with a moderate fire return interval. We used a recursive partitioning algorithm with five topological surface and land cover variables to model host plant locations that were identified during surveys. This model correctly classified 88% of 227 host plant locations. Open land cover, aspect and hill shade were the most important variables to predict host plant occurrence patterns (partial deviance = 49 %, 23 % and 14%, respectively). Our results suggest that grazing and a moderate fire return interval have a positive effect on adult Regal Fritillary density. Conservation and management for Regal Fritillary within KPBS should aim to provide grazed areas with a moderate fire return interval.