Midwest Fish & Wildlife Conference 2017

AUTHORS: Andrew J. Caven, Kelsey C. King, Joshua D. Wiese, and Emma M. Brinley Buckley

ABSTRACT:  Speyeria idalia populations have declined as much as 95 percent over the last 3decades. Here we critically evaluate prairie habitat components along the Platte Riverin central Nebraska that S. idalia populations require in an effort to better instructconservation efforts. We utilized S. idalia count data from long-term monitoringtransects where vegetation, soils, land management, and flooding frequency data arealso collected to describe the habitat constituents associated with S. idalia presence.We utilize comparative statistics, Pearson's correlation analysis, and Random ForestAnalysis to model S. idalia habitat on land owned and managed by a smallconservation NGO. Our findings suggest that S. idalia occupies specific habitat nicheswith a preference for well-drained soils (Inavale series) dominated by facultative uplandplants, most prominently Andropogon gerardii. S. idalia is positively associated withlarge connected tracts of relict prairie containing Viola sororia and very moderatemanagement regimes that remove shrubby cover (negatively associated) and promoteforb cover (positively associated), while providing ample recovery time on burned andgrazed patches for litter development (positively associated). Random Forest Analysisdescribes the presence of Viola sororia, percent forb cover, and habitat connectivity asthe top 3 habitat variables of importance in predicting the presence of S. idalia. Ourfinding that habitat connectivity is a major predictor of S. idalia presence suggestsmany populations may be both spatially and genetically isolated. S. idalia's futuredemands the preservation of tallgrass prairie fragments under management regimesthat promote healthy populations.