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Using a Distance Sampling Approach to Monitor Population Trends of Imperiled Butterflies


Kelsey McCullough, Fish & Wildlife Biologist, US Army Garrison Fort Riley:


The Fort Riley Military Reservation is a 41,188 ha active, Tier 1 training installation situated in the northern portion of the Flint Hills ecoregion located in northeastern Kansas, USA. The gentle-rolling hills and largely open topography associated with the native tallgrass prairie of the Flint Hills ecoregion lends itself to not only force-on-force maneuver training but is also home to a wide array of prairie-obligate flora and fauna. Unfortunately, due to severe losses and continued contraction of North American grasslands many of these species have also suffered drastic population declines. The regal fritillary (Argynnis idalia) and monarch (Danaus plexippus) butterflies were once common sights in North American grassland communities but populations of both species have declined ~99%. Currently, the monarch is a candidate for listing under the endangered species act (ESA) and the regal fritillary is under review to be listed under the ESA. To monitor population trends of these butterfly species on the FRMR we implemented an integrated, multi-species assessment plan to include transects randomly distributed throughout the installation. We used a distance sampling approach to produce density estimates of both butterfly species on the FRMR. We discuss survey design, implementation, logistics, analyses, results, problems, and future developments.

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