Distribution and Habitat Preferences of a Frosted Elfin Subspecies (Callophrys irus hadros, Lycaenidae) in Arkansas

Abstract

The frosted elfin (Callophrys irus) contains a disjunct subspecies (C. i. hadros) found in Texas, Arkansas, Oklahoma, and Louisiana that is being considered for listing under the Endangered Species Act as part of the C. irus complex. We assessed the distribution and habitat preferences of this subspecies in Arkansas. From 2018-2020, we surveyed sites of historical records and other suspected habitat for the butterfly and measured habitat variables that could predict occupancy. We detected C. i. hadros at 45 sites out of 208 sites with Baptisia host plants. Host plant number, density, and patch area were significant predictors of butterfly presence. A targeted analysis of one large population found habitat differences between occupied sites and randomly selected sites within the habitat (MANOVA, F7,46 = 2.47, p = 0.031). Individual contrasts showed that Baptisia percent cover (p = 0.008) and Baptisia abundance (p = 0.016) were higher at occupied sites compared to random sites, while shrub percent cover was lower at occupied sites (p = 0.044). Our results indicate that habitat requirements for this species are somewhat flexible, provided larval host plant species are present at a reasonably large site. Callophrys irus hadros appears widespread but local in the southern and western portions of Arkansas, with many more populations than previously known. However, the majority of detections occurred on public and private rights-of-way, such as utility lines and roadsides. Thus, conservation plans for the frosted elfin may benefit from incorporating habitats currently managed for anthropogenic, rather than conservation, purposes.