Butterflies (Papilionoidea and Hesperioidea) as potential ecological indicators of riparian quality in the semi-arid western United States

Ecological indicators can be used to detect, diagnose, and summarize information about environmental problems. Despite these important values, few indicators have been systematically validated. Broad information on relevance, feasibility, estimates of variance, and interpretation of the ecological indicator is needed for initial validation. Comparisons of ecological indicators can only be accomplished if they are contrasted with standard published criteria. In this paper, information on the potential use of butterflies as indicators of riparian quality is provided within a standard framework. Additionally, data from riparian areas along the Arkansas, Green, Pecos, Rio Grande, and Yampa rivers were collected to validate some specific criterion, such as ease of measurement and information on response to stressors. Information on sampling protocols and a butterfly metric, the Riparian Butterfly Index, is presented along with time needed to characterize butterfly sites. Sensitivity of butterfly assemblages to riparian environmental characteristics was examined using ordination of butterfly data and environmental variables. Characteristic assemblages were associated with high quality versus low quality riparian habitats. Response specificity to habitat and weather was tested with sites on the Arkansas river, which were repeatedly sampled over a 3-year period. An index of abundance varied between years and appeared to be related to weather; however, richness metrics for a given habitat type were consistent between years. Butterflies as ecological indicators were easily measured, integrated floodplain characteristics, and had low variability in response.