THE AMERICAN DIPPER (CINCLUS MEXICANUS) AS A BIOLOGICAL INDICATOR OF WATER QUALITY

J. M. Feck and R. O. Hall. Department of Zoology and Physiology, University of Wyoming, Laramie, Wyoming, 82071.

Avian species are not used as indicators of water quality, yet as a bioassessment tool they may prove more efficient and cost effective than benthic macroinvertebrates and periphyton. Dippers, Cinclus spp., are conspicuous, non-migratory, ubiquitous, stream obligates found worldwide. We hypothesized the presence of dippers may indicate reduced levels of sedimentation and therefore the water quality of streams. We analyzed 17 nesting pairs of dippers on six streams with a range of stream condition (sedimentation) in the Wind River mountains, Wyoming. We caught and color banded dippers. We measured dipper body condition (weight/wing length³), territory size, reproductive success, and bioassessment protocols established by the Wyoming Department of Environmental Quality for water chemistry and geomorphology of streams. Data show a significant relationship between dipper territory size and stream condition (t₁₅ = -2.140; p = 0.049), a non-significant relationship between dipper territory size and body condition. Dipper body condition was negatively correlated with total suspended solids, temperature and entrenchment ratio, and positively correlated with conductivity (R²(adj) = 51.4%). If dippers prove to be good indicator species, they may greatly facilitate bioassessment of streams.