Monday, August 6, 2007

PS 2-17: Effects of landscape changes on American Dipper (Cinclus mexicanus) feeding and breeding ecology

Mazeika S. P. Sullivan, Ryan D. Mann, and Kerri T. Vierling. University of Idaho

The aquatic songbird American Dipper (Cinclus mexicanus) occupies fast-flowing mountain streams and cold-water coastal streams. Dippers rely on aquatic macroinvertebrates and clear, unpolluted streams and have been shown to be excellent indicators of water quality. However, analysis is needed on the effects of landscape changes from logging, grazing, and other uses of mountain resources on dippers. To this end, we are investigating differences in dipper food sources, reproductive measures, and breeding population characteristics across a range of landuse types across Idaho. To date, we have collected data from over 80 dippers across 12 watersheds. Preliminary results from stable isotope analysis indicate that landuse type correlates with dipper dietary composition, and that terrestrial insects may compose a greater proportion of dipper prey than previously documented in certain landscapes. Landscape changes, particularly those that lead to a loss of forest cover and increased sedimentation, also appear to be directly related to the density of breeding populations and to various reproductive measures, including the number and weight of fledglings. 

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