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Effects of rotenone on nesting Ospreys (Pandion haliaetus) at Hyatt and Howard Prairie Reservoirs, OR, 1988-1992

December 30, 2021

To assess the effects of rotenone (fish toxicant) treatment and possible fish removal effects on nesting Osprey (Pandion haliaetus) populations, nests were observed at two reservoirs east of Ashland, Oregon. Hyatt Reservoir was treated with rotenone on October 12, 1989. Howard Prairie was observed as an untreated reference area. Nests at both reservoirs were observed two years pre-treatment (1988, 1989) and two years post-treatment (1990, 1992). The dataset contains Osprey reproductive parameters, foraging parameters, prey delivery rates and bald eagle piracy rates at eight intensively observed nests. Fish stocking records and creel data were obtained from the Oregon Department of Fish & Wildlife for both reservoirs for the study period.