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Estimating Avian Consumption John Day Dam & The Dalles Dam 2009 - 2011

Estimating Avian Consumption John Day Dam & The Dalles Dam 2009 - 2011. NATHAN ZORICH – PRESENTING MICHAEL JONAS PATRICIA MADSON US Army Corps of Engineers Portland District Fisheries Field Unit. Conclusions 2011. Gull numbers were highly variable

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Estimating Avian Consumption John Day Dam & The Dalles Dam 2009 - 2011

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  1. Estimating Avian Consumption John Day Dam & The Dalles Dam 2009 - 2011 NATHAN ZORICH – PRESENTING MICHAEL JONAS PATRICIA MADSON US Army Corps of Engineers Portland District Fisheries Field Unit

  2. Conclusions 2011 • Gull numbers were highly variable • Foraging focused on spillway tailrace • JD’s Temp Spillway Weir outflow • JD’s boat hazing & avian lines worked • Consumption 76% less than 2009 • TDA spillway tailrace below bridge • Recommendations • Sustained boats hazing program • Maintain avian deterrent lines • Prevent nesting near dams

  3. The Problem • Reaching BiOp required smolt survival • 96% Spring • 93% Summer • Avian predation is apparent • Need to prioritize avian deterrent spending • Need for post deterrent evaluation • RPA’s 47, 48, and 68

  4. Methods: Data collection • Direct observation of zones • Dawn to Dark • Count birds by species • Count attacks then evaluate attacks (30 min + 30 min) • Count birds by species • Move to next zone

  5. John Day Dam 2009* *Daily mean gull count n = 99 One dot = one gull

  6. John Day Dam 2010* *Daily mean gull count n = 17 One dot = one gull

  7. The Dalles Dam 2010* *Daily mean gull count n = 34 One dot = one gull

  8. California gull predation

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