Northern Prairie Wildlife Research Center
Ecology and Management of Islands, Peninsulas and Structures for Nesting
Waterfowl Production on Nesting Islands in Mountain Meadows Reservoir, California
Virginia K. Getz
Jones & Stokes Associates, Inc.
1242 14th Avenue
Sacramento, California 95822
James R. Smith
Pacific Gas and Electric Company
3400 Crow Canyon Road
San Ramon, California 94583
In 1976 the California Department of Fish and Game constructed eleven nesting
islands along the northern shoreline of Mountain Meadows Reservoir in northern
California. We studied waterfowl nesting on these islands from March through July
1986 to determine waterfowl production and identify factors influencing productivity.
Nests were located and nesting chronology was followed until the fate of all located
nests and eggs were determined. Thirty-eight Canada goose (Branta canadensis
moffitti) nests were located. Only 5% hatched successfully; 82% were destroyed
by predation. Hatching success of eggs in successful nests was 40%. Forty-three
duck nests were located. Of these nests, 40% hatched successfully and 44% were
destroyed by predation. Hatching success of eggs in successful nests was 87%.
Predation losses were primarily due to canids. Predation losses were greatest
when reservoir elevations dropped, allowing canids to reach the islands. This
study indicates that a combination of distance between island and shore of approximately
60-150 m and water depths of 0.6-1.0 m are required to reduce canid predation
at Mountain Meadows Reservoir.
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