Ecology and Management of Islands, Peninsulas and Structures for Nesting Waterfowl

Controlling Excessive Avian Predation of Duck Nests on Islands at the Canyon Ferry Wildlife Management Area

Tom L. Carlsen
Montana Department of Fish, Wildlife and Parks
P.O. Box 998
Townsend, MT 59644

Jeff Herbert
Montana Department of Fish, Wildlife and Parks
Helena, MT 59620

Robert L. Eng
Fish and Wildlife Program
Montana State University
Bozeman, MT 59715

Intensive duck nest surveys initiated in 1982 on newly created islands on the Canyon Ferry Wildlife Management Area indicated a pioneering population with initial high nest success. Subsequent annual surveys showed expanding population with decreasing nest success. Avian nest predation was the major contributing factor in this decline with 40% of located nests being so destroyed in 1985. In 1986, a 5-year control program using the avicide DRC-1339 was initiated. Avian predation has decreased annually with only 9% of nests located being lost to this cause in 1988. Duck nesting success has improved from a low of 50% in 1985 to approximately 70% in 1988.

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