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

Canada Goose Nesting on Artificial Islands Versus Natural Sites at Malheur National Wildlife Refuge

Gary L. Ivey, Larry R. Ditto, and Richard R. Sjostrom
Malheur National Wildlife Refuge
HC-72, Box 245
Princeton, Oregon 97721


Artificial islands were constructed in managed ponds at Malheur National Wildlife Refuge, Oregon, from 1973 through 1977 to enhance Canada Goose (Branta canadensis moffitti) nesting. A study was initiated in 1975 to evaluate these islands as goose nesting habitat. Artificial islands were highly attractive to nesting geese. Predation was the major factor limiting nest success on both artificial and natural marsh nesting sites. Nest predation rates were higher (72%) on islands than on natural sites (56%) when predators were not controlled (1974-1985). Common Ravens (Corvus corax) were the major nest predator on islands, followed by raccoons (Procyon lotor) and coyotes (Canis latrans). An experimental predator control program was conducted in 1986 through 1988. Nest predation rates were significantly lower than during the previous period of non-predator control, and there was no significant difference in predation rates between artificial islands and natural sites. Nests on islands with little cover suffered higher predation rates than those on islands with good cover. Islands with low profiles (less than one meter tall) supported the best cover.

Wildlife managers should evaluate potential for predation problems before construction of artificial islands. Low profile islands of non-alkaline soils will support good cover needed to reduce nest predation rates; however, selective predator control may be necessary to maintain high goose production on artificial islands.


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