Northern Prairie Wildlife Research Center
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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Geese
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U.S. Department of the Interior |
U.S. Geological Survey