Species that are considered uncertain risk need a more in-depth assessment beyond the Risk Summary to better define the species’ risk to U.S. environments. This additional information will help inform decisions on where, when, and how the species may be used to minimize risks of them becoming invasive.
Mute Swan (Cygnus olor) is a species of swan native to Europe, Russia, and parts of the Middle East. C. olor has been used commercially for sport hunting, specimen collecting, food, pets, display animals, and horticulture. The history of invasiveness is high. The species was inadvertently and purposefully introduced, and then spread on its own into various portions of South Africa, New Zealand, Asia, and North America. C. olor competes for food with native and migrating waterfowl resulting in the elimination of individual plant species and decline in wetland plant diversity. C. olor also directly competes with native waterfowl for breeding and over wintering habitat by driving them away from desired wetlands and have even been known to kill adult and juvenile ducks and geese. C. olor has been documented as a cause of or implicated in significant declines in native species in Europe and potentially in North America. The climate match is high. All states had a high individual climate scores. The certainty of this assessment is high. The overall risk assessment category is high.
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Uncertain Risk
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