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Environmental and human influences on trumpeter swan habitat occupancy in Alaska

TitleEnvironmental and human influences on trumpeter swan habitat occupancy in Alaska
Publication TypeJournal Article
Year of Publication2009
AuthorsSchmidt, JH, Lindberg, MS, Johnson, DS, Schmutz, JA
JournalThe Condor

Approximately 70–80% of the entire population of the Trumpeter Swan (Cygnus buccinator)depends for reproduction on wetlands in Alaska. This makes the identification of important habitat features andthe effects of human interactions important for the species’ long-term management. We analyzed the swan’s habitatpreferences in five areas throughout the state and found that swan broods occupied some wetland types, especiallylarger closed-basin wetlands such as lakes and ponds, at rates much higher than they occupied other wetlandtypes, such as shrubby or forested wetlands. We also found a negative effect of transportation infrastructure on occupancyby broods in and around the Minto Flats State Game Refuge, Kenai National Wildlife Refuge, and TetlinNational Wildlife Refuge. This finding is of particular interest because much of the Minto Flats refuge has recentlybeen licensed for oil and gas exploration and parts of the Kenai refuge have been developed in the past. We also investigatedthe potential effects of the shrinkage of closed-basin ponds on habitat occupancy by nesting TrumpeterSwans. We compared nesting swans’ use of ponds with changes in the ponds’ size and other characteristics from1982 to 1996 and found no relationships between occupancy and changes in pond size. However, we believe thatthe recent and rapid growth of Trumpeter Swan populations in Alaska may become limited by available breedinghabitat, and anthropogenic and climate-induced changes to the swan’s breeding habitats have the potential to limitfuture production.

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